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CIE IGCSE Biology > Chapter 16 - Reproduction > Flashcards

Chapter 16 - Reproduction Flashcards

1
Q

What is asexual reproduction?

A

Asexual reproduction is a process resulting in the production of genetically identical offspring from one parent.

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2
Q

Can bacteria reproduce asexually?

A

Yes, bacteria produces exact genetic copies of themselves in a type of asexual reproduction called binary fission.

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3
Q

Can plants reproduce asexually?

A

Yes, plants can reproduce asexually using bulbs and tubers; these are food storage organs from which budding can occur, producing new plants which are genetically identical to the parent plant. Some plants grow side shoots called runners that contain tiny plantlets on them. These are able to grow roots and develop into separate plants

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4
Q

What are the advantages of asexual reproduction?

A

Population can be increased rapidly when conditions are right.
Can exploit suitable environments quickly.
More time and energy efficient.
Asexual reproduction is completed much faster than sexual reproduction.

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5
Q

What are the disadvantages of asexual reproduction?

A

Limited genetic variation in populations. Offspring are genetically identical to their parents.
Population is vulnerable to changes in conditions and may only be suitable for one habitat.
Disease is likely to affect the whole population as there is no genetic variation.

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6
Q

Why is asexual reproduction beneficial to crop plants?

A

Specifically in crop plants, asexual reproduction can be advantageous as it means that a plant that has good characteristics such as high yielding, disease resistant and hardy can reproduce asexually, and the offspring will show the same characteristics.

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7
Q

What is 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.

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8
Q

What is fertilisation?

A

Fertilisation is the fusion of the nuclei of gametes.

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9
Q

What is a gamete?

A

A gamete is a sex cell. They contain a haploid nucleus meaning they only have 23 chromosomes. E.g. an egg and sperm in humans and pollen grains and ovules in plants.

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10
Q

What happens when two gametes fuse?

A

When 2 gametes fuse, they become a zygote which contains a diploid nucleus and has 46 chromosomes.

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11
Q

What are the advantages of sexual reproduction?

A

Increases genetic variation.
The species can adapt to new environment due to variation, giving them a survival advantage.
Disease is less likely to affect population due to variation.

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12
Q

What are the disadvantages of sexual reproduction?

A

Takes time and energy to find mates.
Difficult for isolated members of the species to reproduce.

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13
Q

What is an advantage of crop plants reproducing sexually?

A

Most crop plants reproduce sexually which is an advantage because it means variation is increase and a genetic variant may be produced which is better able to cope with weather changes or produce a significantly higher yield.

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14
Q

What is a disadvantage 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 having a high yield.

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15
Q

Diagram of a flower

A
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16
Q

What is a sepal?

A

Protects unopened flower.

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17
Q

What are petals?

A

Brightly coloured in insect pollinated flowers to attract insects.

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18
Q

What is an anther?

A

Produces and released the male sex cell (pollen grain).

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19
Q

What is a stigma?

A

Top of the female part of the flower which collects pollen grains.

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20
Q

What is an ovary?

A

Protects the female sex cell (ovum).

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21
Q

What is an ovule?

A

Contains the female sex cells (found inside the ovary).

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22
Q

Diagram and characteristics of an insect pollinated flower

A
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23
Q

Diagram and characteristics of a wind pollinated flower

A
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24
Q

What type of pollen do insect pollinated flowers produce?

A

Insect pollinated flowers produce smaller amounts of larger, heavier pollen grains that often contain spikes or hooks on the outside so they can easier stick to insects.

