Biology Unit 4 Review

Chargaff found that for DNA __________.

• the ratio of A to C is close to 1:1 and the ratio of G to T is close to 1:1

• A + T = G + C

• the ratio of A to T is close to 1:1 and the ratio of G to C is close to 1:1

• the ratio of A to G is close to 1:1 and the ratio of T to C is close to 1:1

• A + T = 50% of the total bases

Cytosine (C) makes up 42% of the nucleotides in a sample of DNA from an organism. Approximately what percentage of the nucleotides in this sample will be thymine? 

• 8%

• 16%

• 21%

• 60%

The scientist(s) that was/were given credit for first determining the structure of DNA is/are: 

• Hershey and Chase

• Watson and Crick 

• Chargaff

• Griffith

Rosalind Franklin's X-ray crystallography data suggested DNA is double stranded and has a uniform diameter. These observations can be used to rule out base pairing between two of the same nucleotide because ________.

• the antiparallel orientation of strands would result in one of the pair being upside down

• identical nucleotides would not have the appropriate number of hydrogen bonding sites to pair

• an A-A pair is wider than a C-C pair

• thymine dimers are removed by excision repair

Monomers for the synthesis of DNA are called __________. 

• disaccharides

• amino acids

• monosaccharides

• nucleotides

• fatty acids

In DNA, the two purines are __________, and the two pyrimidines are __________.

• adenine and thymine; cytosine and guanine

• cytosine and guanine; adenine and thymine

• cytosine and thymine; adenine and guanine

• adenine and cytosine; guanine and thymine

• adenine and guanine; cytosine and thymine

Which one of the following statements is correct?

• Adenine forms three covalent bonds with thymine; guanine forms two covalent bonds with cytosine.

• Adenine forms two hydrogen bonds with thymine; guanine forms three hydrogen bonds with cytosine.

• Adenine forms three hydrogen bonds with thymine; guanine forms two hydrogen bonds with cytosine.

• Adenine forms two hydrogen bonds with guanine; thymine forms three hydrogen bonds with cytosine.

• Adenine forms two covalent bonds with thymine; guanine forms three covalent bonds with cytosine.

The two antiparallel strands of nucleotides that form the DNA double helix are held together by __________. 

• covalent bonds between carbon atoms in deoxyribose molecules

• ionic bonds between guanine and cytosine

• ionic bonds between guanine and cytosine

  5' deoxyribose and phosphate bonds

• covalent bonds between nitrogen atoms in adenine and in thymine

• hydrogen bonds between nucleotide bases

Which of the following characteristics of DNA allows it to carry a vast amount of hereditary information?

• sequence of bases

• phosphate-sugar backbones

• complementary pairing of bases

• antiparallel orientation

One strand of a DNA molecule has the base sequence 5′-ATAGGT-3′. The complementary base sequence on the other strand of DNA will be 3′- __________-5′.

• TATCCA

• TGGAUA

• TGGATA

• ATAGGT

• UAUCCA