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  1. Revision notes
  2. IGCSE
  3. Biology
  4. Cambridge International
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  6. Eye Function - Focus

Eye Function - Focus

Biology: Cambridge International GCSE Supplement, topic 14.2.4

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Previous topic14.2.3 Eye Function - LightNext topic14.2.5 Eye Function - Detecting Colour

Biology: Cambridge International GCSE Supplement contents

  1. 1 Classification of Living Organisms

    • 1.1 Characteristics of Living Organisms

      • 1.1.1 MRS GREN
      • 1.1.2 M.R.S.
      • 1.1.3 G.R.E.N.
    • 1.2 Concept and Uses of Classification Systems

      • 1.2.1 Classification
      • 1.2.2 Linnaean Classification
      • 1.2.3 Ancestors & DNA
      • 1.2.4 Dichotomous Keys
    • 1.3 Features of Organisms

      • 1.3.1 Kingdoms - Animals & Plants
      • 1.3.2 Kingdoms - Fungi, Prokaryotes, Protoctista
      • 1.3.3 Vertebrates
      • 1.3.4 Anthropods
      • 1.3.5 Plant Classification
      • 1.3.6 Cellular Structures - Cells
      • 1.3.7 Cellular Structures - Viruses
  2. 2 Organisation of the Organism

    • 2.1 Cell Structure

      • 2.1.1 Animal Cells
      • 2.1.2 Plant Cells
      • 2.1.3 Properties of Prokaryotes
      • 2.1.4 Cells & Tissues
      • 2.1.5 Organs
      • 2.1.6 Organ Systems
      • 2.1.7 Organisms
      • 2.1.8 Ciliated Cells
      • 2.1.9 Root Hair Cells & Palisade Mesophyll Cells
      • 2.1.10 Neurones
      • 2.1.11 Red Blood Cells
      • 2.1.12 Sperm & Egg Cells
    • 2.2 Size of Specimens

      • 2.2.1 Magnification
      • 2.2.2 Microscopy
      • 2.2.3 Orders of Magnitude
      • 2.2.4 Microscopy - Calculations
      • 2.2.5 Converting Measurements
      • 2.2.6 End of Topic Test - Cells
      • 2.2.7 Exam-Style Questions - Cell Structure & Microscopy
  3. 3 Movement Into & Out of Cells

    • 3.1 Diffusion

      • 3.1.1 Diffusion
      • 3.1.2 Factors Affecting Diffusion
      • 3.1.3 Surface Area : Volume
    • 3.2 Osmosis

      • 3.2.1 Water
      • 3.2.2 Osmosis
      • 3.2.3 Osmosis Experiment
      • 3.2.4 Osmosis in Plants
      • 3.2.5 Osmotic Balance
      • 3.2.6 Required Practical - Osmosis
    • 3.3 Active Transport

      • 3.3.1 Active Transport
      • 3.3.2 Transport in Cells
      • 3.3.3 Carrier Proteins
      • 3.3.4 Grade 9 - Cell Transport
      • 3.3.5 End of Topic Test - Cell Transport
      • 3.3.6 Exam-Style Questions - Substance Exchange
  4. 4 Biological Molecules

    • 4.1 Biological Molecules

      • 4.1.1 Chemical Elements
      • 4.1.2 Larger Molecules
      • 4.1.3 Testing for Biological Molecules
      • 4.1.4 DNA
      • 4.1.5 DNA Pairings
  5. 5 Enzymes

    • 5.1 Enzymes

      • 5.1.1 Enzymes
      • 5.1.2 Rate of Enzyme Action
      • 5.1.3 Investigating Rate
      • 5.1.4 End of Topic Test - Enzymes
      • 5.1.5 Grade 9 - Enzymes
  6. 6 Plant Nutrition

