Paper 1 June 2020 Flashcards
Describe how energy for the photosynthesis reaction is gained by plants.
light
(light) is captured / trapped /
absorbed by chlorophyll /
chloroplasts
Suggest one possible cause of the anomalous result
- scale / value was misread
- there was air / oxygen in the
syringe / measuring cylinder
/ apparatus - the lamp / light was moved
- temperature changed
- had different mass / length
of pondweed - pondweed had not
acclimatised
How did the students deal with the anomalous result?
did not use it in calculation (of
mean
Why did the rate of photosynthesis decrease from 35 °C to 45 °C?
enzyme(s) lose the shape of the
active site
What is meant by the term diffusion?
movement / spreading out of
molecules / particles
from (an area of) high(er)
concentration to (an area of)
low(er) concentratio
Which two changes will increase the rate at which carbon dioxide diffuses into the
mesophyll cells? (tick)
increased carbon dioxide
concentration in the air
increased number of stomata
that are open
Explain how the human lungs are adapted for efficient exchange of gases by diffusion
- (many) alveoli
- provide a large(r) surface area (: volume)
- capillaries are thin
or alveoli / capillary walls are thin or one cell thick
or capillaries are close to the alveoli - which provides short diffusion path (for oxygen / carbon
dioxide) - breathing (mechanism) moves air in and out
or lungs are ventilated - to bring in (fresh) oxygen
- to remove carbon dioxide
- to maintain a concentration / diffusion gradient
- large capillary network (around alveoli)
or good blood supply - to remove oxygen(ated blood) quickly
- to bring carbon dioxide to the lungs quickly
- to maintain a concentration / diffusion gradient
Name the process by which water molecules enter the root hair cel
osmosis
Explain how the nitrate ions in Figure 4 are transported into the root hair cell.
active transport
(because) energy is needed
(to move nitrate ions) from a
low(er) concentration (in the
soil) to a high(er) concentration
(in the root / cell
Give two similarities between the prokaryotic cell and the eukaryotic cells
(both have)
* cytoplasm
* (cell) membrane
* DNA / genetic material
* ribosomes
Give three differences between the prokaryotic cell and the eukaryotic cells
in Figure 5.
- prokaryotic cell is smaller
- prokaryotic cell has no
mitochondria - prokaryotic cell has no
nucleus
or DNA is free in the
cytoplasm
or genetic material is free in
the cytoplasm - prokaryotic cell has a single
loop of DNA
or prokaryotic cell has a
single loop of genetic material - prokaryotic cell has plasmids
Describe what happens during each stage of the cell cycle.
DNA / chromosomes replicate /
duplicate
mitochondria / ribosomes / subcellular structures increase in
number
or mitochondria / ribosomes /
sub-cellular structures replicate
(stage 2)
one set of chromosomes is
pulled / moved to each end of
the cell
(stage 3)
the cytoplasm and cell
membrane divides (to form two
cells)
Which two products are formed when lipids are broken down?
fatty acids
glycerol
Explain the ‘lock and key theory’ of enzyme action. (3)
enzyme binds to the substrate
because they are
complementary (shapes)
(so) substrate is broken down
(into products)
(so) products are released
or 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 (so only fits one type of
lipid molecule)
Describe how the students would find out if the liquid from the leaf contained glucose
add Benedict’s (solution
reagent to the liquid)
boil / heat
(if glucose is present the blue)
colour changes to yellow / green
/ orange / brown / (brick)red
Describe how the students would find out if the liquid from the leaf contained starch.
add iodine solution / reagent (to
the liquid)
(if starch is present) it changes
colour to blue / black (from
yellow / orange / brown)
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) have been
converted to glucose
(so the glucose can be) used for
respiration / (named) metabolic
reactions
or (so the glucose can be) used
to release energy
(because) there is no light to
make (new / more) glucose by
photosynthesis
Suggest one way the students could develop the investigation to find out more about
glucose and starch production in plants
- test roots / stems of plants (in
the light and dark) - test other species of plant
- measure the concentrations
of glucose and 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?
- to deter herbivores
- to prevent animals damaging
it
What type of defence response are poisonous berries?
chemical
One reason for yellow leaves and stunted growth is a deficiency of nitrate ions in
the soil.
Explain two other possible reasons for the yellow leaves and stunted growth.
