Questions Corrections 2019

Question 1

Give two reasons why the total biomass of the Daphina in the pond is different from the total biomass of the algae

Answer 1

Non digestible parts
Used in respiration or lost as carbon dioxide

Question 2

Give two benefits of understanding the human genome

Answer 2

Tracing human migration patterns
Diagnosis of inherited disorders

Question 3

Plan an investigation to show the effect of light from one direction on the growth of plant seedlings

Answer 3

1) Several seedlings in each batch and measure the heights of shoots
2) Leave some in dark with light from one side
3) Controls with rotating on clinostat and control variables such as the same temperature
4) Leave for 24 hours
Record appearances of seedlings and re measure heights of shoots by using thread
5)Calculate mean height increase for each group
Use ruler to estimate angle of bending
6) Compare the growth of plants with light from one direction with plants in darkness

Question 4

Explain how phototropism in a plant shoot helps the plant to survive

Answer 4

Leaves absorb more light
So more photosynthesis
So produces more glucose

Question 5

Explain how the persons eye could adjust to form a clear image of a nearer object

Answer 5

Ciliary muscles contract
So they have a small diameter
Suspensory ligaments loosen
So lens thickens
So lens os more convergent
And light rays focused on the retina

Question 6

Explain why a long sighted person has difficulty seeing objects nearly

Answer 6

Lens cannot be thickened enough
So light focuses behind the retina

Question 7

Describe how spectacle lenses can correct long sightedness

Answer 7

Convex lens
So light rays bent more
So light rays focused on retina

Question 8

Why are these steps in the tissue culture technique used:

Several groups of cells are scraped off the leaf
Nutrients are added to the agar jelly
Hormones are added to the agar jelly
The plant cells are kept in sterile conditions
The plant cells are kept at 20 Celsius

Answer 8

So many plants can be produced
For making protein or for making chlorophyll
So differentiation occurs
To prevent growth of microorganisms
So optimum means good growth

Question 9

Explain how the kidneys reduce water loss

Answer 9

Higher concentration of blood causes more ADH release (from pituitary gland)
Increased permeability of kidney tublules
So increased water reabsorption

Question 10

Explain two biological reasons why most doctors think that a kidney transplant is better than dialysis

Answer 10

Changes in concentrations of substances like urea are minimised so less chance of causing damage to body cells

Not repeatedly puncturing skin
So less chance of infection

Question 11

Suggest three ways the scientists could maintain a high rate of reproduction in the bacterial culture

Answer 11

Add more sugar
Increase temperature
Add more oxygen

Question 12

Glyphosate is a herbicide
Explain the advantage of making crop plants resistant to glyphosate

Answer 12

Can use the glysophate to kill weeds but not affect crop
So less competition for light
So crops have higher yield

Question 13

Explain why a person with Type 2 diabetes often has a higher blood insulin concentration

Answer 13

Cells absorb less glucose
So glucose concentration in blood remains high
Do pancreas releases more insulin