Topic 6 - Exam Questions

Question 1

Explain why the presence of microorganisms on the skin and in the gut helps to prevent pathogenic organisms multiplying in the body (3 Marks)

Answer 1

~ Flora in the gut and skin are better adapted to the conditions.

~ They can outcompete pathogenic organisms.

~ Bacteria secrete enzymes, which help to destroy pathogens.

Question 2

Explain why there are relatively few species of bacteria in the stomach (2 Marks)

Answer 2

~ pH is too low for enzymes to function.

~ Bacteria in the stomach may have adaptations for survival in these conditions.

Question 3

Describe how the production and action of interferons differs from the production and action of lysozyme (3 Marks)

Answer 3

~ Interferons are involved with viral infections, lysozyme is involved with bacterial infections.

~ Interferons are produced by infected cells, lysozyme are present in phagocytes.

~ Interferons inhibit viral replication, lysozyme kills bacteria.

Question 4

Explain the meaning of the non-specific immune response (2 Marks)

Answer 4

~ Response is not dependant on previous infection.

~ Involves inflammation, interferon production and phagocytosis.

Question 5

Explain why bacteria are able to multiply in the bloodstream when they enter the body (3 Marks)

Answer 5

~ Warm conditions available.

~ Suitable temperature for bacterial enzymes.

~ Amino acids present for growth.

Question 6

Answer 6

Question 7

Scientists have recently discovered a new class of antibiotics that bind to ribosomes.

Exaplin why antibiotics could affect the production of proteins in ribosomes (3 Marks)

Answer 7

~ Ribosome shape is altered.

~ mRNA is prevented from binding.

~ Translation cannot occur.