Explanation

• Soil has different layers called horizons, each with specific properties.
• The plough pan is a hard, compact layer formed just below the depth reached by ploughing.
• It restricts root growth and water movement.

Last verified on 22-01-2026

Explanation

• Soil is home to a wide variety of living organisms that maintain soil fertility.
• Nematodes make up 80–90% of the living animals in soil.

Additional information:

• Nematodes are microscopic roundworms found in almost all soils.
• They help control pests and recycle nutrients for plants.

Last verified on 22-01-2026

Explanation

• Plants absorb light for photosynthesis mainly using chlorophyll pigments.
• The effective range of light absorbed is the visible spectrum that drives photosynthesis.
• Light outside this range is less effective for producing energy in plants.

Last verified on 22-01-2026

Explanation

• Chlorophyll is a compound that is called a Chelate.
• Photosynthesis depends on the presence of chlorophyll for the absorption of light.

Additional information:

There are about six closely related chlorophylls:

1. chlorophyll a
2. chlorophyll b
3. chlorophyll c
4. chlorophyll d
5. chlorophyll e
6. chlorophyll f

Last verified on 22-01-2026

Explanation

• A sales tax is a tax imposed by the government on a wide range of goods and services.
• It is collected at the point of sale from consumers.

Additional information:

• Sales tax is usually a percentage of the sale price, e.g., 17% in Pakistan.

Last verified on 22-01-2026

Explanation

• Honeybees have a unique sex-determination system called haplodiploidy.
• Queen and worker bees develop from fertilized eggs, making them diploid.

Additional information:

• Drones (male bees) develop from unfertilized eggs and are haploid.
• This system helps maintain colony structure and division of labor.

Last verified on 22-01-2026

Explanation

• Plants are classified based on shared characteristics and natural environment.
• A plant species is the basic unit of classification where plants can reproduce among themselves.

Additional information:

• A species is capable of natural reproduction within its group.
• Example: Triticum aestivum (common wheat) is a plant species.

Last verified on 22-01-2026

Explanation

• The study of humans has multiple branches focusing on biology, culture, and history.
• Anthropology specifically studies the evolution and biological development of humans.
• It examines humans as part of the animal kingdom and their physical, social, and cultural traits.

Last verified on 22-01-2026

Explanation

• The chemical used specifically for mite control is called Acaricide.
• Acaricides target mites and ticks rather than general insects.
• They are widely used in agriculture and livestock management.

Last verified on 22-01-2026

Explanation

• The first two steps in plant hybridization are Emasculation and Pollination.

Additional information:

• Emasculation: Removing male parts (anthers) from the flower to prevent self-pollination.
• Pollination: Transferring pollen from the chosen male parent to the emasculated flower.

Last verified on 22-01-2026