Cell StructureEdexcel GCSE Biology: Flashcards
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What is the function of the nucleus?
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- What is the function of the nucleus?
- Contains DNA as chromosomes; controls the cell's activities
- Name the four sub-cellular structures found in animal cells.
- Nucleus, cell membrane, mitochondria, ribosomes
- Name the three additional structures found in plant cells but not animal cells.
- Cell wall, chloroplasts, permanent vacuole
- What is the function of the cell wall in plant cells?
- Made of cellulose; provides structural strength and support
- What is the function of chloroplasts?
- Contain chlorophyll and are the site of photosynthesis
- Define plasmid DNA.
- Small circular loops of extra DNA found in bacterial cells, separate from the main chromosomal DNA
- Name the five sub-cellular structures found in a bacterial cell.
- Chromosomal DNA, plasmid DNA, cell membrane, ribosomes, flagella
- Explain how the sperm cell is adapted to its function.
- Acrosome digests the egg's membrane; haploid nucleus contributes half the chromosomes; many mitochondria release energy; tail enables swimming
- How does the egg cell prevent fertilisation by more than one sperm?
- The cell membrane changes structure immediately after the first sperm enters, blocking any further sperm
- What is the function of ciliated epithelial cells?
- Cilia beat in a coordinated way to move mucus and trapped particles away from the lungs
- Explain why electron microscopes reveal more detail than light microscopes.
- They have much higher magnification and resolution, allowing smaller sub-cellular structures to be seen clearly
- Define resolution.
- The ability to distinguish between two separate points that are close together
- State the magnification formula.
- Magnification = image size ÷ actual size
- Order these unit prefixes from largest to smallest: nano, milli, pico, micro.
- Milli (×10⁻³), micro (×10⁻⁶), nano (×10⁻⁹), pico (×10⁻¹²)
- How is total magnification calculated on a microscope?
- Total magnification = eyepiece lens magnification × objective lens magnification