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.

Explanation

• T₃ (Triiodothyronine) and T₄ (Thyroxine) are thyroid hormones.
• They are produced in the thyroid gland.
• They are formed by iodination of the amino acid tyrosine.
• Iodinated tyrosine molecules (iodotyrosine) combine to form T₃ and T₄.
• Dopamine and GABA are neurotransmitters, not thyroid hormone precursors.

Last updated question 17-02-2026

Explanation

Active transport is a critical process in the nephron used to reabsorb solutes against their concentration gradients

Proximal Tubule:

This is the primary site of active transport, where approximately 65–70% of filtered sodium is reabsorbed via the Na⁺/K⁺-ATPase pump.

It also uses secondary active transport to reabsorb 100% of filtered glucose and amino acids.

Last updated question 17-02-2026

Explanation

•  Mammary glands are modified sweat glands.
•  They produce milk for offspring.
•  Structurally, they retain sweat gland features.
•  They are present in mammals only.
•  Hormones regulate their secretion.

Last updated question 17-02-2026

Explanation

 Sodium is most heavily reabsorbed in the proximal tubule of the kidney,

Accounts for approximately 65% to 70% of the total filtered sodium. 

Last updated question 17-02-2026

Explanation

The dependent variable is the factor that is measured or observed as a response to changes made by the experimenter.

In this specific experiment, the scientist is investigating how salt affects plant life

Therefore, the number of plants is the measured outcome that "depends" on the salinity levels.

Explanation

Explanation

Antonie van Leeuwenhoek first observed yeast cells using his single-lens microscope in 1680. 

Explanation

Explanation

Last updated question 17-02-2026