OpenRevise

Exam questions · Biology · Reproduction, Meiosis and Variation

Asexual and Sexual Reproduction

  • 6 exam questions
  • 20 marks
  • 9 quick checks
  1. 1 State [2 marks]

    State two differences between asexual and sexual reproduction.

    Show answerHide answer

    Model answer

    Any two from: asexual reproduction needs one parent but sexual needs two; asexual does not involve gametes; asexual offspring are identical to the parent but sexual offspring are different; asexual uses mitosis only.

    Mark scheme

    • First difference — 1 mark
    • Second difference — 1 mark
  2. 2 State [2 marks]

    State two advantages of asexual reproduction.

    Show answerHide answer

    Model answer

    Any two from: no need to find a mate; a rapid reproductive cycle; uses less energy; successful features are kept.

    Mark scheme

    • First advantage — 1 mark
    • Second advantage — 1 mark
  3. 3 Explain [3 marks]

    Explain why there is no variation in the offspring produced by asexual reproduction.

    Show answerHide answer

    Model answer

    Asexual reproduction involves only one parent, and the cells divide by mitosis. Mitosis produces genetically identical cells, so the offspring have exactly the same genes as the parent and as each other.

    Mark scheme

    • One parent, mitosis — 1 mark
    • Produces identical cells — 1 mark
    • Offspring have the same genes — 1 mark
  4. 4 Explain [3 marks]

    Explain one advantage of sexual reproduction to a species.

    Show answerHide answer

    Model answer

    Sexual reproduction produces variation. If the environment changes or a new disease appears, some individuals may have features that help them survive. They can then reproduce, so the species survives.

    Mark scheme

    • Produces variation — 1 mark
    • Some individuals may survive a change — 1 mark
    • The species continues — 1 mark
  5. 5 Explain [4 marks]

    A farmer grows a field of potato plants that were all grown from tubers of one parent plant. A new disease spreads through the field. Explain why the whole crop may be lost.

    Show answerHide answer

    Model answer

    The potato plants grown from tubers are the result of asexual reproduction, so they are all genetically identical clones. If the disease can infect one plant, it can infect all of them, since none of them has a gene that gives resistance. There is no variation, so no plant is likely to survive.

    Mark scheme

    • Grown from tubers, which is asexual — 1 mark
    • All are genetically identical — 1 mark
    • None has resistance — 1 mark
    • No variation, so none may survive — 1 mark
  6. 6 Evaluate [6 marks]

    Some organisms, such as strawberry plants, can reproduce both asexually and sexually. Evaluate the advantages to the strawberry plant of using both methods.

    Show answerHide answer

    Model answer

    Asexual reproduction by runners lets the plant spread quickly and produce new plants that are exactly like the parent, which is useful when the parent is well suited to the habitat. It needs no mate and no pollination. However, the plants are clones, so they are all affected by the same disease or change. Sexual reproduction by flowers and seeds needs pollination and takes longer, but it produces variation, so some seedlings may be resistant to disease or better suited to a changed environment. The seeds can also be spread further. Using both gives the plant a quick increase in numbers and, in the long term, variation for survival.

    Mark scheme

    • Asexual: quick spread, no mate — 1 mark
    • Asexual: clones keep successful features — 1 mark
    • Asexual disadvantage: clones all affected by disease — 1 mark
    • Sexual: variation — 1 mark
    • Sexual: helps survival in change / seeds spread — 1 mark
    • A reasoned conclusion — 1 mark

Quick check

  1. 1

    How many parents are needed for asexual reproduction?

    1. AOne
    2. BTwo
    3. CThree
    4. DNone
    Show answerHide answer

    A: One

    Asexual reproduction needs only one parent.

  2. 2

    What are the offspring of asexual reproduction called?

    1. AGametes
    2. BZygotes
    3. CClones
    4. DMutants
    Show answerHide answer

    C: Clones

    Offspring that are genetically identical to the parent are clones.

  3. 3

    Which is a disadvantage of sexual reproduction?

    1. AIt produces variation
    2. BA mate has to be found
    3. CIt uses mitosis
    4. DThe offspring are clones
    Show answerHide answer

    B: A mate has to be found

    Sexual reproduction needs a mate to be found, which takes time and energy.

  4. 4

    Which is an advantage of asexual reproduction?

    1. AIt produces variation
    2. BIt needs two parents
    3. CIt uses meiosis
    4. DIt has a rapid reproductive cycle
    Show answerHide answer

    D: It has a rapid reproductive cycle

    A rapid reproductive cycle means many offspring can be made quickly.

  5. 5

    Why is variation important to a species?

    1. AIt makes the species grow bigger
    2. BIt stops mutations
    3. CSome individuals may survive a change or disease
    4. DIt makes reproduction quicker
    Show answerHide answer

    C: Some individuals may survive a change or disease

    With variation, some individuals may survive a change in the environment or a new disease.

  6. 6

    Which organism reproduces asexually by runners?

    1. AStrawberry plant
    2. BHuman
    3. CDog
    4. DFrog
    Show answerHide answer

    A: Strawberry plant

    Strawberry plants grow runners, which form new plants that are clones of the parent.

  7. 7

    Why did potato blight destroy so many crops in Ireland?

    1. AThe potatoes were too big
    2. BThe summers were too hot
    3. CThe plants were diploid
    4. DThe potatoes were genetically identical, with no resistance
    Show answerHide answer

    D: The potatoes were genetically identical, with no resistance

    The plants were clones and none was resistant, because there was no variation.

  8. 8

    Which statement about sexual reproduction is correct?

    1. AThe offspring are identical to one parent
    2. BGametes fuse, so the offspring are genetically different
    3. CIt uses only mitosis
    4. DIt needs no mate
    Show answerHide answer

    B: Gametes fuse, so the offspring are genetically different

    Gametes fuse at fertilisation, and the random mix of genes makes the offspring genetically different.

  9. 9

    A species lives in a very stable environment where it is already well adapted, and mates are hard to find. Which type of reproduction may be better?

    1. AAsexual, because it needs no mate and keeps the successful genes
    2. BSexual, because it needs no mate
    3. CSexual, because it produces clones
    4. DNeither
    Show answerHide answer

    A: Asexual, because it needs no mate and keeps the successful genes

    Asexual reproduction needs no mate and keeps the successful genes, so it suits a stable environment where mates are scarce.