AS Paper 2 Practise Questions

Question 1

Explain the function and structure of sieve tube elements

Answer 1

Function - Translocation of assimilates, allows mass flow down a pressure gradient, from source to sink
Structure- long and hollow continuous tubes, living, walls are thin and not lignified with sieve plates that limit passing

Question 2

Explain the structure and function of companion cells

Answer 2

Function - Non structural support to sieve tube elements, gains sucrose from source using H+ ions to active load
Allows the loading of sucrose solutes into sieve tube elements
Structure - Cytoplasm has lots of mitochronida, a large nuclues
Plasmodesmata connecting sieve tube elements

Question 3

What is the test for proteins

Answer 3

Add Biuret

Question 4

What is a function of OH- ions in the body

Answer 4

Catalyses reactions
Determines and regulates pH
Determining shape of proteins

Question 5

How do you carry out a test for lipids and what is the aparatus needed

Answer 5

Test tube
Filter paper and funnel
Pipette

Add test solution to ethanol
Mix with water
Filter and add water
Result is a milky suspension

Question 6

How would you carry out a test for starch and what apparatus would you need

Answer 6

Spotting tile
Test tube
Dropping bottle

Add a few drops of iodine solution to the test solution

Result - Brown to blue black

Question 7

How would you test the concentration of glucose using a calorimeter

Answer 7

Calibrate using distilled, zero absorbance
Add 600nm red
Place samples in
Use a range of known glucose concentrations
Measure percantage transmission, absorption of glucose solution

Question 8

What can CITES do to help increase numbers of a species being hunted

Answer 8

Regulate the trade in that area
Meaning they can bread and increase in number
Prevent live trade
Raise awareness and educate locals and goverments

Question 9

How do vaccination programmes help the prevent an epidemic

Answer 9

Prevents the spread into wider population
Through herd immunity
Minimises possibility of outbreak

Question 10

What are the properties of collagen

Answer 10

Fibrous
Insoluble
High tensile strength
Resistant to streching

Question 11

How does meiosis create genetic variation

Answer 11

The crossing over in prophase 1
Independent assortment of homologous chromosomes in metaphase 1 and chromatids in metaphase 2