2017 wrong

Question 1

sodium ions from salt absorbed by cells lining gut
some of these have carrier protein NHE3
which actively transports one na in, h out
how?

Answer 1

co transport
using hydrolysis of atp
na ion and proton bind to protein
changing proteins shape to move sodium ion across membrane

Question 2

High absorption of salt from the diet can result in a higher than normal concentration of salt in the blood plasma entering capillaries. This can lead to a build-up of tissue fluid how

Answer 2

high salt
lower water potential of tissue fluid
less water returns to capillary by osmosis

Question 3

Suggest one advantage to a bacterium of secreting an extracellular protease in its natural environment.

Answer 3

to digest protein
so they can absorb amino acids for growth or destroy toxic protiens

Question 4

Describe the action of these membrane-bound dipeptidases and explain their
importance.

Answer 4

hydrolysis dipeptides to amino acids which can move across cell membrane

Question 5

Describe how presentation of a virus antigen leads to the secretion of an antibody
against this virus antigen.

Answer 5

helper T cell binds to antigen
stimulating specific B cell
B cell clones
forming plasma cells that release antibodies

Question 6

how to collect and process data from these seeds to investigate whether there is a difference in seed size between these two populations of trees.

Answer 6

random Samp,e of seeds from each population
large sample size so represents full population
calculate mean and standard deviation
use t test - figure out sig Dif or due to chance