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Biology MA > 3A reproduction > Flashcards

3A reproduction Flashcards

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1
Q

what are the two types of reproduction

A

asexual and sexual

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2
Q

in sexual reproduction what specialized sex cells are produced

A

gametes

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3
Q

what are the two types of gametes

A

sperm (mobile male gamete), ovum (stationary female) (pl. OVA)

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4
Q

what is fertilisation?

A

when the sperm moves to the egg and fuses to produce a zygote that undergoes cell division and develops an embryo

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5
Q

what is the single cell formed by fertilization?

A

zygote

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6
Q

what happens in asexual reproduction

A

there are no gametes or fertilisation!
cells in one part of the body divide by mitosis to form a structure that breaks away from the parent body and grows into a new organism.

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7
Q

what are some types of asexual reproduction?

A

budding (reproducing by having the cell walls divide to form a small version of the adult which eventually breaks off), fission (separation of a body into two new bodies)

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8
Q

organisms that reproduce asexually

A

Hydra, starfish

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9
Q

organisms that reproduce sexually

A

humans, birds, fish

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10
Q

is fertilisation involved in asexual reproduction

A

no

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11
Q

are the formation of gametes by meiosis involved in asexual reproduction

A

no only in sexual

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12
Q

how do the offspring of (a)sexual reproduction compare to other offspring and parent/s

A

asexual: genetical identical copies
sexual: a lot of genetic variation

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13
Q

pros and cons of asexual reproduction

A

PROS
- more efficient
- faster
- all good characters preserved
- more reliable
CONS
- if environment changes all individuals who haven’t adapted enough will be affected (could die out)
- bad traits, genetic mutations
- unable to adapt to change may cause overcrowding

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14
Q

pros and cons of sexual reproduction

A

PROS
- les likely to die due to genetic variation because they are able to adapt
- means offspring won’t receive parents’ disadvantages
CONS
- need to find another parent
- no guarantee fertilisation will take place
- takes longer

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15
Q

what is a gene

A

a section of DNA that determines a particular characteristic of feature. Genes can be found in the nucleus of a cell on the chromosones

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16
Q

what is mitosis?

A

cells divide by mitosis meaning the new cells that are produced are identical copies of the original cell

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17
Q

what are the 4 stages of any sexual reproduction?

A
  • gametes are produced
  • male gamete is transferred to the female gamete
  • fertilisation must occur - sperm cell fuses with the egg
  • zygote formed develops into new individual
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18
Q

where are gametes produced and how

A

sperm-testes
eggs-ovaries
both are produced when cells inside these organs divide
they are produced by MEIOSIS - which produces cells that are not genetically identical and have only half the number of chromosomes as the original cell

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19
Q

what is Meiosis?

A

MEIOSIS - which produces cells that are not genetically identical and have only half the number of chromosomes as the original cell

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20
Q

what are cells that have full number of chromosones?

A

diploid

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21
Q

what are cells that have hlaf the normal no. number of chromosones?

A

haploid

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22
Q

explain fertilisation in detail

A

once the sperm has reached the egg, its nucleus must enter the egg and fuse with the nucleus. As each gamete has only half the normal no chromosomes, the zygote formed by fertilisation will have full no chromosomes.
In humans, the sperm and egg have only 23 chromosomes and a zygote has 46, like all other cells

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23
Q

what does fertilisation do?

A

restore diploid chromosone number
adds additional layer of genetic variation

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24
Q

what is special about sperm and eggs

A
  1. sperm has flagellum
  2. they are all unique as they are formed by meiosis therefore, each time they are brought together there is a diff combo of genes
  3. an extra membrane (fertilisation membrane) prevents addisitonal sperm form entering when the nucleus of a sperm cell has already gotten in
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25
Q

why must a zygote have complete no. cells

A

to be able to divide by mitosis repetedly

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26
Q

what happens in each gender during sexual intercourse

A

sperm, produced in the testes by meiosis, passes along the sperm duct and is mixed with fluid from seminal vesicles. this is called semen and is ejaculated through the urethra into vagina. Sperm begins to swim to oviducts. There may be an egg which cna be fertilised.

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27
Q

What is ovulation

A

each month an egg is released into an oviduct from one of the ovaries

28
Q

what happens after fertilisation?

A

the zygote formed will form into an embryo, which will implant in the lining of the uterus. Here the embryo will develop a placenta, which allows the embryo to receive materials such as oxygen and nutrients from a mother’s blood. It also allows embryo to get rid of waste products such as urea and CO2 aswell as anchoring embryo to uterus. The placenta secretes female hormones, especially progesterone which prevens embryo form being rejected and aborted.

29
Q

what is placenta?

A

placenta - allows the embryo to receive materials such as oxygen and nutrients from a mother’s blood.
It also allows embryo to get rid of waste products such as urea and CO2 aswell as anchoring embryo to uterus.
The placenta secretes female hormones, especially progesterone which prevens embryo form being rejected and aborted.

