What this topic covers
Cells has 4 subtopics:
- Cell structure
- All cells arise from other cells
- Transport across cell membranes
- Cell recognition and the immune system
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A Level AQA Biology · Topic 2 of 8
Cells – A Level AQA Biology revision notes
Choose a subtopic. Cells covers Cell structure, All cells arise from other cells, Transport across cell membranes, and Cell recognition and the immune system in A Level AQA Biology. 18 lessons in 4 subtopics.
Revise Cells for A Level AQA Biology, including Cell structure, All cells arise from other cells, and Transport across cell membranes.
18
Lessons
4
Subtopics
Cells lessons by subtopic
18 lessons, grouped by subtopic.
Cell structure
- Prokaryotic Cell Structure: Inside and Out: Describe the key structural features of prokaryotic cells, including the cell wall, cytoplasm, ribosomes, and circular DNA; Explain how prokaryotic cell structure differs from eukaryotic cell structure with reference to specific features; Compare the size of prokaryotic and eukaryotic cells and relate size to function
- Prokaryotic Cell Features: Plasmids, Capsule, and Flagella: Describe the structure and function of plasmids in prokaryotic cells; Explain the role of the capsule in protecting prokaryotic cells; Describe the structure and function of flagella in prokaryotic cells
- Viruses: Acellular Structure: Explain why viruses are described as acellular and non-living; Describe the structural components of a virus particle, including genetic material, capsid, and attachment proteins; Compare the structure of viruses with that of living cells
- Microscopy Techniques: Compare the principles, capabilities, and limitations of optical microscopes, transmission electron microscopes, and scanning electron microscopes; Explain the difference between magnification and resolution, using precise scientific terminology; Calculate magnification using the formula: magnification = size of image / size of real object
- Cell Fractionation and Ultracentrifugation: Describe the principles of cell fractionation, including the conditions required to preserve cell components; Explain the process of ultracentrifugation and how it separates organelles by density and size; Analyse the order in which organelles are pelleted during differential centrifugation
- Exploring Eukaryotic Cells: Nucleus, Membranes, and Energy: Describe the structure and function of the cell-surface membrane, nucleus, mitochondria, and chloroplasts in eukaryotic cells; Explain how the ultrastructure of each organelle relates to its specific function; Compare the roles of mitochondria and chloroplasts as energy-transducing organelles
- Eukaryotic Organelles: Golgi, Lysosomes, and Endoplasmic Reticulum: Describe the structure and function of the rough and smooth endoplasmic reticulum in eukaryotic cells; Explain the role of the Golgi apparatus and Golgi vesicles in processing and secreting proteins; Explain how lysosomes function as membrane-bound organelles containing hydrolytic enzymes
- Specialisation and Organisation in Eukaryotic Cells: Describe the structure and function of the cell wall and cell vacuole in eukaryotic cells; Explain how eukaryotic cells become specialised for specific functions in complex multicellular organisms; Apply knowledge of cell structure to explain adaptations of specialised eukaryotic cells
All cells arise from other cells
- The Cell Cycle and Mitosis: Explore the eukaryotic cell cycle, focusing on DNA replication and the stages of mitosis.
