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AQA BIOLOGY GCSE: ANIMAL AND PLANT SYSTEMS
EXAM OVERVIEW 2025-2026 QUESTIONS AND ANSWERS
Main function of the digestive system- CORRECT ANSWER ✔✔ To digest food and absorb the nutrients
obtained from digestion.
Role of the pancreas and salivary gland in the digestive system- CORRECT ANSWER ✔✔ The pancreas and
the salivary gland are glands which produce digestive juices containing enzymes.
Role of the stomach in the digestive system- CORRECT ANSWER ✔✔ Produces hydrochloric acid - which
kills any bacteria present and provides the optimum acidic pH for the protease enzyme to function.
Role of the small intestine in the digestive system- CORRECT ANSWER ✔✔ The small intestine is the site
where soluble food molecules are absorbed into the bloodstream.
Role of the liver in the digestive system- CORRECT ANSWER ✔✔ Produces bile (stored in the gallbladder)
which emulsifies lipids and allows the lipase enzyme to work more efficiently.
Role of the large intestine in the digestive system- CORRECT ANSWER ✔✔ Absorbs water from undigested
food, producing faeces.
Role of enzymes in the digestive system- CORRECT ANSWER ✔✔ Enzymes act as biological catalysts which
speed up the rate of biological reactions (the breakdown of food) without being used up.
Effect of enzyme shape on function- CORRECT ANSWER ✔✔ Enzymes have a specific active site which is
complementary to their substrate.
Metabolism- CORRECT ANSWER ✔✔ The sum of all the reactions in a cell or an organism.
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Types of metabolic reactions catalysed by enzymes- CORRECT ANSWER ✔✔ ●Building larger molecules
from smaller molecules eg. glucose to starch. ●Changing one molecule to another eg. glucose to fructose. ●
Breaking down larger molecules into smaller molecules eg. carbohydrates to glucose.
Lock and key hypothesis of enzyme function- CORRECT ANSWER ✔✔ The shape of the enzyme active site
and the substrate are complementary, so can bind together to form an enzyme-substrate complex.
Effect of temperature on enzyme action- CORRECT ANSWER ✔✔ Up to a certain point, increasing
temperature increases enzyme action, as molecules have a higher kinetic energy. Above a certain temperature,
the shape of the active site is altered and the enzyme becomes denatured, so it can no longer catalyse the
reaction. The optimum temperature is around 37°.
Effect of pH on enzyme function- CORRECT ANSWER ✔✔ The optimum pH for most enzymes is 7 (apart
from proteases in the stomach). If the pH is too extreme, the shape of the active site may be altered and the
enzyme may no longer work.
Production of carbohydrases, proteases and lipases in the body- CORRECT ANSWER ✔✔ ●Carbohydrases:
amylase - salivary gland and pancreas; maltase - small intestine. ●Proteases: pepsin - stomach; others -
pancreas and small intestine. ●Lipases: pancreas and small intestine.
Role of carbohydrases in the digestive system- CORRECT ANSWER ✔✔ Carbohydrases break down
carbohydrates into monosaccharides and disaccharides. Amylase breaks down starch into maltose, and maltase
breaks down maltose into glucose.
Role of proteases in the digestive system- CORRECT ANSWER ✔✔ Proteases break down proteins into amino
acids.
Proteases- CORRECT ANSWER ✔✔ Proteases break down proteins into amino acids.
Lipases- CORRECT ANSWER ✔✔ Lipases break down lipids into fatty acids and glycerol.
AQA BIOLOGY GCSE: ANIMAL AND PLANT SYSTEMS
EXAM OVERVIEW 2025-2026 QUESTIONS AND ANSWERS
Main function of the digestive system- CORRECT ANSWER ✔✔ To digest food and absorb the nutrients
obtained from digestion.
Role of the pancreas and salivary gland in the digestive system- CORRECT ANSWER ✔✔ The pancreas and
the salivary gland are glands which produce digestive juices containing enzymes.
Role of the stomach in the digestive system- CORRECT ANSWER ✔✔ Produces hydrochloric acid - which
kills any bacteria present and provides the optimum acidic pH for the protease enzyme to function.
Role of the small intestine in the digestive system- CORRECT ANSWER ✔✔ The small intestine is the site
where soluble food molecules are absorbed into the bloodstream.
Role of the liver in the digestive system- CORRECT ANSWER ✔✔ Produces bile (stored in the gallbladder)
which emulsifies lipids and allows the lipase enzyme to work more efficiently.
Role of the large intestine in the digestive system- CORRECT ANSWER ✔✔ Absorbs water from undigested
food, producing faeces.
Role of enzymes in the digestive system- CORRECT ANSWER ✔✔ Enzymes act as biological catalysts which
speed up the rate of biological reactions (the breakdown of food) without being used up.
Effect of enzyme shape on function- CORRECT ANSWER ✔✔ Enzymes have a specific active site which is
complementary to their substrate.
Metabolism- CORRECT ANSWER ✔✔ The sum of all the reactions in a cell or an organism.
, 2|Page
Types of metabolic reactions catalysed by enzymes- CORRECT ANSWER ✔✔ ●Building larger molecules
from smaller molecules eg. glucose to starch. ●Changing one molecule to another eg. glucose to fructose. ●
Breaking down larger molecules into smaller molecules eg. carbohydrates to glucose.
Lock and key hypothesis of enzyme function- CORRECT ANSWER ✔✔ The shape of the enzyme active site
and the substrate are complementary, so can bind together to form an enzyme-substrate complex.
Effect of temperature on enzyme action- CORRECT ANSWER ✔✔ Up to a certain point, increasing
temperature increases enzyme action, as molecules have a higher kinetic energy. Above a certain temperature,
the shape of the active site is altered and the enzyme becomes denatured, so it can no longer catalyse the
reaction. The optimum temperature is around 37°.
Effect of pH on enzyme function- CORRECT ANSWER ✔✔ The optimum pH for most enzymes is 7 (apart
from proteases in the stomach). If the pH is too extreme, the shape of the active site may be altered and the
enzyme may no longer work.
Production of carbohydrases, proteases and lipases in the body- CORRECT ANSWER ✔✔ ●Carbohydrases:
amylase - salivary gland and pancreas; maltase - small intestine. ●Proteases: pepsin - stomach; others -
pancreas and small intestine. ●Lipases: pancreas and small intestine.
Role of carbohydrases in the digestive system- CORRECT ANSWER ✔✔ Carbohydrases break down
carbohydrates into monosaccharides and disaccharides. Amylase breaks down starch into maltose, and maltase
breaks down maltose into glucose.
Role of proteases in the digestive system- CORRECT ANSWER ✔✔ Proteases break down proteins into amino
acids.
Proteases- CORRECT ANSWER ✔✔ Proteases break down proteins into amino acids.
Lipases- CORRECT ANSWER ✔✔ Lipases break down lipids into fatty acids and glycerol.
