biology paper 1 Flashcards

Question 1

Q

whats the diffrence between eukaryotes and prokaryotes?

2 marks

Answer

A

eukaryotes are made from complex eukaryotic cells for things like animals and olants
prokaryotes is a single prokaryotic cell made for things like bacteria

Question 2

Q

what do bacteria cells contain?

5 marks

Answer

A

chromosomal DNA (in cytoplasm cuz no nucleus)
ribosmes
cell membrane
Plasmid DNA - small loops od extra DNA
Flagellum -> hair structure the rotates to move it

Question 3

Q

what is the diffrence between haploid and diploid?

1 marks

Answer

A

haploid have half the number of chromosomes as a diploid cell

Question 4

Q

explain how the egg and sperm are specialised for there funtion.

6 marks

Answer

A

EGG:
- nutrients in cytoplasm
- haploid nucleus
- after fertilisation, the membrane changes structure to block sperm
SPERM:
- long tail to swim
- lots of mitochondria for energy
- acrosome at front stores enzymes to get though eggs membrane
- haploid nucleus

Question 5

Q

how are ciliated epithelial cells specialised?

3 marks

Answer

A

line the surface of organ
cilla on surface
that moves substances in one direction along the surface
e.g lining of air ways have them to move mucus away from lungs

Question 6

Q

What is the difference between a light and an electron microscope?

4 marks

Answer

A

light 1590:
- Work by passing light through the specimen
- They let us see cellular structures.

electron 1930:
- They use electrons that can have a very high magnification and resolution
- They let us see internal structures of subcellular structures.

Question 7

Q

practical

How would you view a specsman using a light microscope?

6 marks

Answer

A

Take a thin slice of your specimen and put it on a clean slide
Use a pipette to put a drop of water in the middle to secure it
If specimen is colours or transparent, drop a stain on it (iodine)
Gently press down cover slip on so there are no air bubbles trapped under it. Then clip it to the stage.
Select the lowest objective lens And used the adjustment knob to move the stage up so The specimen is in close focus.
Then adjust the focus with the fine adjustment knob until you get a clear image.
If you need greater magnification, switch to a higher objective lens and refocus
Position of ruler at the stage and use it to measure the diameter of the area visible To work out the magnification

Question 8

Q

How would you work out total magnification

1 mark

Answer

A

eyepiece lens mag x objective lens mag

Question 9

Q

practical

How can you investigate the effect of pH on enzyme activity?

6 marks

Answer

A

Put a drop of iodine into every hole of a spotting tile
Place a bonson burner on a heap proof mat and tripod and gauze
Put beaker of water on top tripod and heat until thirty five degrees measured using a thermometer
Use syringe to Add 3cm^3 of amylase solution. one centimetres cubed of buffer solution with a pH of 5 using measuring cylinders and put in the beaker and wait 5mins
Use a different syringe to add 3cm^3 of starch solution to a boiling tube
Immediately mix the contents of the boiling tube and start a stopwatch
Use continuous sampling to record how long it takes for the amylase breakdown all of the starch By sampling it in an iodine solution untill it remains browny orange.
Repeat experiment with different ph values and make sure. and make sure to continue any control variables

Question 10

Q

how do you calculate rate of reaction for the enzyme practicalif you dont know the amount of change?

1 mark

Answer

A

1000/time

otherwise change / time

Question 11

Q

Why do plants and animals have enzymes?

2 marks

Answer

A

Many molecules in the food we eat are too big So. Digestive enzymes break them down into smaller soluble molecules that can pass through its digestive system
Plant store starch, which needs to be broken down into glucose to respire So enzymes need to break them down.

Question 12

Q

what enzyme breaks down:

Carbohydrates (starch)
Proteins
Lipids

3 marks

and what do they turn to

Answer

A

amylase turn it it sugar e.g (glucose)
protease converts it to amino acids
lipase turns it to fatty acids and glycerol

Question 13

Q

practical:

How can you test for sugar?

3 marks

Answer

A

Add Benedict’s reagent (blue) to a sample and heat the water to 75 degrees.
If it’s positive it will form a Coloured precipitate.
The higher the concentration, the further the colour change.e.g the highest is brick red

Question 14

Q

How can you test for starch?

Answer

A

Add iodine
Is starches present it will go from browny-orange to blue black
otherwise it will stay browny-orange

Question 15

Q

How do you test for lipids?

4 marks

Answer

A

Shake the substance with ethanol for about a minute until it dissolves.
then Pour water
If lipids are present a precipitate will form showing up as a Milky colour
The more lipids, the more noticeable

Question 16

Q

How do you test for proteins?

5 marks

Answer

A

Biruret test
Add a few drops of potassium hydroxide to make solution alkaline
Add copper sulphate (blue)
If proteins solution will go purple
else it will stay blue

Question 17

Q

practical

How can you burn food to see how much energy it contains?

