Bio unit 3

Question 1

what are pathogens?

Answer 1

pathogens are microorganisms that cause infectious disease.

Question 2

examples of pathogens

Answer 2

viruses, bacteria, protists or fungi

Question 3

3 ways pathogens infect plans or animals

Answer 3

direct contact, by water or air

Question 4

Why can bacteria make you feel sick?

Answer 4

they can produce poisons/toxins that damage tissues.

Question 5

what are protists?

Answer 5

single celled eukaryotes. e.g parasites

Question 6

Which types of pathogens can reproduce rapidly inside the body?

Answer 6

bacteria and viruses

Question 7

How can viruses affect us?

Answer 7

they can live and reproduce inside cells which causes cell damage.

Question 8

What are the 3 types of viral diseases?

Answer 8

-measles
- HIV
- Tobacco mosaic virus

Question 9

-What are the symptoms of measles and how serious is this disease?
- How are children protected from it?
-How does it spread?

Answer 9

• fever and a red skin rash, could be fatal if complications arise.
• Young children are vaccinated against it.
• spread by inhalation of droplets from sneezes and coughs.

Question 10

HIV

Answer 10

• flu-like illness
• unless controlled with antiretrovial drugs, virus attacks the body’s immune cells
• Late stage HIV or AIDS happens when the body’s immune system becomes so badly damaged that it can no longer deal with other infections or cancers.
  -spread by sexual contact or exchange of bodily fluids like blood.
• can happen when drug users share needles.

Question 11

Tobacco Mosaic virus

Answer 11

• widespread plant pathogen that affects many species of plants like tomatoes.
• Gives distinctive ‘mosaic’ pattern of decoloration on the leaves.
• affects growth of plant due to lack of photosynthesis.

Question 12

What are the two types of bacterial diseases?

Answer 12

• salmonella
• gonorrhoea

Question 13

Salmonella

Answer 13

• food poisoning spread by bacteria ingested in or on food prepared in unhygenic conditions.
  -vaccination can control spread.
• symptoms are fever, abdominal cramps, vomiting and diarrohea.
• caused by bacteria and toxins they secrete.

Question 14

gonorrhoea

Answer 14

• sexually transmitted disease
• symptoms are thick yellow or green discharge from vagina and penis, pain on urinating.
• spread can be controlled with antibiotics or use of barrier method of contraception. e.g condom

Question 15

what is a fungal disease?

Answer 15

-rose black spot
- purple or black spots develop on leaves that often turn yellow and drop early.
-affects growth of plant bc photosynthesis is reduced.
- spread in the environment by water or wind.
- can be treated using fungicides or removing infected leaves.

Question 16

what is a protist?

Answer 16

pathogens that cause malaria

Question 17

malaria

Answer 17

• the malarial protists has a life cycle that includes the mosquito.
• causes recurrent episodes of fever and can be fatal.
• spread of malaria is controlled by preventing the vectors from breeding and by using mosquito nets to avoid being bitten.

Question 18

defence systems of human body against pathogens

Answer 18

skin- acts as a barrier and stops pathogens from entering the body, if scab heals itself
nose- Cells in the nose produce mucus. This traps pathogens before they can enter the lungs. When the nose is blown, mucus is removed and any pathogens are trapped within it.
- trachea and bronchi have hairs called cilia. The ciliated cells waft their hairs and move mucus and pathogens upwards towards the throat where it is swallowed into your stomach.
-stomach- contains HCL that kills bacteria in foods and drinks.

Question 19

what does the immune system do if a pathogen enters the body?

Answer 19

tries to destroy pathogen.

Question 20

how do white blood cells defend against pathogens?

Answer 20

• Phagocytosis, white blood cells engluf foreign cells and digest them.
• Antibody production,
• every invading pathogen has unique molecules (called antigens) on their surface.
• when some type of wbc come across new antigen produce proteins called antibodies.
• antibodies lock onto invading cells so they can be found and destroyed by other wbc.
• antibodies produced rapidly, carried around body to find simliar bacteria, viruses.
• if person infected by same pthaogen again wbc produce antibodies fast. (the persoin is immune and wont get sick)

-Antitoxin production, neutralise toxins produced by invading bacteria.

Question 21

how can spread of diseases be prevented?