    • 6.1 Photosynthesis

      • 6.1.1 Photosynthesis
      • 6.1.2 Photosynthesis - Plant Gas Exchange
      • 6.1.3 Uses of Glucose
      • 6.1.4 Ion Deficiency Conditions
      • 6.1.5 Rate of Photosynthesis
      • 6.1.6 Photosynthesis Experiments
      • 6.1.7 Photosynthesis Equation
      • 6.1.8 Photosynthesis - Calculations
      • 6.1.9 Limiting Factors
      • 6.1.10 Limiting Factors 2
      • 6.1.11 Grade 9 - Photosynthesis Experiment
      • 6.1.12 Exam-Style Questions - Photosynthesis
    • 6.2 Leaf Structure

      • 6.2.1 Leaf Structure
      • 6.2.2 Stomata
      • 6.2.3 Plant Tissues
      • 6.2.4 Leaf Adaptations
      • 6.2.5 End of Topic Test - Photosynthesis
  7. 7 Human Nutrition

    • 7.1 Diet

      • 7.1.1 Diet
      • 7.1.2 Vitamins & Minerals
      • 7.1.3 Scurvy & Rickets
    • 7.2 Digestive System

      • 7.2.1 Digestive System
      • 7.2.2 Functions of the Digestive System
      • 7.2.3 Steps of Digestion
    • 7.3 Physical Digestion

      • 7.3.1 Physical Digestion - Human Tooth
      • 7.3.2 Teeth Types
      • 7.3.3 Tooth Diseases
    • 7.4 Chemical Digestion

      • 7.4.1 Digestive Enzymes
      • 7.4.2 Examples of Digestive Enzymes - Amylases
      • 7.4.3 Examples of Digestive Enzymes - Proteases
      • 7.4.4 Examples of Digestive Enzymes - Lipases
      • 7.4.5 Chemical Digestion - Stomach
      • 7.4.6 Exam-Style Questions - Digestive Enzymes
      • 7.4.7 Pepsin & Trypsin
    • 7.5 Absorption

      • 7.5.1 Small Intestine
      • 7.5.2 Villi
  8. 8 Transport in Plants

    • 8.1 Xylem & Phloem

      • 8.1.1 Plant Vessels
      • 8.1.2 Specialised Plant Cells - Xylem
    • 8.2 Water Uptake

      • 8.2.1 Water Uptake
      • 8.2.2 Specialised Plant Cells - Root Hair
      • 8.2.3 Exam-Style Questions - Transport in Plants
    • 8.3 Transpiration

      • 8.3.1 Transpiration
      • 8.3.2 Transpiration Tissues - Xylem
      • 8.3.3 States of Stomata
      • 8.3.4 Rate of Transpiration
      • 8.3.5 Measuring Transpiration
    • 8.4 Translocation

      • 8.4.1 Translocation Tissues - Phloem
      • 8.4.2 Translocation
      • 8.4.3 End of Topic Test - Plant Transport
  9. 9 Transport in Animals

    • 9.1 Circulatory Systems

      • 9.1.1 Circulatory Systems
      • 9.1.2 Double Circulatory Systems
    • 9.2 Heart

      • 9.2.1 Mammal Heart Function
      • 9.2.2 Mammal Heart Structure
      • 9.2.3 Heart Monitoring
      • 9.2.4 Exercise Recovery
      • 9.2.5 Heart Disease
      • 9.2.6 Treatment of Heart Disease
    • 9.3 Blood Vessels

      • 9.3.1 Types of Vessels - Arteries
      • 9.3.2 Types of Vessels - Veins
      • 9.3.3 Types of Vessels - Capillaries
      • 9.3.4 Important Vessels
      • 9.3.5 End of Topic Test - Circulatory System
      • 9.3.6 Exam-Style Questions - Circulatory System
    • 9.4 Blood

      • 9.4.1 Blood Components
      • 9.4.2 Red Blood Cells
      • 9.4.3 White Blood Cells
      • 9.4.4 Platelets
      • 9.4.5 Blood Clotting
  10. 10 Diseases & Immunity

