cameroon gce A/L june 2013 Biology Paper 2

cameroon gce june  2013 BiologyPaper 2

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1. Conifers are non-following plants which bear seeds during reproduction
(a) State three ways in which these plants have advanced more than non-seed bearing plants.
(b) Explain how seed bearing plants are adapted to life on land.
(c) How do conifers differ from flowering plants?

2. (a) Explain what is meant by:
(i) Homeostasis
(ii) Negatives feed back in living organisms
(b)Describe how variations in plasma glucose concentration are adjusted in mammals

3. (a) (i) List the components of blood
(ii) What are the meaning functions of mammalian blood?
(b) A nursery school girl aged 4 old sustained a wound while playing with her mates during break in the school garden.Outline the process that will occur to prevent this girl from bleeding to death.
(a) How is CO2 carried by blood?

4. (a) Describe the different stages involved in the birth of a mammals
(b) Discuss the role of hormones in birth and lactation
(c) Explain the effect o cigarette smoking by a pregnant woman on her unborn child.

5. (a) What is meant by ‘’carring capacity’’ of a habitat?
(b) Discuss the ways in which
(i) competition
(ii) Predation and
(iii)Parasitism and desease
Limit the size of natural populations.
(c)How can abiotic factors affect the size of populations?

6. (a) Explain the following as used in genetics:
(i) Linkage and sex linkage
(ii) Sex determination in man
(b) In apes the shape of the snout is controlled by a sex-linked gene.Sex is determined the same way as in humans.The gene for long snout is dominant over short snout, but when present together a cleft snout is formed. Using suitable letters for the gene,

(i) Determine the genotypes of a female ape with a cleft snout,a male ape with a short snout,a male ape with a long snout and a female ape with a long snout.
(ii) Show how the expected genotypic and phenotypic probalitiezs of the baby apes will come about when a male âpe with a long snout is mated with a cleft snout female ape.

7. (a) How do enzymes catalyse a reaction?
(b) Describe and explain the effects of temperature on enzymes activity
(c) Describe the stages that are involved in producing bacteria that can be use to make human proteins.

8. Fermentation is a biotechnology process involved the culturing of micro-organisms in an aqueous suspension in a culture vessel know as fermenter
(a) Describe the main steps involved in penicillin production through this process
(b) How can yeast be used to produce bread?
(c) State four advantages of ‘’Fed- batch’’ culture in biotechnology?