Question

question 1
which nitrogen base binds with cytosine?
a uracil
b adenine
c thymine
d guanine

question 2
in a dna molecule, the nitrogen base adenine always bonds with what other nitrogen base?
a adenine
b cytosine
c guanine
d thymine

Explanation:

• Question 1: In DNA, the nitrogen - base pairing follows the rule that cytosine (C) pairs with guanine (G). Uracil (U) is found in RNA and pairs with adenine (A) in RNA. Adenine (A) pairs with thymine (T) in DNA. Thymine (T) pairs with adenine (A).
• Question 2: In DNA, adenine (A) always bonds with thymine (T) through two hydrogen bonds. Adenine - adenine bonding is not a standard base - pairing in DNA. Cytosine (C) pairs with guanine (G). Guanine (G) pairs with cytosine (C).

Answer:

• Question 1: d. guanine
• Question 2: d. Thymine