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16. Reproduction Flashcards

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1
Q

What does asexual reproduction NOT require?

A

Asexual reproduction does not involve sex cells or fertilisation

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2
Q

What does asexual reproduction require?

A

Only one parent is required

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3
Q

Due to only one parent being required, what is different from sexual reproduction?

A

there is no fusion of gametes and no mixing of genetic information

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4
Q

What is a similarity between the parent and the offspring in asexual reproduction?

A

As a result, the offspring are genetically identical to the parent and to each other (clones)

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5
Q

Asexual reproduction defintion

A

Asexual reproduction is defined as a process resulting in genetically identical offspring from one parent

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6
Q

How do bacteria reproduce?

A

Bacteria produce exact genetic copies of themselves in a type of asexual reproduction called binary fission:

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7
Q

How can plants reproduce asexually?

A

Plants can reproduce asexually using bulbs and tubers

  • by using runners
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8
Q

What are bulbs and tubers?

A

these are food storage organs from which budding can occur, producing new plants which are genetically identical to the parent plant

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9
Q

What are runners?

A

Some plants grow side shoots called runners that contain tiny plantlets on them (a good example of this are strawberry plants. These will grow roots and develop into separate plants, again being genetically identical to the parent plant

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10
Q

What are 4 advantages of asexual reproduction?

A

population can be increased rapidly when conditions are right
can exploit suitable environments quickly
more time and energy efficient
reproduction completed much faster than sexual reproduction

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11
Q

What are 3 disadvantages of asexual reproduction?

A

limited genetic variation in population - offspring are genetically identical to their parents
population is vulnerable to changes in conditions and may only be suited for one habitat
disease is likely to affect the whole population as there is no genetic variation

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12
Q

When (in what organism) is asexual reproduction particularly advantageous and why?

A

Specifically in crop plants, asexual reproduction can be advantageous as it means that a plant that has good characteristics (high yield, disease-resistant, hardy) can be made to reproduce asexually and the entire crop will show the same characteristics

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13
Q

sexual reproduction definition

A

Sexual reproduction is a process involving the fusion of the nuclei of two gametes (sex cells) to form a zygote (fertilised egg cell) and the production of offspring that are genetically different from each other

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14
Q

Fertilisation definition

A

Fertilisation is defined as the fusion of gamete nuclei, and as each gamete comes from a different parent, there is variation in the offspring

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15
Q

What is a gamete?

A

A gamete is a sex cell

in animals: sperm and ovum; in plants pollen nucleus and ovum

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16
Q

How do gametes differ from normal cells? What is this called?

A

Gametes differ from normal cells as they contain half the number of chromosomes found in other body cells – we say they have a haploid nucleus

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16
Q

How do gametes only have half the number of chromosomes found in the body?

A

This is because they only contain one copy of each chromosome, rather than the two copies found in other body cells

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17
Q

How many chromosomes does a normal cell have compared to a gamete?

A

In human beings, a normal body cell contains 46 chromosomes but each gamete contains 23 chromosomes

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18
Q

What is a zygote?

A

When the male and female gametes fuse, they become a zygote (fertilised egg cell)

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19
Q

How many chromosomes does a zygote have and what is this called?

A

This contains the full 46 chromosomes, half of which came from the father and half from the mother – we say the zygote has a diploid nucleus

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20
Q

What are 3 advantages of sexual reproduction?

A

increases genetic variation
the species can adapt to new environments due to variation, giving them a survival advantage
disease is less likely to affect population (due to variation)

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21
Q

What are 2 disadvantages of sexual reproduction?

A

takes time and energy to find mates
- difficult for isolates members of the species to reproduce

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22
Q

In what way do most crop plants reproduce and how is this beneficial?

A

Most crop plants reproduce sexually and this is an advantage as it means variation is increased and a genetic variant may be produced which is better able to cope with weather changes, or produces significantly higher yield

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23
Q

What may be a disadvantage as a result of crop plants reproducing sexually?

A

The disadvantage is that the variation may lead to offspring that are less successful than the parent plant at growing well or producing a good harvest

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24
Q

What are the reproductive organ of the plant?

A

flowers

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25
Q

What do flowers contain?

A

They usually contain both male and female reproductive parts

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26
Q

What do plants produce which acts as the male gamete?

A

Plants produce pollen which contains a nucleus inside that is the male gamete

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27
Q

What is a difference between pollen and sperm?

A

Unlike the male gamete in humans (sperm), pollen is not capable of locomotion (moving from one place to another)

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28
Q

What is pollination?

A

plants have to have mechanisms in place to transfer pollen from the anther to the stigma
This process is known as pollination

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29
Q

In what two ways can pollination occur?

A

here are two main mechanisms by which it occurs: transferred by insects (or other animals like birds) or transferred by wind

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30
Q

Does the structure of insect and wind=pollinated flowers differ?

A

YES
The structure of insect and wind-pollinated flowers are slightly different as each is adapted for their specific function

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31
Q

Sepal definition

A

protects unopened flower

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32
Q

petals definition

A

brightly coloured in insect-pollinated flowers to attract insects

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33
Q

anther definition

A

produces and releases the male sex cell (pollen grain)

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34
Q

stigma definition

A

top of the female part of the flower which collects pollen grains

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35
Q

ovary definition

A

produces the female sex cell (ovum)

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36
Q

ovule definition

A

contains the female sex cells (found inside the ovary)

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37
Q

How do the petals differ in an insect vs wind pollinated flower?

A

🦟 - large and brightly coloured to attract insects

🌬 - small and dull, often green or brown in colour

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38
Q

How does the scent and nectar differ in an insect vs wind pollinated flower?

A

🦟- present - entices insect to visit the flower and push past stamen to get to nectar
🌬 - absent - no need to waste energy producing these as no need to attract insects

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39
Q

How does the number of pollen grains differ in an insect vs wind pollinated flower?

A

🦟 - moderate - insects transfer pollen grains efficiently with a high chance of successful pollination
🌬 - large amounts - most pollen grains are not transferred to another flower so the more produced, the better the chance of some successful pollination occurring

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40
Q

How do the pollen grains differ in an insect vs wind pollinated flower?

A

🦟 - larger, sticky and / or spiky to attach to insects and be carried away
🌬 - smooth, small and light so they are easily blown by the wind

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41
Q

How do the anthers differ in an insect vs wind pollinated flower?

A

🦟 - inside flower, stiff and firmly attached to brush against insects
🌬 - outside flower, swinging loose on long filaments to release pollen grains easily

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42
Q

How does the stigma differ in an insect vs wind pollinated flower?

A

🦟 - inside flower, sticky so pollen grains stick to it when an insect brushes past
🌬 - outside flower, feathery t catch drifting pollen grains

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43
Q

When does cross-pollination occur?

A

Cross-pollination occurs when the pollen from one plant is transferred to the stigma of another plant of the same species

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44
Q

Why do most plant carry out cross-pollination?

A

This is the way most plants carry out pollination as it improves genetic variation

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45
Q

What is self-pollination?

A

Occasionally, the pollen from a flower can land on its own stigma or on the stigma of another flower on the same plant – this is known as self-pollination

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46
Q

What is a disadvantage of self-pollination?

A

Self-pollination reduces genetic variety of the offspring as all the gametes come from the same parent (and are therefore genetically identical)

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47
Q

Why is a lack of variation in offspring a disadvantage?

A

Lack of variation in the offspring is a disadvantage if environmental conditions change, as it is less likely that any offspring will have adaptations that suit the new conditions well

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48
Q

What is a disadvantage of cross-pollination?

A

On the other hand, cross-pollination relies completely on the presence of pollinators and this can be a problem if those pollinators are missing (eg the reduction in bee numbers is of great importance to humans as bees pollinate a large number of food crops) – this doesn’t apply to wind-pollinated plants

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49
Q

When does fertilisation occur?

A

Fertilisation occurs when a pollen nucleus fuses with an ovum nucleus in the ovule

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50
Q

How does the pollen travel to the ovary, if it can’t move?

A

As the pollen has no ‘tail’ to swim to the ovary of a plant, in order to reach the ‘female’ nucleus in the ovary it has to grow a pollen tube

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51
Q

What condition is necessary for the pollen to grow a pollen tube?

A

This only happens if the pollen grain has landed on the right kind of stigma (i.e. of the same species as the flower the pollen came from)

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52
Q

What happens once the pollen has grown a pollen tube?

A

The nucleus inside the pollen grain slips down the tube as it grows down the style towards the ovary

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53
Q

What does the ovary contain?

A

The ovary contains one or more ovules which each contain an ovum with a female nucleus that a male pollen nucleus can fuse with

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54
Q

What happens once the nucleus has travelled down the pollen tube?

A

the nuclei (pl) have joined together, that ovule has been fertilised and a zygote has been formed

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55
Q

What happens to the zygote in the ovary? (plants)

A

The zygote will start to divide and eventually form a seed within the ovule

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56
Q

Why do different fruits have different numbers of seeds?

A

As different plants have different numbers of ovules, this explains why different fruits (which develop from the ovary) have different numbers of seeds (which develop from the ovules)

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57
Q

What is germination?

A

Germination is the start of growth in the seed

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58
Q

What three factors are required for successful germination?

A

water
oxygen
warmth

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59
Q

Why is water needed for germination?

A

allows the seed to swell up and the enzymes in the embryo to start working so that growth can occur

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60
Q

Why is oxygen needed for germination?

A

so that energy can be released for germination

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61
Q

Why is warmth needed for germination?

A

germination improves as temperature rises (up to a maximum) as the reactions which take place are controlled by enzymes

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62
Q

What factor does not make a difference for germination?

A

As carbon dioxide is not necessary for germination but also does not inhibit it, it makes no difference whether it is present or not

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63
Q

How could you set up an experiment to investigate germination?

A

Set up 4 boiling tubes each containing 10 cress seeds on cotton wool
Set each test tube as shown in diagram below
Leave tubes in set environment for a period of time: A, B and C incubated at 20°C; D placed in a fridge at 4°C
Compare results and see which tube has the greatest number of germinated seeds

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64
Q

Will a seed germinate if it has 1 factor present e.g oxygen but not any others?

