Exam Pack 7

Question 1

Explain the movement of O2 into the gas exchange system of an insect when it is at rest

Answer 1

MP1 - O2 is used in aerobic respiration
MP2 - so an O2 gradient can be formed
MP3 - so O2 diffuses into insect

Question 2

Why does pressure in tubes and CO2 released increase with abdominal pumping?

Answer 2

MP1 - Abdominal pumping is linked to CO2 release

MP2 - Abdominal pumping increases pressure in the body

MP3 - CO2 moves down pressure gradient out of body

Question 3

Why is the solution for homogenisation buffered

Answer 3

To maintain a constant pH, so that proteins don’t denature

Question 4

Describe how you would carry out an investigation to find the optimum temperature for the activity of urease

Answer 4

1. Measure volume of product produced in a given time, to measure urease activity @ different temperatures of equal intervals
2. Controls would be conc of urease and pH of solution
3. How to keep each temperature constant - use a water bath

Question 5

A person may develop influenza twice within a short time. Use information from the pie chart to explain why.

Answer 5

MP1 - there are 4 different strands of influenza

MP2 - therefore the person doesn’t have memory cells against the 2nd strand

Question 6

The information in the pie chart is valuable to companies who make influenza vaccines, use your knowledge of antigens to explain why

Answer 6

1. They know that people are most likely to be infected with strain 1
2. Vaccines only work against certain strain because antigens are different