Explanation

The photoelectric effect does not occur if the frequency of the incident light is below the threshold frequency.

The threshold frequency is the minimum frequency required for the incident photons to have enough energy to eject electrons from the surface of the material.

If the frequency is below this value, no electrons are emitted, regardless of the light intensity.

Explanation

Dehydrohalogenation involves the removal of a hydrogen halide from an alkyl halide

Typically carried out in the presence of alcoholic KOH

Explanation

In a reverse-biased PN junction, the reverse current is typically very small, usually in the range of microamperes (μA).

This current is primarily due to minority charge carriers.

Explanation

Quaternary

(Haemoglobin has a quaternary structure as it consists of multiple polypeptide chains.)

Explanation

The peptidoglycan cell wall is a unique and defining feature of bacteria.

It provides structural support and protection, helping bacteria maintain their shape.

Peptidoglycan is not found in amoeba, protozoa, or viruses, as these organisms have different structural components.

Explanation

Aluminum (Al) reacts with oxygen to form a thin protective oxide layer (Al₂O₃) that prevents further oxidation.

This is why it doesn’t react aggressively with oxygen after this initial reaction.

Explanation

The wings of birds and flying lizards are examples of convergent evolution, where different species evolve similar traits independently, often due to similar environmental pressures.

Explanation

The percentage yield is the most common measure of efficiency in chemical reactions, comparing actual yield to theoretical yield.

Explanation

The canal system is a characteristic of Porifera (sponges), used for water circulation and filtration.

Explanation

Oxygen cannot be detected directly in an organic compound using common detection methods, unlike chlorine, nitrogen, and phosphorus.