A

NO - needs all 3 factors

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65
Q

Prostate Gland definition

A

produces fluid called semen that provides sperm cells with nutrients

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66
Q

Sperm Duct definition

A

Sperm passes through the sperm duct to be mixed with fluids produced by the glands before being passed into the urethra for ejaculation. Muscular tube that connects testis to urethra.

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67
Q

Urethra definition

A

Tube running down the centre of the penis that can carry out urine or semen. A ring of muscle in the urethra prevents the urine and semen from mixing

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68
Q

Testis definition

A

Contained in a bag of skin (scrotum) and produces sperm (male gamete) and testosterone

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69
Q

Scrotum definition

A

Sac supporting the testes outside the body to ensure sperm are kept at temperature slightly lower than body temperature

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70
Q

Penis definition

A

Passes urine out of the body from the bladder and allows semen to pass into the vagina of a woman during sexual intercourse

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71
Q

Oviduct definition

A

Connects the ovary to the uterus and is lined with ciliated cells to push the released ovum down it. Fertilisation occurs here

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72
Q

Ovary definition

A

Contains follicles in which ova (female gametes) are produced which will mature and develop when hormones are released

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73
Q

Uterus definition

A

Muscular bad with a soft lining where the fertilised egg (zygote) will be implanted to develop into a foetus

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74
Q

Vagina definition

A

Muscular tube that leads to the inside of the woman’s body, where the male’s penis will enter during sexual intercourse and sperm are deposited

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75
Q

Fertilisation definition

A

The fusion of the nuclei from a male gamete (sperm cell) and a female gamete (egg cell)

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76
Q

Why do gametes have adaptations?

A

They have adaptations to increase the chances of fertilisation and successful development of an embryo

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77
Q

What 3 adaptations does a sperm have?

A

has a flagellum (tail)
contains enzymes in the head region (acrosome)
contains many mitochondria

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78
Q

How does a sperm having a tail help it in its function?

A

Enables it to swim to the egg

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79
Q

How does a sperm having enzymes in the head region help it in its function?

A

To digest through the jelly coat and cell membrane of an egg cell when it meets one

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80
Q

How does a sperm containing many mitochondria help it in its function?

A

Provide energy from respiration so that the flagellum can move back and forth for locomotion

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81
Q

What 2 adaptations does an egg cell have?

A

cytoplasm containing store of energy
- jelly like coating that changes after fertilisation

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82
Q

How does an egg cell having cytoplasm containing a store of energy help it in its function?

A

provides energy for the dividing zygote after fertilisation

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83
Q

How does an egg cell having a jelly like coating help it in its function?

A

forms an impenetrable barrier after fertilisation to prevent other sperm nuclei entering the egg cell

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84
Q

Comparison of male and female gametes in terms of size

A

SPERM: very small (45nm)
EGG: large (0.2mm)

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85
Q

Comparison of male and female gametes in terms of structure

A

SPERM: Head region and flagellum, many structural adaptations
EGG: Round cell with few structural adaptations, covered in a jelly coating

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86
Q

Comparison of male and female gametes in terms of mobility

A

SPERM: Capable of locomotion
EGG: not capable of locomotion

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87
Q

Comparison of male and female gametes in terms of numbers

A

SPERM: produced every day in huge numbers (around 100 million per day)
EGG: thousands of immature eggs in each ovary, but only released each month

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88
Q

What is a zygote?

A

A fertilised egg cell (when nuclei of sperm and egg combine)

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89
Q

Where does the zygote travel after fertilisation?

How long does this take?

A

Towards the uterus

3 days

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90
Q

Where does the zygote travel after fertilisation?

How long does this take?

A

Towards the uterus

3 days

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91
Q

How does a zygote turn into an embryo?

A

It divides several times to form a ball of cells known as an embryo

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92
Q

What is implantation?

A

When the embryo embeds itself in the thick lining of the uterus and continues to grow and develop

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93
Q

How long is the gestation period for humans?

A

9 months

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94
Q

What happens in the first 12 weeks? (development of a baby)

A

the major development of organs

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94
Q

What happens in the first 12 weeks? (development of a baby)

A

the major development of organs

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95
Q

How does the embryo get its nutrients

A

the embryo gets nutrients from the mother by diffusion through the uterus lining

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96
Q

3 things which are completed by 12 weeks (development of a baby)

A

After this point the organs are all in place, the placenta has formed and the embryo is now called a fetus

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97
Q

After 12 weeks, what happens during the rest of the gestation period?

A

The remaining gestation time is used by the fetus to grow bigger in size

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98
Q

What is the fetus surrounded by and what does this contain?

A

The fetus is surrounded by an amniotic sac which contains amniotic fluid

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99
Q

What is the amniotic fluid made from?

A

the mother’s blood plasma

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100
Q

What is the role of the umbilical cord?

A

The umbilical cord joins the fetus’s blood supply to the placenta for exchange of nutrients and removal of waste products

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101
Q

What nutrients does the fetus need while developing?

Where do these nutrients come from?

A

glucose, amino acids, fats, water and oxygen

from the mother’s blood

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102
Q

Does the blood supply of the fetus and mother mix?

A

NO

The bloods run opposite each other, never mixing

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103
Q

Where does the blood supply of the mother and fetus “meet”?

A

in the placenta

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104
Q

How is the fetus connected to the placenta?

A

By the umbilical cord

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105
Q

Apart from nutrients, what does the mother’s blood supply contain?

A

The mother’s blood also absorbs the waste products from the fetus’s blood in the placenta

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106
Q

What sort of waste products may the fetus produce?

A

carbon dioxide and urea

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107
Q

Why do waste products need to be removed from the fetus’ bloodstream?

A

so that they do not build up to dangerous levels

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108
Q

By what process do these nutrients/waste products move from fetus to mother?
Why?

A

Movement of all molecules across the placenta occurs by diffusion due to difference in concentration gradients

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109
Q

How is the placenta adapted for efficient diffusion?

A

The placenta is adapted for this diffusion by having a large surface area and a thin wall for efficient diffusion

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110
Q

What does the placenta act us?

A

The placenta acts as a barrier to prevent toxins and pathogens getting into the fetus’s blood

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111
Q

What sorts of things might the placenta not be able to prevent from passing through it?
What does it depend on?

A

Not all toxin molecules or pathogenic organisms (such as viruses, eg rubella) are stopped from passing through the placenta (this usually depends on the size of the molecule)

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112
Q

What are pregnant women advised not to do during pregnancy?

A

Smoke, drink alcohol, do drugs

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113
Q

What happens immediately after the baby is born?

A

The umbilical cord is cut and tied off to prevent bleeding. Shrives up and falls off after a few days leaving the belly button

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114
Q

What happens to the placenta after the baby has been born?

A

The placenta detaches from the uterus wall shortly after birth and is pushed out due to contractions in the muscular wall of the uterus – known as the afterbirth

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115
Q

What are the six (simple) stages of birth?

A

Amniotic sac breaks
Muscles in the uterus wall contract
Cervix dilates (gets wider)
Baby passes out through the vagina
Umbilical cord is tied and cut
Afterbirth is delivered

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116
Q

What are the six (simple) stages of birth?

A

Amniotic sac breaks
Muscles in the uterus wall contract
Cervix dilates (gets wider)
Baby passes out through the vagina
Umbilical cord is tied and cut
Afterbirth is delivered

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117
Q

What is antenatal care?

A

Antenatal (before birth), care is the name given to the care and advice given to expectant mothers along with checks on fetal growth and development

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118
Q

What 3 pieces of advice are expectant mothers given?

A

having a balanced diet
exercise to stay fit
health precautions such as avoiding infections, tobacco, alcohol and other drugs

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119
Q

What does a woman need to take to have a fully healthy diet while pregnant? Why?

A

need to take folic acid to prevent developmental issues with the fetus

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120
Q

What happens to the mammary glands during pregnancy?

A

Enlarge and become prepared to secrete milk

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121
Q

What causes the mother to be stimulated to release milk shortly after birth?

A

sucking action of the baby at the breast

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122
Q

What are the advantages of breastfeeding? (4)

A

contains exactly the right nutrients in the right amounts the baby needs at different stages
contains antibodies which help the baby prevent infection
helps develop a bond between mother and baby
is free

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123
Q

What are the disadvantages of breastfeeding? (2)

A

if it does not come easily to the mother it can contribute to postnatal depression
responsibility for feeding the baby is solely with the mother

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124
Q

What are the advantages of bottle feeding? (2)

A

allows the father to bond with the baby
- allows the mother more freedom as she is not solely responsible for feeding the baby

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125
Q

What are the disadvantages of bottle feeding? (2)

A

risk of infections increased if bottles and equipment are not properly sterilised
is expensive

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126
Q

What is the function of the amniotic sac?

A

A fluid-filled sac that protects the embryo from damage and unequal pressures from acting upon it.

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127
Q

Why are birth control methods important?

A

Birth control methods are important in keeping family sizes small and in limiting the increase in the human population

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128
Q

What 4 categories of contraception methods are there?

A

Humans can use mechanical, chemical, surgical and natural contraceptive methods to prevent a pregnancy

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129
Q

What can some types of birth control methods protect the user from?

A

Some birth control methods also give protection from sexually transmitted infections

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130
Q

What is abstinence?

A

avoiding sexual intercourse completely

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131
Q

What is the rhythm method?

A

avoiding sexual intercourse during the fertile period of the menstrual cycle when ovulation occurs

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132
Q

Using the rhythm method how can a woman work out the exact time of ovulation?

A

the exact time ovulation happens can be worked out by monitoring body temperature and quality of cervical mucus

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133
Q

Is the rhythm method reliable?

A

No, it’s the least reliable method

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134
Q

What are the two chemical types of birth control?

A

IUD/IUS

Contraceptive pill, implant, injection

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135
Q

What does IUD / IUS stand for?

