Question

A plant is incubated with excess water, plentiful co2, but no light for 7 days. 1. Predict the change in mass of the plant after 7 days and 2. justify your response. 3. Describe what major metabolic process has occurred in those 7 days

Answer 1

1.) There will be an decrease in mass of plant after 7 days.

2.) There will be no photosynthesis occurs in this plant because of absence of light which is an essential part of photosynthesis reaction in plants.

This can be proven by the black paper strip cover experiment in which we cover half of leaf with black paper and left half uncovered for few days in light with all suitable resources.

After few days we check the presence of glucose in both the covered and uncovered parts with the help of iodine and we found no carbohydrate formation in covered part.

But the leaf is living so there will be a continuous process of cellular respiration which uses the stored energy in the form of starch.

3.) The major metabolic process occurs during this period is cellular respiration which occurs in following three stages-

Glycolysis- breakdown of glucose in pyruvate. It occurs in cytoplasm.

One molecule of glucose breaks down in two molecules of pyruvate.

Krebs cycle-it occurs in matrix of mitochondria.

It changes the pyruvate into Acetyl co-A and release of carbon dioxide and energy rich molecule like NADH and FADH2.

Electron transport system- it converts the the energy rich molecule like NADH and FADH2 into ATP.

One molecule of glucose gives as many as 34 ATP or more, up to 38 ATP.