Master GCSE Biology

MS1:

- A prokaryote is a single-celled organism that lacks a true nucleus and membrane-bound organelles (1)

MS2:

- The cell membrane is selectively permeable, allowing only certain substances to enter and leave the cell (1)

- It controls the movement of substances across the membrane, such as oxygen, carbon dioxide, and nutrients (1)

- This helps maintain the correct concentration of substances and provides a stable internal environment for the cell (1)

MS3:

- The nucleus contains the cell's DNA, which carries genetic instructions (1)

- During cell division, the DNA in the nucleus replicates, ensuring that each daughter cell receives a complete set of genetic material (1)

- The nuclear envelope breaks down and the chromosomes condense and become visible (1)

- The chromosomes line up at the cell equator and divide, with each daughter cell receiving one copy of each chromosome (1)

MS4:

- Chloroplasts are organelles found in plant cells that carry out photosynthesis (1)

MS5:

- Magnification alone is not sufficient to determine the structure of a cell because it does not provide sufficient resolution (1)

- Resolution refers to the ability to distinguish between two closely spaced objects, and requires high-quality lenses (1)

MS6:

- Binary fission is a form of asexual reproduction in bacteria (1)

- The bacterial cell elongates and its DNA replicates (1)

- The cytoplasm divides into two identical daughter cells, each with its own copy of DNA and organelles (1)

MS7:

- Diffusion is the movement of particles from an area of high concentration to an area of low concentration (1)

MS8:

- The larger the surface area, the faster the rate of diffusion (1)

- This is because there are more molecules of the substance present on the larger surface area, leading to a more rapid concentration gradient (1)

MS9:

- Osmosis is the movement of water molecules across a semi-permeable membrane from an area of high water concentration to an area of low water concentration (1)

- In plant cells, the cell membrane and vacuole are semi-permeable (1)

- Water molecules move into the cell, making the vacuole expand and the cell turgid (1)

- This provides support and helps maintain the shape of the cell (1)

MS10:

- Prophase (1)

- Metaphase (1)

- Anaphase (1)

- Telophase (1)