6 marks

calorimetry

Answer

A

Weigh a small amount of the food then put it onto a mounted needle.
Add a set volume of water to a boiling tube Held by a clamp
Measure the temperature of the water, then set fire to the food using a bunsen burner flame. Make sure the bunsen burner isn’t near the water or is may mess it up
Hold the burning food under the boiling tube until it goes out, then relight the food and hold it under the tube. Keep. doing this until it won’t set fire again.
Measure the final temperature of the water
mass of water x temp change x 4.2 (SHC of water) = energy in food

food must be flamable

Question 18

Q

practical

How do you investigate osmosis with diffrent concentrations using pattato?

7 marks

could be with any plant based thing and with pH / temp / conc

Answer

A

Prepare a bunch of solutions with arranging water concentration
Cut a potato into the Same sized pieces (1cm^2)
Divide Pieces into groups of 3 and use a electronic balance for the mass of each group.
Place one group into each solution
Leave cylinders for about 40 minutes.
Dry the pieces, to remove any excess water
Weigh each group again and record your results
Repeat experiment at different water concentrations

You also can say a more concentrated sucrose solution meaning a less concentrated water solution

Question 19

Q

What do you do with your results after a osmosis practical?

4 marks

Answer

A

Work out percentage change
((final mass - inital mass)/inital mass) x100
Plot a graph.
Where percentage change hits the zero on the graph. That is the concentration of water in the plant

Question 20

Q

what happens in interphase?

3 marks

Answer

A

DNA is spread out in long strings
subcellular structures duplicate
DNA is copied and forms X shaped chromosomes that is an exact duplicate of each other

Question 21

Q

what happens in mitosis?

8 marks

4 stages

Answer

A

Prophase - chromosomes condense and the membrane around the nucleus breaks down, allowing the chromosomes to lie free in the cytoplasm
metaphase - chromosomes lineup in the centre
anaphase - spindle fibers pull chromosomes apart, then chromatids are pulled to opposite ends
telophase - membranes form around each of the sets of chromosomes becoming nuclei

Question 22

Q

what is cytokines?

1 marks

Answer

A

before the end of telophase, the cytoplasm and cell membrane divide to form separate cells.

Question 23

Q

what is the difference between cell differentiation, cell division and cell elongation?

3 marks

Answer

A

cell differentiation -> A process where is cell becomes specialised
cell division -> mitosis
cell elongation -> where a plant cell expands making the cell bigger -> growing the plant

Question 24

Q

how is cancer caused?

3 marks

Answer

A

if there is a mutation that causes a change in genes that controls cell division it may start dividing uncontrollably
this can result in a mass of abnormal cells (tumour)
if the tumour invades and destroys surrounding tissue, it’s called cancer

Question 25

Q

what is meristem?

3 marks

Answer

A

cells in plants that divide by mitosis
produse unspecilised cells that can divide into any type of cell
they can form specilised tissue like xylem and phloem

Question 26

Q

what is the diffrence between stem cells and adult stem cells?

3 marks

Answer

A

stem are found in human embryos
they can produce any cell
adults are in bone marrow and replace damged cells - only producing certain cells

Question 27

Q

what are the risks of using stem cells in medicine?

3 marks

Answer

A

Tumour development - stem cells divide and can be unable to be controled
disease transmission - viruses live in cells -> if virus is in donor it will be passed on
rejection -> cells will see stem as foreign and trigger a immune response -> drugs can be taken to suppress it but there will be a higher risk of getting a disease

Question 28

Q

what are all the parts of the brain and what do they do?

4 marks

Answer

A

cerebrum (largest) - right hemisphere controls the left muscles vice versa - it controls movement, intelligents, language and vision
cerebellum - coordination and balance
medulla oblongata - contols unconscious activities e.g. breathing and heart rate

Question 29

Q

what are CT scanners?

3 marks

Answer

A

uses x-rays to produse an image
shows main structure
can show diseased / damaged structures and is patient has lost function

Question 30

Q

whta are PET scanners?

4 marks

Answer

A

use radioactive chemicals to show active parts of the brain
they are very detailed can can be used to investigate structure and funtion in real time
used for studying disorders that change brains activity
compared to normal brain (without e.g. alzheimers)

Question 31

Q

why is it hard to treat CNS?

3 marks

brain and spinal cord

Answer

A

hard to repair damage
hard to access
risk of further damage

Question 32

Q

how does the CNS coordinate a responce?

6 marks

Answer

A

receptors detect a stimulus
information is coverted into electrical impulses
the its sent along sensory neurones to CNS
CNS descides what to do
impules are sent along relay neurones
CNS sends info to effector along a moter neurone and responds (muscle contracts)

Question 33

Q

what is the difference between the 3 main neurones?

