AQA A LEVEL BIOLOGY Paper 2 2022 STUDY
GUIDE WITH COMPLETE SOLUTIONS
What is negative feedback? - ✔✔✔-A response that returns a change in levels,
back to normal.
What is positive feedback? - ✔✔✔-A response that amplifies a change from the
normal level.
Which factors influence blood glucose concentration? - ✔✔✔-Eating food
containing carbohydrates, glucose absorbed from intestine to blood.
Exercising, more glucose is used in respiration to release energy.
What is the effect of insulin? - ✔✔✔-Decreases blood glucose concentration.
,How does insulin work? - ✔✔✔-Secreted by beta cells in islets of Langerhans in
pancreas, when blood glucose too high.
Insulin binds to specific receptors on cell surface membranes of target cells,
increases permeability of cell membrane to glucose (increases number of channel
proteins in cell membrane), cells take up more glucose by facilitated diffusion,
enzymes convert glucose to glycogen and so stored in cytoplasm. Rate of
respiration increases.
What is the effect of glucagon? - ✔✔✔-Increases blood glucose concentration.
What is Type I diabetes? - ✔✔✔-Gene mutation.
Autoimmune response on beta cells of islets of Langerhans. Body can't produce
insulin.
What is Type II diabetes? - ✔✔✔-Poor diet, lack of exercise, obesity.
Glycoprotein loses responsiveness to insulin. Cells don't take up enough glucose.
How does glucagon work? - ✔✔✔-Secreted by alpha cells in the islets of
Langerhans in pancreas.
Binds to specific receptors on cell surface membranes of target cells, activates
enzymes to convert glycogen to glucose. Rate of respiration decreases.
What is the role of adrenaline? - ✔✔✔-Increases blood glucose concentration by
activating secretion of glucagon.
, How does adrenaline work? - ✔✔✔-Binds to specific receptors on cell surface
membranes of target cells, activates enzymes to convert glycogen to glucose.
What is the secondary messenger model? - ✔✔✔-Demonstrated by adrenaline
and glucagon as they cause glycogenolysis to occur inside cell even though they
bind to receptors on the outside of the cell.
Adrenaline or glucagon bind to specific complimentary receptors on the cell
membrane. They activate adenylate cyclase. Convert ATP to cyclic AMP. cAMP
activates protein kinase A. Protein kinase A activates a cascade to break down
glycogen to glucose.
What is osmoregulation? - ✔✔✔-The control of water and salt levels in the body,
by ADH.
How does the body respond to a decrease in water potential? - ✔✔✔-Detected by
osmoreceptors in hypothalamus. Hypothalamus produces more ADH, posterior
pituitary gland secretes more ADH into blood. ADH travels in blood to kidney and
attaches to receptors on collecting duct. ADH increases permeability of cell
membranes to water so more water is absorbed by osmosis. Less water lost in
urine so smaller volume of urine, more concentrated.
How does the body respond to an increase in water potential? - ✔✔✔-Detected
by osmoreceptors in hypothalamus. Hypothalamus produces less ADH, posterior
pituitary gland secretes less ADH into blood.
Less ADH travels in blood to kidney and attaches to receptors of collecting duct.
ADH decreases permeability of cell walls to water so less water absorbed by
osmosis. More water lost in urine so large volume of urine, less concentrated.
GUIDE WITH COMPLETE SOLUTIONS
What is negative feedback? - ✔✔✔-A response that returns a change in levels,
back to normal.
What is positive feedback? - ✔✔✔-A response that amplifies a change from the
normal level.
Which factors influence blood glucose concentration? - ✔✔✔-Eating food
containing carbohydrates, glucose absorbed from intestine to blood.
Exercising, more glucose is used in respiration to release energy.
What is the effect of insulin? - ✔✔✔-Decreases blood glucose concentration.
,How does insulin work? - ✔✔✔-Secreted by beta cells in islets of Langerhans in
pancreas, when blood glucose too high.
Insulin binds to specific receptors on cell surface membranes of target cells,
increases permeability of cell membrane to glucose (increases number of channel
proteins in cell membrane), cells take up more glucose by facilitated diffusion,
enzymes convert glucose to glycogen and so stored in cytoplasm. Rate of
respiration increases.
What is the effect of glucagon? - ✔✔✔-Increases blood glucose concentration.
What is Type I diabetes? - ✔✔✔-Gene mutation.
Autoimmune response on beta cells of islets of Langerhans. Body can't produce
insulin.
What is Type II diabetes? - ✔✔✔-Poor diet, lack of exercise, obesity.
Glycoprotein loses responsiveness to insulin. Cells don't take up enough glucose.
How does glucagon work? - ✔✔✔-Secreted by alpha cells in the islets of
Langerhans in pancreas.
Binds to specific receptors on cell surface membranes of target cells, activates
enzymes to convert glycogen to glucose. Rate of respiration decreases.
What is the role of adrenaline? - ✔✔✔-Increases blood glucose concentration by
activating secretion of glucagon.
, How does adrenaline work? - ✔✔✔-Binds to specific receptors on cell surface
membranes of target cells, activates enzymes to convert glycogen to glucose.
What is the secondary messenger model? - ✔✔✔-Demonstrated by adrenaline
and glucagon as they cause glycogenolysis to occur inside cell even though they
bind to receptors on the outside of the cell.
Adrenaline or glucagon bind to specific complimentary receptors on the cell
membrane. They activate adenylate cyclase. Convert ATP to cyclic AMP. cAMP
activates protein kinase A. Protein kinase A activates a cascade to break down
glycogen to glucose.
What is osmoregulation? - ✔✔✔-The control of water and salt levels in the body,
by ADH.
How does the body respond to a decrease in water potential? - ✔✔✔-Detected by
osmoreceptors in hypothalamus. Hypothalamus produces more ADH, posterior
pituitary gland secretes more ADH into blood. ADH travels in blood to kidney and
attaches to receptors on collecting duct. ADH increases permeability of cell
membranes to water so more water is absorbed by osmosis. Less water lost in
urine so smaller volume of urine, more concentrated.
How does the body respond to an increase in water potential? - ✔✔✔-Detected
by osmoreceptors in hypothalamus. Hypothalamus produces less ADH, posterior
pituitary gland secretes less ADH into blood.
Less ADH travels in blood to kidney and attaches to receptors of collecting duct.
ADH decreases permeability of cell walls to water so less water absorbed by
osmosis. More water lost in urine so large volume of urine, less concentrated.
