DNA replication is semi-conservative in nature. This was experimentally proved in eukaryotes by:
1. Hershey and Chase
2. Macleod and McCarty
3. Meselson and Stahl
4. Talyor and his colleagues
1. Hershey and Chase
2. Macleod and McCarty
3. Meselson and Stahl
4. Talyor and his colleagues
Which one of the following experiments of Frederick Griffith resulted in the discovery of bacterial transformation?
| 1. | S-stain(heat-killed) → injected in to Mice → Mice lived |
| 2. | S-strain (heat killed) + R-strain(live) → injected in to Mice → Mice died |
| 3. | S-stain → injected in to Mice → Mice died |
| 4. | R-strain → injected in to Mice → Mice lived |
Given below are two statements: One is labelled as Assertion (A) and the other is labelled as Reason (R)
| Assertion (A): | Semiconservative replication was experimentally proved by Mathew Meselson and Franklin Stahl (1958) |
| Reason (R): | Meselson and Stahl used radioactive isotope \(^{15}N\) and equilibrium density gradient centrifugation technique. |
In the light of the above statements, choose the correct answer from the options given below:
| 1. | (A) is True but (R) is False. |
| 2. | (A) is False but (R) is True. |
| 3. | Both (A) and (R) are True and (R) is the correct explanation of (A). |
| 4. | Both (A) and (R) are True but (R) is not the correct explanation of (A). |
With respect to nucleosome, which of the following statements is incorrect ?
| 1. | Nucleosome contains 120 bp of DNA helix. |
| 2. | Nucleosomes are seen as 'beads' on string' under Electron Microscope. |
| 3. | DNA is wrapped around positively charged histone octamer to form nucleosome. |
| 4. | Nucleosome is the repeating unit of chromatin. |
One of the strands of double stranded DNA has base composition as follows: 15% A, 15% T, 40%G and 30%C. What will be the percentage of these bases in the complementary strand ?
1. 15% A, 15% T, 30% G , 40% C
2. 15% A, 30% T, 40% G , 15% C
3. 15% A, 15% T, 40% G , 30% C
4. 15% A, 40% T, 15% G , 30% C
What would be the proportions of light and hybrid density DNA molecule, respectively if Meselson and Stahl's experiment was continued for 60 minutes?
1. 50%, 50%
2. 25%, 75%
3. 75%, 25%
4. 100%, 0%
1. 1
2. 3
3. 2.5
4. 2
1. Eukaryotic mRNAs get 5' caps and 3' tails.
2. Prokaryotic genes are expressed as mRNA, which is more stable in the cell.
3. Eukaryotic exons may be spliced in alternative patterns.
4. Prokaryotes use ribosomes of different structure and size
1. 8%
2. 16%
3. 31%
4. 42%
| Assertion (A): | Expressed sequence tags (ESTS) which was used in human genome project it identify all the genes that are expressed as DNA. |
| Reason (R): | Complete DNA sequence is decoded. |
| 1. | Both (A) and (R) are true and (R) is the correct explanation of (A). |
| 2. | Both (A) and (R) are true but (R) is not the correct explanation of (A). |
| 3. | (A) is true but (R) is false. |
| 4. | Both (A) and (R) are false. |
- If both the assertion and the reason are true and the reason is a correct explanation of the assertion
- If both the assertion and reason are true but the reason is not a correct explanation of the assertion
- If the assertion is true but the reason is false
- If both the assertion and reason are false
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