Question

question 9
the polymerase chain reaction (pcr) consists of three steps, as shown in the picture below. these steps, in the correct order, are:

a. 1. annealing; 2. denaturation ; 3. elongation.
b. 1. denaturation; 2. annealing; 3. elongation.
c. 1. elongation; 2. denaturation ; 3. annealing.
d. 1. denaturation; 2. elongation; 3. annealing.

question 10
mutations are
a. changes in dna that are present in only one generation and are not passed on to offspring.
b. heritable changes in the sequence of dna bases.
c. mistakes in the incorporation of amino acids into proteins.
d. changes in the mrna of an organism.

Explanation:

• For Question 9:
• In PCR, the first step is denaturation, where the double - stranded DNA is separated into single strands by high temperature.
• The second step is annealing, where primers bind to the complementary sequences on the single - stranded DNA.
• The third step is elongation, where DNA polymerase adds nucleotides to the primers to synthesize new DNA strands.
• For Question 10:
• Mutations are heritable changes in the DNA sequence. Option A is incorrect as mutations can be passed on. Option C is about protein synthesis errors, not mutations. Option D is about mRNA changes, but mutations are in DNA.

Answer:

• Question 9: B. 1. denaturation; 2. annealing; 3. elongation.
• Question 10: B. heritable changes in the sequence of DNA bases.