30
Q

what are the differences between sexual and asexual reproduction?

A

lots of genetic variation in sexual, identical in asexual,
fertilisation and meiosis in sexual but not in asexual

31
Q

how can plants reproduce by natural methods?

A

e.g, runners (strawberries)
A slender fast growing stem that grows horizontally over the soil surface and puts down roots to form new plants
e.g., tubers (budding) (potato)
underground food stores over winter and provide new plant with food until it can make its own
e.g., bulbs (daffodils, onions)
base of leaves become swollen with food-buds in bulbs form into its own plant

32
Q

how can plants be reproduced by artificial methods?

A

e.g., cutting
a piece of a plant’s stem with a few leaves attatched, is cut from a healthy and planted into damb soil, or compost, where it will grow roots and develop into a new plant
e.g., grafting
a cut stem of one plant is attatched to rootstock (with good flower/fruit) of another plant (stock), which has strong established system e.g., fruit trees, growth
e.g., micropropagation
adapt it to our own use with consistent quality and desired features

33
Q

how to take a cutting, step by step

A

remove a small piece of stem, with leaf attatched if possible
dip the stem into rooting hormone powder to encourage root growth
place the cutting into some compost/ straight into a container full of water
water the compost and cover the plant pot eith a clean polyhtene bag
transport into a bigger pot when the stem has produced roots

34
Q

what are the pros of artificial propagation>

A

allows us to adapt a plant to our specific needs, can produce specific features, fast production of large number of genetically identical plants

35
Q

why do cells carry out mitosis?

A

to produce starting cells (asexual reproduction), growth, repair tissue, replacement of dead cells

36
Q

whati is the aim of mitosis

A

to coppy genetic information and seperate it into 2 cells

37
Q

explain mitosis fully

A
  1. Prior to the start of mitosis, DNA replicates. A cell that has not yet started to divide has a clear nucleus surrounded by a nuclear membrane, and individual chromosomes cannot be seen.
  2. Once mitosis begins, duplicated chromosomes begin to condense and become visible inside the nucleus. A spindle starts to form in the cytoplasm.
  3. The nuclear membrane has now disappeared, and the duplicated chromosomes line up along the equator of the cell. The spindle forms from either pole of the cell and attaches to the centre of the chromosomes
  4. The sister chromatids are pulled apart and spindle fibres pull the now chromosomes them to the opposite poles of the cell.
  5. The chromosomes reach the poles of the cell. The spindle begins to break down and the nuclear membrane starts to reform around the chromosomes.
    The cytoplasm begins to cleave in half along the equator of the original cell.
  6. The cytoplasm splits in two. New cell membranes form.
    Two new daughter cells are formed. Each cell contains exactly the same DNA as the original parent cell - genetically identical daughter cells.
38
Q

what type of cell do gametes produce?

A

somatic (aka not sperm or egg cells)

39
Q

what is the number of times the cell is divided during mitosis and meiosis?

A

mitosis-1
meiosis-2

40
Q

what is the number daughter cells produced during mitosis and meiosis?

A

mitosis - 2
meiosis - 4

41
Q

what is the number of chromosones in daughter cell produced during mitosis and meiosis?

A

mitosis -46
meiosis-23

42
Q

what is the type of cell produced during mitosis and meiosis?

A

mitosis- somatic
meiosis- gamete

43
Q

is there genetic variation in/ during mitosis and meiosis?

A

mitosis-no
meiosis-yes

44
Q

where in plants do mitosis and meiosis occur?

A

mitosis-everywhere especially roots
meiosis-ovule, anthers

45
Q

where in mammals do mitosis and meiosis occur?

A

mitosis-everywhere
meiosis-reproductive organs

46
Q

where are gametes in plants found

A

pollen nuclei found in plants, ova in ovules and ovaries

47
Q

how can male gametes get to female sex organs before fertilisation?

A

self pollination, cross pollination

48
Q

pros for cross pollination/self pollination?

A

CP-more variation
SP-more reliable especially if isolated

49
Q

How does the stigma vary in insect pollinated and wind pollinated flowers and how are they adapted for pollination?

A

wind - STIGMA EXPOSED - so that wind blows pollen away - there is no need for stigma to be protected as it doesn’t need to get pollen
wind- STIGMA ARE FEATHERY to get pollen grains blowing in the wind
insect - STIGMA ENCLOSED WITHIN THE FLOWER - to make sure insect comes in contact with pollen

50
Q

How does the pollen grains vary in insect pollinated and wind pollinated flowers and how are they adapted for pollination?

A

wind- pollen grains are small, smooth, inflated to be more easily carried by wind
insect - large and sticky with hooks to stick to insect’s bodies

51
Q

How does the nectaries vary in insect pollinated and wind pollinated flowers and how are they adapted for pollination?