A

an intrauterine device or intrauterine system

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136
Q

what is an IUD and who fits it?

A

a small device fitted inside the uterus by a doctor or nurse

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137
Q

How does an IUD work?

chemical aspects

A

it releases sex hormones which thicken the mucus produced in the cervix, making it difficult for sperm to swim into the uterus
it also thins the lining of the uterus, making it more difficult for a fertilised egg to implant

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138
Q

How does an IUD work?

physical aspects

A

an IUD also interferes with the passage of sperm through the uterus, in which way it is acting as a barrier method of birth control

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139
Q

What may a contraceptive pill, implant or injection contain?

A

may contain just progesterone or a mixture of progesterone and oestrogen

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140
Q

Is the contraceptive pill, implant, injection method effective?

A

Yes, very when taken regularly

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141
Q

In what ways is a contraceptive implant or injection better than the pills?

A

both last several months
- increase the effectiveness as they remove the risk of forgetting to take a pill regularly

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142
Q

What are the 3 types of barrier methods of birth control?

A

Condom
Femidom
Diaphragm

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143
Q

How do barrier contraceptive methods work?

A

All work by preventing sperm from reaching the egg

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144
Q

What is a condom?

A

latex sheath worn over the penis

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145
Q

How does a condom work?

A

prevents sperm entering the vagina as ejaculate remains in condom

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146
Q

What does a condom also protect from (apart from preventing pregnancy)?

A

Protects against STI’s

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147
Q

What is a femidom?

A

latex sheath inserted into the vagina

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148
Q

What is a diaphragm?

A

a rubber cap that fits over the entrance to the cervix

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149
Q

How does a diaphragm work?

A

prevents entry of sperm into the uterus

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150
Q

What is often used alongside a diaphragm?

A

often used with a spermicide (cream which kills sperm)

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151
Q

What are the 2 types of surgical methods of birth control?

A

vasectomy
- female sterilisation (tubal ligation)

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152
Q

How does a vasectomy work?

A

the sperm ducts are cut, meaning that no sperm is present in the semen when ejaculation occurs

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153
Q

How does female sterilisation work?

A

the oviducts are cut or tied off, preventing eggs from reaching the uterus or sperm from reaching the eggs

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154
Q

Are surgical methods of birth control effective? What’s the downside?

A

very effective but difficult to reverse

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155
Q

How do Contraceptive Hormones in the Pill Work?

A

They work by mimicking some of the hormone levels during pregnancy
By raising the levels of progesterone and oestrogen, the uterus lining is maintained and development of another egg cell is prevented
This means that sex at any time of the month cannot cause pregnancy as no egg is released to be fertilised

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156
Q

When and why are fertility treatments used?

A

In situations where couples find it difficult to conceive, fertility treatments can improve their chances

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157
Q

What 3 types of fertility treatments are there?

A

Artificial Insemination
Fertility Drugs
In Vitro Fertilisation (IVF)

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158
Q

When is Artificial Insemination used?

A

If the male is not producing healthy sperm

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159
Q

What is the process of artificial insemination ?

A

donor sperm is used
- The sperm are placed into the female’s vagina at the fertile point in her menstrual cycle

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160
Q

What social issues can be considered with artificial insemination?

A

The male must be able to cope with the fact that the child is not biologically his
Sperm donors may father multiple children who are not able to know their parentage

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161
Q

When are fertility drugs used?

A

This method is used when the female is not producing enough eggs

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162
Q

What types of hormones are in fertility drugs and what do they do?

A

Hormones, including FSH, are given to her to stimulate egg production

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163
Q

What social issues can be considered with fertility drugs?

A

Several eggs can be released at once so this increases the chance of multiple births (twins or triplets etc)

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164
Q

When is IVF used?

A

If the female cannot conceive naturally even after taking fertility drugs, or if there are issues with both male and female fertility in a couple, IVF can be used

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165
Q

What are the 4 stages of IVF?

A

This involves fertility drugs being given to the female to stimulate egg production before they are harvested from the ovary
The eggs are then inseminated in a petri dish using sperm from the male
Once embryos have formed, they are placed back into the uterus of the female
Several embryos are implanted to increase the chance of one developing further

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166
Q

What social issues can be considered with IVF?

A

IVF is relatively expensive and not all couples can afford it
As several embryos are implanted, the risk of multiple births is quite high
Some women use IVF to get pregnant at a later age than they would be able to conceive naturally

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167
Q

How are STI’s passed on?

A

Unprotected sexual intercourse can lead to the transfer of pathogens via exchange of body fluids

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168
Q

What is an example of an STI that can develop into something else?

A

HIV (Human Immunodeficiency Virus), the virus that usually leads to the development of acquired immunodeficiency disease (AIDS)

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169
Q

How can HIV be spread (apart from sexually)? (4)

A

HIV can also be spread via:

sharing needles with an infected person,
blood transfusions with infected blood
from mother to fetus through the placenta
mother to baby via breastfeeding

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170
Q

What symptoms do people usually get immediately after infection? (HIV)

A

people often suffer mild flu-like symptoms

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171
Q

Do people who first get HIV know they’re infected? Why?

A

These symptoms pass and for a period of time infected people might not know they are infected

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172
Q

What specific thing does HIV infect?

A

The virus infects a certain type of lymphocyte of the body’s immune system

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173
Q

What do lymphocytes usually do?

A

Normally lymphocytes seek out and destroy pathogens that enter the body, producing antibodies that attach to pathogens, enhancing phagocytic activity

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174
Q

How does HIV avoid detection by lymphocytes?

A

HIV avoids being recognised and destroyed by lymphocytes by repeatedly changing its protein coat

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175
Q

How does HIV manage to survive in the body?

A

It then infects a certain type of lymphocyte and uses the cells’ machinery to multiply

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176
Q

What does HIV do to the body’s immune system?

A

This reduces the number of lymphocytes of the immune system, and also the number of antibodies that can be made

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177
Q

How does HIV lead to AIDS?

A

It decreases the body’s ability to fight off infections, eventually leading to AIDS (Acquired immunodeficiency)

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178
Q

What does HIV attach to?

A

HIV attaches to receptors on lymphocyte

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179
Q

How does HIV enter the lymphocyte?

A

HIV injects its genetic material into the lymphocyte, which becomes a HOST CELL

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180
Q

What happens to the lymphocyte after HIV is done with it?

A

After making many copies of itself, the host cell is destroyed by HIV

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181
Q

In what 4 ways can the spread of STI’s be controlled?

A

Limiting the number of sexual partners an individual has
Not having unprotected sex, but making sure to always use a condom
Getting tested if unprotected sex or sex with multiple partners has occurred
Raising awareness by education programmes

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182
Q

When are primary sexual characteristics developed and what are they?

A

Primary sexual characteristics are present during development in the uterus and are the differences in reproductive organs etc between males and females

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183
Q

What are secondary sexual characteristics?

A

Secondary sexual characteristics are the changes that occur during puberty as children become adolescents

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184
Q

What are the secondary sexual characteristics controlled by?

A

They are controlled by the release of hormones – oestrogen in girls and testosterone in boys

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185
Q

What are examples of secondary sexual characteristics in females? (4)

A

breasts develop
body hair grows
menstrual cycle begins
hips get wider

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186
Q

What are examples of secondary sexual characteristics in males? (5)

A

growth of penis and testes
growth of facial and body hair
muscles develop
voice breaks
testes start to produce sperm

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187
Q

What changes occur to both boys and girls?

A

growth of sexual organs and growth of body hair

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188
Q

What other changes, apart from physical, can happen during puberty? Why? What are examples?

A

Emotional changes also occur due to the increased levels of hormones in the body
These include more interest in sex and increased mood swings

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189
Q

When does the menstrual cycle start and what is it controlled by?

A

Starts in early adolescence in girls (around age 12) and is controlled by hormones

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190
Q

How long is the average menstrual cycle?

A

The average menstrual cycle is 28 days long

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191
Q

When does ovulation occur? What happens?

A

Ovulation (the release of an egg) occurs about halfway through the cycle (day 14) and the egg then travels down the oviduct to the uterus

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192
Q

What causes menstruation?

A

Failure to fertilise the egg causes menstruation (commonly called a period) to occur – this is caused by the breakdown of the thickened lining of the uterus

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193
Q

How long does menstruation last?

A

Menstruation lasts around 5 – 7 days and signals the beginning of the next cycle

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194
Q

What happens after the menstruation cycle finishes?

A

After menstruation finishes, the lining of the uterus starts to thicken again in preparation for possible implantation in the next cycle

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195
Q

What is the menstrual cycle controlled by and where do these things come from?

A

The menstrual cycle is controlled by hormones released from the ovary and the pituitary gland in the brain

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196
Q

When do oestrogen levels rise?

A

Oestrogen levels rise from day 1 to peak just before day 14

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197
Q

What changes does oestrogen cause?

A

stimulates the uterus to develop a lining (to replace lining lost during menstruation)
post-ovulation, inhibits FSH and LH production in the pituitary gland
causes the egg to mature

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198
Q

When is the peak in oestrogen levels?

A

The peak in oestrogen occurs just before the egg is released

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199
Q

When does progesterone levels rise?

A

Progesterone stays low from day 1 – 14 and starts to rise once ovulation has occurred

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200
Q

What changes does progesterone cause?

increase
decrease

A

The increasing levels cause the uterine lining to thicken further
a fall in progesterone levels causes the uterine lining to break down (menstruation / ‘period’)
- maintains lining of uterus
- inhibits FSH and LH production

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201
Q

What secretes FSH and LH?

A

the pituitary gland

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202
Q

What changes does FSH cause?

A

stimulates egg maturation in the follicles of the ovary
- stimulates follicles in the ovaries to secrete oestrogen

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203
Q

When is LH secreted?

A

The pituitary gland is stimulated to release luteinising hormone (LH) when oestrogen levels have reached their peak

204
Q

What changes does LH cause?

