AQA GCSE Biology Paper 1 Overview

Covers: Cells, Organization, Infection and Response, Bioenergetics.

Cells

• Types of Cells
  • Eukaryotic Cells: Have a nucleus (e.g., plant and animal cells).
  • Prokaryotic Cells: Do not have a nucleus.
• Cell Structures
  • Cell Membrane: Semi-permeable, controls what enters and exits the cell.
  • Cell Wall: In plant cells and bacteria, made of cellulose for support.
  • Cytoplasm: Where most chemical reactions occur.
  • Mitochondria: Site of respiration, energy release.
  • Ribosomes: Site of protein synthesis.
  • Chloroplasts: In plant cells, site of photosynthesis.
  • Vacuole: Stores cell sap.
• Microscopes
  • Light Microscopes: Lower resolution, can see cells and nucleus.
  • Electron Microscopes: High resolution, can see subcellular structures.

Practical: Culturing Bacteria

• Use aseptic technique to prevent contamination.
• Incubate bacteria at 25°C.
• Use antibiotics to test bacterial resistance.

Cell Division

• Mitosis: Process of cell division for growth and repair.
  • Steps: Duplication, alignment, separation, and formation of two identical cells.

Specialized Cells and Stem Cells

• Specialization: Different cell types for different functions.
• Stem Cells: Can develop into different cell types.
  • Found in embryos, bone marrow, and plant meristems.
• Ethical Considerations: Cloning and stem cell use.

Diffusion, Osmosis, and Active Transport

• Diffusion: Movement from high to low concentration.
• Osmosis: Diffusion of water through a semi-permeable membrane.
• Active Transport: Movement against concentration gradient using energy.

Organization

• Hierarchy: Cells → Tissues → Organs → Organ Systems.
• Digestive System: Breaks down food into nutrients.
  • Role of Enzymes: Biological catalysts, specific to substrates.
  • Lock and Key Model: Substrate fits enzyme's active site.

Respiratory System

• Air pathway: Trachea → Bronchi → Bronchioles → Alveoli.
• Alveoli: Site of gas exchange.

Circulatory System

• Heart Structure: Double circulatory system.
  • Flow of Blood: Right atrium → Right ventricle → Lungs → Left atrium → Left ventricle → Body.
• Blood Vessels: Arteries (away from heart), veins (toward heart), capillaries (exchange).

Non-communicable Diseases

• Examples: Cardiovascular disease (CHD), diabetes, cancer.
• Risk Factors: Diet, smoking, alcohol, lack of exercise.

Communicable Diseases

• Pathogens: Viruses, bacteria, fungi, protists.
  • Examples: Measles, HIV, Salmonella, Malaria.
• Body Defenses: Skin, mucus, white blood cells.
• Vaccines: Induce immunity by exposing to inactive pathogen.

Bioenergetics

• Photosynthesis:
  • Occurs in chloroplasts.
  • Equation: 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂
• Respiration:
  • Aerobic: Uses oxygen, more efficient.
  • Anaerobic: Less efficient, produces lactic acid.

Practical: Photosynthesis

• Measure rate by observing oxygen production from pondweed.

Metabolism

• Sum of all chemical reactions in the organism.
• Involves respiration, conversion of glucose, synthesis of lipids, proteins.

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Note: This summary emphasizes the key points and practicals necessary for understanding the topics covered in the AQA GCSE Biology Paper 1. It is advised to delve deeper into each subject for a comprehensive understanding.