Exam questions · Biology
Reproduction and Meiosis
- 18 exam questions
- 56 marks
- 27 quick checks
Sexual and Asexual Reproduction
Just this lesson-
1 State [1 mark]
State the name of the male gamete in a flowering plant.
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Model answer
Pollen.
Mark scheme
- Pollen (cell) — 1 mark
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2 Describe [2 marks]
Describe what is meant by asexual reproduction.
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Model answer
Asexual reproduction involves only one parent, and there is no fusion of gametes. The offspring are genetically identical to the parent.
Mark scheme
- One parent, no gametes — 1 mark
- Offspring are identical — 1 mark
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3 Explain [3 marks]
Explain why the offspring from sexual reproduction show variety.
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Model answer
In sexual reproduction, a male gamete fuses with a female gamete. The gametes are made by meiosis, so they are genetically different. The genetic information from the two parents is mixed, so the offspring are different from the parents and from each other.
Mark scheme
- Gametes from two parents fuse — 1 mark
- Genetic information is mixed — 1 mark
- Offspring are different from each other — 1 mark
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4 Compare [3 marks]
Compare mitosis and meiosis.
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Model answer
Mitosis forms two genetically identical cells, but meiosis forms four genetically different cells. Mitosis is used in growth and in asexual reproduction, while meiosis forms gametes in the reproductive organs. In mitosis the cells have the full number of chromosomes, but in meiosis they have half the number.
Mark scheme
- Identical and non-identical cells — 1 mark
- Two cells and four cells, or growth and gametes — 1 mark
- Full and half the number of chromosomes — 1 mark
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5 Explain [4 marks]
Strawberry plants can reproduce by growing new plants on runners, and by producing seeds. Explain the differences between the offspring from the two methods.
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Model answer
The plants that grow from runners are produced by asexual reproduction, with only one parent and only mitosis. They are genetically identical to the parent, so they are clones. The seeds are made by sexual reproduction, when the gametes of two plants fuse. The plants from seeds have a mixture of the genes of the two parents, so they are genetically different from the parent and from each other.
Mark scheme
- Runners are asexual, with one parent — 1 mark
- Offspring are identical clones — 1 mark
- Seeds are sexual, with fusion of gametes — 1 mark
- Offspring are different, genetic information mixed — 1 mark
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6 Evaluate [6 marks]
A farmer grows a crop of identical plants that were produced by asexual reproduction. Discuss the advantages and disadvantages of this.
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Model answer
All of the plants are clones, with the same genes, so every plant will have the same characteristics, such as yield and fruit size, which makes the crop uniform and predictable for the farmer. Only one parent is needed, and many identical plants can be produced quickly. However, there is no variation in the crop. If a new disease arrives, or the environment changes, then all of the plants are equally likely to be affected, because they have the same genes, so the whole crop could be lost. A crop produced by sexual reproduction would have variation, so some plants may survive, but the plants would not all be the same.
Mark scheme
- Clones are identical, so a uniform crop — 1 mark
- Only one parent, fast production — 1 mark
- No variation — 1 mark
- All affected by the same disease — 1 mark
- Whole crop could be lost — 1 mark
- Sexual reproduction would give variation — 1 mark
Quick check
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1
Which of these is the male gamete in animals?
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C: The sperm cell
The sperm cell.
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2
How many parents are involved in asexual reproduction?
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A: One
One.
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3
Which type of cell division makes gametes?
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D: Meiosis
Meiosis.
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4
What are genetically identical offspring called?
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B: Clones
Clones.
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5
Why does sexual reproduction lead to variety?
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C: Genetic information from two parents is mixed
Genetic information from two parents is mixed.
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6
Which type of cell division is involved in asexual reproduction?
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A: Mitosis only
Mitosis only.
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7
How many cells does meiosis form from one cell?
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D: Four
Four.
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8
What are the male gametes of a flowering plant?
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B: Pollen cells
Pollen cells.
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9
Which statement about mitosis is correct?
