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Biology > Reproduction > Flashcards

Reproduction Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

what is sexual reproduction

A

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

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2
Q

what is a gamete

A

a sex cell (in animals: sperm and ovum; in plants: pollen nucleus and ovum)

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3
Q

how do gametes differ from normal cells and why

A

they contain half the number of chromosomes found in other body cells - we say they have a haploid nucleus. 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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4
Q

how many chromosomes are in a normal body cell in humans

A

46

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5
Q

how many chromosomes are in a normal gamete in humans

A

23

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6
Q

what happens when the male and female gamete fuse

A

they become a zygote (fertilised egg cell)
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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7
Q

what are the advantages of sexual reproduction

A

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

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8
Q

what are the disadvantages of sexual reproduction

A

1) takes time and energy to find mates
2) difficult for isolated members of the species to reproduce

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9
Q

what is asexual reproduction

A

the process resulting in genetically identical offspring being produced from one parent

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10
Q

what kind of reproduction does not involve gametes or fertilisation

A

asexual

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11
Q

how many parents are required for asexual reproduction, and what is the outcome

A

only one parent is required so there is no fusion of gametes and no mixing of genetic information. as a result, the offspring are genetically identical to the parent and to each other (they are clones)

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12
Q

what is the most common way plants reproduce

A

asexual reproduction

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13
Q

how do bacteria create exact genetic copies of themselves

A

a type of asexual reproduction called binary fission

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14
Q

how does binary fission occur

A

1) the contents of the parent bacterial cell double, where the circular chromosome and all of the other parts of the cell duplicate
2) this means that the genetic material (DNA) of the bacteria has replicated
3) the cell divides by binary fission, and two genetically identical daughter cells are produced

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15
Q

what are the advantages of asexual reproduction

A

1) population can be increased rapidly when the conditions are right
2) can exploit suitable environments quickly
3) more time and energy efficient
4) reproduction is completed much faster than sexual reproduction

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16
Q

what are the disadvantages of asexual reproduction

A

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

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17
Q

what are the key differences between sexual and asexual reproduction

A

1) the number of parents organisms
2) how offspring are produced (the type of cell division required)
3) the level of genetic similarity between offspring
4) the possible sources of genetic variation in offspring
5) the number of offspring produced
6) the time taken to produce offspring

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18
Q

how many parent organisms are there in asexual vs sexual reproduction

A

1 in asexual and 2 in sexual

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19
Q

what type of cell division is required to produce offspring in asexual vs sexual reproduction

A

mitosis in asexual and meiosis in sexual

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20
Q

what level of genetic variation in offspring are there in asexual vs sexual reproduction

A

only mutation in asexual and three sources in sexual:
1) the contribution of 50% of their DNA from each of the two parents
2) the production of gametes by meiosis (resulting in new combinations of alleles on the chromosomes)
3) the random assortment of chromosomes into gametes during meiosis

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21
Q

what is the number of offspring produced in asexual vs sexual reproduction

A

usually relatively large number in asexual and usually relatively limited numbers in sexual

22
Q

what is the time taken to produce offspring in asexual vs sexual reproduction

A

usually relatively fast in asexual and usually relatively slowly in sexual

23
Q

what path does the sperm take to reach the egg

A

the sperm follow a chemical trail that starts in the cervix, moves through the uterus and up into the oviduct where the egg is located

24
Q

what propels the sperm

A

their tails

25
Q

where is the male nucleus contained

A

in the head region of the sperm

26
Q

what is the function of the prostate gland

A

produces fluid called semen that provide sperm cells with nutrients

27
Q

what is the function of the sperm duct

A

sperm passes through the sperm duct to be mixed with fluids produced by the glands before being passed into the urethra for ejaculation

28
Q

what is the function of the urethra

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

29
Q

what is the function of the testes

A

contained in a bag of skin (the scrotum) and produces sperm and testosterone

30
Q

what is the function of the scrotum

A

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

31
Q

what is the function of the penis

A

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

32
Q

what is the function of the oviduct

A

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

33
Q

what is the function of the ovary

A

contains ova which will mature and develop when hormones are released

34
Q

what is the function of the uterus

A

muscular bag with a soft lining where the fertilised egg will be implanted to develop into a foetus

35
Q

what is the function of the cervix

A

ring of muscle at the lower end of the uterus to keep the developing foetus in place during pregnancy

36
Q

what is the function of the vagina

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

37
Q

why does the sperm have a flagellum (tail)

A

enables it to swim to the egg

38
Q

why does the sperm contain enzymes in the head region (acrosome)

A

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

39
Q

why does the sperm contain many mitochondria

A

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

40
Q

why does the egg have cytoplasm containing a store of energy

A

provides energy for the dividing zygote after fertilisation

41
Q

why does the egg have a jelly like coating that changes after fertilisation

A

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

42
Q

what is the difference in size between a sperm vs an egg

A

a sperm is very small whereas an egg is large

43
Q

what is the difference in structure between a sperm vs an egg

A

sperm has a head region and flagellum and many structural adaptations such as a tail, whereas an egg is a round cell with few structural adaptations, covered in a jelly coating

44
Q

what is the difference in mobility between a sperm vs an egg

A

a sperm is capable of locomotion wheres an egg is not

45
Q

what is the difference in numbers produced between a sperm vs an egg

A

sperm are produced every day in huge numbers (around 100 million per day), whereas thousands of immature eggs are in each ovary but only one released each month

46
Q

during ejaculation in the male, where do the sperm cells move along

A

millions of sperm cells move along the sperm duct

47
Q

what are the sperm suspended in

A

semen (a fluid secreted by the prostate gland)

48
Q

during sexual intercourse, where is semen ejaculated

A

into the vagina of the female, near the cervix

49
Q

how do the sperm reach the uterus

A

the sperm cells follow a chemical trail and travel through the plug of mucus in the cervix to reach the uterus

50
Q

what happens once the sperm reach the uterus

A

the sperm cells then travel into the oviducts

51
Q

where do the sperm and egg meet for fertilisation to occur, and when is this most likely to occur

A

in the oviduct, and 1-2 days after the female has ovulated

52
Q

how does the zygote divide, and what is formed after a few days

A

the zygote divides by mitosis to form two new cells, which then continue to divide like this until an embryo is formed after a few days

Biology (1 decks)

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