B5

Question 1

when growing bacteria, how can you avoid contamination?

Answer 1

• sterilising petri dish and culture media before use
• sterilising inoculating loop in red hot flame before and after
• not fully removing lid of petri dish or placing it on desk
• securing petri dish lid in place with strips of tape to let some oxygen in- preventing dangerous anaerobic bacterial growth
• petri dish should be stored upside down to prevent condensation
• incubated at 25degrees to reduce chance of growing harmful pathogens that could survive

Question 2

Measles

Answer 2

type: virus
symptoms: fever, rash
spread by: inhaling droplets from sneezes, coughs
prevention: vaccination, coughing and sneezing into tissues
Treatment: no cure, use painkillers

Question 3

HIV

Answer 3

type: virus
symptoms: initially flu-like, damages immune system- causing AID, where the body can no longer fight off disease
spread by: sexual contact, sharing needles
prevention: wearing protection, not sharing needles
Treatment: no cure, but antiretroviral drugs can prevent people developing AIDS

Question 4

Tobacco mosaic virus

Answer 4

type: virus
symptoms: creates a “mosaic” pattern of discolouration on leaves, stunting growth
spread by: contact with other plants- naturally or by farmer’s gloves
prevention: destroying infected leaves, washing infected tools/gloves
Treatment: no cure

Question 5

salmonella

Answer 5

type: bacteria
symptoms: fever, abdominal cramps, vomiting, diarrhoea
spread by: eating food prepared unhygienically/undercooked meat
prevention: vaccinate chickens, disinfect surfaces, wash hands after touching raw meat
Treatment: antibiotics, fluids

Question 6

gonorrhoea

Answer 6

type: bacteria
symptoms: thick yellow/green discharge, pain when urinating
spread by: sexual contact
prevention: wearing protections
Treatment: antibiotics

Question 7

malaria

Answer 7

type: protist
symptoms: fever
spread by: spread via mosquitoes- the vector
prevention: destroying mosquito breeding grounds, mosquito nets
Treatment: antimalarial drugs

Question 8

rose black spot

Answer 8

type: fungus
symptoms: purple/black spots on leaves, leaves turn yellow and drop off early, stunted growth
spread by: rain or wind
prevention: fungicides, destroying affected leaves
Treatment: fungicides

Question 9

What does the skin do to defend humans from pathogens?

Answer 9

• thick, tough barrier that stops pathogens from getting into blood. Blood clots from to “plug up” cuts to skin

Question 10

Name some symptoms of plant disease

Answer 10

• stunted growth
• decay
• malformed stems or leaves
• pests
• spots on leaves
• abnormal growth
• discolouration

Question 11

how can you identify plant disease?

Answer 11

• referring to manuals or websites
• taking infected plants to labs
• testing kits that contain monoclonal antibodies

Question 12

What are aphids?

Answer 12

• insects that can infect plants. they feed on the sugars in the plant’s phloem tube, causing stunted growth

Question 13

Plants- physical defences

Answer 13

• cellulose in in plant walls acts as a barrier
• tough waxy cuticle on leaves acts as a barrier
• layers of dead cells around stem (like tree bark) fall off, taking pathogens on the surface with them

Question 14

Plants- chemical defences

Answer 14

• plants produce antibacterial chemicals
• plants produce poisons

Question 15

Plants- mechanical adaptions

Answer 15

• thorns, hairs
• leaves can drop or curl when touched (i.e mimosa plant)

Question 16

Nitrate deficiency

Answer 16

symptoms: stunted growth
Explanation: plants use nitrates to make amino acids, and amino acids make proteins, which are required to build and grow plant tissue

Question 17

Magnesium deficiency

Answer 17

symptoms: chlorosis (yellow leaves) leading to stunted growth
Explanation: magnesium needed to make chlorophyll, which is used to trap light for photosynthesis, and is what makes the leaves green