Cell structureOxford AQA IGCSE Biology: Flashcards
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What is the function of the cell membrane in animal cells?
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- What is the function of the cell membrane in animal cells?
- The cell membrane controls the movement of substances in and out of the cell. It is selectively permeable, allowing some substances to pass through whilst blocking others.
- Define the cytoplasm and state its function.
- The cytoplasm is a gel-like substance that fills the cell. It is where most metabolic reactions occur, including respiration and protein synthesis.
- What is the function of the nucleus in animal cells?
- The nucleus controls the activities of the cell by regulating gene expression. It contains chromosomal DNA and controls protein synthesis.
- Describe the function of mitochondria in animal cells.
- Mitochondria are the site of aerobic respiration. They release energy from glucose, which is used to produce ATP for cellular processes.
- What is the function of ribosomes in animal cells?
- Ribosomes are the site of protein synthesis. They read mRNA and translate it into proteins.
- Identify three structures found in plant cells but not in animal cells and explain why plants have them.
- Cell wall: provides structural support and protection. Vacuole: stores water, nutrients and waste; maintains turgor pressure. Chloroplasts: photosynthesis to produce glucose. Plants are stationary and need rigid structure; they produce their own food through photosynthesis.
- What is the function of the cell wall in plant cells?
- The cell wall provides structural support and rigidity to the plant cell. It protects the cell and prevents it from bursting when water enters by osmosis.
- Describe the function of the vacuole in plant cells.
- The vacuole stores water, nutrients and waste products. It maintains turgor pressure, keeping the plant cell rigid and the plant upright.
- What is the function of chloroplasts in plant cells?
- Chloroplasts are the site of photosynthesis. They contain chlorophyll and convert light energy, water and carbon dioxide into glucose.
- State three key differences between prokaryotic and eukaryotic cells.
- Prokaryotic cells: no nucleus (DNA in nucleoid region), no membrane-bound organelles, smaller (1–10 μm), found in bacteria. Eukaryotic cells: have a nucleus containing DNA, have membrane-bound organelles, larger (10–100 μm), found in animals and plants.
- Name the structures found in a bacterial cell.
- Cell membrane, cell wall, cytoplasm, ribosomes, plasmid, flagellum, and chromosomal DNA (located in the nucleoid region, not enclosed by a nucleus).
- What is the function of the flagellum in a bacterial cell?
- The flagellum is a tail-like structure that enables the bacterial cell to move.
- Define a plasmid and state its function in bacterial cells.
- A plasmid is a small, circular loop of DNA found in bacterial cells, separate from the chromosomal DNA. It often carries genes for antibiotic resistance.
- Write the formula for magnification when using a light microscope.
- Magnification = image size ÷ actual size
- Convert 50 micrometres (μm) into nanometres (nm).
- 50 μm = 50,000 nm (multiply by 1,000)
- Convert 0.5 millimetres (mm) into micrometres (μm).
- 0.5 mm = 500 μm (multiply by 1,000)