communicable diseases

Question 1

what is a pathogen

Answer 1

organism that causes disease

Question 2

how does bacteria spread

Answer 2

Reproduce quickly and they damage cells by releasing toxins

Question 3

How do fungi spread

Answer 3

hyphae cause mycelium which can release spores - secreting enzymes

Question 4

how do viruses cause disease

Answer 4

invade cells and take over their genetic machinery and then eventually burst the cells

Question 5

how do protoctista cause disease

Answer 5

entering host cells and feeding on the contest to grow

Question 6

What are physical plant defences

Answer 6

Cellulose cell wall - physical barrier and chemicals which can be activated
waxy cuticles-prevent water getting i where pathogen can reside
bark -physical barrier
closing of stomata
callose-polysaccharide deposited in sieve tubes.
tylose - swelling that fills the xylem vessel making a plug

Question 7

chemical plant defences

Answer 7

terpenoids - oils that have antibacterial properties
tannins - compounds that deactivate enzymes

Question 8

state the blood clotting cascade

Answer 8

platelets bind to damaged blood vessel
inactive thrombokinase turns active stimulating thrombin enzyme.
soluble fibrinogen turns into insoluble fibrin creating a platelet plus –> clot

Question 9

how does inflammation work

Answer 9

histamines cause vasodilation of our blood vessels causing them to allow more blood to pass through

Question 10

name bacterial diseases

Answer 10

– tuberculosis (TB),
bacterial meningitis,
ring rot(potatoes, tomatoes

Question 11

name viral diseases

Answer 11

HIV/AIDS (human),
influenza (animals),
TobaccoMosaic Virus (plants)

Question 12

Name diseases cause by protoctists

Answer 12

malaria,
potato/tomato late blight

Question 13

name fungal diseases

Answer 13

black sigatoka (bananas),
ringworm (cattle),
athlete’s foot (humans)

Question 14

Explain how strains of antibiotic-resistant bacteria appear

Answer 14

Mutation;

Antibiotic is selective agent / pressure;

Resistant strains survive / non-resistant die;

Gene / allele / mutation, passed on to offspring;

Happens over many generations;

AVP, i.e. mutation is random

Question 15

compare neutrophils and macrophages

Answer 15

Neutrophil lobed nucleus & monocyte is bean shaped
monocytes have vacuoles & neutrophils dont

Question 16

why producing an effective vaccine against Plasmodium has proved to be
so difficult.

Answer 16

Plasmodium inside, liver cell / red blood cell;
antibodies cannot reach target / cannot be detected by immune system;
large genome;
antigenic variation / AW;
variation from meiosis;
detail; e.g. independent assortment / crossing over
parasite switches between different versions of proteins;
ref var gene;

Question 17

Explain the importance of B memory cells in immunity.

Answer 17

B memory cells produced in the primary response which are specific to the antigen remain in the blood.
in a secondary immune response then produce symptomless ad quicker response and make antibodies
due to immunological memory