Exam practice

Exam questions

Write your answer. Then open the mark scheme and tick each point you made.

  1. Question 1 of 102 marks

    Give one example of a feature that is inherited and one example of a feature that is caused by the environment.

    Mark scheme
    • Inherited: for example, blood group or natural eye colour
    • Environmental: for example, a scar, a tattoo or the language a person speaks
  2. Question 2 of 102 marks

    A student records the blood group of everyone in her class. Name the kind of chart she should draw, and give a reason.

    Mark scheme
    • A bar chart (with gaps between the bars)
    • Blood group is discontinuous (accept: it falls into separate groups)
  3. Question 3 of 103 marks

    Describe how genetic information passes from parents to their offspring.

    Mark scheme
    • It is carried by genes (accept: DNA or chromosomes) in the egg and the sperm (accept: gametes)
    • An egg and a sperm each carry half the number of chromosomes of a body cell (accept: 23 in humans)
    • They join at fertilisation, so the offspring has a full set, half from each parent
  4. Question 4 of 102 marks

    A brother and a sister have the same two parents. Explain why they look alike but are not identical.

    Mark scheme
    • Alike: both inherited their genes from the same two parents
    • Not identical: each egg and each sperm carries a different mix of the parents’ genes (accept: each child inherits a different combination of genes)
  5. Question 5 of 102 marks

    State what a gene is, and where in a cell genes are found.

    Mark scheme
    • A section of DNA (that controls an inherited feature)
    • On the chromosomes (accept: in the nucleus)
  6. Question 6 of 101 mark

    Write these in order of size, starting with the largest: gene, nucleus, chromosome, cell.

    Mark scheme
    • Cell, nucleus, chromosome, gene (all four in the right order)
  7. Question 7 of 102 marks

    Describe what Rosalind Franklin did, and what Watson and Crick did, to work out the structure of DNA.

    Mark scheme
    • Franklin: took X-ray pictures of DNA (accept: Photo 51), which showed that it is a helix
    • Watson and Crick: used the evidence to build a model of DNA, the double helix
  8. Question 8 of 104 marks

    Soot from factories turned the bark of trees dark. Over many years, dark peppered moths became more common than light ones. Use natural selection to explain why.

    Mark scheme
    • Variation: some moths were light and some dark, and colour is inherited
    • Dark moths were harder for birds to see on the dark bark (accept: better camouflaged)
    • So more dark moths than light moths survived and bred
    • They passed the genes for dark colour to their offspring, so the proportion of dark moths rose with each generation
  9. Question 9 of 102 marks

    Give two reasons why a species may become extinct.

    Mark scheme
    • A change in its environment, such as a change in climate or the loss of its habitat
    • A new predator, a new disease or a new competitor
    • Hunting by humans

    Any two of these, for one mark each.

  10. Question 10 of 102 marks

    Explain what a gene bank is and why gene banks are useful.

    Mark scheme
    • A store of seeds, eggs, sperm or tissue (accept: a store of genetic material)
    • The genes of a species or variety are not lost if it dies out (accept: it may be grown or bred again, or used to breed new crops)
These questions and their mark scheme (PDF)