    • 10.1 Diseases & Immunity

      • 10.1.1 Health Issues
      • 10.1.2 Causing Diseases
      • 10.1.3 Preventing Infection
      • 10.1.4 Human Defence Systems - Non-Specific Defences
      • 10.1.5 Human Defence Systems - Immune Systems
      • 10.1.6 Cholera
      • 10.1.7 Antibodies
      • 10.1.8 Vaccination & Immunity
      • 10.1.9 Passive Immunity
      • 10.1.10 Viruses
      • 10.1.11 End of Topic Test - Health & Disease
  11. 11 Gas Exchange in Humans

    • 11.1 Gas Exchange in Humans

      • 11.1.1 Exchange Surface
      • 11.1.2 Lung Gas Exchange
      • 11.1.3 Alveoli
      • 11.1.4 Breathing Process
      • 11.1.5 Breathing Composition
      • 11.1.6 Breathing & Exercise
      • 11.1.7 Thorax
  12. 12 Respiration

    • 12.1 Respiration

      • 12.1.1 Respiration Uses
      • 12.1.2 Investigating Respiration
      • 12.1.3 End of Topic Test - Respiration
      • 12.1.4 Exam-Style Questions - Respiration During Exercise
    • 12.2 Aerobic & Anaerobic Respiration

      • 12.2.1 Respiration Reactions
      • 12.2.2 Oxygen Use & Debt
      • 12.2.3 Aerobic and Anaerobic Respiration
  13. 13 Excretion in Humans

    • 13.1 Excretion in Humans

      • 13.1.1 Excretion in Humans
      • 13.1.2 Urea
      • 13.1.3 Water Balance
      • 13.1.4 Water in Urine
      • 13.1.5 The Kidneys
      • 13.1.6 Urine Production
      • 13.1.7 Urinary System
      • 13.1.8 Kidney Transplants
      • 13.1.9 Kidney Transplants - Pros & Cons
  14. 14 Coordination & Response

    • 14.1 Coordination & Response

      • 14.1.1 The Nervous System
      • 14.1.2 Reflex Actions
      • 14.1.3 Reflex Arc
      • 14.1.4 Synapses
      • 14.1.5 End of Topic Test - Nervous Control
      • 14.1.6 Exam-Style Questions - Nervous System
    • 14.2 Sense Organs

      • 14.2.1 Sense Organs
      • 14.2.2 Eye Anatomy
      • 14.2.3 Eye Function - Light
      • 14.2.4 Eye Function - Focus
      • 14.2.5 Eye Function - Detecting Colour
    • 14.3 Hormones

      • 14.3.1 Hormones in Humans
      • 14.3.2 Endocrine Glands
      • 14.3.3 Nervous vs Endocrine
      • 14.3.4 Adrenaline
    • 14.4 Homeostasis

      • 14.4.1 Homeostasis
      • 14.4.2 Regulating Internal Conditions
      • 14.4.3 Control Systems
      • 14.4.4 Negative Feedback
      • 14.4.5 Thermoregulation
      • 14.4.6 Thermoregulation - Hot and Cold
      • 14.4.7 Thermoregulation - Skin
      • 14.4.8 Thermoregulation - Sweating & Shivering
      • 14.4.9 Thermoregulation - Hairs
      • 14.4.10 Thermoregulation - Blood Vessels
      • 14.4.11 Blood Glucose
      • 14.4.12 Detecting Glucose
      • 14.4.13 Type 1 Diabetes
      • 14.4.14 End of Topic Test - Homeostasis & Hormones
      • 14.4.15 Grade 9 - Hormonal Coordination
    • 14.5 Tropic Responses

      • 14.5.1 Types of Tropisms
      • 14.5.2 Auxins and Tropisms
      • 14.5.3 Required Practical - Plant Hormones
  15. 15 Drugs

    • 15.1 Drugs

      • 15.1.1 Antibiotics
      • 15.1.2 Antibiotic Resistance
      • 15.1.3 Resistant Bacteria
  16. 16 Reproduction

    • 16.1 Asexual Reproduction

      • 16.1.1 Asexual Reproduction
      • 16.1.2 Advantages of Asexual Reproduction
    • 16.2 Sexual Reproduction

