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EnglandBiology

3.2 Cells

6 dot points across 6 inquiry questions. Click any dot point for a focused answer with worked past exam questions where available.

How does the body recognise and respond to pathogens and foreign cells?

Cell recognition by antigens, including self and non-self; the cellular and humoral immune responses involving phagocytes, T lymphocytes and B lymphocytes; the structure and function of antibodies; the primary and secondary responses and immunological memory; active and passive, natural and artificial immunity, vaccines and herd immunity; antigenic variation; and the use of monoclonal antibodies and the ELISA test.
A focused answer to the AQA 3.2 dot point on cell recognition and immunity. Covers antigens, phagocytosis, the cellular and humoral responses, antibody structure, immunological memory, vaccination, monoclonal antibodies and the ELISA test.
13 min answer →

How does the internal organisation of a eukaryotic cell let it carry out its functions?

The structure of eukaryotic cells, including the structure and function of the cell-surface membrane, nucleus, mitochondria, chloroplasts, Golgi apparatus and Golgi vesicles, lysosomes, ribosomes, rough and smooth endoplasmic reticulum, cell wall and cell vacuole, and the role of these organelles in producing and secreting proteins; the importance of the cytoskeleton.
A focused answer to the AQA 3.2 dot point on eukaryotic cell structure. Covers every required organelle, the protein production and secretion pathway, and the differences between plant, animal, fungal and algal cells.
11 min answer →

How do microscopes and cell fractionation let us study structures too small to see?

Methods of studying cells, including the principles and limitations of optical, transmission electron and scanning electron microscopes; magnification and resolution; measurement and calibration using an eyepiece graticule and stage micrometer; cell fractionation and ultracentrifugation to separate organelles.
A focused answer to the AQA 3.2 dot point on studying cells. Covers optical, TEM and SEM microscopes, the difference between magnification and resolution, graticule calibration, and cell fractionation by ultracentrifugation.
10 min answer →

How does a cell copy and divide its contents accurately during the cell cycle?

The cell cycle, including interphase (DNA replication) and mitosis as a controlled process producing two genetically identical daughter cells; the stages of mitosis (prophase, metaphase, anaphase, telophase) and cytokinesis; the calculation of a mitotic index; the role of mitosis in growth and repair, and how uncontrolled cell division can lead to the formation of tumours and cancer.
A focused answer to the AQA 3.2 dot point on the cell cycle and mitosis. Covers interphase and the four mitotic stages, cytokinesis, mitotic index calculation, and how uncontrolled division produces tumours and cancer.
10 min answer →

How do prokaryotic cells and viruses differ from eukaryotic cells?

The structure of prokaryotic cells, including the cell wall, cell-surface membrane, capsule, circular DNA, flagella and plasmids, and how prokaryotic cells differ from eukaryotic cells; the structure of viruses as acellular, non-living particles including the genetic material, capsid and attachment proteins.
A focused answer to the AQA 3.2 dot point on prokaryotic cells and viruses. Covers bacterial cell structure, the key differences from eukaryotic cells, and why viruses are classed as acellular non-living particles.
9 min answer →

How do substances move into and out of cells across the cell-surface membrane?

The fluid-mosaic model of membrane structure and how substances cross membranes by simple diffusion, facilitated diffusion, osmosis, active transport and co-transport; the role of carrier and channel proteins; the factors affecting the rate of transport across membranes.
A focused answer to the AQA 3.2 dot point on membrane transport. Covers the fluid-mosaic model and simple diffusion, facilitated diffusion, osmosis, active transport and co-transport, plus the factors affecting transport rate.
11 min answer →