AQA GCSE Biology Paper 1 - Overview

This guide covers topics for both higher and foundation tier, double combined trilogy, and triple or separate biology. Key topics include Cells, Organization, Infection and Response, and Bioenergetics.

Cells

• All life consists of cells.
• Microscopes:
  • Light microscopes: View cells, not subcellular structures.
  • Electron microscopes: View organelles, higher resolution.
• Cell Size Calculation:
  • Magnification = Image size / Object size
• Cell Types:
  • Eukaryotic (e.g., plant, animal cells): Have a nucleus.
  • Prokaryotic (e.g., bacteria): No nucleus.
• Organelles:
  • Cell membrane: Semi-permeable, maintains cell integrity.
  • Cell wall: In plants/bacteria, provides rigidity.
  • Cytoplasm: Site for chemical reactions.
  • Mitochondria: Respiration and energy release.
  • Ribosomes: Protein synthesis.
  • Chloroplasts (plants): Site for photosynthesis.
  • Vacuole (plants): Stores sap.
• Bacterial Reproduction (Triple only):
  • Binary fission in bacteria.
  • Culture growth in petri dishes using aseptic technique.
• DNA and Mitosis:
  • Eukaryotic DNA in chromosomes. Humans have 23 pairs.
  • Mitosis: Process of cell duplication for growth and repair.
• Cell Specialization:
  • Examples: Nerve, muscle, root hair cells.
  • Stem cells: Unspecialized, found in embryos, marrow, and plant meristems.
  • Cloning plants: Prevent extinction, produce crops.

Movement and Transport

• Diffusion:
  • Movement from high to low concentration, passive process.
• Osmosis:
  • Water movement across a semi-permeable membrane.
• Active Transport:
  • Movement against the concentration gradient using energy.
• Tissues and Organs:
  • Tissues: Group of similar cells.
  • Organs: Group of tissues.
  • Organ systems: Groups of organs working together.

Digestion and Enzymes

• Digestive System:
  • Breaks down food into nutrients.
• Bile and Enzymes:
  • Bile neutralizes stomach acid, emulsifies fats.
  • Enzymes: Biological catalysts.
• Enzyme Types:
  • Carbohydrases, proteases, and lipases.
  • Lock and key principle for enzyme specificity.
• Enzyme Activity:
  • Affected by temperature and pH.
• Practical Experiments:
  • Impact of temperature/pH on enzyme activity.

Respiratory and Circulatory Systems

• Respiration:
  • Breathing supplies oxygen for cellular respiration.
• Circulatory System:
  • Double circulatory system: Blood returns to heart twice.
  • Heart structure and blood flow path.
  • Blood vessels: Arteries, veins, capillaries.

Diseases

• Non-communicable Diseases:
  • Examples: Cardiovascular diseases, diabetes, cancer.
• Communicable Diseases:
  • Pathogens: Viruses, bacteria, fungi, protists.
  • Protection by immune system.
• Vaccines and Antibiotics:
  • Vaccines introduce inert pathogen to build immunity.
  • Antibiotics kill bacteria, not effective against viruses.

Plants

• Plant Structures:
  • Leaf structure and functions.
  • Xylem and phloem in transpiration and translocation.
• Photosynthesis:
  • Occurs in chloroplasts; affected by temperature, light, and CO2.
  • Practical: Measure rate of photosynthesis.

Metabolism

• Sum of all chemical reactions in a cell or organism.
• Includes processes like respiration and synthesis of biomolecules.

Conclusion

This guide provides a comprehensive review of key topics in AQA GCSE Biology Paper 1. For further study, refer to additional resources and practice questions.