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Northern IrelandBiology

Cells, Viruses and Reproduction

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

How do cells divide, and how does sexual reproduction generate variation?

The cell cycle and mitosis, meiosis and the production of gametes, the sources of genetic variation, and the basics of sexual reproduction in flowering plants and mammals.
A CCEA A-Level Biology answer on the cell cycle and mitosis, meiosis and gamete production, the sources of genetic variation, and the basics of sexual reproduction in flowering plants and mammals.
11 min answer →

How are eukaryotic cells organised, and how is the cell membrane built?

The ultrastructure of eukaryotic cells and the functions of organelles, the difference between prokaryotic and eukaryotic cells, and the fluid-mosaic model of the cell membrane.
A CCEA A-Level Biology answer on the ultrastructure of eukaryotic cells and organelle functions, the differences between prokaryotic and eukaryotic cells, and the fluid-mosaic model of the cell membrane.
11 min answer →

How are gases exchanged and transported in mammals and plants?

Gas exchange surfaces and ventilation in mammals, gas exchange in plants and insects, the transport of oxygen and carbon dioxide in blood, and the structure of the circulatory and transport systems.
A CCEA A-Level Biology answer on gas exchange surfaces and ventilation in mammals, gas exchange in plants and insects, the transport of oxygen and carbon dioxide in blood, and the structure of circulatory and plant transport systems.
11 min answer →

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

Diffusion, facilitated diffusion, osmosis, active transport, endocytosis and exocytosis, and the factors that affect the rate of movement across membranes.
A CCEA A-Level Biology answer on diffusion, facilitated diffusion, osmosis, active transport, endocytosis and exocytosis, and the factors that affect the rate of movement across cell membranes.
11 min answer →

How does water move up a plant, how are sugars moved through the phloem, and how do xerophytes survive in dry places?

Transport and water relations in plants: the structure and function of xylem and phloem, water uptake by roots through the apoplast and symplast pathways, the cohesion-tension theory of the transpiration stream, the factors affecting transpiration and how a potometer measures it, translocation by the mass flow hypothesis from source to sink, and the adaptations of xerophytes that reduce water loss.
A CCEA A-Level Biology answer on transport in plants. Covers xylem and phloem structure, water uptake by the apoplast and symplast pathways, the cohesion-tension theory of the transpiration stream, factors affecting transpiration and the potometer, the mass flow hypothesis of translocation, and xerophyte adaptations.
13 min answer →

What are viruses, and how do they replicate inside host cells?

The structure of viruses, why they are non-cellular, the lytic and lysogenic cycles, the replication of HIV as a retrovirus, and how viruses cause disease.
A CCEA A-Level Biology answer on the structure of viruses, why they are non-cellular, the lytic and lysogenic replication cycles, the replication of HIV as a retrovirus, and how viruses cause disease.
11 min answer →