Biology - Review Qns - 7

Question 1

What are Oomycetes?

Answer 1

Oomycetes are fungus-like pathogens that mainly affect plants. They release molecules that suppress the innate immune response and inhibit apoptosis.

Question 2

What is an Antigen

Answer 2

antigens are molecules, or parts of molecules that interact with the receptors of T lymphocytes, B lymphocytes and with antibodies

Question 3

What are pathogens?

Answer 3

Pathogens are sources of non-self antigens and agents that cause disease

Question 4

Cell mediated response

7 points

Answer 4

Regulated by T lymphocytes-cytotoxic T cells=Tc

When activated, T-cells increase in site and multiply to produce cytotoxic T-cells

Thyme swell due to activity of T cells and other hormones(cytokines).

• cell responses to foreign molecule
• Cytotoxic T cells needs physical contact to exterminate the infected cell
• they kill infected cells by releasing toxic compounds that poke holes within the membrane of the infected cell.
• T helper cells activates B lymphocytes after they have binded with APC

Question 5

What are Arthropods?

Answer 5

Arthropods are invertebrates with external skeletons (or exoskeletons). Some, such as ticks, can transmit bacterial or viral pathogens when they bite.

Question 6

What are Phagocytes

Answer 6

Phagocytes are leukocytes that are able to engulf and break down pathogens in a process known as phagocytosis.

Question 7

What are viruses?

Answer 7

Viruses are composed of genetic material enclosed in a protein coat. Viral antigens change as a virus evolves, which helps the virus evade detection by the host.

Question 8

What are Protozoans?

Answer 8

Protozoans are unicellular, eukaryotic organisms that have multiple stages in a complete life cycle. Many protozoans express different antigens at different stages in their life cycle. This is known as antigenic variation and assists in evading detection by their host’s immune system.

Question 9

Allergic response

Answer 9

Antigens that trigger an allergic response are called allergens
Response only occurs the second time that substance enters the body
Usually hereditary

Question 10

Antigens have:

4 Points

Answer 10

Unique molecular structure

composed of one or more plypeptide chains.
(can also be composed of necleic acids, carbohydrates or lipids)

Can identiry cells as self or non-self

can be found on the surface of the plasma membrane of cells.

Question 11

Leukocytes

What patterns are recognised

Answer 11

TLRs recognise ‘pathogen-associated molecular patterns’ - PAMPs

Question 12

What are Phagocytes?

Answer 12

Phagocytes are leukocytes that are able to engulf and break down pathogens in a process known as phagocytosis.

Some phagocytes also act as antigen-presenting cells

Question 13

Are innate responses remembered

Answer 13

Innate immune responses do not lead to an immunological memory

Question 14

What are prions

Answer 14

Prions are infectious agents that do not contain genetic material

Question 15

Innate immune responses are:

List 4

Answer 15

Non-specific: they do not target a specific antigen

Rapid: they occur within hours

Present in all animals

Fixed responses: they do not adapt

Question 16

What is a ‘non-self antigen’?

Answer 16

Under normal conditions, any foreign molecule is recognised by the immune system as a non-self antigen.

Question 17

What are viroids?

Answer 17

Viroids are a type of self-cleaving RNA enzyme(or ribozyme). They are composed of short, circular strand of RNA that lack a protein coat.

Question 18

Leukocytes

What does the pattern recognition?

Answer 18

Leukocytes have pattern recognition molecules called toll-like receptors TLRs on their surface

Question 19

Bacteria pathogens

Answer 19

Bacteria are prokaryotes that exist almost everywhere. They are not always pathogenic and many support the functions of the human body, but they do always present non-self antigens.

Question 20

When do innate immune responses occur?

Answer 20

When physical, chemical or microbiological barriers are breached.

Question 21

What is ‘self-tolerance’?

Answer 21

Self-antigens do not normally elicit an immune response. This is known as self-tolerance.

Question 22

Fungal pahtogens

Answer 22

Fungal pathogens include yeasts, moulds and yeast-like fungi. They produce glycoproteins and polysaccharides that act as antigens, allowing the immune system to identify them

Question 23

Humoral immunity

5 Points

Answer 23

Relates to body fluids

Involves B lymphocytes which produce specific antibody against foreign antigens

B cells generate plasma cells which secrete antibodies through exocytosis and memory cells

Cytokines released by helps T lymphocytes help to activate B lymphocytes

When B lymphocytes activate they further differentiate into plasma cells and memory B lymphocytes

Question 24

Some phagocytes act as…

Answer 24

Some phagocytes act as antigen-presenting cells

Question 25

What are allergens?

Answer 25

Antigens that elicit an allergic response in susceptible individuals are called allergens.

Question 26

Examples of Cellular pathogens?

