These eight questions follow the chapter from sorting to mutation. Write your answer before you open the explanation.
The lessons are in variation. Record your slips in the mistake log and paper-error review.
Questions
1. Sort these features into continuous or discontinuous: body mass, ABO blood group, tongue rolling, leaf length. (4 marks)
Answer
Continuous: body mass and leaf length. Discontinuous: ABO blood group and tongue rolling.
2. Give two differences between continuous and discontinuous variation. (2 marks)
Answer
Continuous variation has a full range with intermediate values, and a bell-shaped graph. Discontinuous variation has separate groups with no intermediate values, and a bar chart with gaps.
3. Identical twins raised apart differ in height by 5 cm. State the cause and explain. (2 marks)
Answer
The cause is the environment. The twins have the same genes, so the difference must come from surroundings such as diet or health.
4. Explain why blood group is not changed by diet. (2 marks)
Answer
Blood group is controlled by genes, and it does not depend on the environment. Diet changes the body but not the alleles.
5. A class of 40 students is grouped by mass: 40-49 kg has 6, 50-59 kg has 18, 60-69 kg has 12 and 70-79 kg has 4. State the total and the modal group. (3 marks)
Answer
6 + 18 + 12 + 4 = 40. The modal group is 50-59 kg, with 18 students.
6. Using the data in question 5, state the type of variation and explain how you know. (2 marks)
Answer
It is continuous variation. Mass can take any value in the range, and the distribution forms a smooth hump with no gaps.
7. Define mutation and state whether a mutation in a skin cell can be inherited. (3 marks)
Answer
A mutation is a change in the DNA of a gene or chromosome. A mutation in a skin cell is not inherited, because skin cells do not form gametes.
8. Explain how a mutation in a gamete-forming cell can increase variation in a population. (3 marks)
Answer
The mutation produces a new allele. The allele is passed to offspring through gametes, and some individuals show a new feature, so the population varies more.
If you got these wrong
- Questions 1 and 2: revisit comparing continuous and discontinuous variation.
- Questions 3 and 4: read explaining genetic and environmental contributions.
- Questions 5 and 6: work through interpreting variation distributions.
- Questions 7 and 8: see connecting mutation and variation.
If the same error returns, a teacher can trace the cause quickly. See online one-to-one Biology tuition.