Evolution: History of life Assignment

1. In human albinism is caused by an autosomal recessive allele. On average 1 in 10,000 is an albino.

• Give two characteristics of an albino (2marks)
• Using Hardy Weinberg formula p2 +2pq + q2 = 1, determine the frequency of the albino allele in human population (2marks)
• Frequency of heterozygous genotype in the population (2mars)
• Explain why it is difficult to eliminate recessive alleles from a population (4mark)

2. When extensive lakes that existed in Bunyoro were reduced to isolated pools many years ago, four species of fish evolved as a result
Suggest how the drying up of the lake system to isolated pools have resulted in evolution of the four new fish species. (4marks)

Describe how environmental factors act as stabilizing forces to natural selection in an isolates pool after the evolution of a new species.           (3marks)

Suggest what would happen to the fish species if water levels rose and the isolated pools once again formed an extensive lake system. (03marks)

Explain the meaning of the Hardy- Weinberg equilibrium principle (1mark)

State four conditions that must be fulfilled in order the principle to hold true (2marks)

3. Brown eyes in a human population is caused by a dominant allele. If in a population, 84% of the people have brown eyes, using Hardy-Weinberg formula, determine the percentage of the population who are

a) Heterozygous for eye color. Show your working (4marks)

b) Homozygous dominant for eye color. Show your working. (3marks)

c) Outline the causes of gene reshuffling. (3mark)

d) In what way may the variation resulting from gene reshuffling differ from that caused by mutation? (2marks)

e) What is the importance of variation in a population? (2marks)

f) Explain how constancy od species may be maintained through natural selection (03marks)

g) How does the resistance of malaria parasites to malarial drugs occur? (02marks)

h) how may each of the following lead to speciation?

(i) genetic drift (04marks)

(ii) Nonrandom mating (4marks)

4. a i)Using examples. Give the meaning of adaptive radiation of species? (2marks)

ii) State the ecological importance of adaptive radiation (2marks)

b)  How do adaptive radiation and homologous structures give evidence of evolution?

i) Adaptive radiation (3marks)

ii) Homologous structures (3marks)

7. (i) What is meant by natural selection? (2marks)

ii) How does it occur? (6marks)

iii) What is the importance of natural selection? (2marks)

8. a) What do you understand by the gene pool? (2marks)

b) What may cause a gene pool of a population to be static? (2mk)

i) state three factors that may contribute to a change in the frequency of dominant and recessive alleles in a population. (3marks)

ii) Explain how each factor stated in c(i) above may cause a change in the frequency of dominant and recessive alleles in a population. (3marks)

9. i) State Darwin’s theory of natural selection.

ii) State three observations and two deductions from which Darwin derived this theory.

iii) How does the modern view on evolution differ from Darwin’s View?

10. (a)(i) What is a mutation?

ii) State the possible causes of mutation

iii) What is the role of mutation in the evolution of new species?

11. Explain what is meant by each of the following concepts:

i) Continental drift

ii) Divergent evolution

iii) Industrial melanism

Essay questions

1a) What is meant by genetic drift (04 marks)

b) How can the genetic equilibrium of a population be upset? (9marks)

c) Explain how humans influence the evolution of species (7marks)Vestigial organs

2. a) What is meant by the term natural selection? (3marks)

b Describe the role of each of the following in natural selection

i)Mutation (5marks)

ii) Meiosis (8mars)

iii) Fertilization (fertilization (4marks)

3. a) Explain what is meant by variation. (2marka)

b) How does meiosis contribute to variation? (07marks)

c) Describe the role of variation in evolution. (11marks)

4. a) Explain the following

i) Genetic isolation (2marks)

ii) Reproductive isolation (3marks)

b) Explain how the gene frequency of a population may be altered. (15marks)

5.(i) Giving an example, explain what is meant by discontinuous variation? (3marks)

ii) How does sexual reproduction cause variation? (8marks)

iii) Explain how the environment influences the process of natural selection? (9marks)

6. a) Give the different forms of isolation of species (3marks)

b) How may each of the forms of isolation given in (a) above lead to formation of species (17marks)

7. a)What is meant by the following phenomena?

i) Natural selection

ii) Reproductive isolation

iii) Polyploidy  (4marks)

b) Explain the role played by each of the phenomena in (a) above in evolution of new species (11marks)

c) How may species become extinct?                   (5marks)

8. Describe how new species of an organism may arise

9. a) State five evidences of evolution.

b) To what extent do the evidences you have stated in (a), support the theory of evolution?

10. Table 1 shows the number of individual with a given length of fur in a population of terrestrial mammalian species for two different generations. The prevailing climatic temperature during the two generations changed from 15⁰C to 10⁰

Draw a graph of the relationship between fur and the number of individuals at the two temperatures (08marks)

a) What is the optimum length of fur at each temperature? (2marks)

b(i) What is the effect of temperature on fur length among the individuals? (03marks)

ii) Suggest an explanation for the effect of temperature on fur length. (05marks)

c i) From figure 1, describes the trend of resistant strain with the amount of antibiotics used (3marks)

ii) Suggest an explanation for the observed trend of resistant strains with the amount of antibiotics used (03marks)

d i) A bacterium is a haploid organism that produces asexually by fission, twice every minute on average. Using this information, explain the rapid emergence of resistant strain (06marks)

ii) The data in table 1 and figure 1 illustrate the process of natural selection. State the selection pressure in each case (02marks)

e) Giving a reason in each case, predict what the effect of each of the following would be

i) If the use of antibiotics was stopped for a year. (05marks)

ii) If the generation of the terrestrial mammal at a prevailing temperature of 10⁰C was supplied with an abundance of food (03marks)