All Free Biology MCQs with Answers
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19844 questions · page 728 of 1985
7271. First amino acid in the synthesis of protein is:
- A. Glycine
- B. Methionine
- C. Alanine
- D. Phenylalanine
Explanation: Explanation for this question will be added soon!
Correct answer: Methionine7272. The binding of tRNA to ribosomal unit is controlled by:
- A. tRNA synthase
- B. Initiation factor
- C. Elongation factor
- D. Termination factor
Explanation: The binding of tRNA to the ribosomal unit during translation is primarily controlled by a group of proteins known as initiation factors. These factors play a crucial role in various steps of translation initiation, including the binding of mRNA to the small ribosomal subunit, the recruitment of the initiator tRNA, and the assembly of the ribosomal complex.
Correct answer: Initiation factor7273. Which of the followings helps the tRNA to attach on exposed mRNA code at A site:
- A. tRNA synthase
- B. Initiation factor
- C. Elongation factor
- D. Termination factor
Explanation: Explanation for this question will be added soon!
Correct answer: Elongation factor7274. The movement of ribosome to next code is controlled by:
- A. Termination factor
- B. Elongation factor
- C. Initiation factor
- D. tRNA synthase
Explanation: The movement of the ribosome to the next codon on the mRNA during translation is primarily controlled by elongation factors. These factors help in the translocation step of protein synthesis, which involves moving the ribosome along the mRNA molecule to position the next codon in the A site, ready for the entry of the next aminoacyl-tRNA.
Correct answer: Elongation factor7275. The ribosome moves in a direction of mRNA:
- A. 3'
- B. 4'
- C. 5'
- D. 6'
Explanation: During translation, the ribosome moves along the mRNA molecule in the 5' to 3' direction. This means that as the ribosome progresses along the mRNA, it moves towards the 3' end of the mRNA molecule.
Correct answer: 3'7276. The termination codes are recognized by:
- A. Termination factor
- B. Elongation factor
- C. Initiation factor
- D. Releasing factor
Explanation: The termination codons, also known as stop codons, are recognized by proteins called release factors. These release factors bind to the A site of the ribosome when a stop codon (UAA, UAG, or UGA) enters the A site. Unlike tRNA molecules that carry amino acids, release factors do not carry an amino acid.
Correct answer: Releasing factor7277. If the DNA of an human adult is lined up end to end, it will stretch nearly:
- A. 50 billion km
- B. 100 billion km
- C. 200 billion km
- D. 300 billion km
Explanation: If the DNA of a human adult were lined up end to end, it would stretch nearly 100 billion kilometers, reaching a distance roughly equivalent to 60 times the distance from Earth to the Sun. This remarkable length showcases the compact yet intricately organized genetic blueprint that governs the complexity of human life.
Correct answer: 100 billion km7278. The substitution of one or more bases of DNA is called:
- A. Insertion
- B. Point mutation
- C. Deletion
- D. Transposition
Explanation: A point mutation refers to the substitution, insertion, or deletion of a single nucleotide base (or a few bases) in a DNA sequence. When only one base pair is altered, it's specifically referred to as a point mutation. This type of mutation can have various effects, ranging from no observable impact to significant changes in the resulting protein sequence or gene function.
Correct answer: Point mutation7279. The addition of one or a few bases is:
- A. Insertion
- B. Point mutation
- C. Deletion
- D. Transposition
Explanation: The addition of one or a few bases into a DNA sequence is called an insertion mutation. This type of mutation involves the addition of extra nucleotides into the DNA sequence, which can lead to a shift in the reading frame during translation, potentially resulting in a completely different amino acid sequence and protein product.
Correct answer: Insertion7280. Change in gene position is:
- A. Insertion
- B. Point mutation
- C. Deletion
- D. Transposition
Explanation: Explanation for this question will be added soon!
Correct answer: Transposition