AQA A-Level Biology - Paper 2 - Advance Information Topics
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1. What is homeostasis? The maintenance of a constant inter-
nal environment, at a normal level
2. Why is it important that body tem- Low temperatures will lead to the
perature remains stable? slowing down of enzyme controlled
reactions, which can cause death,
and high temperatures will cause en-
zymes to denature as the hydrogen
and ionic bonds break
3. Why is it important that body pH If the pH changes, then the charge
remains constant? of the variable region will change and
ionic bonds will break, denaturing en-
zymes
4. What is negative feedback? When a movement away from the
norm produces a response that re-
turns the value to the norm
5. Where is insulin produced? In beta cells of the islets of Langer-
hans, in the pancreas
6. How does insulin reduce blood glu- Insulin is produced as the blood glu-
cose levels? cose level exceeds the optimum. In-
sulin binds to complementary recep-
tors on liver and muscle cells, which
causes a vesicle containing extra glu-
cose carrier proteins to bind to the
cell membrane, allowing the rate of
facilitated diffusion to increase. In-
sulin then alters the tertiary structure
of the added carrier proteins
7. How is glucose stored in body Glucose is converted to an insoluble
cells? form called glycogen, in a process
called glycogenesis
8. How does glucagon and adrenaline Glucagon / adrenaline bind to com-
increase blood glucose levels? plementary receptors on liver and
muscle cells. This activates adeny-
, AQA A-Level Biology - Paper 2 - Advance Information Topics
Study online at https://quizlet.com/_cngbdw
late cyclase, which converts ATP into
CAMP. CAMP then activates protein
Kinase-A, which hydrolyses glyco-
gen into glucose
9. What is the process of converting Glycogenolysis
glycogen to glucose called?
10. What is the process of converting Gluconeogenesis
non-carbohydrate sources into glu-
cose using glucagon called, to raise
blood glucose levels?
11. Why do Type 1 diabetics not absorb They do not produce insulin, as an
blood glucose normally? autoimmune response killed the beta
cells in the islets of Langerhans
12. Why do Type 2 diabetics not absorb The insulin receptors on liver and
blood glucose normally? muscle cells are less/not responsive
to insulin
13. What are the limitations of using The blood glucose concentration is
clinistix to diagnose diabetes? given as a range, not a precise value,
and it is subjective to match a colour
to a colour chart
14. What is a more precise method to Use a glucometer
diagnose diabetes?
15. What happens if the water potential Osmoreceptors in the hypothalamus
of the blood increases above the detect the change, and stimulate the
norm? pituitary gland to produce less ADH,
so more water is lost as urine
16. What happens if the water potential Osmoreceptors in the hypothalamus
of the blood decreases below the detect the change, and stimulate the
norm? pituitary gland to produce more ADH,
so less water is lost as urine
17.
, AQA A-Level Biology - Paper 2 - Advance Information Topics
Study online at https://quizlet.com/_cngbdw
Describe the process of ultrafiltra- A high hydrostatic pressure forces
tion out smaller molecules such as wa-
ter and ions through the basement
membrane via podocytes, whilst larg-
er molecules such as plasma pro-
teins remain in the blood
18. Describe the reabsorption of glu- Sodium ions are actively transported
cose and water in the proximal con- into the capillary from the epithelial
voluted tubule cells, creating a concentration gradi-
ent. These sodium ions then bind to
glucose and amino acids in the fil-
trate and absorb them into the cell via
facilitated diffusion in the process of
co-transport
19. Describe how water is reabsorbed As the filtrate moves down the de-
in the loop of Henle, and the low wa- scending loop of Henle, water moves
ter potential of the interstitial fluid is out of the filtrate into the interstitial
maintained fluid by osmosis, increasing the con-
centration of the filtrate as sodium
ions remain. This creates a concen-
tration gradient between the medulla
and the loop of Henle for sodium ions.
As the filtrate moves up the ascend-
ing loop of Henle, sodium ions diffuse
out via facilitated diffusion then active
transport, maintaining a low water
potential in the interstitial fluid. Water
does not diffuse out of the ascending
limb as it is impermeable
20. Describe the reabsorption of water ADH is produced by the pituitary
by the DCT and Collecting Duct gland, allowing more aquaporins to
be added to the membrane of the col-
lecting duct and DCT, making them
permeable to water, so water diffuses
down its water potential gradient into
the interstitial fluid via osmosis
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