Infection and Response

Question 1

VIRAL DISEASES

• Attacks immune cells.
• If immune system is badly damaged, it can’t cope.
• Measles: spread by droplets, red skin rash, temperature, lead to pneumonia or inflammation of the brain, vaccinated when young.
• HIV: sexual contact, bodily fluids, share needles, flu-like symptoms, controlled with antiretroviral drugs.

Answer 1

BACTERIAL DISEASES

• Make you feel ill by producing toxins that damage cells and tissue.
• Salmonella: causes food poisoning, suffer from fever, stomach cramps, vomiting, diarrhoea, causes by toxins, eating contaminated food.
• Gonorrhoea: caused by sexual contact, pain when urinating, thick yellow/green discharge, prevent by using barrier methods.

Question 2

FUNGAL DISEASES

• Hyphae (thread like structures) penetrate human skin/surface of plants.
• Black Rose Spot: black/purple spots develop on rose plant leaves, leaf turns yellow and drops off, less photosynthesis so doesn’t grow as well, spread via water/wind, use fungicide, stripping effected leaves, destroying effected leaves.

Answer 2

PROTIST DISEASE

• All eukaryotes and most single-called.
• Some are parasites, live on or inside other organisms and cause damage, transferred by a vector.
• Malaria: caused by a protist, mosquito is the vector, pick up malaria when feeding on infected animal, feeds on another animal and infects it, can be fatal, use insecticide or sleep in nets.

Question 3

HUMAN DEFENCE SYSTEMS

• Skin: acts as a barrier to pathogens, also secretes anti microbial substances to kill pathogens.
• Hairs and mucus in nose trap particles.
• Trachea and bronchi secrete mucus and lined with cilia.
• Stomach produces hydrochloric acid to kill pathogens.

Answer 3

VACCINATION

• Can’t develop the infection and then pass it on.
• Involves injecting small amounts of dead/inactive pathogens.
• These carry antigens so your body produces antibodies.
• If live pathogens of the same type appear, white blood cells rapidly mass-produce antibodies to kill off the pathogen.

Question 4

PAINKILLERS

• Drugs that relieve pain.
• Don’t tackle the cause of the disease or kill pathogens- just reduce symptoms.

Answer 4

ANTIBIOTICS

• Kill/prevent growth of bacteria causing problems.
• Different types of antibiotic kill different types of bacteria.

Question 5

DEVELOPING DRUGS

-Before given to public, go through testing procedure.

3 STAGES →

Answer 5

1. • Tested on human cells and tissue in a lab.
   • Can’t do it on human cells and tissues for a drug that affects multiple body systems.

Question 6

2. • Tested on live animals.
   • Done to see if it produces the right effect, how harmful it is, for dosages.
   • British law says it must be done on two live mammals.
   • Seen as cruel but also the safest way.

Answer 6

3. • Tested on human volunteers.
   • Start in healthy volunteers for side effects.
   • Starts with low dosage and slowly increases.
   • Then tested on people suffering from that illness.
   • Find the optimum dose.
   • Some volunteers given placebo.

Question 7

PRODUCING MONOCLONAL ANTIBODIES

• Lots of clones of a single white blood cell, all the antibodies are identical.
• Inly target one specific antigen.

Answer 7

USES OF MONOCLONAL ANTIBODIES

• Pregnancy tests.
• Treat diseases.
• Research to find specific substances.

Question 8

DETECTION AND IDENTIFICATION OF PLANT DISEASES

• Common signs of disease: stunted growth, spots in leaves, patches of decay, abnormal growths, malformed stem/leaves, discolouration.
• Identification methods: gardening manual/website, take to plant laboratory, use testing kits.

Answer 8

PLANT DEFENCE RESPONSES

-Physical: •Waxy cuticle, barrier
•Cell walls made of cellulose, barrier
•Layers of dead cells, e.g. bark

-Chemical: •Antibacterial chemicals
•Produce poison

-Mechanical: •Thorns and hairs
•Leaves droop/curl
•Mimic other organisms