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25
What type of pollen do wind pollinated flowers produce?
Wind pollinated flows produce large amounts of small, lightweight pollen grains that are usually smooth.
26
What is pollination?
Pollination is the transfer of pollen grains from an anther to a stigma.
27
What is self pollination?
Self-pollination is the transfer of pollen grains from the anther of flower to the stigma of the same flower or a different flower on the same plant. This reduces genetic variety of the offspring because all of the gametes come from the same parent and therefore are genetically identical. Due to the lack of variation, it means that they are less likely to have adaptations to respond to changes in the environment.
28
What is cross pollination?
Cross-pollination is the transfer of pollen grains from the anther of a flower to the stigma of a flower of a different plant of the same species. This improves genetic variation as all of the gametes come from different parents. However, cross pollination relies on the presence of pollinators, and this can be a problem if there is a limited number of pollinators.
29
What is fertilisation?
Fertilisation occurs when a pollen nucleus fuses with a nucleus in an ovule.
30
What is germination?
Germination is the start of growth in a seed. Three factors are required for successful germination: Water, oxygen and warmth.
31
Why is water needed for germination?
Water allows the seed to swell up and the enzymes in the embryo to start working so that growth can occur.
32
Why is oxygen needed for germination?
Oxygen so that energy can be released for germination.
33
Why is warmth needed for germination?
Warmth as germination improves as temperature increases (up to a maximum) as the reactions which take place are controlled by enzymes.
34
Diagram of the male reproductive system
35
What is the function of the prostate gland?
Produces fluid called semen that provides sperm cells with nutrients.
36
What is the function of the sperm duct?
Sperm passes through the sperm duct to be mixed with fluids produced by the glands before being passed into the urethra for ejaculation.
37
What is the function of the urethra?
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.
38
What is the function of the testis?
Contained in a bag of skin (scrotum) and produces sperm (male gamete) and testosterone (hormone).
39
What is the function of the scrotum?
Sac supporting the testes outside the body to ensure the sperm are kept at a temperature slightly lower than body temperature.
40
What is the function of the penis?
Passes urine out of the body from the bladder and allows semen to pass into the vagina of a women during sexual intercourse.
41
Diagram of the female reproductive system
42
What is the function of the oviduct?
Connects the ovary to the uterus and is lined with ciliated cells to push the released ovum down it. This is where fertilisation occurs.
43
What is the function of the ovary?
Contains ova (female gametes) which will mature and develop when hormones are released. Oestrogen is produced here.
44
What is the function of the uterus?
Muscular bag with a soft lining where the fertilised egg (zygote) will be implanted to develop into a foetus.
45
What is the function of the cervix?
Ring of muscle at the lower end of the uterus to keep the developing foetus in place during pregnancy.
46
What is the function of the vagina?
Muscular tube that leads to the inside of the women’s body where the male’s penis will enter during sexual intercourse and sperm are deposited.
47
What is fertilisation?
Fertilisation is the fusion of the nuclei from a male gamete (sperm) and a female gamete (egg cell).
48
Diagram of a sperm cell
49
Why does a sperm have a flagellum (tail)?
Enables it to swim to the egg.
50
Why does the sperm contain enzymes in the head region (acrosome)?
To digest through the jelly coat and cell membrane of an egg cell when it meets one.
51
Why does the sperm contain many mitochondria?
Provide energy from respiration so the flagellum can move back and forth for locomotion.
52
Diagram of an egg cell
53
Why does an egg cell have cytoplasm containing a store of energy?
Provides energy for the dividing of the zygote after fertilisation.
54
Why does an egg cell have a jelly like coating that changes after fertilisation?
Forms an impenetrable barrier after fertilisation to prevent other sperm nuclei from entering the egg cell.
55
What are the differences between a sperm and an egg cell in terms of size, structure, mobility and numbers?
56
What is an embryo?
After fertilisation in the oviduct, the zygote travels towards the uterus and divides several times to from an embryo which is a ball of cells that implants itself into the lining of the uterus to continue to grow and develop.
57
Diagram of a foetus
58
What is the function of the amniotic sac?
The amniotic sac surrounds the foetus and produces amniotic fluid.
59
What is the function of amniotic fluid?
