In a double-stranded DNA, adenine pairs with thymine by how many hydrogen bonds?
A. Two
B. Three
C. One
D. Four
Answer: Option A
Solution (By JKSSB Mock Tests)
Adenine (A) pairs with thymine (T) via two hydrogen bonds. Guanine (G) pairs with cytosine (C) via three hydrogen bonds. This base pairing (complementarity) is key to the double helix structure and ensures accurate replication and transcription. The higher number of bonds between G-C contributes to DNA stability; GC-rich regions are harder to denature.
Explanation:
About 70% CO₂ is carried as bicarbonate. The main stimulus is high CO₂; external respiration is in lungs; diaphragm moves downward (contracts) during inhalation.
Explanation:
Meiosis is reductional division occurring in germ cells to produce haploid gametes (n) from a diploid cell (2n). It involves two successive divisions (Meiosis I and II) and introduces genetic variation through crossing over and independent assortment. Mitosis maintains chromosome number, amitosis is direct division, and fission is asexual reproduction in prokaryotes.
Explanation:
The loop of Henle creates a concentration gradient in the medulla, enabling water reabsorption and concentrated urine. Urine is formed in kidneys, the unit is nephron, ureter connects kidney to bladder.
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