Question

Erwin Chargaff’s work on the composition of nucleic acids began in 1944. His findings, which later became known as Chargaff’s rules, detail the specific pairings that occur in double-stranded DNA molecules.

According to one of Chargaff’s rules, a section of DNA molecule that contains 50 base pairs and has 15 adenine bases must also contain —

{silence}Option A.{silence}
15 guanine bases

{silence}Option Be.{silence}
15 cytosine bases

{silence}Option C.{silence}
15 thymine bases

{silence}Option D.{silence}
15 uracil bases

Answer 1

Some cells can die as a result of external agents such as poison or trauma. However, most cells die through a process known as apoptosis, or programmed cell death.

What is a likely consequence of a mutation that prevents apoptosis?

{silence}Option A.{silence}
A tumor

{silence}Option Be.{silence}
A loss of amino acids

{silence}Option C.{silence}
A lack of cell division

{silence}Option D.{silence}
A reduction in chromosome number

Answer 2

Erwin Chargaff examined DNA samples from different organisms to study base pairing. Some data from DNA samples are shown.

Organism Adenine Guanine Cytosine Thymine
Sea urchin 32.8% 17.7% 17.3% 32.1%
Salmon 29.7% 20.8% 20.4% 29.1%
Wheat 28.1% 21.8% 22.7% 27.4%
Which conclusion is supported by the data in the table?

{silence}Option A.{silence}
Each organism contains more cytosine than any other base.

{silence}Option Be.{silence}
The three organisms have the same sequence of nucleotides.

{silence}Option C.{silence}
All three organisms contain the same types of nitrogen bases.

{silence}Option D.{silence}
The presence of each base is dependent on the size of the organism.

Answer 3

Option C. 15 thymine bases

Answer 4

Option A. A tumor

Answer 5

Option C. All three organisms contain the same types of nitrogen bases.