OCR GCSE Biology Paper 1 Overview

Topics Covered

• Cell Level Systems
• Scaling Up
• Organism Level Systems

Cells

• All life consists of cells
• Microscopes:
  • Light microscopes can see cells, nucleus.
  • Electron microscopes provide finer details (organelles).
• Calculations:
  • Magnification = Image size / Object size
  • Actual size = Image size / Magnification

Cell Types

• Eukaryotic cells: Have a nucleus (e.g., plant, animal cells)
• Prokaryotic cells: No nucleus, have similar organelles

Cell Structures

• Cell Membrane: Semi-permeable, controls entry and exit
• Cell Wall (plants/bacteria): Made of cellulose, provides structure
• Cytoplasm: Site of most chemical reactions
• Mitochondria: Site of respiration, energy release
• Ribosomes: Protein synthesis
• Chloroplasts (plants): Site of photosynthesis
• Permanent Vacuole (plants): Stores cell sap

Bacteria and Growth

• Binary Fission: Doubling every set time interval
• Practical: Culture bacteria on agar, aseptic technique
• Calculating Area: Using πr² or πd²/4

DNA and Genetics

• Genome: Total genetic material
• DNA Structure: Double helix, made of nucleotides (A, T, C, G)
• Human Genome Project: Completed in 2003, mapped genes
• Genotype vs. Phenotype: Code in DNA vs. expressed traits
• mRNA and Protein Synthesis: mRNA copies DNA, proteins made in ribosomes
• Mutations: Can result in non-functional proteins

Enzymes

• Function: Biological catalysts, specific to substrates
• Examples:
  • Amylase: Starch to glucose
  • Proteases: Proteins to amino acids
  • Lipases: Lipids to fatty acids and glycerol
• Enzyme Activity: Affected by temperature, pH
• Practical: Mix amylase with starch, observe with iodine

Respiration

• Aerobic Respiration: With oxygen, exothermic
• Anaerobic Respiration: Without oxygen, produces lactic acid (animals), ethanol (plants/yeast)
• Metabolism: Sum of all reactions

Photosynthesis

• Process: Light energy converts CO2 and water to glucose and oxygen
• Limiting Factors: Temperature, light intensity, CO2 concentration
• Practical: Measure O2 production from pondweed

Scaling Up

• Diffusion and Osmosis: Movement of molecules, passive
• Practical: Potato cylinders in sugar solutions
• Active Transport: Uses energy, moves substances against gradient

Cell Division

• Mitosis: Produces identical cells for growth and repair
• Stem Cells: Unspecialized, potential to treat diseases

Circulatory System

• Heart Structure: Double circulatory system
• Blood Vessels: Arteries (away), veins (toward), capillaries (exchange)
• Coronary Heart Disease: Blockages lead to heart attacks

Plant Systems

• Organs: Leaves, roots, stems
• Xylem and Phloem: Transport water and nutrients
• Transpiration and Translocation: Water movement, food transport

Homeostasis and Control Systems

• Regulation: Blood glucose, temperature, water levels
• Nervous System: CNS and PNS, reflex arcs
• Endocrine System: Hormones, gland functions

Reproduction

• Menstruation: Hormonal regulation of cycle
• Contraception: Methods to prevent fertilization
• IVF: Assisted reproduction technology

Plant Hormones

• Effects: Growth, ripening, phototropism, geotropism

Additional Triple Content

• Bacterial Growth Calculations
• Genetic Material Details
• Enzyme Specifics
• Water and Nitrogen Balance
• Brain Functions
• Eye Accommodation
• Thermoregulation