2019 Biology Paper 1

Question 1

Which of the following 3 plant hormones are involved in leaf abscission?
* auxin
* ethene
* gibberellin

Answer 1

auxin and ethene

Question 2

What makes a compound a hormone?

Answer 2

• Hormones are chemical messengers.
• Hormones are produced in one part of a plant, but have effects in another part.
• Hormones affect the activity of target cells.
• Hormones are long-lasting
• Hormones have a wide-spread effect.

Question 3

State the roles of gibberellin, other than causing an increase in internodal length.

Answer 3

• seed germination
• flowering in long-day plants
• cellular transcription / translation
• prevention of leaf abscission
• aiding in stomatal opening
• promotion of fruit development
• promotion of activity of amylase / hydrolysis of starch

Question 4

What colour is seen from a positive Biuret test? (protein is present)

Answer 4

Purple

Question 5

What colour is seen from a negative biuret test? (protein is not present)

Answer 5

Blue

Question 6

What colour is seen from a negative iodine test? (starch is not present)

Answer 6

Brown / Yellow

Question 7

What colour is seen from a positive iodine test? (Starch is present)

Answer 7

Blue / Purple

Question 8

What is a conjugated protein?

Answer 8

• has a non-protein group
• has a prosthetic group
• prosthetic group attached by covalent bonds / ionic interactions / hydrogen bonds

Question 9

What hormone regulates metabolism?

Answer 9

Cortisol

Question 10

State the functions of adrenaline.

Answer 10

• increases heart rate
• increases blood glucose content
• increases blood flow to muscles
• increases glucogenolysis
• causes pupils to dilate
• decreases blood flow to gut
• increases blood pressure
• dilates bronchioles
• increases air flow to alveoli
• increases breathing rate

Question 11

Why is the ‘dark reaction’ a suitable name for the light-independent reaction?

Answer 11

Light energy is not needed for this stage to occur.

Question 12

Stems planted in different concentrations of auxin showed fewer side shoots with increased auxin concentration. Why?

Answer 12

Auxin causes apical dominance.

Question 13

State the commercial uses of auxin.

Answer 13

• rooting powder
• micropropagation
• weed killers / herbicides
• production of seedless fruit
• prevention of abscission
• promotion of fruit ripening