Consider statements about genetics: 1. Genes are located on chromosomes. 2. DNA replication is semi-conservative. 3. RNA is double-stranded. Which are correct? MCQ with Answer and Explanation
Consider statements about genetics: 1. Genes are located on chromosomes. 2. DNA replication is semi-conservative. 3. RNA is double-stranded. Which are correct?
A. 1 and 2 only
B. 2 and 3 only
C. 1 and 3 only
D. 1, 2 and 3
Answer: Option A
Solution (By JKSSB Mock Tests)
Genes are specific sequences of DNA that code for proteins or RNA, and they are arranged linearly on chromosomes within the nucleus. DNA replication is semi-conservative, meaning each newly synthesized DNA molecule consists of one original parental strand and one newly synthesized strand, as proven by the Meselson-Stahl experiment. RNA is typically single-stranded, allowing it to fold into complex shapes and perform various functions, unlike the double-stranded DNA helix. Thus, statements 1 and 2 are correct.
Explanation:
Adenylyl cyclase converts ATP to cyclic AMP, a second messenger. Guanylyl cyclase makes cGMP, phospholipase C produces IP₃/DAG, PKA is activated by cAMP.
Consider the following statements about vitamins:
1. Vitamin A is fat-soluble.
2. Vitamin C is water-soluble.
3. Vitamin D can be synthesized in the skin by sunlight.
Which of the above is/are correct?
Explanation:
Prokaryotic DNA is typically circular, double-stranded, and found in a nucleoid region without a nuclear membrane. It is not associated with histones (though some Archaea have histone-like proteins). Plasmids are extra-chromosomal DNA. Eukaryotic DNA is linear and complexed with histones. This difference is fundamental in cell classification.
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