Practise AP Biology 6.1 questions by connecting nucleic-acid structure, base pairing and molecular evidence with the transmission of hereditary information.
Telomeres are repetitive sequences of DNA found on the ends of linear chromosomes. With each cycle of DNA replication, a few bases are lost from the telomeres and the length of telomeres decrease. What is the function of telomeres?
to assist in the synthesis of proteins
to protect the genetic information in chromosomes during cell division
to correct mutations in DNA
to inhibit cell division
B
A researcher measured the temperature at which two different samples of double-stranded DNA denature (separate into single strands). Sample 1 denatured at a significantly lower temperature than sample 2 did. Based on the data, the researcher claims that the DNA in sample 2 is composed of a higher percentage of guanine and cytosine than the DNA in sample 1 is. Which of the following best supports the researcher's claim?
The bonds between guanine and cytosine are covalent bonds, which require more energy to disrupt than those between adenine and thymine.
Guanine-cytosine pairs denature at a higher temperature because they have more hydrogen bonds between them than adenine-thymine pairs do.
Adenine-thymine pairs require less energy to separate because adenine and thymine are both single-ring bases.
Guanine-cytosine pairs require more energy to separate because one is a purine and one is a pyrimidine. The corals' adaptation is an example of adaptive radiation because it has resulted in a wide range of species adapting to the new ocean conditions.
B