GCSE Biology Paper 1 Revision

Introduction

• Overview of key content for biology GCSE Paper 1
• Invitation for feedback and requests for chemistry and physics

Cell Biology

Cell Structure and Function

• Two categories of cells: Eukaryotic and Prokaryotic
  • Eukaryotic Cells: True nucleus, DNA in chromosomes (plant and animal cells)
    • Plant Cells: Chloroplast (photosynthesis), permanent vacuole (cell sap), cell wall (structure and support)
    • Common Organelles: Mitochondria (energy), cytoplasm (reactions), cell membrane (control), ribosomes (protein synthesis), nucleus (DNA)
  • Prokaryotic Cells (Bacteria): Free DNA, nucleoid, binary fission, plasmids (antibiotic resistance), flagella (movement)

Specialized Cells

• Animal Cells
  • Nerve Cells: Insulating fat sheath, long branches
  • Muscle Cells: Mitochondria (muscle contraction)
  • Sperm Cells: Acrosome (enzymes), haploid nucleus, mitochondria, tail
  • Egg Cells: Mitochondria (growth), cytoplasm (nutrients), haploid nucleus, membrane changes post-fertilization
  • Epithelial Cells: Ciliated, move mucus
  • Red Blood Cells: Hemoglobin (oxygen transport), biconcave shape, thin membrane
• Plant Cells
  • Root Hair Cells: Large surface area (water and mineral absorption)
  • Xylem: Water movement, lignin, hollow tube
  • Phloem: Companion cells, transport dissolved sugars

Cell Transport

• Diffusion: Passive, high to low concentration
• Osmosis: Passive, water movement from dilute to concentrated solution
• Active Transport: Requires energy, low to high concentration

Cell Division

• Mitosis: Produces genetically identical cells for growth and repair
• Meiosis: Produces genetically different gametes, important for variation

DNA and Microscopy

• DNA Structure: Double helix, nucleotides (phosphate, deoxyribose, bases A-T, C-G)
• Microscopy: Magnification calculations, light microscope vs electron microscope

Enzymes

• Biological catalysts, affected by temperature, pH, and substrate concentration
• Specific enzymes: Amylase (starch to glucose), Protease (proteins to amino acids), Lipase (lipids to fatty acids and glycerol)

Photosynthesis

• Word and balanced chemical equations
• Limiting factors: Light intensity, CO2 concentration, temperature
• Uses of glucose in plants: Stored as starch, cellulose for cell walls, lipids for seeds, respiration

Respiration

• Types: Aerobic (with oxygen) and Anaerobic (without oxygen)
• Fermentation (yeast), lactic acid in muscles
• Response to exercise: Heart rate and breathing increase, glycogen breakdown

Immune System

• White Blood Cells: Phagocytes (engulf pathogens), Lymphocytes (produce antibodies, antitoxins)
• Non-Specific Defenses: Skin, hydrochloric acid, mucus, nose hairs

Diseases

• Communicable Diseases: Spread between organisms
  • Fungal: Athlete's foot, rose black spot
  • Protists: Malaria
  • Viral: TMV, influenza, measles
  • Bacterial: Gonorrhea, salmonella
• Non-Communicable Diseases: Cannot be spread
  • Cancer: Benign vs malignant tumors
  • Coronary Heart Disease (CHD): Cholesterol buildup, treatment with diet, exercise, and stents

Plant Defenses

• Physical: Thorns, bark, waxy cuticle
• Chemical: Poisons, antimicrobial substances
• Mechanical: Structural features

Plant Transport Systems

• Vascular Bundles: Xylem and phloem
• Leaf Structure: Epidermis, palisade cells, spongy mesophyll, stomata, guard cells

Exam Preparation

• Encouragement to review linked content and playlists for further study