paper 1 ppq

Question 1

describe how you would test a leaf to show that it contains starch (4)

Answer 1

• boil leaf in water
• boil in ethanol (remove chlorophyll)
• add iodine solution
• blue black

Question 2

explain the differences between the palisade mesophyll and the spongy mesophyll (4)

Answer 2

• (position) palisade at top, spongy in middle
• (structure) palisade closely packed, spongy have air spaces
• (chloroplasts) palisade have more/many chloroplasts, spongy have fewer/ less
• (palisade cells) absorb sunlight
• spongy allow diffusion

Question 3

describe how the structure of the leaf is adapted for photosynthesis (5)

Answer 3

• leaf has large SA for diffusion and light absorption
• leaf is thin so short diffusion distance
• upper epidermis transparent to allow light through
• palisade mesophyll cells contain many chloroplasts to absorb light
• spongy mesophyll cells have air spaces for gas exchange
• (lower surface) has stomata to absorb carbon dioxide
• xylem/ vascular bundle bring water for photosynthesis

Question 4

a fertiliser contains magnesium ions and nitrate ions, explain the effect of these two ions on the growth of the seedlings (4)

Answer 4

• magnesium ions increase chlorophyll/ chloroplasts
• so more photosynthesis
• which produces carbohydrates/ glucose/ starch
• nitrate ions for amino acids
• nitrate/ amino acid for protein for growth

Question 5

describe the process that converts light energy into chemical energy (3)

Answer 5

description that references these points:
- photosynthesis
- chloroplasts/ chlorophyll
- absorbs/ traps light
- starch/ glucose/ carbohydrates

Question 6

humans need a balanced diet for healthy growth and development, give the function of three components of a balanced diet (3)

Question 7

describe the roll of bile in digestion (3)

Question 8

explain how the structure of the small intestine is adapted for absorption (4)