For questions 1–10 circle or highlight or bold the alternative A, B, C, or D that best answers the question.
1. Some tree creepers in Australia use their long thin beak to probe the bark of trees for insects. Woodpeckers in North America use their long, curved beak to remove insects from the tree bark. Which of the following terms best describes the development of these similar food-gathering methods?
(a) Radial evolution
(b) Punctuated evolution
(c) Convergent evolution
(d) Divergent evolution.
2. In rabbits, short hair (H) is dominant over long hair (h). The offspring produced from a cross between a short-haired female and a long-haired male were one long-haired and seven short-haired individuals. Which of the following combinations represents the genotypes of the parents.
(a) Hh and Hh
(b) HH and hh
(c) HH and Hh
(d) Hh and hh.
3. In Drosophila red eye (R) is dominant to brown (r) and straight wing (S) is dominant to curled wing (s). The offspring from the cross RrSs and rrss are as follows:
• 25% red eyes, straight wings
• 25% red eyes, curled wings
• 25% brown eyes, straight wings
• 25% brown eyes, curled wings.
Of the following, this finding best illustrates:
(a) linkage
(b) mutation
(c) sex-linkage
(d) independent assortment.
4. Normal body (N) in Drosophila is dominant to fat body (n), and red eye (R) is dominant to purple eye (r). The gene for body colour sorts independently to the gene for eye colour. Crosses between flies with the genotype Nnrr and flies with the genotype nnrr produce offspring as follows:
(a) 50% normal with purple eyes: 50% fat with purple eyes
(b) 50% fat with red eyes: 50% normal with red eyes
(c) 50% normal with purple eyes: 50% fat with red eyes
(d) 50% fat with red eyes: 50% normal with purple eyes.
5. Another series of crosses between Drosophila flies with the genotype NNrr and flies with the genotype nnRR yields the following offspring:
(a) 50% normal with red eyes: 50% fat with red eyes
(b) 50% normal with purple eyes: 50% fat with red eyes
(c) all normal with purple eyes
(d) all normal with red eyes.
6. The letter A represents the gene for a dominant trait and the letter a represents the gene for its recessive allele. Which statement concerning the offspring of the first generation is correct if Aa mates with aa?
(a) All of the offspring will exhibit the dominant trait.
(b) All of the offspring will exhibit the recessive trait.
(c) The recessive trait will show up in only 50% of the offspring.
(d) The dominant trait will show up in only 75% of the offspring.
Questions 7 to 10 are based on Figure 1, a pedigree for colour blindness (c) which is sex-linked and recessive to normal colour vision (C). Squares represent males, and circles females. Black squares and circles indicate colour blind individuals.
(MESSAGE ME FOR PICTURE)
7. The genotype of individual 1:
(a) could be either Cc or CC
(b) must be CC
(c) could be either CC or cc
(d) must be Cc.
8. The genotype of individual 3:
(a) could be either Cc or CC
(b) must be Cc
(c) must be CC
(d) could be either CC or cc.
9. If individual 10 marries a woman homozygous for normal colour vision, the chance that they will have a colour blind son is:
(a) 50%
(b) 25%
(c) 0%
(d) 100%.
10. The genotype of individual 11:
(a) could be either Cc or cc
(b) must be Cc
(c) must be C
(d) must be c.
11. A scientific study was carried out to test the effect of commercially produced pyrethrum on an insect population on an isolated island. Pyrethrum was sprayed at weekly intervals for six months. During this time the climatic conditions on the island remained constant. It is known that the insects have a short reproductive cycle and reproduce at a constant rate throughout the year.
The graph below shows the changes in the insect population during the study.
(MESSAGE ME FOR GRAPH)
(a) The following paragraph describes how natural selection can be used to account for these changes in the insect population. Choose from the following words and fill in the blanks to complete each sentence. Each word may be used more than once.
advantage, evolution, identical, offspring, pyrethrum, reproduce, resistant, survive.
Within any population of insects, all the individuals are not ___________________. Some individuals possess a mutation that makes them __________________ to pyrethrum. In an environment that does not contain pyrethrum the pyrethrum resistant insects have no survival __________________ over non-resistant insects.
When ________________ is introduced into the environment, the insects that are ______________ to pyrethrum will _______________, while the others will die. The surviving resistant insects can then _______________, passing on their resistance to their ______________. This process produced varieties of insects that are _______________ to insecticides and is an example of __________________ by natural selection.
(b) Sexually reproducing insect species have a better chance of surviving environmental change than do asexually reproducing insect species. Account for this statement.
12. Give one example for each of the following and indicate how each provides evidence for evolution.
(a) Palaeontology
(b) Comparative embryology
(c) Comparative anatomy
13. Many other scientists had tried to discover the laws governing inheritance but had obtained conflicting and inconsistent results.
(a) Outline the experiments carried out by Gregor Mendel on the inheritance of shape in peas. Describe the crosses he made and the results obtained at each stage.
(b) Describe two aspects of Mendel’s experimental technique that led to him obtaining results that could be accurately explained.
(c) Give one reason why the importance of Mendel’s work was not recognised until some time after it was published.
14. Define the following terms relating to the study of genetics.
(a) gene:
(b) allele:
(c) heterozygous:
(d) dominance:
(e) phenotype:
(f) co-dominance:
15. The inheritance of ginger and tortoiseshell coats is controlled by the sex-linked, dominant orange gene, A, carried on the X-chromosome. Inheritance of sex in cats is similar to humans.
The action of the A gene is to convert black pigment that would be produced by black genes to orange.
If only recessive a genes are present, the cat will be black.
If two A genes are present or only one A gene with no corresponding recessive gene, the cat will be orange.
Tortoiseshell cats are heterozygous for the A gene.
An orange female is mated with a black male.
Using the following symbols, show the genotypes of the parents and the expected ratios of sex and colour in the offspring.
A – orange allele a – black allele
XY – male XX – female
XA or Xa – allele carried on X-chromosome.
16. Hybridisation has often been practised in horticulture and agriculture. 3
(a) Identify one example of hybridisation.
(b) Explain one advantage and one disadvantage of hybridisation.
