Topic 3 - Infection and Response

Question 1

Name the 4 types of pathogen

Answer 1

• bacteria
• virus
• fungi
• protist

Question 2

Describe bacteria

Answer 2

Bacteria are very small cells that multiply rapidly and produces toxins that damage your cells and tissues e.g salmonella

Question 3

Describe viruses

Answer 3

They are not cells. They reproduce rapidly inside host cells (by replicating themselves) and damage the cell e.g flu

Question 4

Describe fungi

Answer 4

They grow between cells and through tissues, causing disease e.g athletes foot

Question 5

Describe protists

Answer 5

They are single-celled eukaryotes that live on or inside other organisms and can cause damage. They are transferred to the organ by a vector e.g a mosquito carrying malaria

Question 6

Describe Salmonella

Answer 6

• bacteria
• symptoms = fever, cramps, vomitting
• treat = poultry vaccination, cook chicken thoroughly, antibiotics

Question 7

Describe Gonorrhea

Answer 7

• bacteria
• symptoms = urinating pain, yellow discharge
• treat = antibiotics, using condoms

Question 8

Describe Measles

Answer 8

• virus
• symptoms = fever, rash, red skin
• treat = vaccine, isolate infected people

Question 9

Describe HIV / AIDS

Answer 9

• virus
• symptoms = mild flu-like
• treat = antiretroviral drugs, use condoms, don’t share needles

Question 10

Describe tobacco mosaic virus

Answer 10

• virus
• symptoms = mosaic pattern + discolouration on leaves
• treat = none, prevent by pest control

Question 11

Describe rose black spot

Answer 11

• fungi
• symptoms = purple/black spots on leaves - weakens plant, poor growth
• treat = remove + burn infected leaves, chemical fungicides

Question 12

Describe malaria

Answer 12

• protist
• symptoms = fever, tiredness
• treat = bed nets, insecticides

Question 13

Describe the three ways white blood cells attack pathogens

Answer 13

• engulfing them (phagocytosis) - surrounds and destoys pathogen
• produces antibodies - lymphocytes produce antibodies that attach onto the antigen on the pathogen, this flags the pathogens for phagocytes to ingest them
• produces antitoxins - neutralise the toxins produced by pathogens

Question 14

Pros and cons of vaccination

Answer 14

Pros:
- controls the spread of diseases and can eradicate them
- reduces epidemics
Cons:
- don’t always work
- can be side effects

Question 15

Describe how vaccines work

Answer 15

• vaccines are small amounts of dead pathogens
• WBC detect the pathogens and produce specific antibodies
• a few of the antibodies stay in the blood once the pathogen is destroyed (called B memory cells)
• if you meet the pathogen again, the memory cells will produces antibodies very quickly

Question 16

What is the difference between antiseptics and antibiotics?

Answer 16

Antiseptics kill microorganisms in the environment. Antibiotics kill bacteria (not viruses) in the body.

Question 17

What is antibiotic resistance?

Answer 17

When strains of bacteria become resistant to antibiotics - meaning antibiotics will stop working

Question 18

What plant does aspirin come from?

Answer 18

Willow tree

Question 19

What plant does digitalis come from?

Answer 19

foxgloves

Question 20

Describe painkillers

Answer 20

Painkillers are drugs that relieve pain but they don’t tackle the cause of the disease or kill pathogens - they just help the symptoms

Question 21

Why is it difficult to develop medicines against viruses?

Answer 21

Viruses reproduce inside the cell so it is difficult to destroy the virus without damaging the cell

Question 22

What are the four stages of drug testing?

Answer 22

• tested on human cells and tissues in the lab
• tested on live animals
• tested on a small group of healthy volunteers
• tested on a larger group of people with the condition

Question 23

Why are mice often tested on?

Answer 23

• small and easy to look after
• mammal (like humans)
• not dangerous to handle
• not endangered

Question 24

What three criteria are they testing for on animals?

Answer 24

• efficacy - if it works
• toxicity - if it’s harmful
• dosage - how much should be used

Question 25

What does blind and double-blind trials mean?

Answer 25

Blind trials are when the patient doesn't know whether they have the real drug or the placebo. Double-blind trials are when neither patient nor a doctor knows who has placebos or real drugs. This prevents bias

Question 26

What is a placebo?

Answer 26

A drug that has no effect and is used to see if the drug only works because of the placebo effect

Question 27

Define monoclonal antibodies

Answer 27

identical copies of one type of antibody

Question 28

Describe how monoclonal antibodies are produced

Answer 28

- mouse gets vaccinated to produce specific antibodies - lymphocytes are collected from mouse spleen - WBC are mixed with myeloma to produce antibodies faster - they create a hybridoma cell + screen to check - clone and collect the antibodies

Question 29

What are the uses of monoclonal antibodies?

Answer 29

- they trigger the immune system to recognise, attack and destroy cancer cells - they block receptors on cancer cells so the cells stop growing and dividing - carry toxic drugs or chemicals without harming cells in the body (drug is attached and released when it binds to target cell) - used in hospitals/labs to monitor levels of chemicals in blood - pregnancy tests

Question 30

Describe how monoclonal antibodies are used in pregnancy tests

Answer 30

- HCG is a hormone found in pregnant women - mobile antibodies attach to the HCG and move up the stick - fixed antibodies attach to mobile antibodies if HCG present (+dye released) - extra antibodies move up and attach to fixed antibodies + dye released to show it works

Question 31

What are some signs of plant disease?

Answer 31

- stunted growth - discolouration of/spots on leaves - insects/pests - areas of decay - growths - malformed stems/leaves

Question 32

Plant diseases can be indentified by ...

Answer 32

- gardening manuals and websites - testing the plant in a lab - test kits using monoclonal antibodies

Question 33

Explain how a deficiency of magnesium could cause yellow leaves and stunted growth

Answer 33

Magnesium is need for chlorophyll so there would be less chloropyhll (not green) which means less light absorbed which means less photosynthesis which means less glucose which means less proteins (less growth).

Question 34

What are physical defences of plants?

Answer 34

Physical barriers that protect the plant. Plants often have a waxy cuticle and cell walls made from cellulose, which provides a barrier

Question 35

What are chemical defences of plants?

Answer 35

Plant can produce antibacterial chemicals which kill bacteria (mint oils) or secrete toxins to hurt insects or animals (foxgloves)

Question 36

What are mechanical defences of plants?

Answer 36

Similar to physical defences but larger. They could have thorns or hairs or leaves that droop when stuff touches it to deter animals. Some plants mimic other organisms e.g the passion flower has yellow spots that look like butterfly eggs to stop butterflies laying their eggs there.