Unit 3 biology

Question 1

Describe viruses

Answer 1

Very small, enters cells and makes many copies of itself, this bursts the cells and allows the virus to travel through the bloodstream

Question 2

Describe bacteria

Answer 2

Small but larger than a virus, multiply rapidly via binary fission, produce toxins that damage cells

Question 3

Describe fungi

Answer 3

Made of hyphae (thread like structures) or single cells, produce spores to spread to other organisms

Question 4

Describe protists

Answer 4

Use vectors (host organisms) to travel from host to host and infect them

Question 5

Give an example of diseases caused by
a.) virus
b.) bacteria
c.) fungi
d.) protist

Answer 5

a.) COVID 19, measles, HIV, TMV (tobacco mosaic virus)
b.) salmonella, gonorrhoea
c.) rose black spot, athletes foot
d.) malaria

Question 6

3 ways how disease is spread

Answer 6

Direct contact
By water (droplets)
By air

Question 7

Symptoms of HIV

Answer 7

Flu like symptoms, will develop into AIDS and a weakened immune system

Question 8

How HIV is spread and how to prevent it to limit the spread

Answer 8

Spread via sexual contact or blood contamination. We prevent it by using condoms, not sharing needles, use antiretroviral drugs to prevent AIDS developing

Question 9

Symptoms of Salmonella

Answer 9

Fever, stomach cramps, diarrhoea, all caused by toxins produced by the bacteria

Question 10

How is salmonella spread and how to limit the spread

Answer 10

Unhygienic conditions and raw meats/egg. Vaccinate poultry, cook food carefully and stop contamination with utensils

Question 11

How to prevent athletes foot (fungal)

Answer 11

Don’t share socks or shoes with other people

Question 12

How to prevent gonorrhoea (bacterial)

Answer 12

Uses condom and treat with penicillin

Question 13

Symptoms of malaria

Answer 13

Fevers and shaking (when protists burst out of blood cells)

Question 14

How is malaria spread and how to prevent it

Answer 14

Female mosquito vectors have malaria sexually reproduce inside them and when they puncture skin, their saliva passes on the protist where it asexually reproduces in the cells. Use pesticides, avoid areas with malaria and get the vaccine

Question 15

Describe the human bodies non specific defence responses (not immune system

Answer 15

The skin: acts as a physical barrier, produces anti microbial secretions, skin flora (good bacteria) compete with bad bacteria for nutrients and space

The nose: has hair and mucus to stop bacteria entering your lungs

The lungs: secrete mucus to trap pathogens, cilia cells sweep up the mucus to the stomach

The stomach: low pH HCl that kills off pathogens in mucus

Question 16

Describe the immune systems response to pathogens

Answer 16

Phagocytosis: chases and engulfs the pathogen and destroys it for excess parts

Antitoxins: bind to the antigens on the bacteria to neutralise them

Antibodies: each pathogen has an antigen on their surface and when the antibody binds to it, It clumps the pathogens together so phagocytosis can take place and memory cells are formed to create a quick response if the pathogen returns

Question 17

What is the purpose of a vaccination

Answer 17

To make a person or group of people immune to a pathogen

Question 18

How does herd immunity work

Answer 18

If most people in a community are vaccinated, then it will protect those that aren’t vaccinated

Question 19

How does a vaccine work

Answer 19

Injects the patient with a weakened form of the pathogen and this stimulates the immune system to make memory cells to create a fast response

Question 20

Advantages of vaccination

Answer 20

Have eradicated many diseases eg smallpox

Epidemics can be prevented via herd immunity

Question 21

Disadvantages of vaccination

Answer 21

May not always be effective

Some people may have allergic reactions to them so not everyone is protected

Question 22

How are antibiotics different to painkillers

Answer 22

Antibiotics only harm bacteria and don’t affect viruses
Painkillers don’t affect the pathogen, only treat the pain, not the cause

Question 23

How can a antibiotic resistance be developed to antibiotics

Answer 23

Mutations are constantly occurring and so they could become resistant, when people don’t take their full course of antibiotics, the resistance ones survive and then become the dominant strand

Question 24

Give two medicines that we got from plants

Answer 24

Aspirin- from willow bark
Digitalis- from foxgloves

Question 25

Who discovered pennecilin and how

Answer 25

Alexander Fleming. He left it growing accidentally after an experiment and it stopped bacteria from growing on where it was placed. It is now used across the world to treat bacterial diseases

