Explanation

• Cotton is a fibre crop grown mainly for the natural fibre obtained from its seeds.
• It is used to manufacture textiles and clothing.
• Cottonseed is also used to produce cottonseed oil and animal feed.
• In Pakistan, cotton is an important cash crop.
• It is a major raw material for the textile industry.

Additional information:

• Scientific name: Gossypium
• Crop season: Kharif

Last verified on 16-10-2026

Explanation

• Aerobic decomposition: Microorganisms decompose organic matter in the presence of oxygen.
• It generally occurs faster and produces carbon dioxide, water, and other products.
• Anaerobic decomposition: Microorganisms break down organic matter in the absence of oxygen.
• It can produce methane, carbon dioxide, and other compounds.
• Both processes are important in composting, sewage treatment, and organic-waste management.

Last verified on 16-10-2026

Explanation

• Biodegradable waste is waste that microorganisms, such as bacteria and fungi, can break down naturally.
• Vegetable waste from farms, including leaves, stems, and spoiled vegetables, decomposes naturally.

Last verified on 16-10-2026

Explanation

• Alkaloids: Tea leaves contain caffeine.
• It is a naturally occurring alkaloid that acts as a stimulant.
• Tannins: Tea leaves contain polyphenolic compounds traditionally called tannins, which contribute to tea’s astringent taste.
• Both substances are found in tea leaves and influence the taste and effects of tea.

Last verified on 16-10-2026

Explanation

• Apomixis: Seed formation without fertilization, meaning the fusion of male and female gametes does not occur.
• The offspring are often genetically identical to the parent plant because the seed develops without normal sexual reproduction.

Additional information:

• Parthenocarpy: Fruit development without fertilization; it commonly produces seedless fruits.
• Grafting: A vegetative propagation method in which parts of two plants are joined.
• Scion: The shoot or stem piece joined to the rootstock during grafting.

Last verified on 16-10-2026

Explanation

• Carbamate and organophosphate insecticides mainly affect the nervous system by inhibiting the enzyme acetylcholinesterase.
• This causes acetylcholine to accumulate at nerve junctions, leading to continuous nerve stimulation, paralysis, and potentially death.
• These insecticides can also be toxic to humans and other animals, so proper handling and protective equipment are essential.

Last verified on 16-10-2026

Explanation

• Predator-prey: One organism (the predator) hunts, kills, and directly eats another living organism (the prey) for food.
• Example: A lion hunting and eating a zebra.

Additional information:

• Parasitism: One organism (the parasite) lives on or inside another organism (the host) and feeds off it. It harms the host but usually does not kill it right away.
• Example: Fleas drinking blood from a dog.
• Mutualism: A close relationship where both organisms help each other and benefit.
• Example: Bees collecting nectar while pollinating flowers.

Last verified on 16-10-2026

Explanation

• Rusting of iron is a chemical change.
• Because iron reacts with oxygen and moisture to form rust (hydrated iron oxide).
• A new substance is formed, and the change cannot easily be reversed.
• Rusting is a slow oxidation process that occurs in the presence of oxygen and water.
• Other examples of chemical changes: Burning wood, cooking food, and digestion.

Last verified on 15-10-2026

Explanation

• Smallest bone: Stapes.
• Location: Middle ear.
• Three ear bones: Malleus, Incus, Stapes.

Additional information:

• Longest bone: Femur (thigh bone).
• Adult human skeleton: Usually 206 bones.
• Newborn: About 300 bones at birth; many later fuse together.
• Human skull: 22 bones (8 cranial + 14 facial)

Last verified on 03-09-2026

Explanation

• Diffusion is the natural movement of particles from an area of higher concentration to lower concentration without external force.
• It occurs in gases, liquids, and even solids to some extent.

Last verified on 14-10-2026