Question

1. Exposure of cells to X rays and gamma rays can cause which of the following?

a.frameshift mutations

b.base-pair substitutions

c.physical breaks in chromosomes

d.pyrimidine dimers

Select all components that are part of the first line of defense:

a.lysozyme

b.defensins

c.C3 and C5

d.NOD

e.TLR

f.stomach pH

3.In an inducible operon, which of the following must occur to inhibit gene expression?

a.The repressor must bind to the operator.

b.The inducer must bind to the repressor.

c.The corepressor must bind to the repressor.

d.The inducer is absent.

Drug resistance spreads by______________.

4.Drug resistance spreads by______________.

a.Exposure to drugs causes mutations in bacterial genes.

b.Exposure to drugs alters gene expression in bacteria.

c.Both horizontal gene transfer and the growth of biofilms spread drug resistance.

d.The formation of biofilms protects bacteria from the effects of drugs.

e.Horizontal gene transfer between bacteria spreads R (resistance) plasmids.

5.Major histocompatibility complex proteins are

a.antigens attached to foreign invaders.

b.not really antigens, but rather antibodies produced to mask foreign antigens.

c.glycoproteins found in the cytoplasmic membranes of most vertebrate animal cells.

d.antigens that provoke allergic reactions.

e.antigens that must be processed by cells called histiocytes in order to be recognized by the immune system.

Answer 1

1. Correct answer:- (a) frameshift mutation
Explanation- It is defined as change in the reading frame of a gene (the triplet code).
-There are two types of frameshift mutations:
(i) insertion
(ii) deletion
2. Correct answers:-
(a) Lysozyme
(c) C3 and C5
(f) Stomach pH
Explanation- The first line of defence against infection are the surface barriers that prevent the entry of pathogenic substances.
E.g.- skin, mucous membranes, complement protein.
3. Correct answer:- (a) the repressor must bind to operator.
4. Correct answer:- (c) Both horizontal gene transfer and the growth of biofilms spread drug resistance.
5. Correct answer:-(b) not really antigens, but rather antibodies produced to mask foreign antigens.