B5/B6

Question 1

How do pathogens spread?

Answer 1

Through air, water or direct contact

Question 2

What would you do in order to grow microorganisms in a lab?

Answer 2

-Pour hot, sterile agar gel into a Petri dish- it will harden as it cools
-Inoculate the agar plate- introduce the bacteria on a sterilised loop of wire
-Provide warmth and oxygen
-Keep the dish incubated at a maximum of 25 degrees Celsius in school labs

Question 3

Why is it not possible to vaccinate plants?

Answer 3

They have no immune system

Question 4

What are some ways of preventing infection?

Answer 4

-Hygiene
-Isolating infected
-Destroying vectors
-Vaccinations

Question 5

How can the spread of TMV be prevented?

Answer 5

-Usage of TMV resistant strains of plant
-Good field hygiene/pest control

Question 6

How can Salmonella infection be prevented?

Answer 6

-Poultry vaccinated against bacteria
-Maintaining good food hygiene

Question 7

What happens to the leaves of a plant infected by Rose black spot?

Answer 7

-Purple or black spots form on leaves
-Leaves turn yellow and wilt

Question 8

How does the respiratory system help the body protect itself from pathogens?

Answer 8

-Hair and mucus in the nose trap pathogens
-Trachea/bronchioles secret mucus- traps pathogens, cilia waft mucus up to throat where it is swallowed

Question 9

How does nitrate deficiency affect plants?

Answer 9

The plant cannot convert sugars into protein, causing its growth to be stunted

Question 10

Why does a lack of magnesium cause chlorosis?

Answer 10

The plant cannot make chlorophyll, leading to less photosynthesis

Question 11

Name some symptoms of disease in plants:

Answer 11

-Spots on the leaves
-Areas of rotting or decay
-Growths
-Discolouration

Question 12

List some physical defences of plants:

Answer 12

-Cellulose cell walls protect against microorganisms
-Tough waxy cuticle layer
-The bark on trees
-Dead cells on stems

Question 13

Name the two drugs extracted from foxgloves:

Answer 13

-Digitalis
-Digoxin

Question 14

Explain how medical drugs can be tested before use:

Answer 14

-pre-clinical trials of the new drug on cells/tissues and live animals
-to test toxicity, dosage and efficacy
-clinical trials both on healthy volunteers and patients at very low doses
-so that you can monitor for side effects
-then do trials to find the optimum dosage and test for
efficacy
-double blind trial
-use of placebo, which does not contain the new drug
-peer review of data to help prevent false claims

Question 15

Why do we incubate bacteria at 25 degrees Celsius in school labs?

Answer 15

To reduce the chance of harmful bacteria growing

Question 16

When growing bacteria in a lab, how do you ensure that unwanted microorganisms don’t contaminate a pure culture?

Answer 16

-Sterilise equipment- pass inoculating loop through a flame, boil the solutions/agar
-Use a pre-sterilised Petri dish (newly bought or put into an autoclave)
-Inoculate the agar with a sterile loop
-Partially seal the lid of the Petri dish to prevent microorganisms from the air entering

Question 17

What is the difference between disinfectants and antiseptics?

Answer 17

Disinfectants kill bacteria within the environment, antiseptics kill bacteria on human skin

Question 18

List some plant defence mechanisms:

Answer 18

-Hair
-Thorns
-Mimicry (mimicking elements of nature/surroundings)
-Leaves that curl/droop

Question 19

List some uses of monoclonal antibodies:

Answer 19

-Used in pregnancy tests
-Diagnosing disease
-Measuring and monitoring hormone levels
-Delivering drugs to cancer cells
-Binding to receptors on cancer cells to stop them dividing

Question 20

How does a pregnancy test work to give a positive result?

Answer 20

-Person urinates onto strip
-Urine contains hCG, which binds to free monoclonal antibodies that are complementary to hCG
-hCG binds to a fixed antibody at the test site
-Dye enzyme attached to free antibody binds to substrate on fixed antibody producing a coloured strip
-Remaining free antibodies bind to fixed antibodies at control site producing a colour

Question 21

What is an antibody?

Answer 21

A protein designed to counteract a specific antigen

Question 22

How is measles spread?

Answer 22

Through water droplets from the sneeze of an infected person