Explanation

• Microfilaments are thin, solid protein fibres found in the cytoskeleton of eukaryotic cells.
• They are approximately 7 nm in diameter.
• They are mainly composed of the protein actin.
• Microfilaments help maintain cell shape, support cell movement, and participate in muscle contraction and cell division.

Last verified on 28-10-2026

Explanation

• Viruses are not included because they are acellular.
• It means they lack a cellular structure.
• It can reproduce only inside living host cells.

Additional information:

• The five-kingdom classification was proposed by Robert H. Whittaker in 1969.
• The five kingdoms are Monera, Protista, Fungi, Plantae, and Animalia.

Last verified on 28-10-2026

Explanation

• Freshwater is water that contains a very low amount of salt, typically less than 1% salinity.
• Examples of freshwater sources include rivers, lakes, streams, and underground aquifers.

Last verified on 28-10-2026

Explanation

• Peptide hormones consist of short chains of amino acids linked by peptide bonds.
• Examples include oxytocin and vasopressin.
• They each containing 9 amino acids, and TRH (thyrotropin-releasing hormone), which contains 3 amino acids.

Last verified on 28-10-2026

Explanation

• Myopia (short-sightedness) is a vision defect in which distant objects appear blurry, while nearby objects are usually seen clearly.
• In myopia, light focuses in front of the retina instead of directly on it.
• Myopia is corrected using concave (diverging) lenses.

Additional information:

• Hyperopia (long-sightedness) mainly causes difficulty seeing nearby objects clearly.

Last verified on 28-10-2026