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Biololgy IGCSE continued 13-21 > 16: Reproduction > Flashcards

16: Reproduction Flashcards

1
Q

Describe asexual reproduction

A

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

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2
Q

Advantages & disadvantages of asexual reproduction

a) to a population of a species in the wild
b) to crop production

A

a)
ADVANTAGES
1. only one parent required
2. genetically identical to parent
DISADVANTAGES
1. little genetic variation

b)
ADVANTAGES
1. faster
2. more energy efficient
DISADVANTAGES
1. populations with low genetic diversity
2. compounding resource competition

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3
Q

Describe 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

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4
Q

Difference of nuclei - gametes & zygote

A

Nuclei of gametes = haploid
Nuclei of a zygote = diploid

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5
Q

Describe fertilisation

A

As the fusion of the nuclei of gametes

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6
Q

Advantages & disadvantages of sexual reproduction

a) to a population of a species in the wild
b) to crop production

A

a)
ADVANTAGES
1. lots of genetic variation
DISADVANTAGES
1. genetically unique = not all will be suited to the conditions that suit their parents

b)
ADVANTAGES
1. variations are more viable
2. selective breeding
DISADVANTAGES
1. cannot be done alone
2. long & slow process

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7
Q

Function of receptacle

A

An expanded stem-tip, which provides a supportive base for the flower structures

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8
Q

Function of a sepal

A
  • leaf like structures which protect the flower bud
  • they may be green or look similar to the petals
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9
Q

Function of petal

A
  • often brightly coloured, scented & attractive to pollinators
  • can provide a landing place for small pollinators
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10
Q

Function of nectary

A

A small glandular organ often at the base of the petals that produces a sugary solution called NECTAR to reward pollinators for visiting a flower

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11
Q

Function of stamen

A

A collective name for male sex organs

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12
Q

FOUND IN STAMEN
Function of filament

A

A firm, long stalk that holds the anther in a good position to release pollen on a visiting pollinator

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13
Q

FOUND IN STAMEN
Function of anther

A

The place which produces, contains, and releases pollen grains

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14
Q

FOUND IN STAMEN
Function of pollen

A

Each grain contains a male gamete nucleus
The POLLEN grains are often quite large and rough, so they are better at latching on to the insect
Relatively small quantities are produced as there is a good chance of an insect transferring it to another flower of the same species

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15
Q

Function of carpel

A

A collective name for female sex organs

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16
Q

FOUND IN CARPEL
Function of stigma

A

A platform on which pollen grains land
The site of POLLINATION

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17
Q

FOUND IN CARPEL
Function of style

A

A stiff stalk that holds the stigma in a good position to receive pollen from a visiting pollinator

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18
Q

FOUND IN CARPEL
Function of ovary

A

A hollow chamber which produces and contains ovules
The site of FERTILISATION
Each fertilised ovule will become a seed

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19
Q

FOUND IN CARPEL
Function of ovule

A

Each one contains a female gamete nucleus

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20
Q

Difference between pollen grains of insect-pollinated and wind-pollinated flowers

A

INSECT: smaller amounts (grains = round & sticky or covered in spikes)

WIND: larger amounts (smooth & light pollen grains)

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21
Q

Describe pollination

A

The transfer of pollen grains from an anther to a stigma

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22
Q

Describe self-pollination

A

The 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

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23
Q

Describe cross-pollination

A

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

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24
Q

Effects of self-pollination on a population

A
  • DECREASED genetic variation
  • increased HOMOzygosity
  • harmful recessive characteristics more likely to be expressed
  • LESS reliant on pollinators
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25
Q

Effects of cross-pollination on a population

A
  • INCREASED genetic variation
  • increased HETEROzygosity
  • harmful recessive characteristics less likely to be expressed
  • MORE reliant on pollinators
26
Q

When does fertilisation occur?