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C: It forms genetically identical cells
It forms genetically identical cells.
Meiosis and Fertilisation
Just this lesson-
1 State [1 mark]
State the number of chromosomes in a human egg cell.
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Model answer
23.
Mark scheme
- 23 — 1 mark
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2 Describe [3 marks]
Describe what happens when a cell divides by meiosis to form gametes.
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Model answer
Copies of the genetic information are made. The cell then divides twice, to form four gametes. Each gamete has a single set of chromosomes, and all the gametes are genetically different from each other.
Mark scheme
- Copies of the genetic information are made — 1 mark
- Divides twice, to make four gametes — 1 mark
- Single set of chromosomes, all different — 1 mark
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3 Explain [3 marks]
Explain why gametes must have half the number of chromosomes of a normal body cell.
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Model answer
When the gametes fuse at fertilisation, their chromosomes are added together. If they had the full number, the fertilised egg would have double the normal number. With half each, the fertilised egg has the normal number.
Mark scheme
- Chromosomes are added at fertilisation — 1 mark
- Full number would double the number — 1 mark
- Half each restores the normal number — 1 mark
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4 Calculate [2 marks]
A body cell of a horse has 64 chromosomes. State the number of chromosomes in a horse sperm cell, and in a fertilised horse egg.
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Model answer
A sperm cell has 32 chromosomes, and a fertilised egg has 64.
Mark scheme
- 32 — 1 mark
- 64 — 1 mark
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5 Describe [3 marks]
Describe what happens to a fertilised egg cell as an embryo develops.
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Model answer
The fertilised egg cell divides by mitosis, so the number of cells increases and the cells are identical. As the embryo develops, the cells differentiate, which means that they become specialised.
Mark scheme
- Divides by mitosis — 1 mark
- Number of cells increases — 1 mark
- Cells differentiate — 1 mark
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6 Evaluate [6 marks]
Explain how meiosis and fertilisation produce offspring that are genetically different from their parents, but that have the normal number of chromosomes.
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Model answer
In the reproductive organs, a cell divides by meiosis to form gametes. The cell makes copies of its genetic information, and divides twice, to form four gametes. Each gamete has a single set of chromosomes, which is half the normal number, and the gametes are all genetically different from each other. At fertilisation, a male and a female gamete fuse, and their chromosomes are added together, so the fertilised egg has the normal number of chromosomes. The fertilised egg has genetic information from both parents, and this is a new mixture, so the offspring is genetically different from each parent, which gives variety. The fertilised egg then divides by mitosis, and the cells differentiate as the embryo develops.
Mark scheme
- Meiosis forms gametes — 1 mark
- Half the number of chromosomes — 1 mark
- Gametes are genetically different — 1 mark
- Fertilisation restores the normal number — 1 mark
- Mixture of information from both parents, so variety — 1 mark
- Mitosis and differentiation of the embryo — 1 mark
Quick check
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1
How many cells are formed when one cell divides by meiosis?
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D: Four
Four.
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2
How many chromosomes are in a human sperm cell?
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B: 23
23.
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3
What does fertilisation restore?
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A: The normal number of chromosomes
The normal number of chromosomes.
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4
What type of cell division follows fertilisation?
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C: Mitosis
Mitosis, which makes identical cells.
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5
What happens to the cells of an embryo as it develops?
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B: They differentiate
They differentiate.
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6
Where does meiosis take place?
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D: In the reproductive organs
In the reproductive organs.
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7
How do the four gametes made by one cell compare?
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A: They are all genetically different
They are all genetically different.
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8
A cell has 20 chromosomes. How many are in each gamete made by meiosis?
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C: 10
Half of 20 is 10.
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9
What is an embryo?
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B: A ball of cells formed from a fertilised egg
A ball of cells formed by the division of the fertilised egg.
Advantages and Disadvantages of Sexual and Asexual Reproduction
Just this lesson-
1 State [1 mark]
State one advantage of asexual reproduction.
