EXCRETION/OSMOREGULATION IN DIFFERENT ENVIRONMENTS

Question 1

how do plants make their proteins? (2)

Answer 1

• α-keto gluterate combines with ammonium to make glutamate

- glutamate is converted into other amino acids via transamination of other α-keto acids

Question 2

transamination

Answer 2

enzyme-catalysed reaction that transfers an amino group to an α-keto acid

Question 3

plant excretion

Answer 3

plants do not excrete nitrogen compound because they make what they need

Question 4

excretion in aquatic organisms (2)

Answer 4

• excrete ammonia

- would be toxic, but immediately diluted by water and diffuses

Question 5

excretion in birds/reptiles/insects (4)

Answer 5

• don’t carry excess water
• convert amino acids to uric acid
• uric acid is insoluble and non-toxic
• producing uric acid uses a lot of energy but conserves water

Question 6

excretion in mammals

Answer 6

• excrete urea
• requires energy less toxic than ammonia and is diluted by body fluids
• concentration of urine will depend on water availability

Question 7

loop of henlé and urine conc.

Answer 7

• longer loop of henlé = more opportunity to pump out ions, therefore more water diffusion, more concentrated urine, conserving water

Question 8

types of nephron (2)

Answer 8

• cortical nephron, glomerulus in outer cortex and short loop of henlé, aquatic mammals tend to have more of these
• juxtamedullary nephrons, bowman’s closer to cortex boundary, long loop of henle penetrating deep into medulla

Question 9

metabolic water

Answer 9

• produced from food breakdown and respiration

- zerocoles (desert animals) survive entirely on metabolic water

Question 10

behaviour

Answer 10

• desert animals remain underground, in burrows to prevent water loss
• burrows are cool and humid