6 marks

Answer

A

sensory:
- one long dendron carries impuse from receptor to cell body in the middle
- one short axon carries impuses from cell body to CNS
motor neurone:
- many short dendrites carry nerve impuses from CNS to cell body
- one long axon carries impulses from cell body to effector
relay neurone:
- many short dendrites carry nerve impuses from sensory neurone to cell body
- axon carries impuses from cell body to motor neurones

Question 34

Q

how do synapses connect neurones?

4 marks

Answer

A

connection between neurones = synapes
signals are transferred by chemicals called neurotransmitters that diffuse across gap
neurottransmitters set of new signal on the next neurone
transmittion of nervous impuses are very fast but slowed due to synapes rate of diffustion

Question 35

Q

how do reflexs prevent injury?

7 marks

Answer

A

reflexs are rapid automatic responces
reflex arc
no concous thought so its faster
stimulus is detected and impuses is sent down a sensory neurone to a relay neurone
impuses release neurotransmitters at synapses
then its sent along moter neurone
then goes to an effector and muscle contacts

Question 36

Q

how do reflexs protect the eye?

4 marks

Answer

A

bright light damages eye
light receptors can detect bight light and send message along sensory neurone
the it travels along relay to a moter neurone which tells the circlar muscles in iris to contract
making the pupil smaller

Question 37

Q

what are all the parts of the eye and what do they do?

7 marks

Answer

A

cornea - refracts light into eye
iris - controls how much light enters pupil (hole)
lens - refracts light focusing it on retina
retina - light sensitive part covered in receptors cells called rods and cones
rods - sensitive to dim light and cant see colour
cones - sensitive to clours but not good in dim light
optic nerve - caries electrical impuses, coverted from light info, to brain

Question 38

Q

what is the diffrence between focusing on a near and distant object?

4 marks

Answer

A

distant:
- ciliary mustcle relax allowing suspensory ligments to pull tight
- this makes lens less rounded shape so light is refracted less

close:
- ciliary muscles contract which slacks suspensory ligments
- lens becomes more rounded shape so light is refracted more

Question 39

Q

whats the diffrence between long and short sightedness?

4 marks

Answer

A

long:
- when lens doesnt bend light enough or eye is too short (behide the retina)
- you need a convex lens

short:
- lens bends light too much or eye is too long (in front retina)
- you need a concave lens

Question 40

Q

what causes colourblindness?

2 marks

Answer

A

cause when cones in retina arent working properly
there is no cure

Question 41

Q

what is catarcts?

3 marks

Answer

A

cloudy patch on lens stoping light getting in
causes burred vision and less vivid colours and hard to see in bright light
it can be treated by replacing lens with artificial one

Question 42

Q

how does sexual reproduction work?

3 marks

Answer

A

in fertiltsation, a male gamete(23) fuses with female gamete to produse a ferilised egg (zygote(46))
zygote goes though cell devision by mitosis to develop an embryo
it inherits charicteristics from both

Question 43

Q

how are gametes produced?

6 marks

meiosis

Answer

A

DNA duplicates
in the first devision chromosomes line up in pairs at the centre (one from male one from female
pairs are pulled apart
each new cell will have a mix of mother and fathers chromosomes
in second division they line up in centre again and get pulled apart
you get 4 genetically diffrent haploid daughter cells

Question 44

Q

what are the advantages and disadvantages of asexual reproduction?

4 marks

Answer

A

advantages:
- produces lots very fast
- only one parent needed

disadvantages:
- no genetic variation
- disease can kill whole population

Question 45

Q

what are the advantages and disadvantages of sexual reproduction?

4 marks

Answer

A

advantage:
- gentetic variation
- natuaral selection and evolution
disadvantages:
- takes more time and energy
- 2 parents needed

Question 46

Q

what is DNA made of?

6 marks

Answer

A

polymers called nucleotides
the consist of a sugar, a phosphate group and one base
sugar and phosphate group is the backbone and alternate
2 strands conected in a double helix
T-A and C-G
base join with weak hydrogen bonds

Question 47

Q

how do you extract DNA from Fruit cells?

6 marks

Answer

A

mash you fruit and put it in a beaker containing solution of deterent and salt then mix
deternent breaks down the cell membrane to release DNA
salt will stick DNA together
filter mixture to get froth and big, insoluble bit of cell out
gently add ice cold alcohol to filter
DNA will start to come out as its not soluble in cold alcohol. it will appear as a stringy white precipitate

Question 48

Q

what happens in Transcription?

