cameroon gce A/L june 2009 Biology Paper 2

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Paper 2  click  on the link  below

 

June 2009

1.(a) why are tissues fixed sectioned and stained before being viewed under a microscope ?
(b) show how the structure of (i) Mitochondrion (ii) chloroplast , are adapted to their functions
(c) State the main differences between plant and animal cells.
(3, 11,6 mks)

2 .In Birds and mammals, the body temperature must be kept constant as well as other substances such as
blood.
(a) Why must these substances be kept constant?
(b) Describe how each of them is controlled so as to maintain a steady state in these organisms.

3. (a) Xylem and phloem are tissues concerned with the translocation of in organic-arid organic materials. For
each tissue, describe the possible transport or translocation mechanism involved and comment on any
structural adaptation that might be specially related to transport or translocation.
(b) State briefly why large amounts of water are required by most plants
(c) Outline the properties of water which make it very Important to plants. (10, 6, 4 mks)

4. (a) What is a gene?
(b) Describe the process of protein synthesis
(c) How is protein synthesis controlled?

5. An alternate mechanism for fixing carbon dioxide occurs during photosynthesis occurs in some plants
called C4 plants. These plants possess a leaf structure which enables them carry out their functions properly,
(a) (i) Describe the structure of the leaf of C4 plants which makes it adapted to this type of CO2 fixation.
(ii) What is the significance of the C4 pathway?
(c) What would be the effect of increasing oxygen concentration on (i) C3 photosynthesis
(ii) C4 photosynthesis? Explain your answer. (3,10, 7mks)

6. (a) What do you understand by alternation of generation?
(b) Draw the Life cycle of the fern and explain how it exhibits alternation of generation
(c) Why is water necessary for the life cycle of the fern?

7. The population of industrialized regions such as Douala are exposed to a lot of environmental hazards.
Identify four of these hazards and explain how they influence the population. (20mks)

8. (a) Explain the following terms as used in genetics, showing h6# each deviates from the normal
Mendelian crosses: (i) Linkage (ii) Co-dominance (iii) Epistasis ;
(b) In oats the grain is enclosed by the flower called Lull. Two pure breeding varieties of oat plants-one
black lulled and the other white lulled were crossed. Ail Fi individuals were all grey lulled, When they
were selfed, the following results were obtained:
Black lulled = 418
Grey lulled = 106
White lulled =36
Using suitable letters to represent the alleles, make this cross using a ppnnet square. How does this ratio
deviate from the expected Mendelian ratio?
(c) Outline precisely the problems Involved in measuring growth in multicellular organisms.
(8, 8, 4 mks)

 

 

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