Question 26

How do we carry out tests to decide what drugs are safe for use

Answer 26

Preclinical testing: using cells, tissues and animals to test for efficacy, toxicity and dosage
Clinical Testing:
Tested on healthy volunteers to make sure it’s safe and to work out dosage
Peer review: other scientists must gain the same results as you to prove its repeatable

Question 27

How does single and double blind tests work

Answer 27

Patients are split into two groups, actual testing and placebo affects so we know the actual drugs affect.
They can be single blind: only the doctor knows what drug the patient has
Or it can be double blind: neither the doctor nor patient know which drug they receive in order to remove bias

Question 28

What are common signs of plant disease

Answer 28

Stunted growth: nitrate deficiency
Discolouration: magnesium deficiency
Malformed stems and leaves: aphid infestation
Pests on leaves: caterpillars

Question 29

What are symptoms of rose black spot

Answer 29

Purple or black spots form on the leaf which decreases photosynthesis and turns the leaf yellow. Other areas of general decay

Question 30

How is rose black spot spread and how do we prevent it

Answer 30

Fungal disease spread by spores caught in rain.
Using fungicides on our plants or by burning those plants effected

Question 31

What are the symptoms of Tobacco mosaic virus

Answer 31

Discolouration of the leaves as less photosynthesis takes place

Question 32

How is TMV spread and how can we prevent it

Answer 32

Spread by contact with diseases plants and aphids that act as vectors. We prevent it by using good hygiene in the garden and growing TMV resistant strains

Question 33

Name 3 ways that we use to identify plant diseases

Answer 33

Use gardening manuals or the internet
Use an mAB testing kit
Get a sample tested in a laboratory

Question 34

Explain the effects of a nitrate ion deficiency

Answer 34

Nitrates in the soil convert sugars made into photosynthesis into proteins and the proteins are needed for growth so having less results in stunted growth

Question 35

Explain the effects of a magnesium ion deficiency

Answer 35

magnesium is needed to produce chlorophyll so a lack of magnesium can lead to chlorosis where the leaves appear yellow and photosynthesise less

Question 36

What physical defences have plants developed to avoid harm

Answer 36

-Tough waxy cuticle to prevent bacteria from entering.
-cellulose walls form a physical barrier.
-stems are protected by dead cells like bark to act as a barrier.

Question 37

What mechanical defences have plants developed to avoid harm

Answer 37

-Sharp thorns and needles like on a cactus ward away predators.
-some plants droop when insects land on them so they slide off.
-Mimicry involves a plant appearing differently so that predators are less likely to attack it, examples include:
-Looking unhealthy to avoid being eaten,
-special patterns to make butterflies not lay eggs
-looking like a rock to stop animals landing on it

Question 38

What chemical defences have plants developed to avoid harm

Answer 38

-antibacterial compounds kill bacteria on plants like witch hazel
-many plants are poisonous like foxgloves to avoid herbivores eating them

Question 39

What is a monoclonal antibody

Answer 39

Identical antibodies made from the same immune cell that is specific to an antigen that is often used to treat diseases like cancer

Question 40

How are monoclonal antibodies made

Answer 40

-mice lymphocytes that are stimulated to produce a specific antibody
-they care combined with tumour cells which can rapidly divide
- this produces a hybridoma cell which can produce antibodies and divide very quickly so we quickly clone them to get huge amounts of the antibody

Question 41

What are some other uses of mAB’s

Answer 41

for identifying diseases by trying to locate specific molecules in the body. They bind the antibody to fluorescent dye and send it around the bloodstream, they will build up in one location where the molecule is.
this can also help locate cancers and transport drugs to kill the cancer. by being specific to the cancer they can locate it and bind to it to stop spread

Question 42

How does a pregnancy test work

Answer 42

someone urinates on the end of the stick and the urine travels up into the first zone where there are mobile antibodies with blue dye that are complimentary to HCG hormones found in pregnant women’s urine.
these mobile mAB’s bind to the HCG and travel further up the stick and when they reach the second zone, there are stationary antibodies which also bind to the mAB and when this binds, it releases the blue dye which makes a visible line. the remaining HCG then travel up the stick where they reach more stationary mAB’s and release more dye to prove that the test worked

Question 43

Advantages of mAB’s

Answer 43

-Only bind to specific cells so other cells aren’t affected
-we can engineer them any way we like so they are versatile
- once we have developed one, we can develop lots very quickly

Question 44

Disadvantages of mAB’s

Answer 44

-difficult to attach mAB;s to drugs
-can cost alot to initially develop
-could trigger immune responses as it is foreign to the body