5 marks

Answer

A

RNA polymerase binds to a region of non-coding DNA
the 2 DNA strands unzip and the RNA polymerase moves along one of the strands
it uses the coding DNA in the gene as a template to make mRNA
Base pairing between the DNA and RNA ensures that the mRNA is complementary
after the mRNA moves to ribosomes

Question 49

Q

what is Translation?

4 marks

Answer

A

amino acids are bought to ribosomes by tRNA
the order of in which the amino acids are bought there match the order of base triplets in mRNA (codons)
tRNA’s structure is called an anticodon and is complementary to the codon for the amino acid (makes sure its in correct order)
amino acids are joined together by the ribsomes - this makes polypeptide (protein)

Question 50

Q

what happened during mendels experiments?

2 marks

Answer

A

he crossed a tall and a short pea plant and all the offspring were tall
then he bread 2 of these tall offspring and 1 in 4 of their offspring were short

Question 51

Q

what was mendels conclusions?

3 marks

Answer

A

characteristics are determined by “hereditary units”
units are passed on to offsping unchanged with one unit from each parent
units are either domient are recessive

Question 52

Q

how do sex linked disorders work?

3 marks

Answer

A

Y chromosome is smaller
cuz men only have one X if it contains even a recessive disorder it will stay because there is nothing to counter act so men will be more likely to have it
2:1:1 = not:carrier:affected
25% chance of offpring having it means 50% if male and 0% female

page 40

Question 53

Q

what are the blood groups?

3 mark

Answer

A

|o|o - recessive
|A|o or |A|A - dominant
|B|o or |B|B - dominant
|A|B - dominant

Question 54

Q

what is genetic variation within a species and hows it caused?

4 marks

Answer

A

diffrent alleles which lead to diffrences in phenotypes
its caused by new alleles though mutations
sexual reproduction
the enviroment

Question 55

Q

how do alleles arise?

3 marks

is there any affect

Answer

A

changes to the base sequence
most are neutral
some have a small effect

Question 56

Q

what happens in cystic fibrosis?

2 marks

Answer

A

mutation causes a protein that controls movement of water/salt to stop working
this leads to production of thick, sticky mucus which makes it difficult to breath and digest food

Question 57

Q

what is the human genome project?

3 marks

Answer

A

maping over 20,000 human genes
collaboraration of lots of scientistis
helped identify 1800 genes related disease which has a huge benifit for medicine

Question 58

Q

what are the advantages for the human genome progect?

6 marks

Answer

A

prediction and prevention:
- if we knew what genes give what diseases we could find out what lifesyle is best for each person to avoid problems

testing and treatment:
- inherited disorders are caused by faulty alleles so we can identify the suspected gene that could cause it very quickly
- this means they can be tested and be given better treatment therfore a more likelyhood of a cure

new and better medicine:
- some variations affect how we react to certain deseases and posible treatment
- scientists can design new drugs specifically made for each genetic variation
- this will make more effextive treatment with fewer side effects

Question 59

Q

what are the disadvantages of the human genome project?

3 marks

Answer

A

increase stress - if people think there going to get a disease later on
gene-ism - people with genetic problem be be pressured not to have children
discrimination - employers / life insurence will be more expencive

Question 60

Q

what is natural selection?

5 marks

survival of the fittest

Answer

A

Individual in a population shows genetic variation due to a mutation
Individuals with characteristics that make them better adapted to surviving are more likely to breed (predation, competition)
this means alleles that are better adapted get passed on to offspring
those with less better adapted die off and are less likey to pass on alleles
overtime beneficial charicterteristics become more common

Question 61

Q

what are the evidences fo evolution?

4 marks

Answer

A

Bacteria:
- Bacteria become better adapted to the environment containing antibiotics. due to population becoming resistant to them over time.
- This happens from random mutations being passed on very quickly

fossils:
- By ordering the fossils of age, the newer have changed and developed over many years.
- This can be done due to the deeper the rock the older it is

Question 62

Q

How did Darwin come up with the theory of evolution?

3 marks

Answer

A

He spent five years on a voyage around the world, studying plants and animals (HSS Beagle)
He noticed the Variation in members of the same species. And that those with characteristics most suited to the environment were more likely to survie and pass on characteristics.
He wrote the theory of evolution by natural selection

Question 63

Q

What did Wallace do?

2 marks

Answer

A

Him and Charles Darwin published together
He realised warning colours used on species deterred predators from eating them

Question 64

Q

How did ideas about evolution influence modern biology?