5 examples

Answer 26

Cellular pathogens include:

Bacteria

Fungi

Oomycetes

Protozoans

Some worms and arthropods:

Question 27

What is the Inflammatory response?

Answer 27

Blood vessels widen(vasodilation) to allow blood to flow to area.

Continues until the pathogen is eliminated and damage is healed

Phagocytosis increases in affected area

Cytokines act as signalling molecules to attract other actions

Question 28

What are immunogens

Answer 28

Antigens that elicit an immune response are called immunogens

Question 29

What are Parasitic worms?

Answer 29

Parasitic worms include

Flatworms such as tapeworms

And roundworms such as hookworms

Pinworms and threadworms.

In animals, parasitic worms can regulate the immune system in a number of ways so that the immune response against them is suppressed.

Question 30

Types of barriers to infection

List of 3

Answer 30

Physical

Chemical

Microbiological

Question 31

What is an ‘adaptive immune response’?

Answer 31

An adaptive immune response is one that is specific to a certain antigen.

Question 32

How are ‘adaptive immune responses’ classified?

Answer 32

The adaptive immune response in vertebrates is classified as humoral or cell-mediated.

Question 33

Describe ‘Humoral immunity’

2 sentances

Answer 33

Humoral immunity involves B lymphocytes, which become activated and proliferate when stimulated by specific antigens or cytokines released by helper T lymphocytes.

Activated B lymphocytes become plasma cells that produce antibodies and memory lymphocytes that remain in lymphoid tissues and provide immunological memory.

Question 34

What are ‘Antibodies’?

Answer 34

Antibodies, also known as immunoglobulins, are proteins that bind to specific antigen molecules.

Question 35

Describe ‘Antibodies’?

Answer 35

Antibodies are Y-shaped proteins that have a constant ‘tail’ and variable ‘arm’ regions.

The variable regions have antigen-binding sites and the

constant region recruits components of the immune

system.

Question 36

Types of ‘T Lymphocytes’?

3 types

Answer 36

Cytotoxic T lymphocytes

Helper T lymphocytes

Major Histocompatability complex (I and II)

Question 37

Describe ‘Cytotoxic T lymphocytes’

Answer 37

Cytotoxic T lymphocytes recognise and kill foreign, infected or abnormal host cells by releasing toxic compounds.

Question 38

Describe ‘Helper T lymphocytes’

Answer 38

Helper T lymphocytes secrete cytokines that promote inflammation, and activate macrophages and B lymphocytes.

Question 39

Descibe MHC-I

Major Histocompatability complex I

Answer 39

MHC-I is expressed on all nucleated cells and presents peptide antigens of proteins being produced within the cell to cytotoxic T lymphocytes.

Question 40

Descibe MHC-II

Major Histocompatability complex II

Answer 40

MHC-II is expressed on professional antigen- presenting cells and presents peptides of phagocytosed antigens to helper T lymphocytes.

Question 41

How is Anigen Presentation carride out?

Answer 41

Antigen presentation is carried out by antigen- presenting cells (APCs), including dendritic cells, macrophages and B lymphocytes, and involves antigen fragments of a pathogen being presented on the MHC-II of the host cell. Helper T lymphocytes identify and bind to the complex, and become activated to produce and release cytokines.

Question 42

How do Cytotoxic T kill cells?

Answer 42

Cytotoxic T lymphocytes kill infected cells, which are identifiable by pathogen antigens on MHC-I.

Question 43

What happens after infection?

Answer 43

Memory B and T lymphocytes persist after an infection to enable a larger and faster response upon reinfection with the same pathogen.

Question 44

Differennce between primary & secondary response?

Answer 44

The first infection with a pathogen produces a primary immune response, while reinfection with the same pathogen produces a secondary response due to the presence of memory cells from the primary response (known as immunological memory).

Question 45

What does the lymphatic system do?

Answer 45

The lymphatic system produces lymphocytes and transports them, along with antigen-presenting cells, to the lymph nodes to stimulate adaptive immune responses.

Question 46

What do primary Lympoid organs do?

Answer 46

Primary lymphoid organs (bone marrow and the thymus) are responsible for the production of B and T lymphocytes.

Question 47

Where do T lymphocytes mature?

Answer 47

T lymphocytes mature in the thymus.

Question 48

What are secondary lymphoid organs?

6 items

Answer 48

Secondary lymphoid organs and tissues include:

• Lymph nodes
• Spleen
• Tonsils
• Adenoids
• Appendix
• Peyer’s patches of the small intestine.

Question 49

What do secondary lymphoid organs do?

Answer 49

Secondary lymphoid organs and tissues are the sites where lymphocytes identify and interact with antigen-presenting cells and are then activated to divide and differentiate.