Hydrogencarbonate indicator is a water-soluble solution that can act as a source of carbon dioxide for aquatic photosynthetic organisms. The solution changes colour depending on the concentration of carbon dioxide in the solution. These colours are related to different $$$\mathrm{pH}$$$ values, as shown in Table 1.1. Chlorella vulgaris is a protoctist that is single-celled, aquatic and photosynthetic. It can be immobilised in alginate beads. Alginate beads with immobilised C. vulgaris can be used to measure the rate of photosynthesis. The student used the alginate beads with immobilised C. vulgaris in hydrogencarbonate indicator solution to investigate the rate of photosynthesis in different light intensities. Fig. 1.1 shows some of the apparatus and reagents the student used. Identify the independent variable in this investigation.

Biology

IGCSE&ALevel

CAIE

Exam No：9700_s23_qp_53 Year：2023 Question No：1(b)(i)

Answer:

light intensity ;

Knowledge points:

13.2.1 state that light intensity, carbon dioxide concentration and temperature are examples of limiting factors of photosynthesis

13.2.2 explain the effects of changes in light intensity, carbon dioxide concentration and temperature on the rate of photosynthesis

13.2.3 describe and carry out investigations using redox indicators, including DCPIP and methylene blue, and a suspension of chloroplasts to determine the effects of light intensity and light wavelength on the rate of photosynthesis

13.2.4 describe and carry out investigations using whole plants, including aquatic plants, to determine the effects of light intensity, carbon dioxide concentration and temperature on the rate of photosynthesis

Answer:

Knowledge points:

Solution:

Related Question