CSEC Integrated Science Paper 2 May/June 2012 - Free CXC Past Paper with Answers

(d)

Myra produces very hard water in the laboratory by making a concentrated solution of magnesium sulphate. She places $5 \text{ cm}^3$ of this solution in test tube A. Using distilled water and the concentrated solution, she makes solutions of 20%, 40%, 60% and 80% strength. She places $5 \text{ cm}^3$ of these solutions in test tubes B, C, D and E respectively. She adds $5 \text{ cm}^3$ distilled water to Tube F. She adds four drops of liquid soap to each test tube and shakes each test tube ten times. The results are presented in Figure 1.

Figure 1. Lather columns produced by samples

TABLE 1: HEIGHT OF LATHER COLUMN PRODUCED BY VARIOUS WATER SAMPLES

Sample Strength (%)	100	80	60	40	20	0
Height of Lather (cm)

(d)(i)

Read the height of EACH lather column from Figure 1 and record it in the appropriate section of Table 1.

TABLE 1: HEIGHT OF LATHER COLUMN PRODUCED BY VARIOUS WATER SAMPLES

Sample Strength (%)	100	80	60	40	20	0
Height of Lather (cm)

[3 marks]

Question 2 (15 marks)

(a)

Figure 2 shows a diagram of the human digestive system.

Figure 2. Diagram of the human digestive system

(a)(i)

Identify the structures labelled A and B. Write your answers in the spaces provided.

[2 marks]

(a)(ii)

On the diagram, draw a line and label it C to represent the area where MOST nutrients are absorbed.

[1 mark]

(b)

Complete the dental formula below to represent the number of teeth in an adult man who has all of his teeth in place.

Incisors	Canines	Premolars	Molars
2		2
2		2

[2 marks]

(c)

In a science laboratory, Josh and Sue carried out experiments to measure the composition of $10 \text{ g}$ of samples of Foods X and Y. Table 2 shows the composition and the energy values of each sample of food.

TABLE 2: ENERGY VALUE OF FOODS

Nutrients in $10 \text{ g}$ of Food Sample X (g)	Energy provided by $1 \text{ gm}$ of Nutrient (kJ)	Energy from Nutrients in Food Sample X (kJ)	Nutrients in $10 \text{ g}$ of Food Sample Y (g)	Energy provided by $1 \text{ gm}$ of Nutrient (kJ)	Energy from Nutrients in Food Sample Y (kJ)
Fats	3	39		1	39
Proteins

(c)(i)

Using the information in Table 2 determine which food sample provides MORE energy.

[3 marks]

(c)(ii)

Which food sample, X or Y, would be more suitable for an athlete, a growing child and a person with his gall bladder removed? Give ONE reason for EACH answer.

An athlete Reason

A growing child Reason

A person with his gall bladder removed Reason

[6 marks]

(d)

The children want to swim immediately after having lunch but their mother insists that they wait for at least two hours to allow their food to digest.

Give a reason why they should NOT swim so soon after eating.

[1 mark]