More bio past papers Flashcards by India Rutherford

Mitochondria are

the site of AEROBIC respiration!!!!!

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Why do you blot the potatoes in that one osmosis experiment?

Get rid of excess water on the surface that is not actually in the cells, otherwise the mass reading would be higher

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How does fibre affect your diet?

Aids digestion/prevents constipation

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How does protein affect your diet?

More-> growth

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How does more fat affect your diet?

Can cause CHD/heart attack/narrowing of arteries
May need a stent
may lead to obesity- a risk factor in type2 diabetes

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How does cholesterol affect your diet?

CHD/heart attack/narrowing of arteries
stents/statins

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How do carbohydrates affect your health?

good for providing energy

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How do you keep safe while handling knives?

cut away from body/use chopping board/keep fingers away from blade

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why is “The cover slip is lowered onto the onion epidermis at an angle”?

prevent air bubbles

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why is iodine solution added to the onion?

To stain the onion to see parts of the cell

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In what ways could you improve the scientific drawing? Non exhaustive

include magnification
continuous lines
don’t draw overlapping cells
wider cell walls
no shading
draw all cells
no gaps between cells
nuclei in right position
label

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how would an image look different if you used an electron microscope instead?

more magnified
more detail/higher resolution/see more subcellular structures
black+white

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How does mimicry help the hornet moth survive?

it looks like the hornet so predators tricked and avoid eating it

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Describe the process of mitosis

DNA replicated
chromosomes pull apart
cytoplasm divides
set of chromosomes in each
new cell are identical

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Which environmental conditions would cause the rate of transpiration to be greatest in
a plant?

low humidity high temp

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Explain why multicellular organism D requires a respiratory system, but single celled B does not

D has a smaller SA:V ratio

large to meet demands of cells

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Why do smaller multicellular organisms (D) have a greater metabolic rate?

D has lagrer SA:V ratio and so will lose
heat more quickly (per unit
volume than E)
so requires greater rate of
respiration
(as) respiration is a (large) part
of metabolism
(so) need to generate more heat
(to keep itself warm)

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how is HIV spread?

sexual contact/sharing bodily fluids

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Describe the trends of new cases of HIV in men and women between 2010 and 2018

The important thing is not to mention differences between men and women

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how to prevent HIV spread?

better education (into
prevention of spread of HIV)
condoms more widely
available/cheaper
new / better drugs (to prevent
HIV infection / spread)
better / more testing /
identification (of people with
HIV)

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process of making a MAB for HIV

HIV antigen injected into mouse
collect mouse lymphocytes that make a
specific AB to HIV antigen
lymphocytes combined with tumour cell to create a
hybridoma which is cloned to create many cells that produce the MAB

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Suggest how the monoclonal antibody for HIV helps to prevent a person infected with
HIV developing AIDS.

monoclonal antibody is specific to HIV antigen
monoclonal antibodies attach to HIV antigens
so they can’t bind to human cell

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Name two pieces of laboratory equipment the student could have used to prepare
cells to view using a microscope.

(microscope) slide
* cover slip
* dye / stain
* (mounted) needle
* pipette / dropper
* scalpel
* forceps / tweezers

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The student tried to look at the cells using the microscope.
Suggest one reason why the student could not see any cells when looking through
part A.

objective lens dirty
air bubble
unfocused microscope
no cells in field of view
not switched on

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what is the shape of a plant cell?

there are many different shapes of plant cell

Name some aseptic techniques you could use when doing a bacteria experiment

Sterilise equipment/surfaces sterilise sugar Secure lid w/ tape and only lift a little bit

Name some health conditions that might develop if a person eats a diet high in saturated fat.

CVD/CHD heart attack/disease stroke

Uses of energy released in respiration

muscle contraction keeping warm active transport building larger molecules

Explain why the concentration of carbon dioxide in the tube stayed the same between day 0 and day 5. (it's the dreaded pond snail)

pondweed takes in CO2 for photosynthesis snail AND pondweed are respiring producing CO2

Suggest why the concentration of carbon dioxide increased between day 5 and day 10. The light was blocked on day five. Read the question!

no light, no photosynthesis plant not taking in CO2 both are respiring and releasing CO2

Explain why the death of the pond snail caused the concentration of carbon dioxide to increase after day 10.

Snail is being decomposed by decomposers in water therefore respiration releases co2

Amylase is a polymer of smaller molecules, which are...

AAs

3 places where amylase is made

salivary gland, pancreas, SI

Explain how amylase breaks down starch in terms of "lock and key"

starch binds to active site bc active site+ substrate r complementary bonds between starch molecules are broken to produce smaller molecules

Why did the student leave the starch and amylase solutions before mixing

to allow the solutions to reach the same temp of the water

compare the structure of xylem and phloem

xylem: dead, hollow, no cytoplasm, * both made of cells * both tubular

compare the functions of xylem and phloem

Function - xylem- water / mineral ions -phloem- (dissolved) sugars xylem involved in transpiration phloem involved in translocation xylem transports unidirectionally phloem transports bidirectionally both transport liquids throughout the plant

Describe what happens to cells when a tumour forms

cells divide uncontrollably

Describe how energy for the photosynthesis reaction is gained by plants.

