Bio Topic 13

Question 1

Where is urea formed?

Answer 1

In the liver

Question 2

What is urea made from?

Answer 2

Excess amino acids

Question 3

Which organ excretes carbon dioxide?

Answer 3

The lungs

Question 4

State three things kidneys excrete

Answer 4

-urea
-excess water
-excess ions (salts)

Question 5

State three conditions which alter the volume of urine produced

Answer 5

-temperature
-water intake
-excercise

Question 6

Describe the role of the liver in dealing with excess amino acids
Amino acids are formed from breakdown of proteins during digestion

Answer 6

Amino acids cannot be stored in body (therefore liver converts the ones it can into proteins and the excess needs to be removed)
Deamination creates urea w/ excess amino acids to remove them

Question 7

What is deamination?

Answer 7

Removal of nitrogen-containing portion of amino-acids to produce urea

Question 8

Why is excretion necessary?

Answer 8

To remove toxic waste substances like urea and carbon dioxide
Exess urea can be toxic and harm organisms

Question 9

What is the function of the glomerulus in the kidney?

Answer 9

Blood is at high pressure in glomerulus
Filter out small molecules in the blood (eg. water urea glucose ions)
Large molecules (eg proteins) cannot be filtered out

Question 10

What is the function of the kidney tubule?

Answer 10

Reabsorbing molecules necessary for the body

Question 11

What molecules does the kidney tubule reabsorb?

Answer 11

-all glucose (reabsorbed by active transport)
-most of the water
-some of the salts

Question 12

Describe the last process that takes place in the nephron

Answer 12

Release of wastes:
Liquid left containing urea, excess water & ions is called urine
Urine travels to bladder via ureter