homeostasis

Question 1

When insulin binds to receptors on liver cells, it leads to the formation of glycogen from glucose, this lowers the conc of glucose in liver cells

explain how the formation of glycogen in liver cells leads to the lowering of blood glucose conc

Answer 1

Glucose concentration in cell / liver falls below that in blood (plasma)
which creates / maintains glucose concentration / diffusion gradient;

2. Glucose enters cell / leaves blood by facilitated diffusion / via
   carrier(protein) / channel (protein);

Question 2

why give everyone the same food when measuring their urine conc

Answer 2

food changes the volume of urine produced because it affects the water potential of the blood.

Question 3

suggest how a drug that makes more urine can cause a decrease in blood pressure

Answer 3

more water is removed from the blood right

therefore this decreases blood volume leading to a lower blood pressure

Question 4

describe how urea is removed from the blood

Answer 4

high hydrostatic pressure causes ultrafiltration at renal capsule

Question 5

Explain how urea is concentrated in the filtrate.

Answer 5

Reabsorption of water by osmosis;
At the PCT / descending LoH;
At the DCT / CD;
Active transport of ions / glucose creates gradient (in context)

Question 6

Describe how ultrafiltration produces glomerular filtrate

basement membrane and podocytes

Answer 6

Blood pressure / hydrostatic pressure;

2. Small molecules / named example;
3. Pass through basement membrane / basement membrane acts as filter;
4. Protein too large to go through / large so stays behind;
5. Presence of pores in capillaries / presence of podocytes;

Question 7

explan how urea is concentrated in the filtrate

Answer 7

reabsorption of water at the pct or dct, active transport of ions or glucose creates a gradient

Question 8

generally loop of henle and adh

Answer 8

more water from filtrate re absorbed by osmosis from collecting duct due to a longer loop of henle

sodium ions absorbed from filtrate in ascending limb, gradient established in medulla.

acts on collecting duct, makes cells more permeable

Question 9

a diabetic and a non diabetic person each ate the same amount of glucose, one hour later the glucose conc in the blood of the diabetic person was higher than that of the non diabetic person- why

Answer 9

less insulin so reduced uptake of glucose by cells

reduced conversion of glucose to glycogen

Question 10

the urine of a non diabetic person does not contain any glucose, why

Answer 10

leaves blood at kidney, taken back into the blood from kidney tubules, re absorbed in 1st convuluted tubule.

Question 11

a high blood glucose conc could cause glucose to be present in the urine of a diabetic person, why

Answer 11

large conc of glucose in filtrate

cannot all eb re absorbed 1st convoluted tubule may be too short or the saturation of carriers

Question 12

more glucose in blood= larger vol of urine, why

Answer 12

glucose in filtrate lowers the water potential gradient

this means that less water is re absorbed by osmosis

Question 13

in some forms of kidney disease, proteins from the blood plasma are found in the urine, which part of the neprhon would have to be damaged by the disease to cause proteins from blood plasma to be present in the urine, explain your answer

Answer 13

renal capsule
basement membrane
proteins are large cnd cannot normally pass through the filter
can only pass through if the filter is damaged

Question 14

describe another way the kangaroo rat could obtain water rather than feeding and drinking

Answer 14

metabollic water, from aerobic respiration. have to have aerobic

Question 15

why is everyone given the same food

Answer 15

as food affects blood glucose, and to keep starch intake the same

Question 16

Explain how the formation of glycogen in liver cells leads to a lowering of blood
glucose concentration.

Answer 16

Glucose concentration in cell / liver falls below that in blood (plasma)
which creates / maintains glucose concentration / diffusion gradient;
2. Glucose enters cell / leaves blood by facilitated diffusion / via
carrier(protein) / channel (protein);

Question 17

Adrenaline binds to receptors in the plasma membranes of liver cells. Explain
how this causes the blood glucose concentration to increase.

Answer 17

Adenylate cyclase activated / cAMP produced / second messenger
produced;
2. Activates enzyme(s) (in cell so) glycogenolysis / gluconeogenesis occurs
/ glycogenesis inhibited;

Question 18

urine test no

Answer 18

Urine test only an arbitrary scale / not directly related to concentration /
colour is subjective / few colour values;

Question 19

Diabetic people who do not control their blood glucose concentration may become
unconscious and go into a coma. A doctor may inject a diabetic person who is in a
coma with glucagon. Explain how the glucagon would affect the person’s blood
glucose concentration.

Answer 19

Glycogen to glucose / glycogenolysis by activating enzymes;
If name incorrect this disqualifies.
Gluconeogenesis;

Question 20

when talking ab why smth can lead to type 2 diabetes

Answer 20

ultimately bc

less glucose can DIFFUSE into cells

Question 21

where is all glucose reabsorbed

Answer 21

at the PCT put the full name proximal convoluted tubule

also carrier proteins may be saturated, bang then in as well

Question 22

describe how urea is removed from the blood

Answer 22

Hydrostatic pressure
Causes ultrafiltration (Allow description of ultrafiltration) at Bowman’s capsule /
glomeruli / renal capsule;
Through basement membrane;
Enabled by small size urea molecule;

Question 23

Some desert mammals have long loops of Henle and secrete large amounts of
antidiuretic hormone (ADH). Explain how these two features are adaptations to living
in desert condition

Answer 23

More water (from filtrate) reabsorbed / returned to blood / less lost in
urine;
2. By osmosis;
3. From collecting duct / from end of second convoluted tubule;
4. Due to longer loop of Henle;
For loop of Henle, maximum 2 marks:
5. Sodium / chloride ions absorbed from filtrate in ascending limb;
6. Gradient established in medulla / concentration of ions increases down
medulla;
For ADH, maximum 2 marks:
7. Acts on collecting duct / distal convoluted tubule / second convoluted
tubule;
8. Makes cells more permeable / inserts aquaporins in plasma
membranes;

Question 24

Some people who have diabetes do not secrete insulin. Explain how a lack of
insulin affects reabsorption of glucose in the kidneys of a person who does not
secrete insulin.

Answer 24

High concentration of glucose in blood;

2. High concentration in tubule / in filtrate;
3. Reabsorbed by facilitated diffusion / active transport;
4. Requires proteins / carriers;
5. These are working at maximum rate / are saturated;
6. Not all glucose is reabsorbed / some is lost in urin

Question 25

A high blood glucose concentration could cause glucose to be present in the
urine of a diabetic person. Suggest how.

Answer 25

Large amount / high concentration of glucose in filtrate;
Cannot all be reabsorbed / 1st convoluted tube too short to reabsorb
all of glucose / saturation of carriers;

Question 26

In some forms of kidney disease, proteins from the blood plasma are found in the
urine. Which part of the nephron would have been damaged by the disease to cause
proteins from blood plasma to be present in the urine? Explain your answer.

Answer 26

Glomerulus / Bowman’s capsule / renal capsule;
2. Basement membrane;
3. Proteins are large (molecules) / proteins cannot normally pass through
filter / proteins
can only pass through if filter damaged;

Question 27

The kangaroo rat takes in some water by feeding and drinking. Describe another method
by which the kangaroo rat could obtain wate

Answer 27

aerobic resp