Chapter 11 (Bioenergetic) F.Sc 1st Year Biology Short Questions

Table of Contents

How it was proved that source of Oz in photosynthesis is water.

In 1930s, Van Niel hypothesized that plants split water as a source of hydrogen, releasing oxygen as a by-product. Water and carbon dioxide containing heavy-oxygen isotope 180 were prepared in the laboratory Experimental green plants in one group were supplied with H2O containing 100 and with CO2 containing only common oxygen 18O. Plants in the second group were supplied with H20 containing common oxygen O but with CO2 containing 18O. It was found that plants of first group produced 18O but the plant of second group did not.

Differentiate between photosynthetic and accessory pigments.

Carotenoids and chlorophyll b are called accessory pigments because they absorb light and transfer the energy to chlorophyll a which is main photosynthetic pigment and then initiates the light reactions.

Compare non-cyclic electron flow with cyclic electron flow.

In predominant type of electron transport called non-cyclic electron flow the electrons pass through the two photosystems. In less common type of path called cyclic electron flow only photosystem I is involved.

What is photophosphorylation?

Synthesis of ATP in the presence of light is called photophosphorylation.

What is rubisco?

The Rubisco (ribulose bisphosphate carboxylase), is an enzyme. It is the most abundant protein in chloroplasts, and probably the most abundant protein on Earth. The rubisco catalyzes the a reaction in Calvin cycle when a molecule of CO2 reacts with a highly reactive phosphorylated five carbon sugar named ribulose bisphosphate (RuBP).

How NADH & ATP can inhibit cellular respiration.

NADH inhibits pyruvate decarboxylase and ATP inhibits phosphofructokinase.

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