Question

The stroma and grana are portions of
a. Chloroplasts
b. Mitochondria
c. Ribosomes
d. Chromosome

Answer 1

Hint: The stroma and grana are present inside the cell organelle in which photosynthesis occurs. Stroma is the matrix and grana are the stacks of membranes. It contains a collection of photosynthetic enzymes, starch grains, DNA and ribosomes.

Complete answer:
> Option A: Chloroplasts – The stroma and the grana are the parts of chloroplasts. Stroma is the fluid or the matrix part of the chloroplast. It is bound by a double membranous sheath. It contains several photosynthetic enzymes, starch grains, DNA and ribosomes.
Grana are the stacks of membrane bounded, flattened discoid sacs called thylakoid. Grana usually contains chlorophyll molecules and they are considered as the main functional units of chloroplasts. Hence, it is the correct answer.

> Option B: Mitochondria are the powerhouse of the cell. These are the membrane bounded organelles of the cell. Chemical energy produced by the mitochondria is stored in the form of ATP molecules. Hence, stroma and grana are not present in the mitochondria.

> Option C: Ribosomes are the functional unit production of proteins. They are protein forming organelle used for the translation. These are present in the cytoplasm. They are devoid of stroma and grana.

> Option D: Chromosomes are the thread-like structures located in the nucleus of plant and animal cells. They are made up of protein and DNA. Hence, it is incorrect.

Hence, the correct answer is option (A).

Note: Chloroplasts are present in the higher plants. They contain pigment and are mainly responsible for photosynthesis. Grana are the functional units of chloroplasts and are the site of light reaction and stroma are the matrix in which grana are embedded.