Amniotic fluid protects the foetus during development by cushioning it from bumps to the mother’s abdomen.
60
What is the function of the umbilical cord?
The umbilical cord joins the foetus’s blood supply to the placenta for the exchange of nutrients (glucose and oxygen) and removal of waste products (carbon dioxide and urea).
61
What is the function of the placenta?
The placenta is connected to the foetus through the umbilical cord and prevents the mothers and foetuses’ blood from mixing, exchanges dissolved nutrients such as glucose and oxygen and waste products such as carbon dioxide and urea and acts as a barrier to prevent toxins and pathogens getting into the foetus’s blood (although sometimes some pathogens such as rubella are passed through).
62
What are the effects of oestrogen?
Effects of oestrogen in females include breasts developing, body hair growth, menstrual cycle begins, and hips get wider.
63
What are the effects of testosterone?
Effects of testosterone in males include the growth of penis and testes, growth of facial and body hair, muscles develop, voice breaks, and testes start to produce sperm.
64
How long is the average menstrual cycle?
The average menstrual cycle is 28 days long.
65
What is ovulation?
Ovulation (the release of the egg) occurs about halfway through the cycle at day 14 and then the egg travels down the oviduct to the uterus.
66
What is menstruation?
Failure to fertilise the egg causes menstruation which is the breakdown of the thickened lining of the uterus. Menstruation lasts about 5-7 days and signals the beginning the next cycle.
67
What happens after menstruation?
After menstruation finished, the lining the uterus starts to thicken again in preparation for possible implantation in the next cycle.
68
Diagram of the menstrual cycle
69
What is the menstrual cycle controlled by?
The menstrual cycle is controlled by hormones released from the ovary and the pituitary gland in the brain
70
What is FSH (follicle stimulating hormone)?
FSH (follicle stimulating hormone) is released by the pituitary glands and stimulates egg maturation in the follicles of the ovary. It also stimulates the follicles in the ovary to start releasing oestrogen.
71
What is LH (luteinising hormone)?
LH (luteinising hormone) causes ovulation to occur when LH is at its peak, this results in the formation of a corpus luteum which stimulates the production of progesterone. The pituitary gland is stimulated to released luteinising hormone when oestrogen levels have reached their peak.
72
What is oestrogen?
Oestrogen stimulates the uterus to develop a lining (to replace the lining lost during menstruation) and post ovulation inhibits (stops) FSH and LH production in the pituitary gland.
73
What is progesterone?
Progesterone maintains the thickens the lining of the uterus, inhibits (stops) FSH and LH products and if fertilisation doesn’t occur, levels drop, and menstruation occurs.
74
What are all the hormones involved in the menstrual cycle and what do they do?
The pituitary gland produces FSH which stimulates the development of a follicle in the ovary. An egg develops inside the follicle and the follicle produces oestrogen. Oestrogen causes the growth and repair of the lining of the uterus wall and inhibits (stops) the production of FSH. When oestrogen rises to a high enough level, it stimulates the released of LH from the pituitary gland which causes ovulation (usually around day 14 of the cycle). The follicle becomes the corpus luteoma and starts producing progesterone which maintains the uterus lining. If the egg is not fertilised, the corpus luteum breaks down and progesterone levels drop. This causes menstruation. However, if fertilization does occur, the corpus luteum continues to produce progesterone preventing the uterus lining from breaking down. This happens until the placenta has developed at which it starts secreting progesterone and continues to do so throughout the pregnancy.
75
Diagram of the hormones involved in the menstrual cycle
76
Diagram of where hormones for the menstrual cycle are produced and where they act
77
What is an STI (sextually transmitted infection)?
A sexually transmitted infection (STI) is an infection that is transmitted through sexual contact.
78
What is HIV (human immunodeficiency virus)?
Human immunodeficiency virus (HIV) is a pathogen that causes an STI. A HIV infection may lead to aids.
79
How can HIV be transmitted?
HIV can be transmitted by the spread of body fluids including blood, semen, vaginal secretions, anal fluids and breast milk. This is often done by anal or vaginal intercourse with a person who has HIV while not using a condom or sharing equipment for injectable drugs, hormones and steroids with a person who has HIV.
80
How can you control the spread of STIs?
You can control the spread of STIs by limiting the number of sexual partners you have, not having unprotected sex, getting tested, raising awareness by education programmes and not sharing needles.

CIE IGCSE Biology (21 decks)

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