Explanation

Pakistan is home to around 525 species of fish, found in both freshwater and marine ecosystems.

These include both native and introduced species across rivers, lakes, and coastal waters.

Explanation

A fuse is a thin wire that melts and breaks the circuit if too much current flows, protecting appliances.

It acts as a safety device to prevent damage from overheating or short circuits.

Explanation

The dissolving of salt in water is a physical change because:

Reversible Process: The salt can be recovered by evaporating the water (no new substance is formed).

Molecular Level: Salt (NaCl) dissociates into ions (Na⁺ and Cl⁻) but retains its chemical identity.

Explanation

In mutualism, both organisms benefit: microorganisms help digest cellulose, and herbivores provide food and shelter.

This relationship is cooperative, where neither is harmed but both gain advantages.

Explanation

When kidneys stop working permanently, the most effective long-term solution is kidney transplantation.

It replaces the failed kidney with a healthy one from a donor, restoring normal function.

Explanation

Explanation

Balanced forces are equal in magnitude but act in opposite directions, resulting in no net force (Newton's First Law).

The individual forces have opposite directions, even though their effects cancel out.

Explanation

The speed of sound in blood at body temperature (37°C) is approximately 1570 m/s, as measured in medical studies.

This is due to blood's density and compressibility, which differ from air (343 m/s) or water (1482 m/s).

Explanation

Biocatalysis uses natural catalysts (enzymes) to speed up the decomposition of organic materials.

It helps in converting biomass into useful energy sources like biofuels.

Explanation

Blue green algae (also called cyanobacteria) are prokaryotes, meaning they lack a true nucleus and membrane-bound organelles.

Unlike animals and plants (which are eukaryotes), their DNA floats freely in the cytoplasm.