21000+ Important MCQs for UPSC

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.

Lake Baikal, located in Russia, is the deepest lake in the world, with a maximum depth of 1,642 meters (5,387 feet).

• It is also the largest freshwater lake by volume, containing about 20% of the world's unfrozen freshwater.
• The other options are deep but not as deep as Lake Baikal:
  • Lake Michigan: Maximum depth of 281 meters (923 feet)
  • Lake Titicaca: Maximum depth of 281 meters (922 feet)
  • Lake Victoria: Maximum depth of 83 meters (272 feet)

So, the deepest lake in the world is Lake Baikal (Option B).

The Dead Sea, located between Jordan and Israel, is the world’s most saline lake with a salinity of around 33-35%.

• This is ten times saltier than typical seawater, making it one of the saltiest water bodies on Earth.
• The high salt concentration prevents most marine life from surviving, hence the name "Dead Sea".

Why are the other options incorrect?

• Vaughan Lake – Not known for extreme salinity.
• Lake Superior – A freshwater lake in North America.
• Lake Baikal – The deepest freshwater lake, not a saline lake.

Thus, the Dead Sea (Option B) is the correct answer.

Finland is called the "Land of a Thousand Lakes" because it has a vast number of lakes—approximately 188,000—which cover about 10% of the country's total area. These lakes were formed due to glacial activity during the last Ice Age, creating a unique landscape filled with water bodies, islands, and forests.

Key Points:

1. Largest Lakes – Some of Finland's biggest lakes include Lake Saimaa (the largest in Finland), Lake Päijänne, and Lake Inari.
2. Importance – These lakes are essential for fishing, transportation, tourism, and hydroelectric power generation.
3. Scenic Beauty – The Finnish landscape is known for its beautiful lake scenery, which attracts tourists and nature lovers.
4. Impact of Ice Age – The lakes were carved out by glaciers, making Finland one of the most water-rich countries in the world.

Thus, due to its thousands of lakes, Finland is rightly known as the "Land of a Thousand Lakes."

The world's highest waterfall is Angel Falls, located in Venezuela. So, the correct answer is:

(C) Venezuela

Key Facts about Angel Falls:

1. Height – It is the tallest uninterrupted waterfall in the world, with a height of 979 meters (3,212 feet) and a plunge of 807 meters (2,648 feet).
2. Location – It is situated in Canaima National Park, a UNESCO World Heritage site in Venezuela.
3. River Source – The waterfall originates from the Churún River, which is part of the Carrao River.
4. Discovery – It was named after Jimmy Angel, an American aviator who popularized the falls after flying over them in 1933.
5. Unique Feature – Due to its great height, much of the water evaporates before reaching the ground.

Angel Falls is a major tourist attraction and a symbol of Venezuela’s natural beauty.