Master GCSE Biology

MS1.

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

MS2.

- Ribosomes are small structures that synthesize proteins. (1)

- They are found in the cytoplasm and on the surface of the endoplasmic reticulum. (1)

MS3.

- Eukaryotic cells have a nucleus, mitochondria, chloroplasts (in plant cells), and other membrane-bound organelles. (1)

- Prokaryotic cells lack a nucleus and other membrane-bound organelles. (1)

- Specific examples: nucleus vs. no nucleus, mitochondria vs. no mitochondria. (1)

MS4.

- Provide mechanical support and protection. (1)

- Maintain cell shape. (1)

MS5.

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

- Substances move across the cell membrane by diffusion to reach equilibrium. (1)

MS6.

- Significance: Prevents contamination by microorganisms, which can affect experimental results or harm researchers. (1)

- Steps: Sterilize equipment, use sterile materials, minimize exposure to air, use aseptic technique when handling cultures. (1 x 3)

MS7.

- Chlorophyll. (1)

MS8.

- Before mitosis, DNA replicates into identical sister chromatids. (1)

- During mitosis, these chromatids are separated and distributed to daughter cells, ensuring each daughter cell has the same number of chromosomes as the parent cell. (2)

MS9.

- Importance: Catalyze reactions, reduce activation energy, speed up reactions. (1)

- Environmental factors: Temperature, pH, concentration. (1)

- Effects: Temperature optimum, pH optimum, inhibition at high concentrations. (1 x 2)

MS10.

- The process by which cells become specialized in structure and function. (1)