The apparatus shown was used to investigate the effect of varying carbon dioxide concentration on the rate of photosynthesis. Carbon dioxide concentrations were varied by adding different amounts of sodium hydrogen carbonate (NaHCO₃) to water.

What is the dependent variable in this investigation?

A. Temperature

B. Light intensity

C. Amount of NaHCO₃ added

D. Volume of oxygen produced

Producers extract phosphates and nitrates from soil. Outline how these ions are used in the synthesis of organic molecules.

Explain how the pigments in the chromatogram of spinach are identified.

In 1882, Engelmann investigated photosynthesis by shining light of varying wavelength on a green alga. He observed where aerobic bacteria accumulated.

[Source: Republished with permission of Oxford University Press, from Plant Physiology and Development, Sixth Edition by
Lincoln Taiz, Eduardo Zeiger, Ian M. Møller, and Angus Murphy, 2015. Permission conveyed through Copyright
Clearance Center, Inc.]

What can be deduced from this experiment?

A. Only parts of the chloroplast contained chlorophyll.

B. The distribution of bacteria indicates the action spectrum of photosynthesis.

C. Most oxygen is released from the algae in green light.

D. Chloroplasts reflect blue and red light.

The graph shows the effect of increasing light intensity on the rate of CO₂ uptake by a species of green plant maintained in conditions of constant temperature and CO₂ concentration.

[Source: © International Baccalaureate Organization 2019]

Which statement is consistent with the graph?

A. Photosynthesis stops at high light intensity.

B. Rates of photosynthesis increase with temperature.

C. Cell respiration leads to net production of CO₂ at low light intensity.

D. There is a negative correlation between CO₂ uptake and light intensity.

Identify the following processes as either anabolism or catabolism by placing a tick (√) in the correct box.

Outline how photosynthesis produces glucose.

State two photosynthetic pigments that could be identified using chromatography.

The graph shows the absorption spectra of chlorophyll a and chlorophyll b.

[Source: adapted from F. P. Zscheile and C. L. Comar, 'Influence of Preparative Procedure on the Purity of Chlorophyll
Components as Shown by Absorption Spectra.' Int. J. Plant Sciences, Volume 102, Number 3, Mar., 1941, pp. 463–481.
Used with the kind permission of University of Chicago Press.]

What can be concluded from the graph?

A. Both chlorophyll a and chlorophyll b absorb a large amount of green light

B. Chlorophyll b absorbs red light more efficiently than blue light

C. Other pigments must absorb light between blue and red in the spectrum

D. Chlorophyll a and chlorophyll b have different absorption peaks

Describe how leaf cells make use of light energy.

Suggest how a plastic bag placed around the plant pot prevents carbon dioxide from reaching the plant’s leaves.

Explain the process of photosynthesis.

Explain what the R_f values represent in chromatography.

Explain the effect of temperature on the rate of photosynthesis in this mesocosm.

A chromatograph was made of the photosynthetic pigments of a leaf of the plant.

[Source: Adapted from “Diversity of Photosynthetic Pigments” by Alexander F. Motten in Tested Studies for
Laboratory Teaching, Volume 16 of the Association for Biology Laboratory Education and used by permission of the
author.]

Outline what measurements would be taken to identify pigment X.

The amount of food passing into food chains can be affected by the rate of photosynthesis. Explain the effect of one limiting factor on photosynthesis.

State a suitable solvent for extracting photosynthetic pigments from plant tissue.

Discuss briefly whether the detection of starch in this experiment was proof that photosynthesis had occurred in the leaf.