AQA A-level Biology Paper 1 Latest Update
A vaccine can be used to produce immunity. Describe how memory cells are important in this process. (3) - ANSWER-important because when individual is in contact with virus again, antibodies can be produced at a faster rate in a secondary immune response, a...
A vaccine can be used to produce immunity. Describe how memory cells are
important in this process. (3) - ✔✔✔ANSWER-important because when individual
is in contact with virus again, antibodies can be produced at a faster rate in a
secondary immune response, and so the pathogen can be destroyed faster.
abiotic - ✔✔✔ANSWER-non-living
artery structure - ✔✔✔ANSWER-thick muscle layer so that they can dilate and
contract to smooth blood flow.
thick elastic layer so artery can stretch and recoil with systole and diastole,
smoothing blood flow.
overall thickness of wall is large so that it doesn't burst under pressure.
,artificial active immunity - ✔✔✔ANSWER-involves inducing an immune
response in an individual
WITHOUT them suffering the symptoms of the disease.
e.g. vaccinations
memory cells produced
Attaching lactase to the beads is a more efficient use of lactase than adding the
lactase
directly to cow's milk.
Suggest three reasons why it is more efficient to attach lactase to the beads. -
✔✔✔ANSWER-lactase bead can be reused
continuous process
lactase not present in milk
before cell fractionation, why is the tissue placed in a cold, isotonic buffer? -
✔✔✔ANSWER-cold: reduce enzyme activity that may break down the organelles
isotonic: same water potential as tissue, this prevents organelles shrinking/bursting
due to osmotic loss/gain of water
buffered: so the pH doesn't fluctuate, so that nothing alters the organelle structures
or affects enzyme functioning
biotic - ✔✔✔ANSWER-living
capillary structure - ✔✔✔ANSWER-one cell thick endothelium. allows rapid
diffusion.
numerous, highly branched, so provides a larger surface area.
narrow lumen and diameter.
, spaces in lining to allow tissue fluid to form.
courtship behaviour results in reproductive success by... - ✔✔✔ANSWER-1.
allowing recognition of own species
2. identifying those capable of breeding
3. forming a pair bond
4. synchronising mating
define community - ✔✔✔ANSWER-all the populations of different species living
and interacting in a particular place at the same time.
define ecological niche - ✔✔✔ANSWER-The position occupied by an organism in
a particular ecosystem, dependent upon the resources it uses. The more resources
that are taken into account then the more carefully defined the organism's niche
will be, the organism will become more specialised.
define ecology - ✔✔✔ANSWER-the study of the inter-relationships between
organisms and their environment, including abiotic and biotic factors.
define ecosystem - ✔✔✔ANSWER-dynamic systems made up of a community
and all the non-living factors of its environment. It includes all the living
organisms that interact with one another and also with the physical and non-
physical factors present.
define genome - ✔✔✔ANSWER-the complete set of genes in a cell
define habitat - ✔✔✔ANSWER-the place where an organism normally lives
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