Cells

Describe what a eukaryotic cell is (a eukaryotic cell is…)

A eukaryotic cell is a complex cell containing a nucleus and membrane‑bound organelles

Describe what a prokaryotic cell is (a prokaryotic cell is…)

A prokaryotic cell is a simpler cell without a nucleus

Explain the key difference between eukaryotic and prokaryotic cells (the key difference is…)

The key difference is that eukaryotic cells contain a nucleus whereas prokaryotic cells do not

Describe the function of the nucleus (the nucleus…)

The nucleus contains genetic material and controls the activities of the cell

Describe the function of the cytoplasm (the cytoplasm…)

The cytoplasm is where most chemical reactions occur

Explain the role of the cell membrane (the cell membrane…)

The cell membrane controls the movement of substances into and out of the cell

Describe the function of mitochondria (mitochondria…)

Mitochondria are the site of aerobic respiration and release energy for the cell

Describe the function of ribosomes (ribosomes…)

Ribosomes are the site of protein synthesis where proteins are built from amino acids

Explain the role of the cell wall in plants (the plant cell wall…)

The plant cell wall provides structural support and prevents the cell from bursting

Describe the function of chloroplasts (chloroplasts…)

Chloroplasts contain chlorophyll and are the site of photosynthesis

Explain the role of the vacuole in plant cells (the vacuole…)

The vacuole contains cell sap and maintains turgor pressure to keep the cell rigid

Describe the structure of a bacterial cell (a bacterial cell contains…)

A bacterial cell contains cytoplasm

Explain the role of plasmids in bacteria (plasmids…)

Plasmids are small rings of DNA that carry extra genes such as antibiotic resistance

Describe the function of the bacterial flagellum (the flagellum…)

The flagellum enables the bacterial cell to move through its environment

Explain the purpose of the bacterial capsule (the capsule…)

The capsule protects the bacterium from drying out and from being engulfed by immune cells

Describe the structure of a yeast cell (a yeast cell is…)

A yeast cell is a unicellular eukaryote containing a nucleus

Explain why yeast cells are useful in industry (yeast cells are useful because…)

Yeast cells are useful because they respire anaerobically to produce ethanol and carbon dioxide

Describe the difference in size between eukaryotic and prokaryotic cells (eukaryotic cells are…)

Eukaryotic cells are much larger

Explain what magnification means (magnification means…)

Magnification means how many times larger an image appears compared to the actual object

Describe what resolution means (resolution is…)

Resolution is the ability to distinguish between two separate points as distinct objects

State the magnification formula (magnification is calculated by…)

Magnification is calculated by dividing the size of the image by the actual size

Explain why electron microscopes have higher resolution (they have higher resolution because…)

They have higher resolution because electrons have a much shorter wavelength than light

Describe one advantage of electron microscopes (an advantage is…)

An advantage is that they allow scientists to see sub‑cellular structures in far greater detail

Describe one disadvantage of electron microscopes (a disadvantage is…)

A disadvantage is that they are expensive and require specialised training to use

Explain why light microscopes are still useful (light microscopes are useful because…)

Light microscopes are useful because they allow living cells to be observed in real time

Describe the purpose of staining cells (staining is used to…)

Staining is used to increase contrast so structures become visible under a microscope

Explain why iodine is used in the onion cell practical (iodine is used because…)

Iodine is used because it stains the nucleus and cytoplasm

Describe how to prepare an onion cell slide (you prepare it by…)

You prepare it by placing a thin epidermal layer on a slide

Explain why the coverslip is lowered at an angle (it is lowered at an angle to…)

It is lowered at an angle to prevent air bubbles that would obstruct the view

Describe what a scientific drawing should include (a scientific drawing should include…)

A scientific drawing should include clear lines

Explain why thin samples are needed for microscopy (thin samples are needed because…)

Thin samples are needed because light must pass through the specimen clearly

Describe the conversion between mm and µm (to convert mm to µm…)

To convert mm to µm you multiply by 1000

Describe the conversion between µm and nm (to convert µm to nm…)

To convert µm to nm you multiply by 1000

Explain why scale bars are used in microscopy (scale bars are used because…)

Scale bars are used because they allow accurate measurement of structures in images

Describe the role of the Golgi apparatus (the Golgi apparatus…)

The Golgi apparatus modifies and packages proteins and lipids for transport

Explain why plant cells contain chloroplasts but animal cells do not (plant cells contain chloroplasts because…)

Plant cells contain chloroplasts because they photosynthesise

Describe why bacterial cells do not contain mitochondria (bacteria lack mitochondria because…)

Bacteria lack mitochondria because their reactions occur in the cytoplasm and membrane surfaces

Explain why yeast cells have a cell wall (yeast cells have a cell wall because…)

Yeast cells have a cell wall to maintain shape and prevent bursting during osmosis