CSEC Human and Social Biology Paper 2 May/June 2008 - Free CXC Past Paper with Answers

Complete Table 1 below by writing the correct word from the list provided in brackets. Each word may be used once, more than once or not at all. An example has been done for you. (similar, large, small, present, absent)

TABLE 1. COMPONENTS OF PLANT AND ANIMAL CELLS

Students in a class are discussing plant and animal cells. Rehanna argues that the cell wall and cell membrane are different. To assist Rehanna, you are asked to describe the structure and function of both the cell wall and cell membrane.

Cell wall Structure: Function:

Cell membrane Structure: Function:

Complete the following paragraph by writing the correct answer from the list provided at the end of the paragraph.

Some cells in the human body require more energy than others. Most ___________ require more energy. This energy is provided by the ___________ which are present in ___________ quantities in cells using a lot of energy.

(nervous cells, epithelial cells, muscle cells, ribosomes, mitochondria, chloroplasts, greater, smaller)

Most of our actions are controlled by the central nervous system. State what is a 'reflex action'.

State TWO differences between a reflex action and a voluntary action?

Describe the actions of the nervous system to produce EACH of the following responses.

Kim injures her leg in a vehicular accident. When the doctor hits her below the knee with his rubber hammer, her knee jerks.

Brian claps his hands near your face and you blink.

The lymphatic system acts as a circulatory system which deals specifically with infections.

What is 'lymph'?

Describe how lymph is formed.

Tonsils form part of the lymphatic system. Maya had her healthy tonsils removed.

Suggest ONE possible effect that this may have on her health.

Give ONE reason for your answer in (b) (i) above.

The tricuspid valve is located between the right atrium and right ventricle of the heart. A young man with a weak tricuspid valve tires easily.

Describe the function of a normal tricuspid valve.

How does the structure of the tricuspid valve assist the valve to function properly?

Suggest how a weak tricuspid valve may cause the young man to tire easily.

Respiration is the process whereby living cells produce energy.

Complete the word equation below for aerobic respiration.

Glucose + _________________________ $\rightarrow$ _________________________ + water + energy.

What is anaerobic respiration?

Use your knowledge of how the respiratory system works to explain why EACH of the following persons may have difficulty in breathing:

A chronic smoker

An asthmatic person

Define the term 'homeostasis'.

Control of carbon dioxide in the blood is a negative feedback mechanism. Explain how the body controls carbon dioxide levels in the blood through this mechanism.

Marathon races are becoming very popular in some Caribbean countries. During the race an athlete tends to drink a lot of water.

Explain how the athlete's body uses water to control body temperature.

Why do the kidneys produce less urine, even though the athlete drinks more water?

Figure 2 shows the reproductive tract of the human female. Identify the parts labelled X and Y.

X: Y:

Name ONE birth control method used by males.

During a class discussion, students tell their teacher that a female cannot become pregnant on the first occasion she has sexual intercourse. The teacher informs the students that they are incorrect.

Starting from the point of ejaculation, outline the process of fertilization.

Write ONE statement which will explain the teacher's claim that a female can become pregnant on the first occasion she has sexual intercourse.

Complete EACH of the following sentences by writing the correct word from the list provided in brackets. (reproduction, growth, replace, reproduce, inherited, genetic)

New cells are needed by the body for ____________________ and to ____________________ worn out cells.

The new cells must have the same ____________________ information as the original cells.

Anita notices that she has no dimples but her sister, Sunita, has dimples.

Using D to represent the dominant gene for dimples, and d to represent the recessive gene for no dimples, deduce the genotype for Anita and Sunita.

Genotype of Parents: Gametes: Genotype of F$_{1}$: Genotype of Anita: Genotype of Sunita:

Would the genes determining the presence or absence of dimples also determine the sex (gender) of an individual? Give ONE reason for your answer.

Answer: Reason:

State TWO methods for limiting the spread of AIDS and ONE method for limiting the spread of tuberculosis.

AIDS: Tuberculosis:

Your village is infested with mosquitoes. Using your knowledge of the life cycle of the mosquito, outline to the villagers TWO methods they should use to decrease the number of Aedes aegypti mosquitoes, and explain how these methods would reduce the mosquito population.

Method: Explanation: Method: Explanation:

Define EACH of the following terms:

Sewage

Biodegradable

Many hotels are built close to the ocean and some of them have faulty sewage treatment plants. Explain how the dumping of sewage into the ocean affects the oxygen content of the water, and the food chain.

Oxygen content: Food chain:

Give ONE reason why large quantities of disinfectants should NOT be added to sewage treatment plants.

List TWO factors that affect the rate of breathing.

The air we breathe in contains 20% oxygen and only 0.04% carbon dioxide. The air we breathe out contains 16% oxygen and 4% carbon dioxide.

Explain what happens in the lungs to bring about this change in levels of oxygen and carbon dioxide. Your answer should include:

• the function of breathing
• the role of the blood in the lungs
• the structure and function of the lungs.

Your mother awakes one morning with a high fever, severe headaches and sore throat. She is diagnosed as having the flu.

What is the causative organism of the flu?

State TWO OTHER symptoms your mom may experience.

Advise your mother on THREE things she should do to relieve the symptoms of the flu.

Should you drink from the same glass as your mom? Give ONE reason for your answer.

State ONE function of EACH of the following in the stomach:

a) Hydrochloric acid b) Pepsin c) Renin

Your friend complains that she has not had a bowel movement for a few days. You suspect that she is constipated. Explain to your friend:

Why faeces are said to be egested and NOT excreted

What occurs in the colon to cause constipation

THREE effects of constipation

THREE ways to ease constipation

Which food nutrient is being tested in the above experiment?

Test tube B gives a positive result. What colour will be observed in Test tube B?

Test tube A gives a negative result. What colour will be observed in Test tube A?

Your middle-aged aunt, who is in excellent health, becomes concerned after hearing about the dangers of very high or very low blood sugar levels.

Explain to her how a healthy body maintains its blood sugar levels

• after a meal rich in carbohydrates is eaten
• several hours after the meal.

What is 'diabetes mellitus'?

State TWO symptoms of diabetes mellitus and suggest TWO ways in which the disease may be managed.

State TWO ways in which water could be purified at home.

State THREE ways in which agricultural and industrial activities pollute water.

Flood waters are usually contaminated with faeces. Explain how contaminated flood waters may be dangerous to your health. Your answer should include the causative organism and symptoms for

• ONE named disease caused by drinking contaminated water
• ONE named disease caused by parasites.

For EACH disease named in (b) (i) above, explain the treatment that may be administered to an infected person.

Large amounts of forest have been destroyed worldwide. Describe THREE ways in which deforestation impacts on the water cycle.