Question

1. In the lac operon RNA polymerase first binds to the:

a. promoter

b. operator

c. repressor

d. regulator

2. Spontaneous mutations are:

a. cause by chemicals such as acridine and caffeine

b. caused by physical agents such as ultraviolet light or x-rays

c. the result of errors in the base pairing of nucleotides during replication

d. occur at a rate higher than the rate of induced mutations

3. Which statement about mutations is false?

a. A mutation can alter the genotype of an organism without altering the phenotype

b. Frameshift mutations are typically more serious than point mutations

c. Spontaneous mutations are the result of exposure to mutagens

d. Photoreactivation can take place in non-photosynthetic bacteria

4. DNA viruses are grouped into families based on the following characteristics except:

a. presence of an envelope

b. location of action

c. whether DNA is single stranded or double stranded

d. whether DNA is linear or circular

5. Some members of the spirochetes move by means of:

a. gliding

b. hami

c. peritrichous flagella

d. axial filaments

e. nothing, they are non-motile

6. Microbial growth:

a. refers to the increase in the size of a microbial cell

b. refers to the increase in the frequency of cell division

c. in a single generation time leads to double the cell size

d. in a single generation time leads to double the number of microbes

Answer 1

1) The correct option is a. promoter.

RNA polymerase binds to the promoter of the lac operon. It initiates the process of transcription by binding to the promoter region.

2) The correct option is c. the result of errors in the base pairing of nucleotides during replication.

Spontaneous mutations arise from errors in DNA replication, spontaneous lesions and transposable genetic elements.

3) The correct option is c. spontaneous mutations are the result of exposure to mutagens.

Spontaneous mutations arise from different types of sources such as errors in DNA replication, spontaneous lesions, and transposable genetic elements.

4) The correct option is b. location of action.

DNA viruses are grouped into families based on these characteristics:

Presence of an envelope.

Single stranded or double stranded DNA.

Linear or circular DNA.