Photosynthesis (DP IB Biology: SL)

Which of the following statements about photosynthesis is incorrect?

Paper chromatography can be used to separate photosynthetic pigments obtained from chloroplasts. The chromatography strip shows distinct coloured pigment bands. Which pigments are represented by bands 3 and 4?

Which is the most correct statement about chlorophyll?

The graph shows how the rate of photosynthesis is affected by temperature. Which statements correctly explain why the rate decreases at higher temperatures?

1. Photosynthesis is an enzyme-catalysed metabolic pathway.
2. Enzymes denature at high temperatures.
3. Less carbon dioxide is available in the atmosphere.
4. Rate of respiration increases

A plant is grown in standard atmospheric air with a carbon dioxide concentration of approximately 400 ppm. The level of carbon dioxide is then reduced to below 100 ppm. Which of the following statements about the plant are correct? 

1. The rate of photosynthesis increases.
2. Respiration and growth continue until stored sugars are used up.
3. The rate of photosynthesis decreases.
4. Metabolism is reduced to save energy.

The following graphs show the absorption spectrum for chlorophyll a and the action spectrum showing the relative rate of photosynthesis at different wavelengths of light.

Why do the graphs look different?

A student designed the following experimental set-up to measure the effect of light intensity on the rate of photosynthesis. The experiment was repeated three times.

The results were inconsistent, how could the experimental set-up be improved?

The effect of different colours of light on the growth of Arabidopsis thaliana (thale cress) seedlings was studied. Three different colours of light were tested and measurements of seedling height, shoot length, and biomass were taken.

What conclusions can be drawn from the data?

In photosynthesis, the following reaction occurs: 

2H₂O → 4e^- + 4H⁺ + O₂ 

What happens to the oxygen generated through this reaction?

Most of the world’s iron ores are found in ‘banded iron formations’ which are a distinct type of sedimentary rock with horizontal layers of iron deposited. These are found in rocks that are approximately 1.8 to 2.5 billion years old. How can photosynthesis account for this?

Which of the following statements relating to photosynthesis are correct?

I. Temperature is a limiting factor of photosynthesis.

II. Chlorophyll absorbs wavelengths of light at either end of the visible light spectrum.

III. Plants have a positive net carbon dioxide uptake. 

IV. The only photoautotrophic organisms include plants and algae.

During photosynthesis, the following reaction occurs.

            2H₂O → 4e^- + 4H⁺ + O₂

Which of the following statements relating to this reaction is not correct?

The graph shows the absorption spectra for chlorophyll a.

Which of the following statements, relating to the absorption spectra for chlorophyll and the action spectrum of photosynthesis for green plants, are correct?

I. The absorption spectra of chlorophyll pigments are obtained by measuring their absorption of indigo, violet, blue, green, yellow, orange and red light, whereas the action spectrum of chlorophyll is the wavelengths of light that bring about photosynthesis.

II. The absorption spectra for chlorophyll and the action spectrum of photosynthesis are both plotted using % absorbance on the Y-axis.

III. The absorption spectra for chlorophyll and the action spectrum of photosynthesis both display two main peaks, including a larger peak in the red region (~450 nm) and a smaller peak in the blue region (~670 nm).

IV. The absorption spectrum of chlorophyll displays a trough in the green/yellow portion of the visible spectra (~550 nm), whereas the action spectrum of photosynthesis does not.

A student investigated the effect of light intensity on the rate of photosynthesis by counting the number of bubbles released from the pondweed Elodea canadensis. The results are shown below.

Which of the following statements relating to the utilisation of carbon dioxide at differing light intensities are correct?

I. The rate of carbon dioxide uptake always increases proportionately as light intensity increases.

II. The rate of carbon dioxide uptake will decrease as the plant is moved away from the lamp.

III. The rate of carbon dioxide uptake will be greater at increased light intensities.

IV. The rate of carbon dioxide uptake becomes constant at increased light intensities as carbon dioxide becomes a limiting factor.

The graph below shows how varying light intensity affects the rate of carbon dioxide absorption by leaves, at different, fixed temperatures and carbon dioxide concentrations.

Which of the following rows correctly identifies the possible limiting factor for photosynthesis at I, II, III and IV?