Experimental Contexts

The sample contained three different plant species.

The student counted the number of plants of each of these species in this sample.

One plant was not fully within the square frame. Suggest and explain what you would do about this plant.

______

Count the number of plants of species E in Fig. 2.1, taking into account your answer to (a).

Record your answer in Table 2.1.

Table 2.1

The whole field measured $10\text{ m} \times 20\text{ m}$.

Use the sample in Fig. 2.1 to estimate the number of plants of species E in the whole field and record this value in Table 2.1.

Show your working.

Explain why the student counted the numbers of plants in samples of the field instead of counting the number of plants in the whole field.

______

Suggest two reasons why taking several samples would improve the accuracy of the estimate for the number of plants in the whole field.

1. ______
2. ______

Use the data in Table 2.1 to construct a bar chart to show the estimated number of plants of species C, D and E in the whole field.

Measure and record:

• the thickness of the insulation in your apparatus

______ $\text{mm}$

• the air temperature of the room you are working in.

______ $^\circ\text{C}$

The two test-tubes will be filled with hot water.

You are going to measure and record the temperature of the water in each test-tube as soon as you start timing and then at two-minute intervals for 12 minutes.

When you are ready, raise your hand and the Supervisor will add hot water to each of your test-tubes up to the lines that you have marked.

Caution – the water will be hot.

• Start timing.
• Immediately (at 0 minutes) measure the temperature of the water in each test-tube to the nearest $0.5\,^\circ\text{C}$.
• Record these temperatures in Table 1.1.
• Measure and record the temperature to the nearest $0.5\,^\circ\text{C}$ in each test-tube at two-minute intervals for 12 minutes.

Table 1.1

Use your results from Table 1.1 to describe the loss of heat from the test-tubes and the effect of the insulation.

Humpback whales are large aquatic mammals that maintain a constant body temperature of $38\,^\circ\text{C}$. They spend part of the year in cold polar water and part of the year in warm equatorial water.

Design an investigation that you could carry out to discover the effect of different surrounding water temperatures on the loss of heat by the humpback whale. Use a test-tube filled with water to represent the humpback whale.

In the space below, construct a table to record your results.

Select six seedlings from the dish and measure the height of each stem to the nearest millimetre.

Enter your results in the table.

Calculate the mean height and record it in your table.

State two possible sources of error in measuring the seedlings.

1. ______
2. ______

Use the apparatus provided to cut or crush some of the seedlings. Add drops of iodine solution to the cut or crushed seedlings.

Record your observations and conclusion from this test.

observations = ______
conclusion = ______

On the grid construct a line graph to show the relationship between time and mean height for these seedlings. Join your points with ruled lines.

Use the graph to describe the growth of these seedlings.

______

Use the graph to state the time period during which the rate of growth of the seedlings was greatest.

______

Use the data and your graph to calculate the rate of growth of the seedlings for the five days from day 15 to day 20.

rate = ______

State two variables that need to be controlled whilst growing these seedlings and explain why they need to be controlled.

variable 1 = ______
variable 2 = ______
explanation = ______

The seeds needed water to germinate and for the seedlings to grow.

Design an investigation to determine the effect of the pH of water on the growth (mean height) of seedlings. You should use seedlings grown in Petri dishes in a laboratory.

Construct a line graph of the data on the grid below. Join your points with ruled, straight lines.

Use your graph to find the rate of breathing at five minutes. Show your working on the graph.

rate = ______

Describe how the student could have measured her rate of breathing.

______

Exercise increases the rate of breathing. State one other measurement that the student could have recorded to determine the full effect of exercise on breathing.

______

In the space below, make a large drawing of the cell labelled P. You do not need to label your drawing.

Measure and record the maximum length of cell P in Fig. 2.1.

Maximum length of cell P in Fig. 2.1 = ______ $\text{mm}$

Use the magnification of Fig. 2.1 to calculate the actual length of cell P.

Show your working.

______

State two structures, visible in Fig. 2.1, that are found only in plant cells.

1. ______
2. ______

Using information from Fig. 2.1, suggest how sweet pea flowers might be pollinated. Give a reason for your answer.

Fig. 2.2 shows a developing fruit and the remains of a flower.

Name the parts labelled in Fig. 2.2.

A ______
B ______
C ______
D ______

Suggest how cutting out a small part of the testa may help the seed to germinate.

Design, giving details, an investigation to determine whether cutting out a small part of the testa improves the germination of sweet pea seeds.

Using the information in Table 3.1, state the general relationship between cycling speed and breathing rate.

______

Suggest an explanation for this relationship.

______

The volume of air breathed in and out by the student also changed during this investigation, as shown in Table 3.2.

Table 3.2

The minute volume is found by multiplying the volume of air breathed in and out in each breath by the breathing rate.

Using the information in Table 3.1 and in Table 3.2, calculate the minute volume after cycling at $25\text{ km per hour}$.

Show your working.

minute volume = ______ $\text{cm}^3$

Describe two visible features of this flower that suggest it is likely to be insect-pollinated rather than wind-pollinated.

1. ______
2. ______

Make a large drawing of the structures of the flower shown within the box on Fig. 1.1.

On your drawing label the following structures with a label line, the appropriate letter and its biological name:

A the part of the flower in which pollen grains are produced

B the part of the flower to which the pollen grains are transferred during pollination

C the part of the flower through which the pollen tube grows after pollination.

Record your results and state your conclusions in Table 1.1.

Table 1.1

Suggest how the seed(s) in the ripe fruit may be dispersed, giving reasons for your suggestion.

______