AQA GCSE Biology Paper 1 Overview

Topics Covered

• Cells
• Organization
• Infection and Response
• Bioenergetics

Cells

Eukaryotic and Prokaryotic Cells

• Eukaryotic Cells: Have a nucleus (e.g., plant and animal cells).
• Prokaryotic Cells: No nucleus.
• Both contain similar organelles.

Microscopy

• Light Microscope: Limited visibility, can see cells and nuclei.
• Electron Microscope: Higher resolution, can see organelles.

Cell Structure

• Cell Membrane: Semi-permeable, keeps cell contents inside.
• Cell Wall: Provides rigid structure in plants and bacteria.
• Cytoplasm: Site of most chemical reactions.
• Mitochondria: Site of respiration.
• Ribosomes: Protein synthesis.
• Chloroplasts: Photosynthesis in plant cells.
• Vacuole: Stores sap in plant cells.

Bacteria (Triple Science)

• Multiply by binary fission.
• Practical: Culturing bacteria with aseptic techniques.

DNA and Chromosomes

• DNA stored in chromosomes, humans have 23 pairs.
• Diploid Cells: Full set, 23 pairs.
• Haploid Cells: Gametes, 23 single chromosomes.

Cell Division

• Mitosis: Process of cell division for growth and repair.

Specialized Cells and Stem Cells

• Different cells specialize for specific functions.
• Stem Cells: Can become different cell types.
• Ethical considerations in stem cell use.

Diffusion, Osmosis, and Active Transport

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

Organization

• Tissues: Groups of similar cells.
• Organs: Groups of tissues.
• Organ Systems: Groups of organs.

Digestive System

• Enzymes: Biological catalysts, specific to substrates.
• Types: Carbohydrases, Proteases, Lipases.
• Amylase: Breaks down starch into glucose.
• Proteases: Break down proteins.
• Lipases: Break down lipids.

Circulatory System

• Double circulatory system.
• Heart: Pumps blood; has right and left sides.
• Blood Vessels: Arteries (away), veins (towards), capillaries (exchange).

Infection and Response

• Pathogens: Cause communicable diseases (viruses, bacteria, fungi, protists).
• Virus Reproduction: Invade cells to replicate.
• Bacterial Infections: Release toxins.
• Fungal Infections: Affect plants and animals.

Body Defenses

• Skin, mucus, acid, enzymes, and white blood cells.
• Vaccination: Introduce dead/inert pathogens to stimulate immunity.

Bioenergetics

Photosynthesis

• Endothermic reaction.
• Factors affecting rate: Temperature, light intensity, CO2 concentration.

Respiration

• Aerobic: With oxygen, produces more energy.
• Anaerobic: Without oxygen, produces lactic acid in humans.
• Fermentation: In yeast, produces ethanol and CO2.

Metabolism

• Sum of all cellular reactions.
• Includes respiration, synthesis, and breakdown reactions.

Practical Experiments

• Microscopy: Calculating actual cell size.
• Bacterial Culturing: Aseptic technique.
• Osmosis: Potato cylinder mass change in sugar solutions.
• Enzyme Activity: Amylase and starch reaction times.
• Photosynthesis Rate: Measuring oxygen production in pondweed.
• Respiration: Comparing aerobic and anaerobic outputs.

These notes summarize key concepts needed for the AQA GCSE Biology Paper 1, including practical experiment methodologies and the ethical considerations surrounding specific biological processes.