AQA GCSE Biology Paper 1 Overview

General Introduction

• Comprehensive video covering all necessary topics for AQA GCSE Biology Paper 1.
• Includes key terms, topic summaries, examiner tips, and questions with answers.

Eukaryotic and Prokaryotic Cells

Eukaryotic Cells

• Examples: Plant and Animal cells.
• Key structures: Cytoplasm, Cell membrane, Nucleus (genetic material within).
• Animal cells: Mitochondria, Nucleus, Ribosomes.
• Plant cells: Also have Cell wall, Permanent vacuole, Chloroplasts.
  • Unique to plant cells: Cell wall, Permanent vacuole, Chloroplasts.

Functions of Cell Structures

• Cytoplasm: Gel-like, suspends organelles, site for chemical reactions.
• Cell Membrane: Controls passage of substances.
• Nucleus: Contains genetic material, controls cell activity.
• Mitochondria: Site of aerobic respiration, energy release.
• Ribosomes: Site of protein synthesis.
• Chloroplasts: Contains chlorophyll, site of photosynthesis.
• Cell Wall: Provides strength and support.
• Permanent Vacuole: Filled with cell sap, keeps cell turgid.

Prokaryotic Cells

• Examples: Bacteria.
• Smaller in size compared to eukaryotic cells.
• Structures: Cytoplasm, Cell membrane, Cell Wall.
• Genetic material: Single loop of DNA in cytoplasm, sometimes plasmids.

Cell Specialization and Differentiation

Specialization

• Cells organized from simple to complex: Cell -> Tissue -> Organ -> Organ system -> Organism.
• Examples of specialized cells: Sperm cell, Muscle cell, Nerve cell, Xylem, Phloem, Root hair cell.

Differentiation

• Process where cells become specialized.
• In animals: Occurs early in development.
• In plants: Can occur throughout life in meristems.

Microscopes

• Light Microscope: Uses light to create images, magnifies up to 2000x, cheaper/easier to use, can view living specimens.
• Electron Microscope: Uses electron beams, magnifies up to 2 million times, higher resolution, clearer images, cannot view live specimens.
• Magnification: How much larger the image is compared to the object.
• Resolution: Ability to see two points as separate.

Inhibition Zones Practical

• Tests effectiveness of antibiotics.
• Key step: Aseptic technique to prevent contamination.
• Measure inhibition zones to determine effectiveness.

Mitosis

• Cell division for growth, repair, and development.
• Stages: DNA replication, Cell growth, Cytoplasmic division.

Stem Cells

• Undifferentiated cells with potential to become specialized.
• Types: Embryonic (can become any cell), Adult (limited differentiation), Plant meristems.
• Uses: Disease treatment, cloning, agriculture.
• Ethical concerns with embryonic stem cells.

Diffusion, Osmosis, and Active Transport

Diffusion

• Movement of particles from high to low concentration.

Osmosis

• Diffusion of water across a partially permeable membrane from dilute to concentrated solution.

Active Transport

• Movement against concentration gradient, requires energy.
• Examples: Nutrient uptake by roots, sugar absorption in intestines.

Organization: Digestive and Circulatory Systems

Digestive System

• Functions to break down food into smaller, absorbable components.
• Key organs: Mouth, Esophagus, Stomach, Intestines, Liver, Pancreas.
• Enzymes: Biological catalysts that aid in digestion.

Circulatory System

• Heart: Pumps blood, composed of four chambers.
• Blood vessels: Arteries, Veins, Capillaries.
• Circulatory routes: Pulmonary (lungs) and Systemic (body).
• Heart valves prevent backflow of blood.

Respiratory System

• Lungs: Site for gas exchange.
• Alveoli: Increase surface area for diffusion, have a rich blood supply.

Blood Components

• Plasma: Transports nutrients, waste products.
• Red Blood Cells: Carry oxygen.
• White Blood Cells: Fight infections.
• Platelets: Help in blood clotting.

Coronary Heart Disease

• Caused by blocked coronary arteries.
• Treatments: Stents, Statins, Valve replacements, Heart transplants.

Health and Disease

• Types of diseases: Communicable (infectious) and non-communicable.
• Interaction between different types of diseases.
• Impact on individual, community, and global levels.
• Risk factors and causes for diseases like cancer.

Plant Tissues and Organs

• Tissues: Xylem, Phloem, Meristems, Guard cells, Stomata.
• Functions: Transport, growth, gas exchange.

Metabolism

• Sum of all chemical reactions in an organism.
• Relies on enzymes.