3 long marks

Answer

A

classification - We can now classify organisms based on how closely related they are
Antibiotic resistance - understanding the importance of finishing a drug course to prevent the resistance of bacteria spreading and the need of new antibiotics to fight evolving bacteria
Conservation - understanding the importance of genetic diversity And how it helps the population adapt to changing environment

Answer 65

A

Ardi (4.4mill):
- Feet structure suggest she climbed trees. + ape like toe
- brain the size of a chimpanzees
- Long arms and short legs. and structure suggests she walked upright

Lucy (3.2mill):
- Arched feet adapted for walking
- Brain was slightly larger than Ardi’s
- Arms and legs were between apes and humans

Turkana Boy(1.6mill) discoverd by leakey on expedition:
- Brain size was much larger the lucys
- small, arms and long legs more like humans
- Structure of legs and feet suggests he was better adapted for walking up all right.

Answer 66

A

Ardipithecus - 6mill -> 4mill years ago
Australopithecus - 4.5mill -> 2mill years ago
homo - 2.5mill -> not long ago
homo sapiens - 0.2miil -> today

Answer 67

A

2.5 -> 1.5 million years ago (simple stone tools made by hitting rocks together - used to scrape meat and crack bones)

2 -> 0.3 million years ago (sculpted rock into shape from tools like simple axes for hunting / chopping / scraping / digging)

300k -> 25k years ago ( flint tools / pointed tools / wooden spears)

200k -> present ( flint tools widely used /pointed tools like arrow heads / fidh hooks / needles appeard 50k years ago)

Answer 68

A

Lots of species have similar bone structure
Each structure is adapted to different functions
And limb with five digits
Highly unlikely that they all share A similar bone structure

in a bigger question compare the limps provided

Answer 69

A

Kingdom
Phylum
Class
Order
Family
Genus
Species

Keep penis clean or face getting STI

Answer 70

A

Animals
Plant
Fungi
Prokariotics
Protists

Answer 71

A

Five kingdom classification is outdated
Over time technology has developed and genetics Have increased
It It was said that organisms should first be divided into three large groups
We used to classify organisms using observable characteristics.
As technology improved this included things you could see with microscopes

Answer 72

A

Archaea -> Similar to bacteria But with a different DNA and RNA sequence

Bacteria -> true bacteria

Eukarya -> fungi / plants / animals / protists

Answer 73

A

Artificially selecting organism to breed for a more useful or attractive purposes
From existing stock select organisms with characteristics you want
breed them together
Select the best of the offspring and breed them together.
Continue in a many generations until Get a stronger and stronger

Answer 74

A

genetic variation Gives better characteristics producing more yeild than others.
It can be used in medical research to find the differences between behaviours and the way the brain works.

Answer 75

A

It reduces gene pool Due to inbreeding.
Inbreeding can cause health problems. due to an increase in inheriting harmful genetic defects.
This leads to ethical considerations.
There can also be a serious problem if a new disease appears, as there’s not much variation, so there’s a less chance a resistance allele.

Answer 76

A

Choose the plant you want to clone based on its characteristic
Remove several pieces of the tissue from the parent plant. (Best if you take it from fast growing roots or shoot tip)
Grow tissue on a growth medium containing nutrients and growth hormones.
This is done under aseptic conditions to prevent microbes harming plants
As the tissue produce shoots and roots, they can be moved to potting compost to carry on growing
hundreds of cones can be made

Answer 77

A

get Sample the tissue you want to study By extracting it from the animal
Separate cells using enzymes
It is placed on a culture vessel and bathed in a groove medium containing nutrients, allowing it to grow and multiply.
After many cell divisions, the cell can be spill it up again and be. placed on a separate vessel encouraging further growth
Then it can be stored for future use
This allows you to look at the effect of a particular substance or environment changed on the cells of a single tissue Without needing the whole organism.

Answer 78

A

DNA you want to insert Is cut out of bacteria using a restriction enzyme
The Vector (plasmid / virus) DNA is then cut open using the same enzyme.
Both DNA’s are left with sticky ends, then are mixed together with ligase enzymes
The ligase joins the piece of DNA together to make recombinant DNA (two bits stuck together)
This recombinant DNA is Insert it into the other cells
These cells can now use the gene view inserted to make the protein you want.

plamids are molecules of DNA that can be transfered between bacteria while viruses insert the DNAinto the organism they infect

Answer 79

A

Crops can be genetically modified to resist chemicals tha kill plants Allowing farmers to Spray the crops to kill the weeds without affecting the crop itself (increasing yield)
However, transplanted genes. may get out into the environment. which may also get picked up by weeds creating a new “superweed” variety.
Also modified crops could affect food chains or even human health

.
- In medicine, we can use a genetic engineering bacteria to produce human insulin and other useful proteins.
- However, it’s hard to reject what effect. its modifiying will have on the organism As some animals don’t survive or suffer from health problems afterwards

Answer 80

A

Bacillus thuringiensis Produces a toxin that kills off many insect larvae that are harmful to crops
The gene for the toxin is inserted into the crop, which then produces the toxin in their stem and leaves, making it resistant to the insect pests
The toxin is specific to the insect test. It is harmless to humans and plants and other insects. However, the long-term exposure isn’t yet known.
Insects that feed on the crops constantly exposed to the toxin. So there is a danger that they will develop resistance.
This can be avoided by using other insectatides as well

