Question

Which of the following are covered by a single membrane?

• A. Mitochondria
• B. Vacuole
• C. Nucleus
• D. Plastid.

Answer 1

The correct option is B

Vacuole

The correct option is B:

Explanation of the correct option:

Vacuole.

1. Vacuoles is a single membrane bound sacs which contain non-living or liquid content. There are 3 types of vacuoles
2. Sap vacuole – fluid filled vacuoles, small in animal and young plants, in mature plant cells they occupy 50-90% of cell volume.
3. Food vacuole- contains ingested food particles and is fused with lysosome to form food vacuoles.
4. Contractile-Helps in swelling up and bursting of the cell by collecting liquid. Main function is osmoregulation and excretion.

Explanation of the incorrect options:

Option A:

Mitochondria

1. Are rod shaped organelle seen in eukaryotic cell which is known as the power house of the cell.
2. This organelle is known as the power house of the cell as it contains enzyme necessary for the oxidation of food and also for generating ATP.
3. ATP is known as the energy currency of the cell as it provide energy for new chemical compound formation and mechanical work.
4. Mitochondria is bound by two membrane structures called outer membrane and inner membrane.
5. Outer membrane is smooth and has many pores in them. Inner membrane is highly folded to form structures called cristae, which increases the surface area for ATP synthesis.
6. Mitochondrial matrix contain DNA, ribosomes and enzymes which take part in protein synthesis and respiration respectively.

Option C:

Nucleus

1. Is a dense body seen in the cytoplasm, which contains the genetic material.
2. RBC and sieve elements lack nucleus.
3. It has a double layered nuclear envelope which separates cytoplasm and nucleoplasm.
4. Other components of nucleus is nucleolus and chromatin material. It is known as control center of the cell.

Option D:

Plastids

1. Are double membrane bound cell organelles found in plants which helps in synthesis and storage of certain chemicals.
2. There are mainly two types of plastids
3. Leucoplast- colourless plastid, main function is storage, and are of three types amyloplasts, aleuroplasts and elaioplasts.
4. Chromoplast- are coloured plastids. Mainly two types of chromoplast non-green photosynthetic chromoplast and green photosynthetic chromoplast called chloroplast.

Thus, Vacuole are covered by a single membrane.