Light absorbed by chlorophyll

Explain how nitrate ions are transported into the root hair cell

Active transport because energy needed to move nitrate ions from an area of low conc to high conc

Explain lock and key

enzyme binds to substrate bc they're complementary substrate is broken down products are released and enzyme is not changed

Why does each different type of lipase act on only one specific type of lipid molecule?

Each active site has a specific shape and so only is complementary to one type of lipid molecule

Describe how the students would find out if the liquid from the leaf contained glucose

Add benedict's solution heat colour changes to brick red

Explain why the leaf in the light for four days contained both glucose and starch

glucose from photosynthesis (excess) glucose converted to starch

Explain why the leaf left in a cupboard with no light for two days did contain glucose but did not contain starch.

starch stores converted to glucose so it could be used for respiration to release energy because there's no light to make more by photosynthesis

Suggest one way the students could develop the investigation to find out more about glucose and starch production in plants. (nutrient tests after leaving the leaf in light then darkness)

* test roots / stems of plants (in the light and dark) * test other species * measure concs of glucose/ starch * vary the time in the dark / light * test variegated leaves

What type of defence response are thorns?

mechanical

How do thorns defend the gorse plant?

deter herbivores to prevent animals damaging it

Explain two other possible reasons for the yellow leaves and stunted growth. Do not refer to nitrate ions in your answer.

lack of mg ions so not enough chlorophyll for photosynthesis so not enough glucose to make proteins for growth/release nrg for growth infection by pathogen eg TMV / rose black spot so leaves become discoloured so less photosynethssis so not enough glucose etc infection by aphids remove sugars from phloem not enough glucose etc lack of light so chlorophyll breaks down not enough glucose etc

Where does the heart drug digitalis originate from?

foxgloves

what medicine can you get from foxgloves?

the heart drug digitalis

where does the painkiller aspirin originate from?

willow bark

Control variables in an alcohol / liver disease survey

BMI smoking habits diet medication family history of liver disease fitness levels ethnicity area of UK

Reasons why the liver disease/ alcohol survey may be valid

large number of people in survey long term survey well controlled

Reasons why the liver disease/ alcohol survey may not be valid

under/overestimation of alcohol consumption people may chaneg lifestyle over time some people may drink all their weekly alcohol at once

Result of liver failure - bile

No bile made (describe what bile does) so food not digested/absorbed may lose weight

Functions of the liver

make bile break down lactic acid break down proteins remove toxins eg alcohol store glycogen

results of liver failure- lactic acid

toxic lactic acid not oxidised prolonged O2 debt muscle pain/fatigue

results of liver failure- glycogen

glycogen stores not formed can't control blood glucose conc hyperglycaemia/hypoglycaemia/diabetes/coma may occur

results of liver failure- toxins

can't break down toxins eg alcohol toxins accumulate body poisoned pain/jaundice/swollen liver/portal hypertension may occur

Describe how the mAbs and a fluorescent dye could be used to see any pathogens on the slide.

bind dye to mabs put fluerescent mabs on slide and rinse off mabs will bind to pathogens and show up under the microscope

Describe how a series of clinical tries should be carried out, after animal and tissue testing

given first to healthy volunteers at low dose test toxicity, safety + side effects give to patients w/ the disease test dosage/efficacy/side effects double blind , placebo reference control variables, large trial, long duration

4 Scientists have also used human lymphocytes to make mAbs to other pathogens and to some types of cancer cells. Suggest one reason why these new mAbs have been more successful in treating diseases in humans than mAbs made using mice.

Body won't reject them

What causes symptoms like vomiting and diorhhae in samonelle patients?

toxins secreted by bacteria

How can a patient with a salmonella infection prevent spread to others

wash hands after using toilet/vomiting wash hands before preparing food/don't prepare food isolate disinfect clothes/surfaces don't share cutlery/towels

A person with AIDS may take longer than a healthy person to recover from a Salmonella infection. Explain why.

immune system damaged WBCs can't kill bacteria as effectively

How could farmers prevent salmonella spread?

don't sell infected chickens/eggs give chickens antibiotics keep infected chickens indoors/isolated slaughter infected chickens

The scientist showed the results to the restaurant owner. Both cleaning liquids cost the same per dm3. Suggest one other factor the restaurant owner should consider when choosing which cleaning liquid to use.

health side effects effect on other bacteria interaction with other cleaners ease of use dilution factor vs cost how much time it's effective for

Compare artery + vein structure

Arteries have a thicker layer of muscle tissue and elastic tissue arteries have narrower lumen veins have valves

What condition may be treated with an artificial pacemaker?

arrythmia irregular heartrate

why might an Mg deficiency cause stunted growth and yellow leaves?

yellow due to lack of chlorophyll -> less light absorbed->lower photosynthesis rate->less glucose made->plant converts less glucose to protein so stunted growth