Explanation

• The Earth’s atmosphere is divided into different layers (Troposphere, Mesosphere, and Exosphere).
• Hydrosphere refers to all water bodies on Earth.
• Therefore, Hydrosphere is not part of the atmosphere.

Additional information:

• Troposphere: 0–12 km (weather layer)
• Stratosphere: 12–50 km
• Mesosphere: 50–85 km
• Thermosphere: 85–600 km
• Exosphere: 600 km and above

Last verified on 21-04-2026

Explanation

• Name: Vitamin B-2 (Riboflavin)
• Food sources: Milk, Eggs, Organ meats, Green vegetables, Cereals
• Deficiency causes: Skin problems, sore throat, eye irritation
• Role: Energy production (metabolism)
• Solubility: Water-soluble vitamin

Last verified on 21-04-2026

Explanation

• A barometer measures atmospheric (air) pressure.
• It helps in weather forecasting, detecting storms, and studying climate changes.
• Two common types of barometers: mercury barometer and aneroid barometer.

Last verified on 13-03-2026

Explanation

• A new predator increases predation pressure on prey.
• This leads to a decrease in prey population.
• More prey get hunted and fewer survive.
• Ecosystem balance may temporarily change.
• So, prey population is most directly affected.

Last verified on 12-04-2026

Explanation

• Pepsin is a digestive enzyme in the stomach.
• It works best in strong acidic conditions (low pH).
• This means enzymes have an optimum pH range.
• Outside this range, activity decreases.
• So, it does not work equally at all pH levels.

Last verified on 12-04-2026

Explanation

• Adaptation helps organisms survive in their environment.
• It improves their ability to cope with changes.
• Adapted organisms reproduce more successfully.
• This increases survival chances of the species.
• So, adaptation enhances both survival and reproduction.

Last verified on 12-04-2026

Explanation

• A cell with one cytoplasm and two nuclei indicates division of nucleus but not cytoplasm.
• This means karyokinesis occurred but cytokinesis did not.
• The cytoplasm failed to divide after nuclear division.
• So the correct situation is cytokinesis failure.
• This results in multinucleated cells.

Last verified on 12-04-2026

Explanation

• Gastric juice helps in digestion of food in the stomach.
• It contains acid (HCl) and enzymes like pepsin.
• If its production stops, food cannot be properly digested.
• The immediate effect will be failure of digestion.
• Nutrient breakdown in stomach becomes impossible.

Last verified on 12-04-2026

Explanation

• Spindle fibers are essential for chromosome movement.
• They attach to chromosomes during cell division.
• If spindle fibers are defective, chromosomes cannot separate properly.
• This mainly affects chromosome segregation.
• It can lead to abnormal cell division.

Last verified on 12-04-2026

Explanation

• This situation illustrates Natural Selection.
• Some bacteria naturally have resistance genes.
• Antibiotics kill non-resistant bacteria.
• Resistant bacteria survive and reproduce.
• Over time, population becomes antibiotic-resistant.

Last verified on 12-04-2026