Body Defence Mechanisms

Which of the following is/are chemical barrier(s) to prevent pathogens from entering the body?

(1) sebum on the skin

(2) gastric juice in the stomach

(3) mucus in the bronchus

• (2) only

• (1) and (2) only

• (2) and (3) only

• (1), (2) and (3)

Arrange the following events in the correct sequence.

(1) A blood clot is formed to seal the wound.

(2) A network of protein threads is formed to trap blood cells.

(3) Blood platelets release substances.

(4) Plasma protein is converted into protein threads.

(5) A blood vessel is damaged.

• (3) > (5) > (4) > (1) > (2)

• (5) > (4) > (3) > (2) > (1)

• (5) > (3) > (2) > (4) > (1)

• (5) > (3) > (4) > (2) > (1)

After injury, a wound will become red because

• the body temperature rises.

• arterioles under the skin dilate.

• more phagocytes engulf invading pathogens.

• the capillary walls become more permeable.

Which of the following is/are part(s) of the specific defence mechanism?

(1) production of histamine

(2) phagocytosis

(3) production of antibodies

• (1) only

• (3) only

• (1) and (3) only

• (2) and (3) only

Which of the following comparisons of B cells and T cells is correct?

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Which of the following descriptions about antibodies is/are correct?

(1) Antibodies act only on specific antigens.

(2) Antibodies have a memory for specific antigens.

(3) Antibodies are stored in the lymph nodes after use.

• (1) only

• (1) and (2) only

• (1) and (3) only

• (2) and (3) only

The following lists some events that occur in a primary immune response:

(1) Some B cells differentiate into plasma cells.

(2) Helper T cells bind with a specific antigen.

(3) B cells divide repeatedly.

(4) A specific antibody is produced.

(5) Helper T cells secrete cytokines/lymphokines.

Arrange the events in the correct sequence.

• (2) > (5) > (3) > (1) > (4)

• (2) > (5) > (1) > (3) > (4)

• (3) > (1) > (4) > (2) > (5)

• (5) > (2) > (3) > (1) > (4)

Alex was infected by a pathogen for the first time two months ago. He was then exposed to the same pathogen two weeks ago. Which of the following graphs correctly shows the change in pathogen level in Alex’s blood?

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John received an injection of antibodies in order to develop immunity against tetanus, a bacterial disease which can cause paralysis and death. Which of the following graphs correctly shows the changes in the antibody concentration in his blood?

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Which of the following combinations correctly states the types of immunity?

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