CSEC Biology Paper 2 May/June 2015 - Free CXC Past Paper with Answers

The following chemical equation for photosynthesis represents the reactants used and the products formed.

$6\text{CO}_2 + 6\text{H}_2\text{O} \longrightarrow \text{C}_6\text{H}_{12}\text{O}_6 + 6\text{O}_2$

Unlike plants, animals are unable to synthesize glucose. A boy eats a meal of cassava. Explain how his body converts the starch in the cassava to glucose. Name the organs and the enzymes involved in this process.

Name TWO conditions, which are NOT shown in the equation, that are essential for this process.

Name the gas given off in this process and state which of the reactants produce this gas.

Gas Reactant

Explain TWO ways in which plants utilize the glucose produced during this process.

State THREE environmental factors which affect photosynthesis.

Label the organs in Figure 2 to show

the female gametes (ova) are made

fertilization would normally occur

implantation of a fertilized gamete would normally occur.

Outline the mechanism by which male and female gametes come together in the human reproductive system to form a zygote.

Name the type of cell division by which female gametes are made.

Describe TWO ways in which the type of cell division named in (c) (i) differs from that by which the embryo grows and develops after fertilization of an ovum.

Embryonic stem cells are undifferentiated cells formed as the embryo grows and develops. These cells are capable of differentiating into specialized cells of tissues and organs in the human body.

Suggest TWO reasons why cell specialization is important.

Explain why embryonic stem cells can be used in the treatment of physiological diseases.

Distinguish between the following paired terms: allele/gene; dominant/recessive; homozygous/heterozygous.

Use a genetic diagram to show how a couple with normal pigmentation may produce an albino child. Use the following symbols to represent the alleles: A – normal; a – albino.

Suggest TWO precautions that albino persons living in the Caribbean should take when going outdoors.

Observation of the members of a population shows that there is variation in skin colour. Suggest THREE ways by which this type of variation could occur.

Make a labelled diagram of a horizontal section through the human eye and describe how the eye enables us to see.

Space for diagram

Discuss the effects of alcohol abuse on the human body’s ability to respond to stimuli and maintain homeostasis.

Name THREE characteristics which distinguish a biological species and THREE factors that lead to the formation of a new species.

The distribution of variant forms of the peppered moth, Biston betularia, changed between pre-industrial and post-industrial Britain. Account for the increase in the numbers of the dark form in the post-industrial era.

Use the theory of natural selection to explain antibiotic resistance.