A

wind - nectaries are absent as no insects are being attracted
insect-nectaries present because the insects need to be attracted (a reward)

52
Q

How does the stamen vary in insect pollinated and wind pollinated flowers and how are they adapted for pollination?

A

wind- exposed so the pollen can easily blow away
insect- stamen enclosed within the flower so that insect must make contact

53
Q

How does the petals vary in insect pollinated and wind pollinated flowers and how are they adapted for pollination?

A

wind - green, small as they don’t need to attract insects
insect- brightly coloured, large to attract insects

54
Q

what is self pollination?

A

when the pollen grains are transferred from the anthers of a flower to the stigma by wind/insect

55
Q

what is cross pollination?

A

when pollen grains are transferred from one flower to another which can happen by wind or insect

56
Q

what does pollination do in a plant?

A

transfers pollen grain to the stigma

57
Q

what must happen in a plant for fertilisation to take place?

A

the nucleus of the pollen grain (male gamete) must fuse witht he nucleus of the ovum which is inside an ovule in the ovary

58
Q

what happens so that the nucleus of the male gamete in a plant to the ovum (in ovule in ovary)

A

the pollen grain must form which grows down through through the tissue of the style and into the ovary. Here it curves into around to enter the opening in an ovule. Then the tip of the tube dissolves and allows the pollen grain nucleus to move out of the tube into the ovule. Here it fertilises the ovum nucleus

59
Q

what happens once fertilisation has occured in plants?

A

a number of changes take place in the ovary, leading the fertilised ovule becoming into a seed and the ovary in which it is found becoming a fruit
1. the zygote develops into an embryonic plant with small root (radicle) and shoot (plumule)
2. other contents of the ovule develop into a food store for the young plant when the seed germinated
3. the ovule wall becomes the seed coat or testa
4. the ovary wall becomes the fruit coat; this can rtake many forms depending on the type of fruit

60
Q

what happens after fertilisation in a plant?

A

a number of changes take place in the ovary, leading the fertilised ovule becoming into a seed and the ovary in which it is found becoming a fruit
1. the zygote develops into an embryonic plant with small root (radicle) and shoot (plumule)
2. other contents of the ovule develop into a food store for the young plant when the seed germinated
3. the ovule wall becomes the seed coat or testa
4. the ovary wall becomes the fruit coat; this can rtake many forms depending on the type of fruit

61
Q

what is needed for a plant ot fertilise?

A

the pollen grain must form which grows down through through the tissue of the style and into the ovary. Here it curves into around to enter the opening in an ovule. Then the tip of the tube dissolves and allows the pollen grain nucleus to move out of the tube into the ovule. Here it fertilises the ovum nucleus

62
Q

what happens during germination in a plant?

A

a seed contains a plant embryo consisting of a root (radicle), shoot (plumule), one or two seed leaves (cotyledons), food store either in cotyledons of another part of seed. During germination, the food store is used up, providing the nutrients to allow the radicle and plumule to grow. The radicle grows into soil to absorb water, mineral ions and , plumule grows towards light so photosynthesis can take place. once the plant (seedling is able to carry out photosynthesis, germination is over

63
Q

what is a cotyledon? how many are there in a plant and how does the name change because of this? give examples

A

the seed of plants ususally have one (monocots) or two (dicots) cotyledons which are seed leaves.
dicots - beans, peas
monocots - seeds of grasses and other narrow leaved plants like irises and orchids

64
Q

what (3) conditions are needed for germination?

A

when seeds are dispersed from the parent plant they are ususally very dry, containing around 105 water. this low water content restricts a seed’s metabolism, so that it can remain alive or dormant (inactive) for a long time, sometimes for many years. when it germinates, dormancy comes to an end and the seeds food store is broken down by enzymes and respired aerobically so it needs:
1. WARM TEMPERATURES, so the enzymes can act efficiently
2. WATER FOR CHEMICAL REACTIONS TO TAKE PLACE IN SOLUTION
3. OXYGEN for respiration

65
Q

what is germination?

A

the growth of a new plant from a seed

66
Q

PRACTICAL - describe the investigation to find conditions needed for germination, what will be found

A

small seeds such as peas on mustard will grow on wet cotton wool in a test tube
1. set up 4 test tubes: a,b,c,d
a. seeds on wet cotton wool, maintained at 20C (room temp) - CONTROL
b. seeds on dry cotton wool, 20C
c. seeds boiled in water with. thin surface layer of oil maintained at 20C (to keep all oxygen out)
d. seeds on wet cotton wool placed in a refrigerator at 4C
What will be found?
tube a will germinate
tube b and c won’t germinate
tube d may eventually start to germinate byt more slowly than A
the control-type of seeds, same stage of growth, same amount of water in wet cotton wools, same number of seedlings
being measured-water, oxygen, temp
mke sure to repeat
(how will you measure germination? either % germinated or av height of seedlings)

67
Q
A

Biology MA (11 decks)

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