- Binary Fission and Viruses: Describe the stages of binary fission in prokaryotic cells, including DNA replication and cytoplasmic division; Explain why not all cells in multicellular organisms retain the ability to divide; Compare binary fission in prokaryotes with viral replication, justifying why viruses are considered non-living
- Practical: Mitotic Index: Describe the procedure for preparing stained squashes of cells from plant root tips; Explain how to set up and use an optical microscope to identify the stages of mitosis in stained squashes; Calculate the mitotic index from cell count data
Transport across cell membranes
- Passive Transport: Diffusion and Osmosis: Explain simple diffusion across the phospholipid bilayer, including the limitations imposed by membrane structure; Describe the roles of carrier proteins and channel proteins in facilitated diffusion; Explain osmosis in terms of water potential, including the direction of net water movement
- Active Transport and Co-transport: Explain the mechanism of active transport, including the roles of carrier proteins and ATP hydrolysis; Describe co-transport using the absorption of sodium ions and glucose in the mammalian ileum as an example; Analyse how surface area, number of channel or carrier proteins, and concentration or water potential gradients affect the rate of membrane transport
- Cell Adaptations and Membrane Permeability: Explain how the structural adaptations of specialised cells increase the rate of transport across their internal and external membranes; Describe and explain the factors that affect the permeability of cell-surface membranes; Design and evaluate an investigation into the effect of a named variable on membrane permeability
Cell recognition and the immune system
- Cell Recognition and Immune Response: Antigens and Phagocytosis: Learn about cell surface molecules, antigens, phagocytosis and the destruction of pathogens by lysozymes.
- T and B Lymphocytes: Cellular and Humoral Responses: Explain the role of antigen-presenting cells and helper T cells in coordinating the immune response; Describe the cellular response of T lymphocytes to a foreign antigen, including the role of cytotoxic T cells; Describe the humoral response of B lymphocytes, including clonal selection and antibody release
- Immunity, HIV, Monoclonal Antibodies, and Ethical Considerations (Part 1/2): Discover primary and secondary immune responses, vaccines, active and passive immunity, HIV/AIDS, monoclonal antibodies, ELISA tests, and related ethical issues.
- Immunity, HIV, Monoclonal Antibodies, and Ethical Considerations (Part 2/2): Discover primary and secondary immune responses, vaccines, active and passive immunity, HIV/AIDS, monoclonal antibodies, ELISA tests, and related ethical issues.
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Frequently asked questions
What is Cells?
Cells covers Cell structure, All cells arise from other cells, Transport across cell membranes, and Cell recognition and the immune system in A Level AQA Biology. 18 lessons in 4 subtopics.
What are the stages of mitosis?
The four stages of mitosis are prophase, when chromosomes condense and the nuclear envelope breaks down; metaphase, when chromosomes line up at the equator attached to spindle fibres by their centromeres; anaphase, when spindle fibres shorten and pull sister chromatids to opposite poles; and telophase, when nuclear envelopes reform around each set. The The Cell Cycle and Mitosis notes cover this in full.
What is osmosis?
Osmosis is the net movement of water molecules from a region of higher water potential to a region of lower water potential across a partially permeable membrane, without the use of metabolic energy. The Passive Transport: Diffusion and Osmosis notes cover this in full.
What is the function of the cell wall?
The cell wall is a layer external to the cell surface membrane that provides structural support and rigidity. The Specialisation and Organisation in Eukaryotic Cells notes cover this in full.
What is active transport?
Active transport is the movement of molecules or ions across a cell membrane against their concentration gradient, using energy from the hydrolysis of ATP and specific carrier proteins. The Active Transport and Co-transport notes cover this in full.
What is an antigen?
An antigen is a molecule, usually a protein or glycoprotein, on the surface of a cell, pathogen or toxin that is recognised as foreign by the immune system and stimulates an immune response. The Cell Recognition and Immune Response: Antigens and Phagocytosis notes cover this in full.
What is Fick's law?
Fick's Law states that the rate of diffusion is proportional to surface area and concentration gradient, and inversely proportional to the thickness of the membrane. The Passive Transport: Diffusion and Osmosis notes cover this in full.
What is a plasmid in bacteria?
A plasmid is a small, circular DNA molecule found in prokaryotic cells, separate from the main chromosomal DNA. The Prokaryotic Cell Features: Plasmids, Capsule, and Flagella notes cover this in full.
What is the structure of a virus?
A virus particle has three components: genetic material, which is DNA or RNA; a capsid, a protein coat of repeating subunits called capsomeres that protects the genetic material; and attachment proteins on the surface, which bind to specific receptors on host cells. The Viruses: Acellular Structure notes cover this in full.