Infection and Response

Question 1

What are the two types of viral pathogens

• symptoms
• spread
• cure
• late stage

Answer 1

Measles:
-fever and red skin rash
-spread by breathing in droplets from sneezes and coughs
-most children are vaccinated as can be fatal if there are complications
HIV (causes AIDS)
-spread by sexual contact and or exchange of body fluids
-causes a flu-like illness but if left untreated enters the lymph nodes and attacks the body’s immune cells
-anti-viral drugs slow the process
-late stages the body’s immunes system cannot fight off other infections

Question 2

What is a bacterial disease and what are the two types

• cause
• symptoms
• cure

Answer 2

Bacteria damages cells or produces toxins that damage tissues
Salmonella
-bacteria from uncooked food ingested
-bacteria secrete toxins causing fever, abdominal cramps and diarrhoea
-chickens are vaccinated to control the spread
Gonorrhoea (STD)
-spread by sexual contact
-thick, yellow or green discharge from vagina or penis and pain when urinating
-treated with penicillin but resistant strains have appeared
-contraception such as condoms prevents it

Question 3

What are protists and an example

Answer 3

Protists are single-celled organisms however unlike bacteria are eukaryotic
Malaria
-uses a type of mosquito as a vector
-causes severe fever which reoccurs and can be fatal
-killing mosquitos or using nets can prevent

Question 4

What are some of the bodies defences in preventing pathogens from entering

Answer 4

• Enzymes in tears destroy microorganisms
• Nose traps particles that may contain pathogens
• Glands in stomach produce hydrochloric acid which kills bacteria in food
• Sheets of mucus traps particles and bacteria

Question 5

How do white blood cells defend against pathogens through phagocytosis

Answer 5

When microorgansims invade the body the white blood cells finds it and engulfs it. Once found the white blood cell ingests the microorganism, destroying it.

Question 6

Explain the process of antibody use

Answer 6

Antigens on molecules of the pathogen are markers on the surface of the organism. The white blood cells (lymphocytes) becomes sensitised to the antigens and produce antibodies. The anti bodies lock onto the antigens causing the microorganisms to clump together so other white blood cells can ingest them.

Question 7

Describe how vaccinations help to produce immunity

Answer 7

A weakened or dead strain of the microorganism is injected. Antigens on the modified microorganisms surface stimulate white blood cells to produce specific antibodies. White blood cells that are capable of quickly producing the specific antibody remain in the blood stream

Question 8

What are Monoclonal Antibodies and how are they produced

Answer 8

They are produced from a single cell that has divided to to make many cloned copies of itself

1. a mouse is vaccinated to stimulate the production of antibodies from lymphocytes
2. the antibodies cannot divide by mitosis so are fused together with a tumour cell to from a hybridoma cell
3. the hybridoma cells are grown in tissue cultures where they can be selected and collected

Question 9

What are some of the uses of monoclonal antibodies

Answer 9

• in pregnancy testing kits to bind to the hormone HGC found in early pregnancy urine
• in laboratories to measure levels of hormones and other chemicals in blood
• to locate or identify specific molecules in a cell or tissue by binding them with a fluorescent dye
  (the are not yet widely used as they produce more side effects that expected)

Question 10

What are signs a plant may be diseased and how can they be identified

Answer 10

detected:
-stunted growth
-spots on leaves
-areas of decay
-discolouration
Identified:
-using testing kits which contain monoclonal antibodies
-taking infected plants to a laboratory 
-consulting a garden manual or website

Question 11

What are the symptom and causes of tobacco mosaic virus, aphids

Answer 11

tobacco mosaic virus
-produces distinctive mosaic pattern of discolouration on leaves which reduce chlorophyll content and affect photosynthesis
-affects growth of plant
aphids
-small insect that feeds from the phloem taking sugars away from the plant

Question 12

what are some non-communicable diseases in plants

Answer 12

• stunted growth caused by nitrate deficiency because nitrates are needed for protein synthesis
• chlorosis caused by magnesium deficiency as magnesium ions are needed to make chlorophyll

Question 13

What are the physical defences of plants

Answer 13

• cellulose cell walls

- though waxy cuticle

Question 14

What are some chemical defences of plants

Answer 14

• antibacterial chemicals made by plants such as mint

- poison to deter herbivores made by foxgloves

Question 15

What are some mechanical defences in plants

Answer 15

• thorns and hairs to deter animals from eating and touching them
• leaves that droop or curl when touched
• mimicry to trick animals into not eating them or laying eggs on the leaves (white dead nettle does not sting but looks very similar to stinging nettle)