Biology MCQs with answers Page - 80

The stamen is the male reproductive part of a flower. It consists of two main parts:

1. Anther – Produces pollen grains, which contain male gametes.
2. Filament – Supports the anther.

Other options:

• (A) Stigma – Part of the female reproductive organ (pistil/carpel) where pollen lands.
• (C) Carpel – The female reproductive part of a flower, consisting of stigma, style, and ovary.
• (D) Ovule – Located inside the ovary, it develops into a seed after fertilization.

Thus, stamen is the correct answer.

Acetic acid (CH₃COOH) is the simplest fatty acid because it contains only two carbon atoms and belongs to the carboxylic acid group. Although it is a short-chain fatty acid, it is still considered a fatty acid because it has a carboxyl (-COOH) functional group.

Other options:

• (A) Palmitic acid – A long-chain saturated fatty acid (16 carbon atoms).
• (B) Butyric acid – A short-chain fatty acid (4 carbon atoms), but not the simplest.
• (C) Oleic acid – A monounsaturated fatty acid with 18 carbon atoms.

Thus, acetic acid is the simplest fatty acid among the given options.

Enzymes are primarily globular proteins.

• Globular proteins are spherical or oval-shaped and are water-soluble, which makes them suitable for biochemical reactions.
• Enzymes function as biological catalysts, speeding up chemical reactions in living organisms.
• Their specific 3D structure allows them to bind with substrates efficiently.

Why not the other options?

• (B) Fibrous – Fibrous proteins (like collagen, keratin) provide structural support, but they are not enzymes.
• (C) Helical – Some enzymes may have helical structures (like alpha-helices in their secondary structure), but not all enzymes are helical.
• (D) All of these – Incorrect because enzymes are mainly globular, not fibrous.

Thus, the correct answer is (A) Globular.

Ulva is not a disease; it is a green algae commonly known as sea lettuce. It is a type of marine algae found in oceans and freshwater.

• AIDS is caused by the HIV virus.
• HIV (Human Immunodeficiency Virus) leads to AIDS.
• Flu (Influenza) is caused by the Influenza virus.

Since Ulva is not a disease, it is the correct answer.

Atrichous bacteria lack flagella completely and are non-motile.

• Monotrichous bacteria have a single flagellum at one end.
• Peritrichous bacteria have flagella all over their surface.
• Lophotrichous bacteria have a cluster of flagella at one end.

Since bacteria without any flagella are called atrichous, option B is correct.

Cilia are hair-like structures that help in movement and are found on the surface of some cells.

• They are formed from basal bodies, which originate from centrioles.
• Cell membrane (B) covers the cell but does not produce cilia.
• Cytoplasm (D) is the fluid inside the cell but does not directly produce cilia.

Since cilia originate from centrioles, option C is correct.