Question

Intact chloroplast of green cells can be isolated by
A. Alcohol
B. Acetone
C. Carbon disulphide
D. Sugar solution

Answer 1

Hint: As we already know that the Chloroplast is a very fragile structure and tends to be easily disrupted at the treatment of solutions of higher concentrations. The green leaves such as spinach can be ruptured and subjected to the centrifugation process so as to obtain the intact chloroplast and the broken chloroplast.

Complete answer:
Chloroplast in plants occurs in all the green parts with a size of about 5-10 µm and it is the site for photosynthesis. The organelles like mitochondria and chloroplast would burst in distilled water so as to avoid such disruption, sugar solution can be used to isolate these organelles as they are osmotically fragile and can easily gain water due to endosmosis that automatically leads to rupturing of the organelles. Therefore, the intact chloroplast can be isolated by using sugar solution to avoid the osmotic shock to the organelle and preventing it from rupturing. For isolation of chloroplast, the leaf tissue is broken down using a blender and then the cell wall is broken down using a homogenizer. After that the unbroken tissues or the green leaf and other cell debris are removed by filtering the solution. Then the chloroplasts are collected using Gradient Centrifugation technique and the intact chloroplast and broken chloroplast can be separated by centrifugation allowing them to be kept in sugar solution.
Intact chloroplasts are the best sources for further studies involving the processes like assimilation of carbon, electron transport and phosphorylation.

Hence, the correct answer is option (D).

Note: The green leaves are ruptured in a buffer solution and subjected to centrifugation for the isolation of different organelles. Mitochondria, chloroplast, peroxisome and lysosomes can be obtained at 15000 × g.