A Level H1 Biology Cells Biomolecules Quiz

A-Level Biology H1 Quiz - Cells Biomolecules - Answer Key

Total: 35 marks

Section A: Short Answer Questions [15 marks]

1. State two functions of the cell membrane. [2]

• Controls entry and exit of substances / selective permeability [1]
• Maintains cell shape / provides structural support [1]
• Cell recognition / cell signaling [1]
• Compartmentalization [1] [Accept any 2 valid functions]

2. Name the organelle responsible for ATP production in eukaryotic cells. [1]

• Mitochondrion / mitochondria [1]

3. Describe the arrangement of phospholipids in cell membranes. [2]

• Phospholipids form a bilayer [1]
• Hydrophilic heads face outward / toward aqueous environment [1]
• Hydrophobic tails face inward / away from water [1] [Accept 2 points for full marks]

4. State the monomer units that make up the following biological molecules: [3] (i) Proteins: Amino acids [1] (ii) Carbohydrates: Monosaccharides / simple sugars [1] (iii) Nucleic acids: Nucleotides [1]

5. Name two factors that affect enzyme activity. [2]

• Temperature [1]
• pH [1]
• Substrate concentration [1]
• Enzyme concentration [1]
• Presence of inhibitors [1] [Accept any 2 valid factors]

6. Define the term 'active transport'. [2]

• Movement of substances against concentration gradient [1]
• Requires energy / ATP [1]
• Uses carrier proteins / transport proteins [1] [Accept 2 points for full marks]

7. State three properties of water that make it important for living organisms. [3]

• High specific heat capacity [1]
• Excellent solvent / dissolves polar substances [1]
• High latent heat of vaporization [1]
• Cohesive properties [1]
• Forms hydrogen bonds [1] [Accept any 3 valid properties]

Section B: Structured Response Questions [20 marks]

8. (a) Name structures A and B. [2] A: Nucleus [1] B: Chloroplast [1]

(b) State the function of structure C in photosynthesis. [2]

• Site of light-dependent reactions [1]
• Contains chlorophyll / photosystems [1]
• Produces ATP and NADPH [1] [Accept 2 points for full marks]

(c) Explain why structure D is not found in animal cells. [2]

• Structure D is cell wall [1]
• Animal cells do not need rigid support / have flexible cell membrane instead [1]
• Animal cells need to change shape for movement [1] [Accept 2 points for full marks]

9. (a) Explain the shape of the curve between 0°C and 40°C. [3]

• As temperature increases, kinetic energy increases [1]
• More enzyme-substrate collisions occur [1]
• Rate of reaction increases until optimum temperature [1]

(b) Explain what happens to the enzyme at temperatures above 60°C. [2]

• Enzyme denatures / loses its shape [1]
• Active site changes shape / no longer complementary to substrate [1]
• Hydrogen bonds break [1] [Accept 2 points for full marks]

10. (a) Name the process responsible for the movement of water. [1]

• Osmosis [1]

(b) Explain why there was no change in mass at 20% sucrose concentration. [2]

• Water potential inside and outside are equal [1]
• No net movement of water / equilibrium reached [1]

(c) Predict what would happen to the mass if 50% sucrose solution was used. Explain your answer. [2]

• Mass would decrease further / greater decrease than at 40% [1]
• Higher sucrose concentration creates lower water potential / greater concentration gradient [1]
• More water moves out by osmosis [1] [Accept 2 points for full marks]

11. Describe how glucose molecules are transported across cell membranes in the small intestine. [2]

• Facilitated diffusion using glucose transporters / carrier proteins [1]
• Active transport using sodium-glucose co-transporters / symporters [1]
• Requires ATP / energy [1] [Accept 2 points for full marks]