Answer 81

A

good:
- We need food security For the rising population
- Improves crop yield in drought conditions
- Provides the right balance of Nutrition

bad:
- People argue that it’s not because There isn’t enough food, its because they can’t afford it. So we need to tackle poverty first
- Fear that countries may become too dependent on companies who sell genetically modified seeds
- Sometimes poor soil is the main reason crop fails and genetically modified crops would survive anyway

Answer 82

A

GMO ‘s is a new way of improving crop yields.
if the soil is poor, applying fertilisers is likely to be the best way to increase yield As they contain nutrients. However, it could cause problems in rivers and leaks, causing eutrophication
Pests can also be controlled by using other organisms to reduce the number of pests. However, it may lead to more harmful wildlife then I was before

Answer 83

A

complete physical, mental and social well-being

Answer 84

A

It’s a bacterium (Vibrio cholerae)
It causes diarrhoea
It spreads through contaminated water
It’s prevented by having clean water supplies

Answer 85

A

It’s a bacterium (mycobacterium tuberculosis)
Coughing and long damage is caused
Spreads through the air / coughs
Avoided by avoiding crowded spaces and practising good hygiene And having a well ventilated place

Answer 86

A

It’s a protist
It causes red blood cell damage and even liver damage sometimes
Spreads though mosquitoes acting as a vector. by passing on the protist while not getting the disease themseves
Use mosquito nets and insect repellent to provent bits

Answer 87

A

It’s a bacterium (Helicobacter pylori)
It causes stomach pain, nausea and vomiting
it spreads orally
Reduced by having clean water supplies and hygienic living conditions.

Answer 88

A

It is a virus
It can cause a fever with bleeding
It spread through body fluids
It’s prevented by isolating infected individuals and sterilising any areas where the virus may be present.

Answer 89

A

It’s the fungus that affects ash trees.
It causes leaf loss and bark wounds
It is carried through the air by the wind and spread when diseased ash trees are moved between areas
It can be prevented by removing young, infected ash trees and replanting it with a different species or restricting the import or movement of ash trees

Answer 90

A

A virus attaches itself to a specific host cell and injects its genetic material.
The virus uses proteins and enzymes in the host cell to replicate its genetic material and produce the components of a new virus
The viral components assemble
Host cell splits open releasing the new viruses, which can infect more cells

Answer 91

A

A virus can inject genetic material into the genome of the host cell
The viral genetic material gets replicated along with the host’s DNA every time the host cell divides. But the virus is inactive and no new viruses are made.
Eventually, a trigger causes the viral genetic material to leave the genome and enter into the lytic pathway.

Answer 92

A

bacterium that reproduces inside host cell (STI)
it dont alway show symptoms but can cause infertility in both sex’s
it can be avoided by wearing a condom / avoiding sexual contact or screening them so they can be treated

Answer 93

A

human immunodeficiency virus (STI) - it kills white blood cells
It leads to AIDS when the immune system deteriorates and starts to fails - making them very vulnerable to other pathogens
HIV spreads though body fluids so to provent it uses condoms and avoid sharing needles.
medication can reduces the risk of an infected person passing it on during sex - or a pregnant person giving it to a baby
so screening and proper treatment is very important

Answer 94

A

physical:
- A waxy cuticle Which provides a barrier to stop pathogens entering them or pests, damaging them
- It also stops a water collecting on the leaf which could reduce the risk of infection transferred in water
- Plants are surrounded by a cell wall made from cellulose Which forms a physical barrier? if they make it past a waxy cuticle

chemical:
- They produce chemicals called antiseptics, which kill bacterial nd fungal pathogens. They also produce chemicals to deter pests.

Answer 95

A

quinine Come from the bark of cinchona tree and was used to treat malaria
Aspirin is used to relieve pain and fever - it was developed from a chemical found in the bark / leaves of williow trees

Answer 96

A

Through observations And symptoms
Sometimes plants may show symptoms which are usually due to environmental causes. such as nutrient deficiency.
by changing environment conditions And observing any changes in the plants symtoms It can be determined whether a plant has a disease or not.
Different pathogens spread in different ways so. people can analyse the distribution of disease In the plants to identify the kind of pathogen involved.

Answer 97

A

To allow for accurate identification of sPacific pathogens

Answer 98

A

Pathogens have a unique molecule on their surface called antigens
Antigens from a particular pathogen will be present in a plant infected with that Pavagadh, and can be detected in a sample of plant tissue using monoclonal antibodies
The detection of an antigen unique to a particular pathogen allows that pathogen to be identified and the disease to be diagnosed.

