GCSE Cell Biology 5 — Questions and Answers
Question 1: Why is a high surface area to volume ratio important for cells?
- It allows the cell to store more DNA
- It increases the rate of diffusion of substances in and out of the cell (Correct answer)
- It reduces the energy needed for active transport
- It prevents osmosis from occurring
Correct answer: It increases the rate of diffusion of substances in and out of the cell
A high surface area to volume ratio means substances can diffuse across the membrane quickly relative to the cell's metabolic demands.
Question 2: Embryonic stem cells are described as 'totipotent'. What does this mean?
- They can only differentiate into nerve cells
- They have already specialised and cannot change
- They can differentiate into any type of cell in the organism (Correct answer)
- They only divide by meiosis
Correct answer: They can differentiate into any type of cell in the organism
Totipotent cells can develop into any cell type in the body, including the placenta, making them the most versatile stem cells.
Question 3: A scientist observes that a cell's mitochondria increase in number after regular exercise. What does this suggest?
- Exercise causes cells to undergo meiosis
- Cells adapt to higher energy demands by producing more mitochondria (Correct answer)
- Exercise destroys ribosomes, forcing mitochondria to compensate
- Mitochondria are produced in the nucleus during exercise
Correct answer: Cells adapt to higher energy demands by producing more mitochondria
Increased exercise raises energy demand, so cells respond by increasing the number of mitochondria to produce more ATP.
Question 4: What is the role of the Golgi apparatus in a cell?
- Carrying out aerobic respiration
- Modifying, packaging, and dispatching proteins and lipids (Correct answer)
- Synthesising DNA during cell division
- Absorbing light energy for photosynthesis
Correct answer: Modifying, packaging, and dispatching proteins and lipids
The Golgi apparatus processes proteins from the endoplasmic reticulum, modifies them, and packages them into vesicles for secretion or use within the cell.
Question 5: When a cell is described as 'turgid', what does this mean?
- The cell has lost water and is flaccid
- The cell membrane has detached from the cell wall
- The cell is firm because water has entered by osmosis and the vacuole presses against the wall (Correct answer)
- The cell has undergone plasmolysis
Correct answer: The cell is firm because water has entered by osmosis and the vacuole presses against the wall
Turgidity occurs when water enters the cell by osmosis, filling the vacuole and pushing the membrane against the rigid cell wall, making the cell firm.
Question 6: Which of the following correctly describes the structure of DNA?
- A single-stranded helix made of amino acids
- A double helix made of two polynucleotide strands held together by complementary base pairs (Correct answer)
- A circular strand of RNA found in the cytoplasm
- A triple helix made of glucose units
Correct answer: A double helix made of two polynucleotide strands held together by complementary base pairs
DNA is a double helix consisting of two antiparallel polynucleotide strands linked by hydrogen bonds between complementary base pairs (A-T and G-C).
Question 7: How does the structure of a red blood cell adapt it for carrying oxygen?
- It has a large nucleus to store haemoglobin
- Its biconcave shape increases surface area, and lack of a nucleus maximises haemoglobin space (Correct answer)
- It contains chlorophyll to absorb energy for oxygen transport
- Its thick rigid cell wall speeds oxygen diffusion
Correct answer: Its biconcave shape increases surface area, and lack of a nucleus maximises haemoglobin space
The biconcave disc shape maximises surface area for gas exchange, and the absence of a nucleus allows more room for haemoglobin molecules.
GCSE Cell Biology 5
Why is a high surface area to volume ratio important for cells?