Selective Reabsorption

Question 1

1.

Answer 1

Cells lining PCT have microvilli which increase surface area for protein channels and uptake of Na+.

Question 2

2.

Answer 2

Na+ are actively transported from PCT cells into tissue fluid (blood) which creates a concentration gradient for Na+ to diffuse into PCT cells from filtrate.

Question 3

3.

Answer 3

Na+ diffuse through co-transporter proteins (facilitated diffusion) which allow Na+ to actively carry glucose and amino acids into PCT cells from the filtrate against their concentration gradient.

Question 4

4.

Answer 4

From the PCT cells, Glucose and amino acids diffuse into bloody capillary.

Question 5

5.

Answer 5

The presence of glucose and amino acids in blood decrease water potential, causing water to move out of filtrate into blood leaving behind urea and ions. This means the concentration of the filtrate will increase.