CSEC Biology Paper 3 May/June 2017 - Free CXC Past Paper with Answers

You are required to conduct an experiment using the following materials and procedure.

Materials

250 ml beaker containing 100 ml of water
Filter paper marked with concentric circles as shown in Figure 1
Long forceps
Crystals of coloured substance
Watch glass
Stopwatch

Procedure (i) Before starting the experiment, read through the procedure carefully, then construct a suitable table on page 3, to record the data you will collect. (ii) Pour 100 ml of water into the beaker. (iii) Place the beaker of water on the middle of the filter paper and let it stand until there is no movement of the water. See Figure 1. (iv) Using a long pair of forceps, carefully place a crystal of the coloured substance on the bottom of the beaker of water, as close to the centre of the concentric rings as possible. Note the time that the crystal is placed. (v) Record the time (in seconds) that it takes for the colour to spread to meet the edge of each concentric circle.

Present the results in the table you constructed.

Suggest how the experiment could be modified to investigate the effect of temperature on the spread of the colour through the water.

Explain the process by which the colour spreads through the water.

Explain how this process is important in plants and animals. Use ONE example for plants and ONE example for animals.

Plants Animals

In another experiment, slices are cut from the cucumber shown in Figure 2.

Figure 2. A cucumber cut in half

In the box below, make a large, clearly labelled drawing to show a cross section of the cucumber, twice the size shown in Figure 2.

Six slices of the cucumber are first measured. Three slices are then placed for one hour in each of two solutions:

Solution A – concentrated salt solution Solution B – distilled water

Describe the expected appearance of the slices in EACH solution after one hour.

Solution A Solution B

Explain the process that may have contributed to the change in the appearance of the cucumber slices.

Figure 3 shows the organisms seen by students on a field trip to a wetland ecosystem.

Figure 3. Organisms in a wetland ecosystem

In the space below, construct a food web to show the feeding relationships between six organisms in Figure 3.

Suggest TWO adaptations of the eagle that allow it to carry out its role, and state how EACH adaptation functions.

Describe ONE method that could be used to estimate the change in the distribution of a plant species from the water's edge to 100 m inland (away from the water's edge), and another method to estimate the density of the plant species.

Change in distribution

Density

Change in distribution Density

In the box below, draw a table that could be used to record the data for species density and state a title for the table.

The students also collect soil samples from the shallow part of the pond. They take these samples back to the laboratory where they have access to the apparatus and materials shown in Figure 4.

Figure 4. Apparatus and materials

Draw an annotated diagram in the box below to show how the apparatus and materials could be used to extract organisms from the soil the students collected.

The students also collect soil samples from the shallow part of the pond. They take these samples back to the laboratory where they have access to the apparatus and materials shown in Figure 4.

Draw an annotated diagram in the box below to show how the apparatus and materials could be used to extract organisms from the soil the students collected.

Figure 5 shows the sequence of events in a typical spinal reflex arc.

Figure 5. Sequence of events in a typical spinal reflex arc

Describe a procedure that is used to test a person's knee jerk reflex.

A researcher conducts an experiment to test the hypothesis, 'athletes have a faster reaction time than non-athletes'. The data from this experiment are shown in Table 1.

TABLE 1: REACTION TIME OF ATHLETES AND NON-ATHLETES

On the grid provided on page 15, draw two line graphs of the data in Table 1.

State ONE conclusion that can be drawn from the results of this experiment.

Describe ONE possible source of error in this experiment.

Identify THREE variables that should be controlled in this experiment.

CSEC Biology Paper 3 May/June 2017 Questions

Question 1 (24 marks)

Figure 2. A cucumber cut in half

Question 2 (23 marks)

Figure 3. Organisms in a wetland ecosystem

Figure 4. Apparatus and materials

Question 3 (15 marks)

Figure 5. Sequence of events in a typical spinal reflex arc

TABLE 1: REACTION TIME OF ATHLETES AND NON-ATHLETES