AP Senior Inter Botany VSA Important Questions

1. Name the processes which take place in the grana and stroma regions of chloroplasts?
A. Trapping the light energy and synthesis of ATP and NADPH take place in grana. This set of two reactions are light dependent. So it is called light reaction. The biosynthetic phase where in CO2 and water are converted to Glucose by utilising end products of light reaction occurs in stroma. This set of reactions are together called dark reactions as it do not directly depend up on light.

2. Can chloroplasts be passed on to progeny? How?
A. Yes. chloroplasts can be passed on to progeny. They have genetic material in the form of double stranded circular DNA. They are self reproducing organelles.

3. Where is the enzyme NADP reductase located? What is released if the proton gradient breaks down?
A. NADP reductase enzyme is located in the grana thylakoids on the stroma side. Proton concentration gradient is established along the thylakid membrane between lumen and stroma. The break down of this proton gradient creates energy which is utilised to synthesise ATP.

4. Which tissue transports photosynthates? What experiments prove this?
A. Phloem, the living vascular tissue transports photosynthates in the form of sucrose. Phloem transports food from the leaves upwards and down wards. Thus it is bidirectional. A simple experiment called 'Girdling experiment' explains transportation of food.

5. Distinguish between action spectrum and absorption spectrum.
A. A graph showing the rate of photosynthesis at different wave lengths is called Action spectrum. A graph showing the absorption of light by different pigments at different wave lengths is called absorption spectrum.

6. Of the basic raw materials of photosynthesis, what is reduced? What is oxidised?
A. CO2 is reduced. H2O is oxidised.

7. Define the law of limiting factors proposed by Blackman?
A. According to Blackman (1905) "If a process (like photosynthesis) is conditioned as to its rapidity by a number of separate factors the rate of the process is limited by the factor that is present in a relative minimum value".

8. What is Joseph Priestley's contribution to the study of photosynthesis?
A. Joseph Priestley discovered that green plants absorb toxic gases released by breathing animals and release O2. He used mint, mouse and candle in the experiment.

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