Q. What is the function of ribosomes in protein synthesis?
A.To transcribe DNA
B.To translate mRNA into proteins
C.To replicate DNA
D.To splice RNA
Solution
Ribosomes are the cellular machinery that translate mRNA into proteins by facilitating the assembly of amino acids.
Correct Answer: B — To translate mRNA into proteins
Q. What is the primary structure of DNA composed of?
A.A double helix of nucleotides
B.A single strand of amino acids
C.A triple helix of sugars
D.A circular structure of lipids
Solution
The primary structure of DNA is composed of a double helix formed by nucleotides, which consist of a sugar, phosphate group, and nitrogenous base.
Correct Answer: A — A double helix of nucleotides
Q. What is the significance of the 5' and 3' ends of a DNA strand?
A.They indicate the direction of replication
B.They determine the type of base pairs
C.They are sites for protein binding
D.They are involved in RNA splicing
Solution
The 5' and 3' ends of a DNA strand indicate the direction of replication and transcription, as nucleic acids are synthesized in the 5' to 3' direction.
Correct Answer: A — They indicate the direction of replication
Q. Which nitrogenous base is found in RNA but not in DNA?
A.Thymine
B.Uracil
C.Cytosine
D.Adenine
Solution
Uracil is a nitrogenous base found in RNA, replacing thymine which is present in DNA.
Correct Answer: B — Uracil
Q. Which of the following is a characteristic of the double helix structure of DNA?
A.Antiparallel strands
B.Single-stranded
C.Left-handed twist
D.No hydrogen bonds
Solution
The double helix structure of DNA features two antiparallel strands that are held together by hydrogen bonds between complementary bases.
