Explanation

• The nephron is the functional unit of the kidney.
• Sodium reabsorption occurs at different parts of the nephron.
• Thick loop of Henle actively pumps out Na⁺ using ATP (active transport).
• Thin loop of Henle mainly allows passive movement of water and ions.
• Proximal tubule reabsorbs Na⁺ mainly by secondary active transport; collecting duct fine-tunes Na⁺ under hormonal control (aldosterone).

Last updated question 17-02-2026

Explanation

Explanation

Explanation

• Carolus Linnaeus gave the artificial system of classification. 
• He classified plants mainly based on the number and arrangement of stamens.
• known as the "Father of Taxonomy

Last updated question 17-02-2026

Explanation

• Cholesterol functions as a "fluidity buffer"
• The cell membrane is made of a phospholipid bilayer.
• Cholesterol is present between phospholipid molecules.
• It maintains membrane fluidity and flexibility.

Last updated question 17-02-2026

Explanation

• Musk is a strong-smelling substance used in perfumes.
• It is mainly obtained from musk deer (male).
• It is also obtained from the African civet.
• African civet (also known as civet musk or civetone)
• Goat and sheep do not produce musk.
• Natural musk is rare and expensive, so synthetic musk is commonly used today.

Last updated question 17-02-2026

Explanation

• A meso compound has two or more chiral centers.
• It possesses an internal plane of symmetry.
• Due to symmetry, it is optically inactive.
• The optical activities of chiral centers cancel each other.
• Example: meso-tartaric acid.

Last updated question 17-02-2026

Explanation

Formation of H₂O (H₂ + O₂ → H₂O) is practically irreversible under normal conditions.

Explanation

• Energy transfer in a food chain follows the 10% law.
• Only about 10% of energy passes to the next trophic level.
• About 90% of energy is lost as heat and metabolic activities.
• This loss limits the number of trophic levels in a food web.
• Therefore, energy decreases by approximately 90% at each step.

Last updated question 17-02-2026

Explanation

• DNA sequencing by Sanger method uses ddNTPs.
• ddNTPs lack the 3′-OH group on the sugar.
• Without 3′-OH, no further nucleotide can attach.
• This causes termination of the DNA chain.
• Different labeled ddNTPs help determine the DNA sequence.