BIO 122 Review

A flower has a genotype of Rr. Red flowers are dominant to white flowers. The phenotype of this flower is pink flowers. What pattern of inheritance is this?

• codominance

• heterozygous

• hemizygous

• incomplete dominance

Answer explanation

Incomplete dominance is when the dominant allele is unable to fully mask the recessive allele. This results in a mix of the two flower colors.; red and white make pink.

What scientist in the 1920s studied pneumonia strains in rats and lead to the discovery of DNA as a transforming factor?

Draw the structure of a nucleotide:

Answer explanation

Identify the scientist(s) who used x-ray crystallography to discover the double helix shape of DNA:

• Franklin and Wilkins

• Watson and Crick

• Griffith

• Hershey and Chase

Answer explanation

Franklin and Wilkins were the scientists to capture the first image of the double helix structure of DNA.

What is the central dogma in biology?

Answer explanation

The central dogma is the transcription of DNA to RNA which is transcribed into a protein.

Which nitrogen bases are purines?

• adenine and cytosine

• thymine and cytosine

• guanine and cytosine

• adenine and guanine

Answer explanation

Adenine and guanine are purines because they have a double-ring structure. Thymine and cytosine are pyrimidines because they have a single-ring structure.

What scientist figured out the base pairing of DNA? (A-T and C-G)

Answer explanation

Chargoff discovered the base pairing of nitrogen bases by studying various species. He found that all species had the same percentage of adenines and thymines as well as the same percentage of cytosines and guanines.

Define the following terms:

1. codominance

2. incomplete dominance

3. pleitropy

4. polygenic

5. confounding variable

Answer explanation

1. Codominance is when both of the alleles are dominant. This results in both phenotypes of the alleles to be present. (i.e. red and white flowers)

2. Incomplete dominance is when the dominant allele cannot fully mask the recessive allele. (i.e. pink flowers)

3. Pleiotropy is the phenomenon in which a single allele affects two or more apparently unrelated phenotypic traits.

4. Polygenic is a characteristic, such as height or skin color, that is influenced by two or more genes.

5. A confounding variable is a condition in an experiment that was supposed to be controlled, but something went wrong and conditions changed. (i.e. a window being left open and changing the temp. in one group of the experiment.)