Question 1: The Human Digestive System
(a) The diagram shows part of the human digestive system.
(i) Describe the role of the oesophagus. (2)
The oesophagus transports food from the mouth to the stomach through muscular
contractions called peristalsis. It also prevents the backflow of food using the lower
esophageal sphincter.
(ii) Name the type of food that is first digested chemically in the stomach.
(1)
Proteins.
(iii) Complete the passage by writing a suitable word or words on each
dotted line. (3)
Bile is made in the liver and stored in the gallbladder.
One of its roles is to emulsify lipids.
(iv) Describe the role of the small intestine in digestion. (2)
The small intestine completes the chemical digestion of food using enzymes and
bile. It also absorbs nutrients like glucose, amino acids, and fatty acids into the
bloodstream through villi.
(v) Enzymes help in digestion. Write three characteristics of enzymes. (3)
1. Enzymes are specific to their substrate (lock-and-key mechanism).
2. They work best at an optimum pH and temperature.
3. Enzymes are not consumed in the reaction and can be reused.
(b) Scatter Graph on Starch and Cancer of the Large Intestine
(i) Which country had the greatest proportion of people with cancer of the
large intestine? (1)
Country X (specific name dependent on graph).
(ii) Conclusion about the effect of eating starch on cancer of the large
intestine. (1)
The higher the starch intake, the lower the proportion of people with cancer of the
large intestine.
(iii) Good sources of starch (Tick the two correct boxes). (2)
A Bread
D Pasta
(c) Matching Substances to Their Functions (10)
Name of
Function of Substance
Substance
Stored under the skin and around some
Fat
organs
Used to strengthen tooth enamel Calcium
Broken down into amino acids during
Protein
digestion
Helps in vision Vitamin A
Used in the formation of haemoglobin Iron
A medium in which chemical reactions
Water
occur
Needed for growth of tissues Protein
Prevents constipation Fibre
Provides energy Carbohydrate
Improves immunity Vitamin C
Question 2: Separation of Mixtures
(a) Best Method for Separation (4)
Tick in the following rows:
1. Filtration: For mixtures with an undissolved solid.
2. Evaporation: For soluble solids in a liquid.
3. Chromatography: For separating dyes or colors.
4. Distillation: For separating two miscible liquids.
(ii) Which mixture contains an undissolved solid? (1)
Mixture P.
(b) Separation of Salt and Sand
(i) Fill in the blanks:
1. Beaker.
2. Water.
3. Glass rod.
4. Filter funnel.
5. Conical flask.
6. Water.
(ii) What should be placed in A before the mixture is poured through it? (1)
Filter paper.
(iii) What is the solid removed in Step 2? (1)
Sand.
(iv) Two processes used in this separation. (2)
1. Filtration.
2. Evaporation.
(c) Chromatogram for Dyes
(i) Dye containing three colors. (1)
Dye C.
(ii) Dye containing one color only. (1)
Dye B.
(iii) Incorrect result and explanation. (2)
Result: Dye D.
Explanation: The spot split into multiple colors, but they do not align with primary
colors from the other dyes, indicating contamination or error in application.
(d) Diffusion of Hydrated Copper Sulfate
(i) Color of the liquid after two days. (1)
Blue.
(ii) Label the solute, solvent, and solution. (3)
Solute: Copper (II) sulfate crystal.
Solvent: Water.
Solution: Blue liquid.
(iii) Factor affecting solubility. (1)
Temperature.
Question 3: Lavender Oil Extraction
(a) Sealed Lid and Pressure Valve
(i) Why must the lid be sealed? (1)
To prevent the steam from escaping and maintain pressure.
(ii) What happens if there is no pressure-release valve? (2)
The container may explode due to excess pressure.
(b) Physical State Changes
(i) Change as they cool. (2)
From gas to liquid.
(ii) How separator shows water is denser than oil. (1)
Water settles at the bottom, and lavender oil floats on top.
(c) State Change Diagram
(i) Correct diagram: B (melting or vaporization). (1)
