GCSE - General Certificate of Secondary Education Cell Biology Questions and Answers — Questions and Answers
Question 1: A student observes a bacterial cell and a plant cell under a microscope. Which of the following correctly identifies a structure absent in the bacterial cell but present in the plant cell?
- Cell wall
- Mitochondria (Correct answer)
- Ribosomes
- Cytoplasm
Correct answer: Mitochondria
Plant cells are eukaryotic and contain membrane-bound organelles, including mitochondria, which are the site of aerobic respiration. Bacterial cells are prokaryotic and lack a nucleus and other membrane-bound organelles such as mitochondria. Both cell types have a cell wall (though of different composition), ribosomes for protein synthesis, and cytoplasm.
Question 2: A red blood cell is placed in a solution with a much lower water concentration than its cytoplasm. What is the most likely outcome for the cell?
- It will swell and burst.
- It will shrink and shrivel. (Correct answer)
- It will remain unchanged.
- It will undergo cell division.
Correct answer: It will shrink and shrivel.
The solution has a lower water concentration (and higher solute concentration) than the cell's cytoplasm. Due to osmosis, water will move from a region of higher water concentration (inside the cell) to a region of lower water concentration (outside the cell) across the partially permeable cell membrane. This net loss of water will cause the cell to shrink and shrivel (crenate).
Question 3: A micrograph shows a plant cell that has a length of 50 mm in the image. The magnification used is x1000. What is the actual size of the cell in micrometres (µm)?
- 500 µm
- 0.05 µm
- 50 µm (Correct answer)
- 5000 µm
Correct answer: 50 µm
First, rearrange the magnification formula: Actual Size = Image Size / Magnification. So, Actual Size = 50 mm / 1000 = 0.05 mm. To convert millimetres (mm) to micrometres (µm), you multiply by 1000 (since 1 mm = 1000 µm). Therefore, 0.05 mm * 1000 = 50 µm.
Question 4: Which of the following is the primary reason for mitosis in multicellular organisms?
- Production of gametes for sexual reproduction
- Growth and repair of tissues (Correct answer)
- Creating genetic variation
- Transport of substances across cell membranes
Correct answer: Growth and repair of tissues
Mitosis is a type of cell division that results in two daughter cells each having the same number and kind of chromosomes as the parent nucleus, typical of ordinary tissue growth. Its main purposes in multicellular organisms are to produce new cells for growth, and to replace old, lost, or damaged cells (repair). The production of gametes occurs via meiosis, which creates genetic variation.
Question 5: A root hair cell is a specialised cell found in plants. Which adaptation allows it to maximise the absorption of water and minerals from the soil?
- A thick cell wall to prevent bursting
- A large number of chloroplasts for photosynthesis
- A large surface area to volume ratio (Correct answer)
- A small, compact shape to penetrate soil
Correct answer: A large surface area to volume ratio
Root hair cells have a long, hair-like extension which dramatically increases their surface area to volume ratio. This large surface area provides more space for water to move into the cell by osmosis and for mineral ions to be absorbed by active transport, making absorption more efficient.
Question 6: What is the primary function of mitochondria within an animal cell?
- To store genetic information and control cell activities
- To synthesise proteins
- To control the movement of substances into and out of the cell
- To release energy through aerobic respiration (Correct answer)
Correct answer: To release energy through aerobic respiration
Mitochondria are known as the 'powerhouses' of the cell. Their main function is to carry out aerobic respiration, a process that breaks down glucose in the presence of oxygen to release energy in the form of ATP. This energy is then used to power all other cellular processes.
GCSE - General Certificate of Secondary Education Cell Biology Questions and Answers
A student observes a bacterial cell and a plant cell under a microscope.
Which of the following correctly identifies a structure absent in the bacterial cell but present in the plant cell?