A

When a pollen nucleus fuses with a nucleus in an ovule

27
Q

Describe the growth of the pollen tube

A

Its entry into the ovule followed by fertilisation

28
Q

Structural adaptations of an insect-pollinated
1. flowers
2. stamen
3. carpel

A

flowers = bright, scented, ATTRACTS INSECTS
stamen = INSIDE flower, makes pollen grains
carpel = small surface area INSIDE flower, recieves pollen grains

29
Q

Structural adaptations of a wind-pollinated flower
1. flowers
2. stamen
3. carpel

A

flowers = absent, small
stamen = LONG filaments, anthers hang OUTSIDE the flower
carpel = large & feathery, OUTSIDE the flower (catch pollen by the wind)

30
Q

Environmental conditions that affect germination of seeds

A
  • Water
  • Oxygen
  • A suitable temp
31
Q

Function of the testes

A

Make testosterone & sperm

32
Q

Function of the scrotum

A

Holds testes, nerves & blood vessels

33
Q

Function of sperm duct

A

Move sperm AWAY from its storage place in the testicle

34
Q

Function of prostate glands

A

adds additional fluid to the ejaculate, helps nourish sperm

35
Q

Function of urethra

A

transports semen and urine OUT of the body

36
Q

Function of the penis

A

male organ used for sexual intercourse

37
Q

Function of the ovary

A
  • produces female gametes
  • makes hormones: oestrogen & progesterone
38
Q

Function of the funnel of the oviduct

A

transports the ovaries from the ovaries to the uterus

39
Q

Function of the oviduct

A
  • regulates fertilisation through sperm
  • provides a passage route for the ovary
40
Q

Function of the uterus (endometrium)

A
  • sheds each menstrual cycle
  • after ovulation, gets thicker in preparation for a fertilised egg
41
Q

Function of the uterus (muscle wall)

A
  • helps DILATE the cervix (push fetus out)
42
Q

Function of cervix

A
  • produces mucus (stops sperm from entering uterus when not fertile)
  • protecting against BACTERIA
  • allowing fluids to drain
43
Q

Function of vagina

A
  • allows fluids (menstural blood & discharge) leave the body
  • allows semen to enter the body
44
Q

Describe fertilisation

A

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

45
Q

Adaptive feature of sperm

A
  • has a flagellum (can swim to the egg)
  • contains enzymes in the head region (to digest through the jelly coat & cell membrane of an egg cell when it meets ONE)
46
Q

Adaptive feature of egg cells

A
  • cytoplasm contains a store of energy (provides energy for the dividing zygote after fertilisation)
  • jelly like coating changes after fertilisation (forms an impenetrable barrier after to prevent sperm nuclei entering the egg)
47
Q

Function of the umbilical cord

A

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

48
Q

Function of the placenta

A

acts as a barrier to prevent toxins and pathogens getting into the fetus’s blood
MOTHERS & FOETUS BLOOD DOES NOT MIX

49
Q

Function of the amniotic sac

A
  • secretes & holds amniotic fluid
50
Q

Function of the amniotic fluid

A
  • supports foetus whilst allowing free movement (physical protection)
51
Q

What passes across the placenta and can affect the fetus?

A

Pathogens & toxins

52
Q

Describe the role of testosterone

A
  • process of gamete development
  • development of secondary sexual characteristics
53
Q

Describe the roles of oestrogen

A
  • controlling certain processes in the MENSTURAL cycle each month
  • development of secondary sexual characteristics
54
Q

Describe the menstural cycle (terms: changes in ovaries & living of the uterus)

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
Failure to fertilise the egg = menstruation (a period) to occur - this is caused by the breakdown of the thickened lining of the uterus
LASTS around 5 - 7 days
menstruation finishes = lining of the uterus starts to thicken again in preparation for possible implantation in the next cycle

55
Q

Production of oestrogen

A

made in ovary: follicle cells
function: triggers ovulation, stimulates development of the corpus luteum and its production of progesterone

56
Q

Production of progesterone

A

made in ovary: corpus luteum
function: mains the uterus lining, inhibits FSH production

57
Q

Role of hormones (progesterone & oestrogen, FSH, LH)

A
  • Oestrogen (1-14) = causes the uterine wall to start thickening and the egg to mature
    PEAK in oestrogen occurs just before the egg is released
  • Progesterone starts to rise ONCE ovulation has occurred = causes the uterine lining to thicken further; a fall in progesterone levels causes the uterine lining to break down (menstruation / ‘period’)
    FSH (follicle-stimulating hormone) = stimulates the ovaries to start releasing oestrogen
    LH = causes ovulation to occur and also stimulates the ovary to produce progesterone
58
Q

Describe a sexually transmitted infection

A

an infection that is transmitted through sexual contact

59
Q

What is a human immunodeficinecy virus (HIV)?

A

It is a pathogen that causes an STI

60
Q

What can HIV lead to?

A

AIDS

61
Q

Describe the methods of transmission of HIV?

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

Biololgy IGCSE continued 13-21 (7 decks)

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