12.6

Question 1

What is an immune response? (2 marks)

Answer 1

The specific response to a pathogen, which involves the action of lymphocytes and the production of antibodies.

Question 2

Antibodies are specialised glycoproteins called……. (1 mark)

Answer 2

Immunoglobulins

Question 3

Are antibodies specific or non-specific? (1 mark)

Answer 3

Specific to one type of antigen.

Question 4

Antibodies are complementary to their specific antigen, what model can be used to describe how they bind? (1 mark)

Answer 4

Lock and key model

Question 5

How many polypeptide chains do disulfide bridges hold together? (1 mark)

Answer 5

4 polypeptide chains

Question 6

The constant region is the same in all antibodies, what is its function? (2 marks)

Answer 6

Enables the antibody to attach to phagocytic cells and helps in phagocytosis.

Question 7

The variable region has a different shape in each type of antibody, what causes this? (1 mark)

Answer 7

Its amino acid sequence.

Question 8

Which part of the antibody is specific towards an antigen, how and why? (3 marks)

Answer 8

The variable region.
It is complementary to the shape of the antigen.
To ensure specificity towards an antigen.

Question 9

What is the function of then hinge region in antibodies? (2 marks)

Answer 9

Allows flexibility–> Y shaped section can move further apart to attach to more than one antigen.

Question 10

How do antibodies work? (3 marks)

Answer 10

Binds to antigen.
Antibody-antigen complex stimulates the digestion of bacteria by phagocytosis (like opsonin).
Most pathogens cannot affect body cells once they form an antibody-antigen complex.

Question 11

What is agglutination? (2 marks)

Answer 11

One antibody binds to 2 pathogens, causing them to clump together.
This makes pathogens more easily engulfed by phagocytosis.

Question 12

How do antibodies use neutralisation? (2 marks)

Answer 12

Antibodies can act as antitoxins, binding with toxins produced by pathogens, to make them harmless.

Question 13

Name the two ways antibodies minimise pathogen’s effect on the body. (2 marks)

Answer 13

Agglutination
Neutralisation

Question 14

What is an antigen? (1 mark)

Answer 14

A molecule that stimulates an immune response.

Question 15

What is an antibody? (1 mark)

Answer 15

A protein molecule that can identify and neutralise antigens.

Question 16

What are the specific immune system’s two main types of response to pathogens? (2 marks)

Answer 16

Cellular response
Humeral response

Question 17

What is the specific immune system’s humoral response? (2 marks)

Answer 17

Antibodies
Targets pathogens in body fluids

Question 18

What is the specific immune system’s cellular response? (2 marks)

Answer 18

Highly specialised cells
Target pathogens inside cells

Question 19

Where are lymphocytes found? (1 mark)

Answer 19

Blood and lymph nodes

Question 20

Do lymphocytes or phagocytes recognise antigens on pathogens? (1 mark)

Answer 20

lymphocytes

Question 21

What are two main types of lymphocyte and where are they formed? (2 marks)

Answer 21

B lymphocytes- bone marrow
T lymphocytes- thymus

Question 22

What do T helper cells produce? (1 mark)

Answer 22

Interleukins, a type of cytokine

Question 23

What does interleukin do? (2 marks)

Answer 23

Stimulate B cell and antibody production.
Attracts other T cells and antibodies

Question 24

How do T killer cells kill pathogens? (2 marks)

Answer 24

By producing a chemical called perforin, which makes holes in pathogen cell plasma membranes.