CSEC Biology Paper 3 May/June 2007 - Free CXC Past Paper with Answers

Using ONLY a fully annotated diagram of the internal structure of a leaf, explain the role of the parts involved in photosynthesis. Include in EACH annotation the name of the structure and its function.

Write a balanced equation that effectively summarises photosynthesis.

One effect of hurricanes is the complete removal of foliage (leaves) from trees. Many trees seem to readily survive the loss of all their leaves, even though they are the main photosynthesising organs. Explain how this is possible.

Gardeners sometimes remove leaves and branches from trees with the expecta-tion of improving their yield. Suggest why this is a good practice.

Using ONLY a fully annotated diagram show how the human digestive system is able to effectively perform its function.

Suggest ONE way in which the digestive system protects itself from disease-causing organisms in food.

Identify TWO ways in which the body defends itself against disease organisms and explain the importance of the body having different ways of defending itself from disease.

Most countries are concerned about an outbreak of a communicable disease, even though the disease, for example, 'bird flu', occurs in a distant country and in a species that is not human.

What is a communicable disease?

Explain why countries should be concerned about any outbreak of a communi-cable disease.

What are decomposers?

Explain the role of decomposers in the carbon cycle.

Identify TWO types of decomposers and describe the characteristics they possess that make them suited to their role as decomposers.

Excessive amounts of gases such as carbon dioxide in the atmosphere have resulted in increased trapping of heat energy around the earth, causing higher global temperatures (global warming) similar to that which occurs under greenhouse conditions.

What are the benefits of growing plants under greenhouse conditions?

Suggest TWO reasons why global warming is NOT generally desirable.

Suggest ONE way in which global warming may be advantageous.

Using an example in EACH case, distinguish between the following pairs of terms used in the study of ecology.

• Biotic and physical
• Food chain and food web
• Community and population
• Habitat and environment

Wildlife reserves have become popular tourist destinations in several Caribbean territories. Wildlife authorities must protect plants and animals while providing opportunity for people to benefit from the natural beauty of the reserves.

Suggest THREE biological factors that wildlife authorities should consider before giving the public access to a wetland (swamp) reserve. For EACH factor you identify suggest what precautions the authorities may take in allowing public access.

In one Caribbean territory, visitors to the coral reef were allowed to experience its beauty by snorkeling, swimming and walking on the reef with plastic shoes. Within two decades, the reef deteriorated drastically and visitors were no longer allowed to walk on the reef.

What are the MAIN lessons to be learnt from this example?