Answer 21

• being hygienic
  -destroying vectors
• isolating infected individuals
• vaccination

Question 22

vaccination

Answer 22

• introducing small quantities of dead or inactive forms of pathogens into body to stimulate wbc to produce antibodies.
• If same pathogen re-enters the body the wbc respond quick to produce correct antibodies, preventing infection.
• epidemic can be prevented if a large percentage of population is vaccinated

Question 23

antibiotics, example

Answer 23

e.g penicillin
- medicines that help to cure bacteria by killing infective bacteria inside the body.
- important that specific bacteria treated by specific antibiotics.
- these have greatly reduced deaths from infectious bacterial diseases.
- strains resistant to antibiotics is a great concern.
- cant kill viral pathogens.

Question 24

painkillers

Answer 24

-used to treat symptoms of disease but no not kill pathogens
-difficult to develop drugs that kill viruses without also damaging the body’s tissues.

Question 25

where do many drugs originate from?

Answer 25

plants and microorganisms

Question 26

whaere did digitalis the heart drug come from?

Answer 26

foxgloves

Question 27

where does the painkiller aspirin come from?

Answer 27

willow

Question 28

who and how was penicillin discovered?

Answer 28

-Discovered by alexander fleming - when clearing out petri dishes containing bacteria, he noticed one had mould and area around mould did't have bacteria. - he found that mould on the petri dish was producing a substance that killed the bacteria, penecillin.

Question 29

What needs to happen to new drugs?

Answer 29

They have to be tested and trialled before being used to check they are safe and effective

Question 30

what 3 things are new drugs tested for?

Answer 30

- toxicity - efficacy - dose

Question 31

preclinical testing

Answer 31

done in laboratory using - cells - tissues - live animals

Question 32

clinical testing

Answer 32

- uses healthy volunteers and patients - very low doses of the drug are given at the start of the clinical trial. - If drug is found to be safe, further clinical trials are carried out to find the optimum dose for the drug. - in double blind trials, some patients are given a placeobo

Question 33

monoclonal antibodies

Answer 33

- produced from a single clone of cells. - The antibodies are specific to one binding site on one protein antigen and so are able to target a specific chemical or specific cells in the body.

Question 34

how are monoclonal antibodies produced?

Answer 34

- stimulating mouse lymphocytes to make a particular antibody. - lymphocytes are combined with a partciular kind of tumour cell to make a cell called the hybridoma cell. - The hybridoma cell can divide and make the antibody. - single hybridoma cells are cloned to produce many identical cells that all produce the same antibody. - a large amount of the antibody can be collected and purified.

Question 35

ways monoclonal antibodies can be used:

Answer 35

- for diagnosis such as in pregnancy tests - in labs to measure the levels of hormones and other chemicals in blood, or to detect pathogens. - to treat some diseases, like in cancer th monoclonal antibody can be bound to a radioactive substance, a toxic drug or a chemical which stops cells growing and dividing. Delivers the substance to the cancer cells without harming other cells in the body.

Question 36

disadvantage of monoclonal anti

Answer 36

create more side effectrs than expected. Not yet as widely used as everyone hoped when they first were developed.

Question 37

how can plant disease be detected?

Answer 37

- stunted growth - spots on leaves - areas of decay - growths - malformed stems or leaves - discolouration - presence of pests

Question 38

identification of plant disease can be made by:

Answer 38

- reference to a gardening website - taking infected to lab to identify pathogen - using testing kits that contain monoclonal anti

Question 39

Why do plants suffer defficiencies?

Answer 39

if not get mineral ions from soil

Question 40

nitrate deficiency

Answer 40

Nitrates are needed to make proteins, for growth. A lack of nitrate causes stunted growth.

Question 41

magnesium deficiency

Answer 41

magnesium ions needed to make chlorophyll, which needed to trap light for photosynthesis. Plants without mag suffer from chlorosis and have yellow leaves.

Question 42

what ways can a plant be infected:

Answer 42

viral,bacterial,fungal pathogens and insects like aphids

Question 43

Plant physical defence responses

Answer 43

- tough waxy cuticle on leaves, acts as barrier. - cellulose cell walls, other barrier for pathogens that make past waxy cuticle. - layers of dead cells around stem, like outer bark on trees which fall off and act as barrier.

Question 44

chemical plant defences

Answer 44

- antibacterial chemicals, kill bacteria - poisons to deter herbivors

Question 45

mechanical adaptations

Answer 45

- thorns and hairs deter animals - leaves which droop or curl when touched, prevent from being eaten or knock off insects - mimicry to trick animals to not eat them