Question

why is trna called transfer rna?
a it carries/transfers a specific amino acid to the ribosome during protein synthesis.
b it carries/transfers codes for proteins from the cytoplasm to the dna.
c it carries/transfers the code for one gene from the dna to the ribosome.
d they look like a little truck under the microscope.
question 23
what type of bonds hold complementary base pairs together in a dna double helix?
a peptide bonds
b covalent bonds
c glycosidic bonds
d hydrogen bonds

Explanation:

• For the first question:
• tRNA (transfer RNA) has an anticodon that pairs with a codon on mRNA. It also has a specific amino acid attached to it. During protein synthesis (translation), it "transfers" the correct amino acid to the ribosome where the amino acids are linked together to form a polypeptide chain.
• Option b is incorrect because DNA is in the nucleus (in eukaryotes) and codes are transferred from DNA to mRNA (not from cytoplasm to DNA).
• Option c is incorrect because mRNA (messenger RNA) carries the code for a gene from DNA to the ribosome, not tRNA.
• Option d is a joke and not a scientific reason.
• For the second question:
• Peptide bonds link amino acids together in a polypeptide chain (in proteins), so option a is wrong.
• Covalent bonds are strong bonds (e.g., in the sugar - phosphate backbone of DNA), but the bonds between complementary base pairs are not covalent. So option b is wrong.
• Glycosidic bonds link sugar molecules (e.g., in carbohydrates), so option c is wrong.
• In a DNA double helix, complementary base pairs (A - T and G - C) are held together by hydrogen bonds. Adenine (A) and thymine (T) form two hydrogen bonds, while guanine (G) and cytosine (C) form three hydrogen bonds.

Answer:

1. A. It carries/transfers a specific amino acid to the ribosome during protein synthesis.
2. D. hydrogen bonds