B5: Communicable Diseases

Question 1

What is a disease?

Answer 1

A disorder of a function in our body that is not caused by physical damage.

Question 2

What are antigens?

Answer 2

Proteins that provoke our body’s immune response ( they are usually on the surface of pathogens).

Question 3

What conditions do bacteria need to divide every 20 mins?

Answer 3

food, water, oxygen and warmth

Question 4

What are the body’s ‘first line of defence’ and how do they defend? (4)

Answer 4

Skin: Stops microbes entering body
Stomach acid: Kills many microbes
Nose : hair/mucus traps pathogens
Trachea/bronchi : secrete mucus that traps pathogens

Question 5

What is the role of a phagocyte?

Answer 5

To ingest microbes/pathogens and destroy them.

Question 6

What do B-cells do?

Answer 6

They produce antibodies COMPLEMENTARY to the ANTIGENS on the surface of the pathogen.
They destroy the antigen

Question 7

What do T-cells do?

Answer 7

They produce anti-toxins to counteract toxins made by pathogens

Question 8

What is meant by a memory cells?

Answer 8

A type of white blood cell that remembers the same type of pathogen for faster antibody production in the future infections

Question 9

What are white blood cells?

Answer 9

Cells in the blood that help fight disease.

Question 10

What is an antibody?

Answer 10

A molecule made by the immune system that recognises pathogens and helps get rid of them.

Question 11

What is an immune system?

Answer 11

The part of our body that helps to fight disease caused by pathogens.

Question 12

Why do some people argue that viruses aren’t living things?

Answer 12

Because viruses can only reproduce inside a host cell/ don’t cover all characteristics of life and not made of cells

Question 13

How do bacteria cause disease? (2)

Answer 13

Enter cells, reproduce and kill cells
or
Release toxins and paralyse cells’ organelles

Question 14

How is malaria prevented?

Answer 14

• use mosquito nets
• stop mosquitos breeding
• use insecticides

Question 15

Why are memory cells helpful? (2)

Answer 15

• faster antibody production
• more antibodies are produced
• antibody concentration stays in blood longer

Question 16

Name some viruses, their symptoms and how it is spread (9)

Answer 16

MEASLES
symptoms : fever , red skin rash
spread : droplets
NO CURE but vaccination can help

HIV/AIDS
symptoms: flu like symptoms
(after remaining in immune system for long, it can’t deal with infections/cancers. This leads to AIDS)
spread : sexual contact/ exchange of bodily fluids/ needles
GOOD NUTRITION AND ANTIRETROVIRAL DRUGS HELP PREVENT AIDS

TOBACCO MOSAIC VIRUS
symptoms : mosaic pattern on leaves
spread : contact/vectors
NO CURE BUT FILED HYGEINE CAN PREVENT

Question 17

Name some bacterial diseases, their symptoms and how it is spread (6)

Answer 17

SALMONELA
symptoms : fever, abdominal pain, vomiting, diarrhoea
spread : contaminated food not fully cooked
HYGIENE IN KITCHEN, VACCINATED CHICKENS IN UK PREVENT

GONORRHOEA
symptoms : discharge, pain when urinating
spread : unprotected sexual contact
ANTIBIOTICS AND CONDOMS PREVENT/TREAT

Question 18

Name some fungal infections, their symptoms and how it is spread (6)

Answer 18

ATHLETE’S FOOT
spread : contact to infected surfaces
ANTIFUNGAL DRUGS CAN TREAT

ROSE BLACK SPOT:
symptoms: purple/black spots on leaves, leaves turn yellow and drop off
spread: spores from fungus are carried by the wind/water
FUNGICIDE CHEMICALS, REMOVING AFECTED LEAVES AND BREDDIN RESTISTNT PLANTS PREVENT/TREAT

Question 19

What are the effects of rose black spot on the plant? (3)

Answer 19

loss of leaves means less CHLOROPLASTS
for PHOTOSyNTHESIS
LESS ENERGY /GROWTH to make flowers

Question 20

Name some protist infections, their symptoms and how it is spread (3)

Answer 20

MALARIA
symptoms : fever
spread : mosquitos vector ( bite from female mosquito)
IF TREATED EARLY DRUGS CAN BE EFFECTIVE

Question 21

what are the effects of aphids infesting a plant/ how are they destroyed?

Answer 21

aphids have long sharp mouthpieces to pierce through the surface of the stem to the phloem and feed on SUGAR FILLED SAP.
the lack of sap WEAKENS the plant
Aphids can also act as a VECTOR transmitting disease.

Biological pest control and pesticides can DESTROY them

Question 22

Why are NITRATES/ MAGNESIUM important to a plant and the symptoms of deficiency.

Answer 22

Nitrates:
USE : production of amino acids for proteins
SYMPTOMS: less protein growth, upper leaves plate green, lower leaves yellow/dead, stunted growth

Magnesium:
USE : synthesis of chlorophyll for photosynthesis
SYMPTOMS : yellowing of leaves (CHLOROSIS) due to lack of chlorophyll , stunted growth

Question 23

What are some signs of plant disease? (7)

SSAD MGV

Answer 23

SSAD MGV

Stunted growth
Spots of leaves
Areas of decaying/rotting
Discolouration of leaves

Malformed stems/leaves
Growths
Visible pests

Question 24

Physical plant defences ? (4)

Answer 24

cellulose cell wall - protects from invasion
Waxy cuticle - barrier to pathogens from entering
Bark - tough layer around the stem to prevent pathogens entering
Leaf fall - infected leaves could fall off

Question 25

Chemical plant defences . (3)

Answer 25

• some plants produce chemicals with ANTIMICROBIAL properties.
• plant extracts have ANTIBACTERIAL EFFECTS (used in creams, oil, mint, witch hazel)
• plants are being studied for potential source of ANTIBIOTICS

Question 26

Required practical method : growing E. coli

Answer 26

• 1) wash hands/clean surfaces ( so unwanted bacteria doesn’t grow)
  2) work close to bunsen and loosen lid of broth bottle
• 3) Flame the loop ( steralise it)
  4) remove lid/loosen lid with little finger of writing hand
• 5) flame lip of bottle, the dip loo in bottle/remove (reduce risk of contamination/sterilise)
• 6) flame lip of the bottle again/replace lid ( reduce risk of contamination/sterilise)
• 7) lift base of Petri dish and steak a pattern ( separate bacteria into colonies)
• 8) flame the loop again (sterilise)
• 9) secure with 2 pieces of tape ( secure lid on but allow O2 for E.Coli)
• 10) label name, date and microorganism
• 11) incubate upside down at 24 degrees (so colonies form but other bacteria doesn’t form)
• 12) don’t open plate again(so we don’t harm others/ourselves)

Question 27

explain why TMV plants have stunted growth (4)

Answer 27

• less photosynthesis
• less glucose
• for respiration, so won’t have enough energy to grow
• less amino acids for growth , bc glucose is needed to make amino acid