- lack of magnesium (ions) (1)
(so) not enough chlorophyll
for (efficient) photosynthesis
(1)
(so) not enough glucose to
make proteins for growth
AND
- infection by pathogen /
bacteria / virus / fungus (1)
(so) leaves become
discoloured / yellow so less
photosynthesis (1)
(so) not enough glucose to
make proteins for growth
OR
- infected by aphids (1)
(which) remove sugars from
phloem (1)
(so) not enough glucose to
make proteins for growth
or not enough glucose to
release energy for growth (1)
AND
- lack of (available) light (1)
(so) chlorophyll breaks down
(1)
(so) not enough glucose to
make proteins for growth
or not enough glucose to
release energy for growth (1)
Suggest how nodules benefit the bacteria.
bacteria) obtain glucose / sugar
(from the plant)
(glucose used) for respiration
or (glucose used) for making
other named substances
Explain how the nodules benefit the gorse plant.
(gorse plant) obtains nitrate
(ions)
needed for amino acids /
protein
Which plant material was chewed as a painkiller?
willow bark
Scientists analysed the data to study the effect of consuming alcohol on liver disease.
Age and gender were two factors controlled in this analysis
Suggest two other factors which the scientists would have controlled
- BMI / morphology / obesity level
- smoking habits
- diet
- medication
- family history of liver disease
- fitness levels
- ethnicity
- area of UK they live in
Consuming alcohol with meals instead of not with meals decreases the relative risk of
developing cirrhosis of the liver.
Give two other conclusions about the relative risk of developing cirrhosis of the liver
related to alcohol consumption.
- consuming alcohol increases the
RR (with / without meals) and
supporting data - consuming less than 50 g/week of
alcohol with meals does not
increase the RR - even (small amounts of alcohol at)
25 g/week increases the RR if not
with meals
Suggest two reasons why the data is considered to be valid.
any two from:
* large number in survey
* long term / 15 year survey
Suggest one aspect of the survey which might reduce validity
any one from:
* people underestimate /
overestimate alcohol
consumption
* people may change (lifestyle /
drinking) habits over time
* some people may drink all their
weekly alcohol at once
Cirrhosis of the liver leads to liver failure.
Describe the effects of liver failure on the human body.
- no bile made (in the liver)
o fats / lipids are not emulsified
o surface area of fats / lipids not increased
o pH of small intestine will not be alkaline / neutralised
o enzymes (in small intestine) will not work effectively
or (named) food not digested / absorbed
o so may lose weight - lactic acid not broken down / oxidised
o accumulation of lactic acid in blood / body
o lactic acid is toxic or body will be poisoned
o oxygen debt higher / prolonged
o so muscle pain / fatigue - proteins / amino acids will not be broken down (in liver)
o (amino acids) not deaminated
o amino acids not made into urea or will not form
ammonia
o (however) any ammonia formed is toxic
o so accumulation of amino acids in blood / body - liver does not break down / remove other toxins (like alcohol)
o toxins accumulate in blood / body
o body will be poisoned
o so pain or jaundice or swollen liver or portal
hypertension occurs - glycogen stores will not be formed
o cannot control blood glucose
o so hyperglycaemia / hypoglycaemia / diabetes / coma
may occur
Describe how the mAbs and a fluorescent dye could be used to see any
Candida albicans pathogens on the slide.
bind fluorescent dye to mAbs
put (bound) fluorescent mAbs
on the slide (and rinse off)
mAbs will bind to Candida
albicans / pathogens and show
up under the microscope
Explain how increased phagocytosis of the Candida albicans pathogen will help
the patient.
more Candida albicans /
pathogens will be engulfed /
killed by phagocytes / white
blood cells
therefore less damage to cells /
tissues / organs
The mAbs treatment for Candida albicans is now ready for clinical trials on people.
Describe how the clinical trials should be carried out
- given first to healthy volunteers
o at (very) low dose
o to test it is safe or to test for toxicity or to check for
any side effects - then to some patients (with the disease) or people with the
disease
o to test for the correct / optimum dose
o to check for any side effects
o to test for efficacy or to test if it works
o in a double blind trial
o where neither patients nor doctors know who has
the mAbs and who has a placebo (or alternative
treatment) - reference to large trial or long duration or control variables
Suggest one reason why these new mAbs have been more successful in treating
diseases in humans than mAbs made using mice
- (the body will) not reject the
mAbs
or (the body is) less likely to
reject the mAbs - mouse mAbs are (more
likely to be) rejected - the human lymphocytes
have already responded to
that infection / cancer cell so
they are known to work
against the disease