A

stimulates ovulation (release of egg into oviduct)
- stimulates ovary to produce progesterone (ovulation results in the formation of a corpus luteum which secretes p)

205
Q

What happens if the egg is fertilised and pregnancy does occur? (menstrual cycle)

A

If pregnancy does occur the corpus luteum continues to produce progesterone, preventing the uterus lining from breaking down and aborting the pregnancy

206
Q

During pregnancy, at what point does the corpus luteum stop producing progesterone?

A

It does this until the placenta has developed, at which point it starts secreting progesterone and continues to do so throughout the pregnancy

207
Q

Describe sexual reproduction.

A

Sexual reproduction is a process involving the fusion of the nuclei of two gametes to form a zygote and the production of offspring that are genetically different from each other.

208
Q

Describe fertilization.

A

Fertilization is the fusion of the nuclei from a male gamete (sperm) and a female gamete (egg cell).

209
Q

The nuclei of gametes are _____ and the nucleus of a _______ are diploid.

A

The nuclei of gametes are haploid and the nucleus of a zygote are diploid.

210
Q

What are the three functions of the male reproduction system?

A

Produces testosterone.
Manufactures the male gametes.
Delivers them to the site of fertilization.

211
Q

What is the function of the following male reproductive part:
- Testes.

A

Made up of many coiled tubes which produce the male gametes (sperm).
The cells between the tubes produce testosterone.

212
Q

What is the function of the following male reproductive part:
- Scrotum.

A

Sac of skin that encloses the testes and hang outside of the body between the legs where the testes are protected.
Temperature is 2 - 3°C lower than the body temperature - ideal for sperm development.

213
Q

What is the function of the following male reproductive part:
- Sperm ducts.

A

Carries sperm from the testis to the urethra.

214
Q

What is the function of the following male reproductive part:
- Prostate gland.

A

Produces fluid which makes up most of the sperm.

215
Q

What is the function of the following male reproductive part:
- Urethra.

A

Carries semen from the sperm duct to the tip of the penis.
Carries urine, a valve prevents this happening at the same time.

216
Q

What is the function of the following male reproductive part:
- Penis.

A

Erectile tissue can be stiffened by filling with blood. Once erect can be used to deliver sperm to the vagina of the female (ejaculation).

217
Q

What are the four functions of the female reproductive system?

A

Produces oestrogen/progesterone.
Develops female gametes.
Accepts sperm.
Allows development/birth of the fetus.

218
Q

What is the function of the following female reproductive part:
- Ovaries.

A

Contains thousands of follicles which develop the ova (eggs) and produce oestrogen and progesterone.

219
Q

What is the function of the following female reproductive part:
- Oviducts (Fallopian tubes).

A

Carries the ovum to the uterus.
(Fertilization usually occurs in the first third of the oviduct).

220
Q

What is the function of the following female reproductive part:
- Uterus.

A

Site of implantation and development of the fetus.

221
Q

What is the function of the following female reproductive part:
- Cervix.

A

Ring of muscle at the lower end of the uterus.

222
Q

What is the function of the following female reproductive part:
- Vagina/ birth canal.

A

Receives the penis during intercourse, sperm are deposited here.
Baby passes down the vagina during birth.

223
Q

How are sperm cells and egg cells made?

A

Egg cells and sperm cells are made by meiosis.

224
Q

What is the function of the following adaptive feature of sperm:
- Flagellum.

A

Flagellum is a tail used for swimming.

225
Q

What is the function of the following adaptive feature of sperm:
- Middle piece containing mitochondria.

A

Middle piece containing mitochondria to release energy so the sperm can swim.

226
Q

What is the function of the following adaptive feature of sperm:
- Enzymes in the acrosome.

A

The acrosome is a vesicle containing enzymes to dissolve through the jelly surrounding the egg cell.

227
Q

What is the function of the following adaptive feature of egg cells:
- The food/ energy stored in the cytoplasm.

A

Cytoplasm contains a store of energy that provides energy for cell division after fertilization.

228
Q

What is the function of the following adaptive feature of egg cells:
- Jelly coat.

A

Jelly coat changes after fertilization to form an impenetrable barrier to prevent other sperm nuclei entering the egg cell.

229
Q

Compare male and female gametes in terms of:
- Size.

A

Sperm cell = Small, very little food store.
Egg cell = Much larger than sperm cell as it contains a food store in the cytoplasm

230
Q

Compare male and female gametes in terms of:
- Movement/ mobility.

A

Sperm cell = Contains a lot of mitochondria to release energy so the sperm can swim using tail movement.
Egg cell = Does not move itself (is moved along the oviduct by cilia and peristalsis.

231
Q

Compare male and female gametes in terms of:
- Structure/ Adaptive features.

A

Sperm cell = Flagellum, Mitochondria, and enzymes in the acrosome.
Egg cell = Energy stores in the cytoplasm, jelly coat that changes at fertilization so only one sperm cell enters and fertilizes.

232
Q

What number of chromosomes do sperm cells and eggs cells have?

A

23 which is the haploid number.

233
Q

Compare male and female gametes in terms of:
- Number produced.

A

Sperm cell = (100 000 000) many per day from puberty to old age.
Egg cell = One a month from alternate ovaries from puberty to middle age (menopause), except when pregnant or taking the contraceptive pill.

234
Q

Describe what happens during sexual intercourse.

A

During sexual intercourse, the penis becomes erect and enters the vagina. Sperm are released from the testes and travel by peristalsis along the sperm ducts. Contractions of the urethra move the seminal fluid through the penis into the vagina.

235
Q

What happens in early development?

A

The zygote forms an embryo which is a ball of cells that implants into the lining of the uterus.

236
Q

What happens at fertilization?

A

Enzymes released by the acrosome break down the jelly coat so that the nucleus of the sperm can fertilize the nucleus of the egg cell.
The ovum membrane alters to form a barrier to the entry of other sperm.
The new cell contains a set of genetic material from the mother and a set from the father. It is a diploid zygote with 46 chromosomes.
The fertilized ovum or zygote now starts to divide by mitosis and continues to move down the oviduct by peristalsis of the oviduct muscles and the beating of cilia to the uterus where it implants in the thickened uterus lining.
Once the embryo is attached to the lining of the uterus, some of its outer cells combine with some of the mother’s cells and a placenta begins to develop.

237
Q

What are the 6 functions of the placenta?

A

exchange of dissolved nutrients e.g. glucose, amino acids, and excretory products e.g. urea.
Exchange of dissolved gases by diffusion e.g.oxygen and carbon dioxide.
Antibodies diffuse from the mother to the baby to provide passive immunity.
Protection of the fetus from the mother’s immune system.
- there is no direct contact between maternal and
fetal blood. The mother’s blood flows under high
pressure and would damage the delicate blood
vessels of the fetus also if the mother and fetus
have different blood groups then the mother’s
antibodies and platelets may cause it to clot.
It provides a barrier to toxins and pathogens however some toxins e.g. nicotine, alcohol, heroin, and pathogens can diffuse across the placenta and affect the fetus.
Secretion of hormones (progesterone) which maintains the lining of the uterus during pregnancy as the corpus luteum breaks down.

238
Q

What is the umbilical cord?

A

The umbilical cord connects the fetus to the placenta.

239
Q

What is the function of the umbilical cord?

A

The cord contains the umbilical artery which carries deoxygenated blood and wastes (e.g. carbon dioxide and urea) from the fetus to the placenta and the umbilical vein which carries oxygenated blood and nutrients(e.g. glucose and amino acids) from the placenta to the fetus.

240
Q

What does the amniotic fluid protect the fetus against?

A

mechanical shock.
drying out.
temperature fluctuations.

241
Q

What is the fetus surrounded by throughout pregnancy?

A

Throughout pregnancy the fetus is surrounded by a membrane called the amniotic sac which contains amniotic fluid.

242
Q

What are the 6 secondary sexual characteristics in males?

A

Facial hair develops.
Chest broadens.
Voice deepens.
Hair develops on chest, under armpits and in pubic region.
Penis and testes become larger.
Sperm production begins.

243
Q

What are the 5 secondary sexual characteristics in females?

A

Breasts develop.
Hips broaden.
Hair grows under armpits and in the pubic region.
Vagina enlarges.
Oestrogen begins the cycle of egg production and prepares the uterus lining for implantation.

244
Q

Fill in the missing spaces:
At puberty, a person becomes _________ able to ____________. At puberty the ______ instructs the _____________ __________ to make ______________ (Follicle Stimilauting Horomore and Luteinizing Hormone) that stimulate the ____________ ____ ________ to release the ___ hormones into the ______ _________. The testes release __________ and the _________ release oestrogen. These hormones only affect the ____________ _____ which have ______ to recognise them.

A

At puberty, a person becomes physically able to reproduce. At puberty the brain instructs the pituitary gland to make hormones (Follicle Stimilauting Horomore and Luteinizing Hormone) that stimulate the primary sex organs to release the sex hormones into the blood stream. The testes release testosterone and the ovaries release oestrogen. These hormones only affect the target organs which have receptors to recognise them.

245
Q

The menstrual cycle is a long term process controlled by a number of hormones, which:

A

Prepare the uterus to receive any fertilised ova.
Control the development of mature ova.

246
Q

What is the menstrual cycle?

A

The cycle of producing and releasing mature ova is called the menstrual cycle.

247
Q

Fill in the missing spaces:

Girls are born with ____________ of potential _____ ______ in their ______. Each potential egg is surrounded by a ____ _____ ___ ______ and together they form _ _________ (____________ _________ __________). Ovaries ___ _____ produce any more _____ in their lifetime. At puberty (between 10 and 15 years) some of the ______ start to _______ and girls start to have _______.

A

Girls are born with thousands of potential egg cells in their ovaries. Each potential egg is surrounded by a small group of cells and together they form a follicle (Follicle Stimulating Hormone). Ovaries do not produces any more eggs in their life time. At puberty (between 10 and 15 years) some of the follicles start to develop and girls start to have periods.