Answer 99

A

If a plant is infected with a pathogen, the pathogen’s D N a will be present in the plant’s tissue
Scientists have techniques that allow them to detect even small amounts of pathogen dna in a sample of plant tissue, allowing them to identify the particular pathogen that is present.

Answer 100

A

The skin acts as a barrier to pathogens, and if it gets damaged, blood clots quickly seal the cut and keep organisms out.
Here’s a mucus in your nose. Trap particles that could contain pathogens.
Cells in your trachea and bronchi also produce mucus which traps pathogens
cells that line, the trachea and bronchi have cilia, which. are hair like structures which moves the mucus up to the back of the throat where it can be swallowed

Answer 101

A

The stomach produces hydrochloric acid, which kills most pathogens that are swallowed.
The eye produces a chemical called lysozyme, which kills bacteria on the surface of the eye.

Answer 102

A

They start to reduce proteins called antibodies, which bind to the newly invading pathogen so it can be destroy by other white blood cells.
Antibodies produced a very Pacific to that pathogen, so they won’t lock them to any of our pathogens.
Antibodies are produced rapidly and flow all around the body to find similar pathogens.

Answer 103

A

When a pathogen first enters the body, the response will be slow because there aren’t any B lymphocytes that can make the antibody needed to lock onto the antigen.
Eventually, the body will produce enough right antibodies to overcome the infection
Memory lymphocytes remain the body for a long time.
After this happened, the person will become immune as they have the ability to quickly respond to a second infection of that pathogen.
The second response will be faster and stronger and normally gets rid of the pathogen before you begin to show symptoms.

Answer 104

A

It involves injecting dead or inactive pathogens into the body
They are antigenetic, so even though they are harmless, your body still makes antibodies.
Antigens trigger memory lymphocytes to be made.
If live pathogens of the same type get into your body, there will already be Memory lymphocytes
The second immune response will be fast So you’re less likely to get the disease

Answer 105

A

pros:
- Epidemics can be prevented if a large percentage of the population are immunised.
- Even people who aren’t immunised are unlikely to catch it because there would be few people who can pass it on This is known as herd immunity.
- Some diseases get virtually wiped out by this process

cons:
- Sometimes it doesn’t work
- Some people can get bad reactions to vaccines.

Answer 106

A

Monoclonal antibodies are produced from lots of Clones Meaning the antibodies are identical and will target one specific protein antigen.
tumour cells devide lots but B-lymphocytes that produse these antibodys dont
However, you can fuse these together using a myeloma tumour cell to make a hybridoma
These can clone lots of identical cells very quickly To produce monoclonal antibodies which are collected and purified
You can make monoclonal antibodies bind to anything So you can allow them to target a spacific cell or chemical in the body.

Answer 107

A

the stick contains antibodies with blue beads attached.
The test strip has some more antibodies that bind to the hormone.
If you’re pregnant, the hormone binds to the antibodies on the blue beads.
Then the urine moves up the stick and carries the hormone and the beads which bind to the antibodies on the strip
leaving the blue beads to get stuck, turning it blue.
If you’re not pregnant the urine still moves up carrying the blue beads, but nothing sticks So it doesn’t go blue

Answer 108

A

Antibodies are labelled with radioactive elements
Then they are given to a patient through a drip and goes into the blood
When the antibodies come in contact with a cancer cell, they bind to the tumour markers.
A picture of the patient is taken through a special camera that detects radioactivity and will show cancer cells as a bright spot
this can be used to show the size and spreading of a tumour

Answer 109

A

Anti-cancer drug is attached to monoclonal antibodies
Antibodies are given to patients through a drip
The antibodies target Pacific cells because they only bind to tumour markers
The drug kills the cancer cell, but doesn’t kill any normal body cells
Other cancer treatments can affect normal body cells as well as killing the cancers
so the side effects of antibody-based drug are lower than other methods

Answer 110

A

When blood clots, protein in the blood joined together to form solid mesh
monoclonal antibodies have been developed that bind to these proteins.
You can attach a radioactive element to these antibodies.
If you inject them into the body and take a picture using a camera that sees radiation, it will have a very bright spot where the blood clot is.
This is useful because you can easily find a potential harmful blood clot. (before it becomes harmful)

Answer 111

A

preclinical testing:
- First tested on human cells and tissue
- After it’s tested on live animals to tested the drug works - Finds how toxic it is and the best dosage.

clinical testing:
- A drug is tested on a healthy volunteer to make sure it has no harmful side effects.
- He is tested on people with illness to find the optimum disc that is most effective and with the fewest side effects.
- Patients are randomly put into two groups and 1 is given the new drug and the other one is given a placebo. - This makes sure it is actually the drug that is helping not just a placebo effect
- Clinical trials are blind, so the patient doesn’t know. whether they are getting the drug or the placebo. - most the time is a double blind, so the patient or doctor doesn’t know So there is no subconscious influence

