More bio past papers Flashcards
Mitochondria are
the site of AEROBIC respiration!!!!!
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
How does fibre affect your diet?
Aids digestion/prevents constipation
How does protein affect your diet?
More-> growth
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
How does cholesterol affect your diet?
CHD/heart attack/narrowing of arteries
stents/statins
How do carbohydrates affect your health?
good for providing energy
How do you keep safe while handling knives?
cut away from body/use chopping board/keep fingers away from blade
why is “The cover slip is lowered onto the onion epidermis at an angle”?
prevent air bubbles
why is iodine solution added to the onion?
To stain the onion to see parts of the cell
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
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
How does mimicry help the hornet moth survive?
it looks like the hornet so predators tricked and avoid eating it
Describe the process of mitosis
DNA replicated
chromosomes pull apart
cytoplasm divides
set of chromosomes in each
new cell are identical
Which environmental conditions would cause the rate of transpiration to be greatest in
a plant?
low humidity high temp
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
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)
how is HIV spread?
sexual contact/sharing bodily fluids
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
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)
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
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
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
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
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