248
Q

What is a sexually transmitted infection?

A

Sexually transmitted infection is an infection that is transmitted through sexual contact.

249
Q

What is human immunodeficiency virus (HIV)?

A

Human immunodeficiency virus (HIV) is a pathogen that causes AIDS (and STI).

250
Q

Name ways in which a sexually transmitted infection may be transmitted.

A

in blood through transfusions, hypodermic needles, and mixing of blood.
in semen during unprotected sexual intercourse with an infected person.
across the placenta during pregnancy.
during birth when the mother and baby’s blood streams come in close contact.
during breast feeding through breast milk.

251
Q

Name ways in which a sexually transmitted infection may be transmitted.

A

in blood through transfusions, hypodermic needles, and mixing of blood.
in semen during unprotected sexual intercourse with an infected person.
across the placenta during pregnancy.
during birth when the mother and baby’s blood streams come in close contact.
during breast feeding through breast milk.

252
Q

How can one prevent catching a sexually transmitted infection?

A

By using condoms, drug users must not share needles, screen blood for transfusions.

253
Q

How can one treat a sexually transmitted infection?

A

Anti-retroviral drugs can be given along with counseling. There is NO cure.

254
Q

What are the signs/ symptoms for HIV?

A

There are none for HIV. After 8 - 10 years it will develop into Acquired immunodeficiency syndrome (AIDS).

255
Q

What is AIDS?

A

AIDS is a collection of diseases which result from the weakening of the immune system.

256
Q

What are the symptoms of AIDS?

A

Symptoms include flu symptoms, swollen glands, high temperature.

257
Q

What is the result of AIDS?

A

Aids cannot be cured as it is from the Human immunodeficiency virus, so death will result.

258
Q

What are the four functions of oestrogen (released by follicle)?

A

Repairs uterus lining.
Inhibits Follicle Stimulating Hormone.
Stimulates Luteinising Hormone release.
Stimulates development of female sexual characteristic.

259
Q

What are the two functions of luteinizing hormone (released by the pituitary gland)?

A

Stimulates release of mature ovum.
Development of the corpus luteum.

260
Q

What are the three functions of progesterone (released by corpus luteum)?

A

Thickens uterus lining.
Inhibits Follicle Stimulating Hormone.
Prevents Menstruation.
Prevents production of more eggs.

261
Q

What days do menstruation, repair phase, ovulation, receptive phase, and premenstrual phase take place?

A

Menstruation = Day 0 - Day 5.
Repair Phase = Day 6 - Day 12.
Ovulation = Day 13 - Day 15.
Receptive Phase = Day 16 - Day 21.
Premenstrual Phase = Day 22 - Day 28.

262
Q

What does FSH do (released by the pituitary gland)?

A

Stimulate follicle growth to secrete oestrogen and develop the ovum.

263
Q

What happens if fertilization happens in regard to progesterone levels?

A

If fertilization does take place progesterone levels remain high and the uterus lining is maintained.

264
Q

What happens if fertilization does not happen in regard to progesterone levels?

A

If fertilization does not take place the progesterone levels decrease and menstruation takes place.

265
Q

Define Asexual reproduction

A

A process resulting in the production of genetically identical offspring from one parent

266
Q

Advantages of asexuall reproduction

A

Population can be increased rapidly
Can exploit suitable environments quickly
Time and energy efficient
Reproduction is completed much faster than sexual reproduction

267
Q

Disadvantages of asexual reproduction

A

limited genetic variation in population
population is vulnerable to changes in conditions and may only be suited for one habitat
Disease is likely to affect the whole population as there is no genetic variation

268
Q

Why is axexual reproduction is crop plants prefered

A

As it means that a plant that has good characteristics can be made to reproduce asexually and the entire crop will show the same characteristics

269
Q

Define Sexual reproduction

A

A process involving the fusion of the nuclei of two gametes to form a zygote and the production of offspring that are genetically different from each other

270
Q

What are the nuclei of the gametes?

A

Haploid

271
Q

What is the nucleus of a zygote?

A

Diploid

272
Q

What are advantages of sexual reproduction

A

Increases genetic variation
Species can adapt to new environment due to
variation
Disease is less likely to affect population due to variation

273
Q

What are the disadvantages of sexual reproduction?

A

Takes time and energy to find males

Difficult for isolated members of the species to reproduce

274
Q

Define Fertilisation

A

The fusion of gamete nuclei

275
Q

sepals?

A

Protects unopened flower

276
Q

petals?

A

Brightly coloured to attract insects

277
Q

anther

A

produces and releases the male sex cell

278
Q

stigma

A

top of the female part that collects pollen grains

279
Q

ovaries

A

produces the female sex cell

280
Q

ovule

A

contains the female sex cell

281
Q

insect pollinated petals

A

large and brightly coloured to attract insects

282
Q

insect pollinated scent and nectar

A

entices insects to visit the flower and push past stamen to get to nectar

283
Q

insect pollinated pollen grains

A

large sticky spiky to attach to insects

284
Q

insect pollinated anthers

A

inside flower stiff to brush against insects

285
Q

insect pollinated stigma

A

inside flower sticky so pollen grains stick to it when an insect brushes past

286
Q

wind pollinated petals

A

small, dull

287
Q

wind pollinated scent and nectar

A

no need to waste energy producing those

288
Q

wind pollinated pollen grains

A

Large amounts most pollen are not transferred to another flower.

289
Q

wind pollinated anthers

A

outside flower swinging loose on long filaments to release pollen grains easily

290
Q

wind pollinated stigmas

A

Outside to catch drifting pollen grains

291
Q

When an insect carrying pollen lands on the flower describe the events that lead to seed formation

A

When it lands the stigma inside the flower brush against the insect. It is sticky so the pollen sticks to it. A pollen tube then grows down the style towards the ovary and enters the ovary via the micropyle (small hole in ovary) at this point fertilisation occurs and the ovule developed into a seed which developed into a fruit. (Ovule wall becomes seed coat)

292
Q

What does the radicle become?

A

The first root

293
Q

What does the plumule become

A

The first shoot

294
Q

What does the cotyledon become

A

The first leaf and food store

295
Q

What is function of the testa?

A

It covers and protects the embryo before germination (seed coat)

296
Q

What is dormancy?

A

The period of time between fertilisation and germination

297
Q

What is germination

A

The process by which a seed changes into a plant. Root, shoot appears the seed cost splits.

298
Q

Why is water needed for germination

A

Water is needed in order to burst that tests and allows the radicle and plumule to develop. It also allows metabolic reactions to happen as it activates enzymes

299
Q

Why is oxygen needed for seeds to germinate

A

Oxygen is needed for aerobic respiration to happen

300
Q

Why is a warm temperature needed for germination?

A

A warm temperature not only lets the seed know when it should germinate but it also lets rapid enzyme reactions to happen.

301
Q

What is a zygote?

A

The 1st cell after fertilisation when the diploid number has been restored.

302
Q

What is the stamen made up of, where is it and what does it do?
Insect pollinated

A

The stamen is made up of the anther and the filament (which holds up the anther)
They are the long stick things inside the flower.
They produce pollen grains which stick or hook onto the insects. The anther and filament are firm and stiff to brush against the insects.

303
Q

What is the stigma and where is it?

Insect pollinated

A

The stigma is also inside the flower and the stamen are on top of it. It is sticky so pollen grains stick onto it when an insect brushed past.

304
Q

What do petals look like on insect pollinated flowers?

A

They are large and brightly coloured to attract insects

305
Q

How else to insect pollinated flowers attract insects

A

They have sweet, sugary nectar which attracts insects.

306
Q

Where is the stamen and what does it do?

Wind pollinated flower

A

The stamen is outside the flower and the anthers are loose on long filaments so pollen grains are released easily, the grains are smooth and lights so can be carried by the wind and not clump together

307
Q

Where is the stigma and what does it do

Wind pollinated flower

A

It is outside and feathery to catch drifting pollen grains

308
Q

What do the petals look like on a wind pollinated flower?

A

They are small and usually green or brown.

309
Q

What is the definition of pollination?

A

The transfer of pollen from the anther to the stigma then ovule to allow fertilisation to take place.

310
Q

What happens when pollen lands on the stigma?

A

A pollen tube is grown down the style and into the ovary, the nucleus of the pollen grains passes down the tube to fertilise the egg cell in the ovule (fertilisation). The embryo developed and the ovary forms the fruit and the ovules become seeds.

311
Q

What is germination?

A

The process where a plant grows from a seed.

312
Q

How do germinating seeds get their food before they can photosynthesise?

A

They use up their food stores until they can photosynthesise

313
Q

What is a gamete?

A

Also known as a sex cell. A female and male gamete undergo fertilisation to become a zygote. In a plant the female gamete is the egg and the male gamete is the pollen.

314
Q

What happens when plants asexually reproduce?

A

They produce a clone. Some plants have lateral buds on the outside which grows another plant others have side branches with plantlets on them (spider plant) and others produce runners which extend and grow a plant from that (e.g. Strawberry plants) this can be done artificially through tissue culture and taking cuttings

315
Q

What is the function of the upper epidermis

A

Is protects the plant whilst letting the sun shine in as it is thin and transparent

316
Q

What is the palisade mesophyll

A

A layer of palisade cells which absorb light. They are near the surface so light can get to them easily and palisade cells are filled with chloroplasts

317
Q

What is the xylem

A

It is made from dead cells and lignin. It moves water through the plant from the roots to the leaves via the stem.

318
Q

What is the phloem

A

It is made from living cells and moves dissolved sugars from photosynthesis and other soluble food molecules from the leaves to growing and storing tissues

319
Q

What is the spongy mesophyll

A

It is filled with air spaces to allow CO2 to diffuse from the stomata tot he photosynthesising cells. It provides a large internal sa:v

320
Q

What is the lower epidermis

A

The lower epidermis is at the bottom of the leaf. It contains guard cells that open and close the stomata where gas exchange happens, water vapour is also lost through the stomata during transpiration

321
Q

What is the cuticle

A

A thin waxy protective layer on top of the leaf. It reduces water loss by evaporation and prevents entry of pathogens

322
Q

What happens days 1-5 of the menstruales cycle?