Answer 112

A

Bacteria are cultured in a growth medium
This contains carbohydrates, minerals, proteins and vitamins needed for it to grow
growth mediums can be a solid agar jelly, which form visible colonies on the surface of the jelly or could spread out.
To make an agar plate, hot agar jelly is poured into shadow round of plastic called petri dishes.
When Jelly is cooled and set - Wire loops can be used to transfer microorganisms to the a agar jelly.
Alternatively, a sterile dropping pipette and spreader can be used to get an even covering of bacteria.
Then the microorganisms multiply
Microorganisms are kept at 25 Degrees Because harmful pathogens are less likely to grow at this temperature.
Outside of school, scientists may use higher temperatures to provide optimum temperatures for growth.

Answer 113

A

Put paper discs soaked in different types of antibiotics on an agar plate that has got an even coating of bacteria.
The antibiotics should diffuse into the agar jelly. Antibiotic resistant bacteria aren’t affected by the antibiotic and will continue to grow on the agar but non resistant ones will die.
Make sure to use a control like a paper disc that has not been soaked in antibiotic. Then you can be sure any difference between the growth of the bacteria and the control disc is due to the effect of the antibiotic alm.
Leave the plate for 48 hours at 25 degrees Celsius.
The more effective that antibiotic is against the bacteria, the larger the inhibition zone

Answer 114

A

The petri dishes and growth medium must be sterilised before use. This can be done by using a scene called an autoclave which uses steam at a high pressure and temperature to kill any microorganisms present.
Put the isoculating loop over a bunsen burner to kill unwanted organisms.
Liquid bacterial cultures should be kept in a cultural vial with a lid To prevent unwanted organisms getting in.
petri dishes should be covered with a lid which should be lightly tapped on to stop Microorganisms from the air getting in.
The dishes should be stored upside down to stop drops of condensation falling on the agar.

Answer 115

A

You look at the relative size of the inhabitation zone.
You can do it by eye or for the most accurate results. Use a ruler to find the diameter.
To calculate the area of the inhabitation zone, do Pi R ^2.

Answer 116

A

Nicotine increases a heart rate which increases blood pressure.
High blood pressure damages artery walls and builds up fatty deposits in the arteries which risks a heart attack or stroke.
It increased the risk of blood clots forming in arteries which can restrict or block blood flow, leading to heart attacks or strokes.

Answer 117

A

A diet with too much or too few nutrients can lead to malnutrition.
Not getting enough exercise and having a diet in high fats and sugar risks factors for obesity.
Drinking to much alcohol is a major risk factor for the development of liver disease.
This is because when alcohol is broken down by enzymes, some of the products are toxic.

Answer 118

A

Areas where there is a high level of of obesity, smoking and access to alcohol leads to more likelihood of non-communicable diseases in that area.
They are very expensive on a national level because the National Health Service for raised resources for treatments.
A reduction in the number of people able to work can affect a country’s economy if They stopped being able to work
They are very common and the number and the number one cause of death world wide So these diseases can hold back development of countries.

Answer 119

A

If you have lots of muscle which has a high amount of mass It could say they are overweight, even though they are not.

Answer 120

A

Cholesterol is a fatty substance that the body needed to make things like cell membranes, but too much can cause fatty deposits to build up in the arteries restricting blood flow.
Deposits appear in areas where the artery wall has been damaged.
Fatty deposits also trigger blood clots to form, which can block blood flow completely. If this happens, The heart muscle the artery is supplying will cause a heart attack.
A blockage to the brain would deprive the brain of oxygen and cause a stroke.

Answer 121

A

Healthy balanced diet
Low saturated fat
Regular exercise
Stop smoking

Answer 122

A

Statins reduce the amount of cholesterol in the bloodstream, which slows down the rate which fatty deposits form - could cause liver damage tho
Anticoagulant are drugs which make blood clots less likely to form. However, it could cause access bleeding.
Antique Hypertensives reduce blood pressure, helping prevent damage to blood vessels, reducing the risk of fatty deposits forming. - but could cause headaches / fainting

Answer 123

A

Stents are choose inserted inside arteries to keep them open, making sure blood can pass through. Lowering the risk of heart attack. - Over time they can narrow again and irritate the artery and make scar tissue grow. patient also has to take drugs to stop blood clotting
If part of a blood vessel is blocked, a piece of healthy vessel is taken from somewhere else and is used to bypass the blocked section.
The whole heart can be replaced with a donor heart. However, a new hot does not always start punting properly, and drugs have to be taken to stop the body rejecting it. - Heart surgery has the risk of bleeding blood clots and infection.

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