Reference no: EM13876950

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.

7. Give one example for each of the following and indicate how each provides evidence for evolution.

(a) Palaeontology

(b) Comparative embryology

(c) Comparative anatomy

8. 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.

9. Define the following terms relating to the study of genetics.

(a) gene:

(b) allele:

(c) heterozygous:

(d) dominance:

(e) phenotype:

(f) co-dominance:

10. 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.

11. Hybridisation has often been practised in horticulture and agriculture.

(a) Identify one example of hybridisation.

(b) Explain one advantage and one disadvantage of hybridisation.