Practise handling biological information, planning and evaluating investigations, and applying the mathematical skills assessed across CAIE IGCSE Biology.
Some students set up the apparatus shown in Fig. 6.1 to compare transpiration in two sets of leaves.
Set A was kept in a transparent bag and set B was left in the open air.
All other conditions were kept constant.
The mass of the leaves in each set was measured at the start of the investigation and after five hours.
Fig. 6.1
The students needed two additional pieces of apparatus to take measurements so that they could calculate the rate of transpiration from their results.
State the two additional pieces of apparatus the students needed to take the measurements.
1
2
A student investigated the effect of different wavelengths of light on the rate of photosynthesis of the water plant, Cabomba.
The student used the apparatus shown in Fig. 6.1.
Fig. 6.1
The student collected the gas produced by the plant for five minutes. The results are shown in Table 6.1.
Table 6.1
Describe the effect of wavelength of light on the rate of photosynthesis as shown in the student's results in Table 6.1.
You will gain credit if you use data from the table.
State how the student would calculate the rates of photosynthesis from the results in Table 6.1.
State why the student:
kept the lamp at the same distance during the investigation,
Scientists measured the rate of photosynthesis in the leaves of a sunflower plant, Helianthus annuus.
The scientists used the apparatus shown in Fig. 3.1 to measure the rate of photosynthesis.
Fig. 3.1
The apparatus in Fig. 3.1 maintains a constant temperature and a constant humidity.
The apparatus was left for 15 minutes.
Explain how the scientists would use the readings for the concentration of carbon dioxide in chambers 1 and 3 to calculate the rate of photosynthesis.
The scientists carried out another investigation using the same apparatus at different temperatures.
They measured the rate of uptake of carbon dioxide in the light and then they measured the rate of release of carbon dioxide in the dark.
The results are shown in Fig. 3.2.
rate of carbon dioxide uptake and release per hour per of leaf
Fig. 3.2
Use the information in Fig. 3.2 to complete Table 3.1.
Table 3.1
Explain why the results in Table 3.1 are expressed as 'per of leaf' rather than 'per leaf'.
Fig. 4.1 is a diagram of a virus.
Fig. 4.1
The human immunodeficiency virus (HIV) infects and destroys lymphocytes.
The number of lymphocytes in the blood of a person infected with HIV was measured over a period of 84 months.
The results are shown in Fig. 4.2.
number of lymphocytes per of blood
Fig. 4.2
Use the information shown in Fig. 4.2 to calculate the percentage change in the number of lymphocytes from month 10 to month 60.
Give your answer to two significant figures.
.
Describe the changes in the number of lymphocytes, over the 84 months following infection with HIV, shown in Fig. 4.2.