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Model answer
Only one parent is needed, or it is faster, or it is more efficient.
Mark scheme
- A correct advantage — 1 mark
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2 Describe [2 marks]
Describe how a strawberry plant can reproduce both sexually and asexually.
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Model answer
It reproduces sexually by producing seeds from flowers, and asexually by growing runners, which form new plants.
Mark scheme
- Seeds, sexually — 1 mark
- Runners, asexually — 1 mark
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3 Explain [3 marks]
Explain why sexual reproduction gives a survival advantage when the environment changes.
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Model answer
Sexual reproduction produces variation in the offspring. If the environment changes, some of the offspring may have characteristics that are better suited to the new conditions. These survive and reproduce, by natural selection, and pass on their genes.
Mark scheme
- Variation in the offspring — 1 mark
- Some are better suited to the new conditions — 1 mark
- They survive and reproduce, natural selection — 1 mark
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4 Explain [3 marks]
Explain why malarial parasites reproducing sexually in the mosquito may make malaria harder to treat.
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Model answer
Sexual reproduction gives variation, with new combinations of genes. Some of the parasites may be resistant to a drug. These survive the treatment and reproduce, so the resistant parasites become more common.
Mark scheme
- Sexual reproduction gives variation — 1 mark
- Some are resistant to the drug — 1 mark
- They survive and become more common — 1 mark
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5 Explain [4 marks]
A daffodil can reproduce by bulb division and by seeds. Explain one advantage of each method.
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Model answer
Bulb division is asexual, so it needs only one parent, and it is faster and gives many identical plants, which will all flower and grow well in the same conditions. Seeds are produced by sexual reproduction, which gives variation, so if the environment changes some of the plants may survive.
Mark scheme
- Bulb division needs one parent, or is faster — 1 mark
- Many identical plants, favourable conditions — 1 mark
- Seeds give variation — 1 mark
- Survival if the environment changes — 1 mark
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6 Evaluate [6 marks]
A rare plant species can be grown from seed, or from cuttings. A conservationist wants to increase the number of plants quickly. Evaluate the two methods, and suggest which would be better in the long term.
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Model answer
Cuttings are asexual reproduction, and need only one parent, so many identical plants can be made quickly, and each will have the same characteristics as the parent, which will be well suited to the habitat. This is a quick way of increasing the number of plants. However, all the plants will be clones, with no variation, so a disease or a change in the environment could kill them all. Growing from seed is sexual reproduction, which is slower, because the plants have to flower and be pollinated, but the seeds produce variation, so some of the plants may be resistant to a disease, or suited to a changed environment. In the long term, the variation from seeds is better for the survival of the species, but cuttings could be used first to increase the number quickly.
Mark scheme
- Cuttings are asexual and quick — 1 mark
- Identical plants, same suited characteristics — 1 mark
- No variation, so all affected by disease or change — 1 mark
- Seeds are sexual and slower — 1 mark
- Seeds give variation, so some survive — 1 mark
- Conclusion with a reason — 1 mark
Quick check
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1
Which is an advantage of sexual reproduction?
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C: It produces variation in the offspring
It produces variation in the offspring.
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2
Which is an advantage of asexual reproduction?
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A: It is more time and energy efficient
It is more time and energy efficient, because no mate is needed.
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3
Where do malarial parasites reproduce sexually?
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B: In the mosquito
In the mosquito.
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4
How do fungi reproduce asexually?
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D: By spores
By spores.
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5
How do strawberry plants reproduce asexually?
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A: By runners
By runners.
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6
How do daffodils reproduce asexually?
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C: By bulb division
By bulb division.
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7
Why does variation help a species when the environment changes?
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B: Some individuals may be better adapted and survive
Some individuals may be better adapted, and survive.
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8
Which of these is a disadvantage of asexual reproduction?
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D: There is no variation in the offspring
There is no variation in the offspring.
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9
How can humans speed up natural selection?
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A: By selective breeding
By selective breeding.