A

First day the lining of the uterus is shed and then FHS is released from the pituitary gland stimulating the growth of a new egg cell surrounded by a cluster of cells called a follicle

323
Q

What happens days 5-14

A

The follicle cells produce oestrogen which causes the lining of the uterus to build up again. Around day 14 ovulation happens (where a mature egg is released) and LH is released.

324
Q

Where is FSH released from and what is its role?

A

FSH is released from the pituitary gland and causes an egg to mature in an ovary and stimulates the ovaries to release oestrogen

325
Q

Where is oestrogen released from and what is its role?

A

Released from the ovaries and it stops FSH being produced (so that only one egg matures in a cycle). Repairs and thickens the uterus lining. Stimulates the pituitary gland to release LH.

326
Q

Where is LH released from and what is its role?

A

It is released from the pituitary gland and triggers ovulation (the release of a mature egg)

327
Q

Where is progesterone released from and what is its role?

A

It is released from the ovaries and it maintains the lining of the uterus during the middle part of the menstrual cycle and during pregnancy.

328
Q

What happens if fertilisation does not occur in the oviduct/fallopian tube?

A

The egg travels down the oviduct and is shed with the uterus. (The egg travels down the oviduct for 14 days and the oestrogen and progesterone levels fall in the last 2 days)

329
Q

What is implantation?

A

A
When the embryo embeds itself into the uterus lining

330
Q

What does the zygote undergo to become the embryo?

A

Mitosis

331
Q

How long is the average menstrual cycle

A

28 days

332
Q

How does the amniotic fluid protect a developing embryo and foetus?

A

It acts as a ‘shock absorber’ to protect it from bumps to the mothers body and provides a stable environment by regulating temperature

333
Q

Where do substances diffuse across from the mothers blood and the baby’s blood?

A

The intervillous space

334
Q

How does the intervillous space protect the baby?

A

It can help stop harmful pathogens and some viruses from getting into the babies blood stream

335
Q

What is transferred through the umbilical cord?

A

To the baby: small soluble nutrients (glucose, other sugars, amino acids, fatty acids and glycerol) and oxygen (as it can not do gas exchange by itself) antibodies are also transferred across (as they are very small) to provide immunity
To the mother: carbon dioxide and urea

336
Q

How is the placenta adapted for exchange?

A

The lining is folded and has villi to increase surface area. It also has a big blood supply.

337
Q

What blood vessels are in the umbilical cord?

A

Veins and arteries

338
Q

What is the urethra?

A

the tube inside the penis that can carry urine or semen. A ring of muscle ensures that urine and semen do not get mixed up.

339
Q

What happens in the sperm duct and sex glands?

A

The sperm pass through the sperm ducts, and mix with fluids produced by glands. The fluids provide the sperm cells with nutrients. The mixture is semen

340
Q

What are the functions of the testes?

A

To produce sperm

To make the hormone testosterone

341
Q

What do the two ovaries contain?

A

Ova (eggs) ovum (egg)

342
Q

How do the eggs get from the ovary to the uterus?

A

Each ovary is connected to the uterus by an oviduct (fallopian tube). The oviduct is lined with ciliated cells. Every month, an ovum (egg) develops and becomes mature, and is released from an ovary. The cilia waft the ovum along inside the oviduct and into the uterus.

343
Q

What is the uterus and the cervix

A

The uterus is a muscular bag with a soft lining. It is where a baby develops until its birth. The cervix is a ring of muscle at the lower end of the uterus. It keeps the baby in place while the woman is pregnant.

344
Q

What is the vagina and cervix

A

The vagina is a muscular tube that leads from the cervix to the outside of the woman’s body. The opening to the vagina has folds of skin called labia that meet to form a vulva.
The urethra also opens into the vulva, but it is separate from the vagina. It passes urine out of the body from the bladder.

345
Q

What are the functions of a penis

A

to pass urine out of the body from the bladder
- to pass semen into a woman

346
Q

What are the functions of a penis

A

to pass urine out of the body from the bladder
- to pass semen into a woman

347
Q

Asexual reproduction

A

process resulting in the production of genetically identical offspring from one parent

348
Q

Asexual reproduction

A

process resulting in the production of genetically identical offspring from one parent

349
Q

Sexual reproduction

A

the process involving the fusion of the nuclei of two games (sex cells) to form zygote and the production of offspring that are genetically different from each other.

350
Q

Fertilization

A

the fusion of two gamete nuclei

351
Q

Pollination

A

transfer of pollen grains from the anther to the stigma of the flower or flowers

352
Q

Self-pollination

A

the transfer of pollen grains from the anther of a flower to the stigma of the same flower or different follower on the same plant

353
Q

Cross pollination

A

transfer of pollen grains from the anther of a flower to the stigma of a flower on a different plant of the same species

354
Q

Sexually transmitted diseases

A

the infection that is transmitted via body fluids through sexual contact

355
Q

purpose of reproduction

A

to make sure a species can continue its generation

356
Q

The nuclei of gametes are

A

haploid

357
Q

The nucleus of a zygote

A

diploid

358
Q

advantages of asexual reproduction

A

organisms do not need to find a partner and this saves time and energy
offsprings are genetically identical to their parents, none of the offsprings will be less well adapted to the environment
organisms reproduce even in isolation and prevent extinction in the wild
the single organism can develop a colony hence very useful in crop production

359
Q

disadvantages of asexual reproduction

A

does not lead to genetic variation in a population the species may only be suited to one habitat
spreading diseases or change in the environment may affect all the individuals in a population which may lead to the extinction of species
population can be difficult to control in the wild which increases the competition among the species for survival
-negative mutation live longer
in asexual organisms, diseases can be inherited from the parent

360
Q

advantages of sexual reproduction

A

produces genetic variation in the offspring. the species can adapt to new environments due to variation, which gives them a survival advantage and prevent the extinction
a disease is less likely to affect all the inviduals in a population

361
Q

advantages of sexual reproduction

A

produces genetic variation in the offspring. the species can adapt to new environments due to variation, which gives them a survival advantage and prevent the extinction
a disease is less likely to affect all the individuals in a population

362
Q

Disadvantages of sexual reproduction

A

time and energy are needed to find a mate
not possible for an isolated inviduals to reproduce

363
Q

Differences between sexual and asexual reproduction

A

sexual reproduction:
- 2 parents
- Cells divide by meiosis
- Variation and diversity
asexual reproduction:
- 1 parent
- Cells divide by fission or budding
- Little variation

364
Q

similarities between sexual and asexual reproduction

A

Both processes are types of reproduction and both produce offspring

365
Q

similarities between sexual and asexual reproduction

A

Both processes are types of reproduction and both produce offspring

366
Q

types of asexual reproduction

A

yeast budding
binary fission

367
Q

budding

A

the process by which a new, duplicate plant or animal begins to form at the side of the parent and enlarges until an individual is formed
- very common in plants and some animals
- example: cactus and hydra
- budding is very common in yeast
- in budding, an outgrowth (bud)develops from the body water. the bud grows to form a daughter organism which detaches to become independent. cytoplasm divides unequally

368
Q

binary fission

A

type of cell division in unicellular organisms which produces two organisms after the complete division of the cells. binary fission is common in bacteria. in binary fission, a single-cell bacterium divides into two identical daughter bacteria. bacteria reproduce by this method where all conditions such as availability of nutrients, temperature, and moisture are available

369
Q

stages of binary fission

A

cell elongation
replication of DNA, forming 2 identical DNA strands. the newly formed strands of DNA move to the opposite poles of the cells.
in the middle of the cell, a construction appears which deepens progressively.
cell divides into two equal halves, followed by the formation of a cross wall to form 2 independent daughter cells

370
Q

fragmentation

A

in this form, the body of the parent breaks down into distinct pieces, each of which can produce offspring. example: pieces of coral broken off in storms can grow into new colonies, a new starfish can grow from one detached arm, and some plants can grow from cutting them up and replanting them( tissue culture is also a method to reproduce some plants)

371
Q

vegatative reproduction/propogation

A

green plants are quite sophisticated in their methods of asexual reproduction. offspring may be produced by rynners, blubls , rhizomes or tubes

372
Q

tubers

A

potato plant

373
Q

bulbs

A

onions, garlic

374
Q

runner

A

strawberry

375
Q

rhizomes

A

ginger

376
Q

stamen

A

anther
filament

377
Q

carpel or pistil

A

stigma, style, ovule, ovary

378
Q

4 parts of an insect-pollinated complete flower

A

1) calyx
2)corrola
3) stamen
4) carpel

379
Q

petal

A

only one

380
Q

corrola

A

many petals

381
Q

sepal

A

only one

382
Q

calyx

A

more than 1 speal

383
Q

petal function

A

the colorful part of the flower. attracts insects in insect-pollinated plants

384
Q

anther function

A

male part of the plant. makes pollen

385
Q

filament function

A

joins the anther to the rest of the flower and provides angle for pollination

386
Q

stigma function

A

female part of the plant. recieves pollen

387
Q

ovary

A

contains the ovules

388
Q

ovule function

A

contains female gametes

389
Q

pollen

A

contains male gametes

390
Q

nectary function

A

makes nectar to attract insects in insect pollinated plants

391
Q

nectary function

A

makes nectar to attract insects in insect pollinated plants

392
Q

male reproductive system in plants

A

stamen consists of 2 parts, an anther and a filament
anther is where meiosis occurs to produce haploid pollen
if filament is a stalk that supports the anther and provides an angle for pollination

393
Q

female reproductive system in plants

A

carpel consists of stigma, style, ovary, and ovule
- sticky stigma receives pollen and also provides nutrition
- pollen grows a tube down the style
- meiosis occurs in the ovary to produce a haploid nucleus

