Biology · May / June 2024 · Paper 42 · Question 4

magnesium (ions) / AVP ;

any four from:

1

(algae) photosynthesise in light / no photosynthesis in the dark ;

2

carbon dioxide is, used / absorbed / taken / AW, in photosynthesis ;

3

(purple because CO2 used in) photosynthesis results in, pH increase / becomes (more) alkaline / less acidic ; 4

(algae) respire in light and dark ;

5

carbon dioxide is, produced / released / AW, in respiration ;

6

in light there is a higher (rate of) photosynthesis than (the rate of) respiration ;

7

(yellow because CO2 given off from) respiration results in, pH decrease / more acidic / less alkaline / becomes (nearer to) neutral ;

total of three from:

X: light (intensity) ;

Y max two from:

temperature ;

carbon dioxide concentration ;

(amount of) chlorophyll / (number of) chloroplasts ; water ;

tissue: phloem ;

molecule: amino acids ;

any six from:

1

(starch is broken down by) physical / mechanical, digestion ;

2

(physical digestion / AW) uses teeth / occurs in the, mouth / (involves churning) in stomach ;

3

(physical digestion) increases surface area (for faster enzyme activity) ;

4

chemical digestion / break down (of insoluble molecules) into (smaller) soluble molecules (by enzymes) ; 5

salivary glands / pancreas, secrete / make, amylase ; 6

amylase (breaks down) starch to maltose ;

7

maltase is found on epithelium (lining) of, small intestine / duodenum / ileum ;

8

(maltase) breaks down maltose to glucose ; 9

(optimum) pH for, amylase / maltase / carbohydrase is, neutral / 7 / 8 ;