Topic 6B - Microorganisms and Immunity

Question 1

EQ. Suggest what bactericidal antibiotics are. (2 marks)

Answer 1

• bacteria cells burst

- therefore destroying the cells

Question 2

EQ. Suggest what bacteriostatic antibiotics are. (2 marks)

Answer 2

• there’s no cell division

- so the bacteria cannot replicate

Question 3

EQ. Suggest how hospitals could improve the prevention and control of the spread of infections. (3 marks)

Answer 3

• isolate infected patients
• sterilize the used pillows
• improve laundry by washing at a higher temperature
• make sure people always wash hands

Question 4

EQ. Explain the immune response to a second vaccination. (3 marks)

Answer 4

• because of the first vaccination
• there are already antibodies present
• and memory cells present
• therefore they can start producing antibodies immediately

Question 5

EQ. Explain the advantage of vaccinating people twice against a virus. (2 marks)

Answer 5

• they can produce antibodies quicker

- so they can destroy the virus quicker

Question 6

EQ. Give two differences between the genetic material of bacteria and viruses. (2 marks)

Answer 6

• bacteria contain circular DNA, viruses contain linear DNA

- bacteria contain just DNA, viruses contain DNA and RNA

Question 7

EQ. Describe how macrophages ingest the bacteria. (2 marks)

Answer 7

• it engulfs the bacteria by endocytosis

- the bacterium is stored inside the vacuole

Question 8

EQ. Explain how a person can develop artificial active immunity following vaccination. (4 marks)

Answer 8

• an attenuated version of the pathogen is injected into you
• this stimulates an immune response
• macrophages as APC are activated
• there is a production of memory T cells

Question 9

Name the type of cell in the human immune system that is infected by HIV

Answer 9

T helper cells

Question 10

Name the enzyme used to produce DNA from viral RNA in an infected cell

Answer 10

Reverse transcriptase

Question 11

EQ. State two characteristic features of antibodies. (2 marks)

Answer 11

• Y shape
• antigen binding site region
• a constant region

Question 12

EQ. Suggest why data about HIV infections are often estimates. (2 marks)

Answer 12

• because HIV can be dormant

- symptoms dont always show

Question 13

EQ. A person who has been vaccinated becomes infected with HPV-16. Explain the role of the T cells in the body of this person. (3 marks)

Answer 13

• person already has memory T cells
• these memory T cells recognise the antigens specific to HPV-16
• T helper cells activate T killer cells
• T killer cells attack cells infected with HPV-16 virus

Question 14

EQ. Describe the role of decomposers, such as microorganisms, in the carbon cycle. (2 marks)

Answer 14

• decomposers break down organic material

- decomposers respire and release carbon dioxide

Question 15

What cell produces antibodies

Answer 15

plasma cell

Question 16

what type of immunity is obtained when a newborn baby drinks from the milk produced by its mother and from a vaccine

Answer 16

natural passive immunity/ artificial active immunity

Question 17

EQ. Explain how changes in the blood vessels result in the redness and swelling seen at the site of inflammation. (4 marks)

Answer 17

• histamines are released
• vasodilation in blood vessels
• increases blood flow
• permeability increases
• so more blood plasma can enter the tissue causing swelling

Question 18

EQ. Explain the effects of interferons. (3 marks)

Answer 18

• interferons activate cells involved in the specific immune response like T helper cells which activate B cells
• interferons trigger inflammation
• interferons prevent viral replication by inhibiting the production of viral proteins

Question 19

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

Answer 19

• blood provides an ideal PH for bacterial enzymes
• provides amino acids for growth
• provides glucose for respiration

Question 20

What is the purpose of a placebo

Answer 20

to show the drug has an effect