394
Q

female reproductive system in plants

A

carpel consists of stigma, style, ovary, and ovule
- sticky stigma receives pollen and also provides nutrition
- pollen grows a tube down the style
- meiosis occurs in the ovary to produce a haploid nucleus

395
Q

flowers vary depending on

A

pollination mechanism

396
Q

wind pollination

A

when pollination occurs with the help of wind

397
Q

insect pollination

A

when pollination occurs with the help of insects or other pollinators

398
Q

advantages of self-pollination

A

very few pollen grains can pollinate the flower
-purity of the race is maintained
self-pollination avoids wastage of pollen grains
less chance of failure of pollination

399
Q

disadvantages of self-pollination

A

no variations occur if a plant gets hit by a disease. there is no possibility of survival and population decreases
it does not result in the creation of new species, a lower rate of evolution
continuous self-pollination results in weak progenies

400
Q

advantages of cross pollination

A

the offspring are healthier due to variation
the seeds produced in large numbers are more visible
the seeds develop and germinate properly and grow into proper plants
results in genetic variation because cross-pollinated can be carried out between two different varieties of the same species

401
Q

difference between the pollen grains of insect oi

A

in insect-pollinated flowers, produced pollen grains that are smaller and lighter in weight, which can be carried in wind easily.
in insect-pollinated flowers, they produced pollen grains that are larger in size, stick and spiny which helps to carry the pollen grain

402
Q

perianth

A

sepal + petal

403
Q

fertilization process in plants

A

after pollen lands on the stigma. a pollen tube grows down the style to the ovary
the generative cells create the 2 sperm nuclei ( mitosis)
double fertilization occurs( one sperm fertilizes) the egg
one sperm fertilizes the 2 polar nuclei together( central cell)

404
Q

endo sperm

A

provide nutrition for growing embryos and in human population

405
Q

Result of double fertilization

A

the sperm nucleus and egg nucleus joined to form a diploid embryo
the other sperm nucleus and the two polar nuclei to form a triploid endosperm. the endosperm is the nutrients supply for energy

406
Q

insect pollinated

A

large, brightly colored petals to attract insects
often sweetly scented to attract insects
moderate quantity of pollen- less wastage than wind pollination
-pollen is often sticky or spiky to stick to insects
anthers firm and inside to brush against insects
stigma inside the flower so that the insect brushes it
stigma has a sticky coating, pollen sticks to it

407
Q

wind pollinated

A

small petals, often brown or dull green- no need to attract insects
no scent: no need to attract insects
-no nectar: no need to attract insects
-pollen produced in great quantities because it does not reach another flower
pollen is very light and smooth: so it can be blown in the wind and stops it from clumping together
-anther loosely attached and dangle out to release pollen into the wind
stigma hangs outside the flower to catch the drifting pollen stigma feathery or net-like to catch the drifting pollen

408
Q

sexual reproduction involves 2 parents who have

A

sex organs

409
Q

sexual reproduction involves 2 parents who have

A

sex organs

410
Q

gametes

A

sex cells

411
Q

male gametes

A

sperm

412
Q

female gametes

A

egg ( ova )

413
Q

zygote aka

A

fertilized egg

414
Q

human reproductive system male parts

A

1) scortum
2) testicles
3) testosterone
4) sperm
5) prostate gland
6)urethra
7) epididymis

415
Q

scrotum

A

pouch-like sac holding both testicles in a separate compartment that hangs underneath the penis. maintains temperature for spermatogenesis

416
Q

testicles/ testes gland

A

2 glands in the male, located in the scrotum , which produce male hormones(testosterone)

417
Q

Testosterone

A

the male reproductive hormone made by the testicles which causes a change in puberty

418
Q

spermatogenesis

A

process in which sperm cells are produced

419
Q

sperm

A

the microscopic cells produced by the male testicles which can fertilize the female ovum

420
Q

prostate gland

A

man’s gland that helps make a sewer which is highly alkaline

421
Q

urethra

A

a tube that connects with the vas differentia to carry sperm cells out of the body

422
Q

epididymis

A

the structure that forms a mass over the back and upper part of each testis, stores sperm cells for further maturity

423
Q

vas deferens ( sperm duct)

A

sperms move by the process of peristalsis

424
Q

human reproductive system- female

A

1)vagina
2) cervix
3) uterus
4) oviduct ( fallopian tubes)
5) ovaries

425
Q

vagina

A

passageway between the uterus and the outside of a woman’s body which receives the sperm cells. the site where sperm cells get fully matured

426
Q

cervix

A

opening from the uterus to the vagina. It produces mucus which provides nutrients for the sperm and is alkaline in nature

427
Q

uterus

A

the place where the fetus grows and develops in a woman’s abdomen

428
Q

oviduct( fallopian tubes)

A

2 tubular structures reading from the ovaries to the uterus. site where fertilization takes place

429
Q

ovaries

A

organs holding a woman’s egg. which produces the female hormone estrogen and progesterone

430
Q

Adaptive features of sperm

A

sperm cells are specialized in a number of ways. the head contains a haploid nucleus. they have a flagellum ( tail) which moves by energy generated by many mitochondria and propels the cells. the head of the cell contains an acrosome, which secretes acrosomal enzymes to break the cell membranes during fertilization.

431
Q

Adaptive features of ovum

A

An egg cell has adapted to its function through the presence of cytoplasm, which increases its surface area to store nutrients. it has a maximum number of mitochondria. it is surrounded by a jelly coat ( zona pellucida) which maintains the entry of only one sperm head. also protects the embryo in the early stages

432
Q

compare sperm and ova

A

both sperm and egg cells have haploid nuclei. both sperm and egg cells have a large number of mitochondria. sperm cells are very small in comparison to large egg cells. sperms are produced in large numbers as one or two eggs are produced in each cycle. sperm cells are motile whereas egg cells are non-motile. sperm cells have acrosome which is absent in egg cells. sperm cells have a tail to swim which is absent in egg cells. sperm cells have either “x” or “y” chromosomes whereas egg cells have only ‘x’ chromosomes. the jelly coat is absent in sperm cells and present in egg cells. egg cells have stored nutrients which is absent in sperm cell

433
Q

fertilization process in humans

A

the sperm swim through the cervix across the uterus and enters the oviduct. the sperm may be stuck to the surface. the acrosome at the head of the sperm secretes enzymes that digest the part of the cell membrane of sperm as well as an egg cell. the jelly coat becomes hard to prevent the entry of other sperms. then the male nucleus fuses with the female nucleus termed as fertilization. the fertilized egg becomes the zygote which starts to divide by mitosis to form an embryo which is a cluster of cells that implants into the wall of the uterus , a process termed implantation

434
Q

Amniotic sac

A

1) protects the fetus from functional injuries
2) prevents the entry of pathogens
3) absorbs the metabolic wastes of the developing fetus
4) produces amniotic fluid
amniotic fluid accomplishes numerous functions for the fetus include:
- protection from outside injury by cushioning sudden blows or movements
- allows frictionless fetal movement and permits symetrical musculoskeletal development
- maintaining a relatively constant temperature for the environment surrounding the fetus. thus protecting the fetus from heat loss
- maintains the osmotic balance in developing fetus

435
Q

functions of placenta

A

the placenta is a temporary organ formed during the pregnancy form of the embryo during implantation in the endometrium.
placenta develops an amniotic sac to protect the fetus
placenta secretes progesterone hormone to keep endometrium intact and strong during pregnancy
placenta never allows the mixing of maternal and fetal blood
-placenta helps in the gaseous exchange of the developing fetus through the diffusion process
placenta provides nutrition for the fetus
placenta removes metabolic wastes and excretory products from the fetus

436
Q

umbilical cords 3 functions

A

primarily it serves as an oxygen source for the fetus, this is especially important because the fetus is unable to breathe having neither functional lungs nor an oxygen source and the cord provides the fetus the oxygen it needs to live
the umbilical cord also serves as a source of nutrients. including carbohydrates, proteins, fasts as well as vitamins and minerals along with antibodies for passive immunity
finally the umbilical cord transfers metabolic waste products and deoxygenated blood away from the fetus near the maternal circulation where the exchange of gases and removal of excretory products take place.

437
Q

male timeline: secondary sex characteristics

A

1) growth and development of facial hair, armpit, and pubic hair
2) a deepening of the voice
3) broadening of shoulders
4) muscles become stronger: sperm produced in adult amounts, throughout lude, if good health is present, there is validity to be a father

438
Q

female timeline: secondary sex characteristic

A

1) growth and development of armpit and pubic hair
2) widening of the hip bone ( pelvic bone)
3) growth and development of memory glands
4) start of the menstrual cycle- monarch
age 45-55 menopause ( cycle stops, cannot be a mother again)

439
Q

estrogen

A

the hormone responsible for the secondary sexual characteristics of the female controls the menstrual cycle, responsible for the growth and development of the endocardium. produced by the ovaries

440
Q

progesterone

A

the hormone produced by the yellow bodies which help the lining of the uterus( endometrium) strong and intact during pregnancy

441
Q

follicle-stimulating hormone ( FSH)

A

a substance that brings to life a few of the ovum in one of the ovaries. it is secreted by the pituitary gland in the brain

442
Q

lutenizing hormone( LH)

A

causes the follicle to burst, and allows the ovum to fall into the opening of the fallopian tube- ovulation. it is also secreted by the pituitary gland

443
Q

ovulation

A

when egg is released from the ovary

444
Q

sexually transmitted infections ( STIs)

A

sexually transmitted infections in an infection that is transmitted via body fluids through sexual contact
human immunodeficiency virus( HIV) is an example of STI, STD and aids

445
Q

HIV full form

A

human immunodeficiency virus

446
Q

AIDS full form

A

acquired immunodeficiency syndrome

447
Q

STD full form

A

sexually transmitted disease

448
Q

HIV

A

transmitted in the blood and semen
unprotected sexual activities
blood transfusion
sharing drug needles and syringes

449
Q

how does HIV affect the immune system

A

destroying the lymphocytes
develop other communicable diseases, the immune system can not produce antibodies
developement of cancer cells, slow function of the brain

450
Q

HIV causes

A

illness and problems for you by attaching your immune system When this happens, other diseases and conditions may occur because of your weakend immune system or because of the long-term effect of HIV on your body which is AIDS

451
Q

Asexual reproduction

A

process resulting in the production of genetically identical
offspring from one parent

452
Q

Advantages of asexual reproduction:

A

wild species that are adapted to
the environment can survive.
isolated wild species can
reproduce because only single
parent is required.
crop plants are genetically
identical therefore they have the
same yield and characteristics.
require less energy.
quick
no gametes
favourable characteristics of
parent passed on
dense colonies outcompete other
species
no pollinators required
reliable
no harmful variation

453
Q

Disadvantage of asexual
reproduction:

A

less variation
lack of diversity in wild plants
risk of overpopulation in wild
plants
competition for resources as all
individuals are close together in
wild plants
wild plants and crops are less
likely to survive to change
environment
no adaptive features in wild
plants
all individuals are susceptible to
the same, diseases/pests in wild
plants
higher risk of extinction in the wild
plants
no evolution in wild plants
genetically identical so higher risk
of inheriting genetic diseases in
both wild and crop plants

454
Q

Sexual reproduction

A

process involving the fusion of the nuclei of two gametes to
form a zygote and the production of offspring that are genetically different from each
other.

