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Topic 2: Cells as the Basis of Life

7 dot points, in syllabus order. Each dot point has a focused answer, with exam-style questions and worked answers where available.

How do plants convert light energy into chemical energy?

Explain how photosynthesis uses light energy to convert carbon dioxide and water into glucose

Photosynthesis in chloroplasts uses light to convert carbon dioxide and water into glucose and oxygen, via light-dependent and light-independent reactions, limited by light, CO2 and temperature.

8 min read →

Why are cells small, and how does size limit exchange with the environment?

Explain how the surface area to volume ratio limits cell size and affects the rate of exchange

As a cell grows, volume increases faster than surface area, so the surface area to volume ratio falls, limiting the rate of exchange and therefore cell size.

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How do cells grow, copy themselves and divide accurately?

Describe the stages of the cell cycle and mitosis and explain how they produce genetically identical cells

The cell cycle (interphase then mitosis and cytokinesis) produces two genetically identical daughter cells; checkpoints control it and failure of control can lead to cancer.

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How do cells release the energy stored in glucose?

Explain how aerobic and anaerobic respiration release energy from glucose to produce ATP

Cellular respiration releases energy from glucose to make ATP; aerobic respiration uses oxygen for a high ATP yield, while anaerobic respiration releases less and produces lactate or ethanol.

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How do prokaryotic and eukaryotic cells differ?

Compare the structure and organisation of prokaryotic and eukaryotic cells

Prokaryotic cells are small with no nucleus or membrane-bound organelles; eukaryotic cells are larger with a true nucleus and membrane-bound organelles.

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How does each organelle contribute to the life of the cell?

Describe the structure and function of the major eukaryotic cell organelles

The structure and roles of the nucleus, mitochondria, ER, Golgi, ribosomes, chloroplasts, vacuole and lysosomes, including how they cooperate to make and export proteins.

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How does the cell membrane control what enters and leaves the cell?

Explain the fluid mosaic model and the mechanisms of passive and active transport across the membrane

The fluid mosaic membrane controls movement of substances by passive transport (diffusion, osmosis, facilitated diffusion) and active transport, which requires energy.

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