All Free Biology MCQs with Answers
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19844 questions · page 724 of 1985
7231. The DNA polymerase adds how many nucleotides to the end?
- A. 2
- B. 3
- C. 4
- D. 5
Explanation: During elongation, an enzyme called DNA polymerase adds DNA nucleotides to the 3' end of the template. Because DNA polymerase can only add new nucleotides at the end of a backbone, a primer sequence, which provides this starting point, is added with complementary RNA nucleotides.
Correct answer: 37232. The strand which elongate towards replication fork is:
- A. Leading strand
- B. Lagging strand
- C. Both (A) and (B)
- D. None of the above
Explanation: Leading strand, which elongates toward the replication fork, is built up simply by adding nucleotides continuously to its growing 3' end. In contrast the lagging strand which elongates away from the replication fork, is synthesized discontinuously as a series of short segments that are later connected.
Correct answer: Leading strand7233. The length of Okazaki fragments is:
- A. 100-200 nucleotide
- B. 200-300 nucleotide
- C. 300-400 nucleotide
- D. 400-500 nucleotide
Explanation: Okazaki fragments are about 100 - 200 nucleotides long in eukaryotes and 1000 - 2000 nucleotides long in prokaryotes.
Correct answer: 100-200 nucleotide7234. Okazaki fragment is a:
- A. RNA
- B. DNA
- C. Protein
- D. Enzyme
Explanation: The term "Okazaki fragment" refers to short, newly synthesized DNA fragments formed on the lagging strand during DNA replication. Okazaki fragments are part of DNA, not RNA.
Correct answer: DNA7235. Okazaki fragments are synthesize by:
- A. DNA polymerase I
- B. Pirmase
- C. Ligase
- D. DNA polymerase III
Explanation: Each Okazaki fragment is synthesized by DNA polymerase III in 5' → 3' direction, beginning at the replication fork and moving away from it.
Correct answer: DNA polymerase III7236. The disease alkaptonuria was studied by:
- A. Beadle and Tatum
- B. Meselson - Stahl
- C. Garrod and Bateson
- D. Watson and Crick
Explanation: Explanation for this question will be added soon!
Correct answer: Garrod and Bateson7237. Experiments on Neurosopora were performed by:
- A. Beadle and Tatum
- B. Meselson - Stahl
- C. Garrod and Bateson
- D. Watson and Crick
Explanation: Beadle and Tatum exposed Neurospora spores to X-rays, expecting that DNA in some of these spores would experience damage in the regions encoding the ability to make compounds needed for normal growth.
Correct answer: Beadle and Tatum7238. Match homogenetisic acid with one of the followings:
- A. Hemophilia
- B. Anemia
- C. Alkaptonuria
- D. Tay Sach's disease
Explanation: In normal individuals, homogentisic acid is broken down into simpler substances. However, in Alkaptonuria it is not broken down due to the lack of suitable enzymes.
Correct answer: Alkaptonuria7239. Which of the followings is absent in minimal medium?
- A. Sugar
- B. Ammonia
- C. Enzymes
- D. Vitamins
Explanation: Beadle and Tatum prepared a minimal medium which included sugar, ammonia, salt and vitamins but enzyme was absent.
Correct answer: Enzymes7240. Minimal medium was prepared by:
- A. Beadle and Tatum
- B. Meselson - Stahl
- C. Garrod and Bateson
- D. Watson and Crick
Explanation: Beadle and Tatum placed subcultures of individual fungal cells on a "minimal" medium that contained only sugar, ammonia, salts, a few vitamins and water.
Correct answer: Beadle and Tatum