455
Q

Fertilisation

A

fusion of the nuclei of gametes.

456
Q

Nuclei of gametes are

A

haploid

457
Q

nucleus of a zygote

A

is diploid

458
Q

Advantages of sexual reproduction

A

maintain/ increase, the population in wild plants
allow variation in wild plants
allow adaptation to, new/ changed
environment(s) in wild plants
allow natural selection/ evolution/ formation
of new species in wild plants
random fusion of gametes in wild plants
ability to express recessive trails in wildplants
allows to use of selective breeding in crop
plants

459
Q

Disadvantages of sexual
reproduction

A

Slow
Lots of energy is
needed
Need 2 parents

460
Q

Sepals:

A

Protect the flower while it is a bud

461
Q

Petals:

A

Brightly coloured and attract insects to flowers

462
Q

Stamen

A

It is male part of flower, consists of long filament and anther at the top which contain pollen grain, which contain male gametes

463
Q

Carpel:

A

It is the female part of flower. It contains ovary, which contains ovules,
which contains female gamete. At top is style with stigma at the top. function of
stigma is to catch pollen grains.

464
Q

Insect pollinated flower

A

large, brightly coloured petals, strong scent, nectar to
attract insects towards them. The anther and stigma are inside the flower so that the
insect brush past them and some pollen stick onto them. The insect then goes to
another flower, looking for more nectar. Pollen grains are sticky and spiky so, some
of the pollen it picked up at the first flower sticks onto the stigma of the second
flower when the insect brushes past it. The stigma is sticky, and many pollen grains
get stuck on it.

465
Q

wind pollinated flower

A

produce much more pollen than insect pollinated flowers.
This is because a lot of the pollen doesn’t land on another flower, so huge amounts
are wasted. Usually no petals because there is no need to attract insects. Their
anthers and stigmas dangle outside the flower, to catch the wind. The filaments of
the anthers are very flexible, so they can swing in the wind and release their pollen.
The feathery stigmas have a large surface area, increasing the chances of catching
pollen.

466
Q

Pollination

A

transfer of pollen grains from an anther to a stigma.

467
Q

Self-pollination

A

transfer of pollen grains from the anther of a flower to the
stigma of the same flower or a different flower on the same plant.

468
Q

Cross-pollination

A

transfer of pollen grains from the anther of a flower to the
stigma of a flower on a different plant of the same species.

469
Q

Self-pollination doesn’t produce

A

lots of variation. Less capacity to respond to changes in the environment. They don’t rely on pollinators

470
Q

Cross-pollination produce

A

variation. More capacity to respond to changes in the
environment. They rely on pollinators.

471
Q

Fertilization occurs when

A

a pollen nucleus fuses with a nucleus in an ovule

472
Q

Events which occur between pollination
and fertilisation.

A

A
pollen lands on stigma
pollen (grain) germinates/ pollen (grain)
grows pollen tube
pollen tube grows down the style
reaches the ovule
(tip of) pollen tube breaks open
male gamete travels down the pollen
tube
male gamete enter ovule
(male gamete) fuse with female
gamete
zygote forms.

473
Q

Events which occur between
fertilisation and production of
seed.

A

zygote (is formed)
divides by mitosis
to form embryo
formation of radicle and
plumule
formation of, cotyledons/
seed leaf/ food reserve
formation of teste/ seed
coat
ref to endosperm
seed formed form ovule

474
Q

Testes produce

A

sperm

475
Q

Testes produce

A

testes, as well as providing a sort of climate control system

476
Q

Sperm duct carries

A

sperm away from testis, it then join up with the urethra just below the bladder

477
Q

Urethra

A

can carry both urine and sperm at different time

478
Q

Prostate gland

A

makes semen, a fluid in which sperm can swim in.

479
Q

Function of penis

A

to enter the vagina and release sperm.

480
Q

Ovaries produce

A

eggs or egg cells.

481
Q

Oviducts lead the

A

egg to uterus.

482
Q

Uterus

A

nourish the developing fetus prior to birth

483
Q

Cervix

A

allows fluids to pass between uterus and vagina

484
Q

Vagina

A

the site where sperms are placed after ejaculation

485
Q

Fertilization is the fusion of the nuclei from a

A

male gamete (sperm) and a female gamete (egg cell).

486
Q

Adaptation of sperm:

A

flagellum to swim
lots of mitochondria to provide energy for swimming by respiration.
enzymes in the acrosome to digest its way through the jelly coat.

487
Q

Adaptation of egg cell:

A

energy store to provide energy and nutrients for the growth and development of
zygote after fertilisation.
jelly coat hardens after the entry of one sperm to prevent entry of multiple
sperms.

488
Q

sperms compared to egg cells

A

Sperm cells are lot smaller than egg cells. Sperm cells are streamlined and egg cells
are round. Sperm cells can move by themselves but egg cells cannot. There are
millions of sperms deposited at the vagina but there are maximum of 2 egg cells in
female reproductive system.

489
Q

In early development,

A

the zygote forms an embryo which is a ball of cells that
implants into the lining of the uterus.

490
Q

Placenta connects the

A

embryo to wall of uterus. Placenta is where substances are exchanged between the mother’s blood and the embryo’s blood.

491
Q

Role of placenta in humans:

A

gas exchange
transfer of dissolved nutrients, from maternal (circulation)/ to fetal.
transfer of excretory products, from fetal/ to maternal;
by diffusion
produces/ secretes, (named) hormones;
passive immunity/ antibodies, from maternal/ to fetal
prevents/ limits, mixing of blood
regulating blood pressure
maternal/ fetal attachment point
red to counter current flow/ maintains concentration gradient

492
Q

Role of amniotic fluid:

A

protection from (mechanical) shock (of fetus)
maintains (constant) temperature (of fetus)
allows movement (of fetus)
prevents dehydration

493
Q

Amniotic fluid and the amniotic sac:

A

maintains temperature ;
mechanical shock protection ;
allows movement (of the fetus) ;
provides support (of the fetus) ;
provides a sterile environment / prevents infections ;
(movement) allows for development of bones and muscles ;
ref. to swallowing (of fluid) ;
lubrication / AW ;

494
Q

Some pathogens and toxins can pass across

A

the placenta and affect the fetus

495
Q

Testosterone cause the

A

secondary sexual characters to develop in boys, like growth
of facial hair and pubic hair, broadening shoulders and general muscular
development and a deepening voice

496
Q

Oestrogen

A

cause the secondary sexual characters to develop in girls, like increase
in size of breast, growth of pubic hairs, hips become wide

497
Q

Site of production of oestrogen and progesterone in the menstrual cycle is the

A

ovaries. After ovulation site of progesterone production is corpus luteum. During
pregnancy site of progesterone production is the placenta.

498
Q

Changes to the lining of uterus during menstrual cycle:

A

loss / thinning, of lining (of uterus), at the beginning of the cycle / during first
week / between day 1–7 ;
regrowth / thickening of, lining (of uterus), during second week / after loss (of
lining) / before ovulation ;
thickness of lining remains constant, in the last two weeks / at the end of the
cycle / after ovulation / if no fertilisation ;

499
Q

The role of FSH.

A

FSH stimulates, development / growth / maturation, of follicles (in ovary) ;
-FSH stimulates, development/growth / maturation, of, egg (cell) / ova / ovum /
(female) gamete(s) ;
-FSH stimulates, production / release / secretion, of oestrogen (from ovary) ;

500
Q

The role of LH.

A

(FSH and) LH (surge) stimulates, ovulation / release of egg from ovary
LH stimulates (corpus luteum / yellow body / empty follicle), secretion /
production / release, of progesterone
decrease in LH decreases secretion of progesterone (by corpus luteum) ;

501
Q

The role of estrogen.

A

Stimulates the uterus to develop a lining (to replace the lining lost during
menstruation)
Post-ovulation, inhibits FSH and LH production in the pituitary gland.

502
Q

The role of progestogen.

A

maintains and thickens lining of the uterus
inhibits FSH and LH production
if fertilisation doesn’t occur, levels drop and menstruation occurs.

503
Q

Sexually transmitted infection (STI)

A

is an infection that is transmitted through sexual
contact.

504
Q

Human immunodeficiency virus (HIV)

A

is a pathogen that causes an STI.

505
Q

HIV infection may lead to

A

AIDS

506
Q

Methods of transmission of HIV:

A

sexual contact
sharing contaminated needles
sharing contaminated syringes
blood transfusion
breast milk
tissue/ organ transplant

507
Q

HIV is not spread through

A

saliva

508
Q

Methods to stop the spread of STIs:

A

never have more than one sexual partner use condoms

Biology Flashcards (20 decks)

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