      • 16.2.1 Sexual Reproduction
      • 16.2.2 Gametes vs. Zygotes
      • 16.2.3 Advantages of Sexual Reproduction
    • 16.3 Sexual Reproduction in Plants

      • 16.3.1 Flower Anatomy
      • 16.3.2 Pollination Methods
      • 16.3.3 Self-pollination & Cross-polination
      • 16.3.4 Germination
    • 16.4 Sexual Reproduction in Humans

      • 16.4.1 Human Reproductive Systems - Male
      • 16.4.2 Human Reproductive Systems - Female
      • 16.4.3 Human Gametes - Sperm Cells
      • 16.4.4 Human Gametes - Egg Cells
      • 16.4.5 Human Gametes - Egg vs. Sperm
      • 16.4.6 Pregnancy
      • 16.4.7 Pregnancy Health
      • 16.4.8 Birth - Labour
      • 16.4.9 Birth - Breast-feeding
    • 16.5 Sex Hormones in Humans

      • 16.5.1 Puberty
      • 16.5.2 Menstruation
      • 16.5.3 Menstrual Cycle
      • 16.5.4 Menstrual Hormones
      • 16.5.5 Baby Planning
      • 16.5.6 Infertility
      • 16.5.7 Fertility Treatments Pros & Cons
      • 16.5.8 End of Topic Test - Reproductive Hormones
      • 16.5.9 Exam-Style Questions - Hormones & Contraception
    • 16.6 Sexually Transmitted Infections

      • 16.6.1 HIV
  17. 17 Inheritance

    • 17.1 Chromosomes, Genes & Proteins

      • 17.1.1 Genome
      • 17.1.2 Genome Diagram
      • 17.1.3 Gene Expression
      • 17.1.4 DNA Pairings
      • 17.1.5 Protein Synthesis
      • 17.1.6 Synthesis Process
    • 17.2 Mitosis & Meiosis

      • 17.2.1 Cell Division
      • 17.2.2 Stem Cells
      • 17.2.3 Meiosis
    • 17.3 Monohybrid Inheritance

      • 17.3.1 Alleles
      • 17.3.2 Phenotype
      • 17.3.3 Sex Determination
      • 17.3.4 Monohybrid Inheritance
      • 17.3.5 Punnett Square
      • 17.3.6 Blood Groups
      • 17.3.7 Sex-linked Disorders
      • 17.3.8 Cystic Fibrosis
      • 17.3.9 Cystic Fibrosis - Punnett Square
      • 17.3.10 Cystic Fibrosis - Pedigree Diagram
      • 17.3.11 Test Crosses
      • 17.3.12 End of Topic Test - Genes & Inheritance
  18. 18 Variation & Selection

    • 18.1 Variation

      • 18.1.1 Variation
      • 18.1.2 Continuous & Discontinuous Variation
      • 18.1.3 Mutations
      • 18.1.4 Sickle Cell Symptoms
      • 18.1.5 Sickle Cell & Malaria
      • 18.1.6 Sickle Cell Inheritance
    • 18.2 Adaptive Features

      • 18.2.1 Adaptive Features
      • 18.2.2 Plant Adaptations
    • 18.3 Selection

      • 18.3.1 Natural Selection
      • 18.3.2 Evolution
      • 18.3.3 Antibiotic Resistance
      • 18.3.4 Selective Breeding
      • 18.3.5 Selective Breeding Process
      • 18.3.6 Uses of Selective Breeding
      • 18.3.7 Grade 9 - Evolution
      • 18.3.8 End of Topic Test - Variation & Evolution
  19. 19 Organisms & Their Environment

    • 19.1 Energy Flow

      • 19.1.1 Energy Flow
    • 19.2 Food Chains & Food Webs

      • 19.2.1 Food Chains & Webs
      • 19.2.2 Decomposers
      • 19.2.3 Trophic Levels
      • 19.2.4 Pyramids of Biomass
      • 19.2.5 Editing Food Chains
      • 19.2.6 Reasons for Energy Wastage
      • 19.2.7 Transfer Efficiency
      • 19.2.8 Exam-Style Questions - Biomass
      • 19.2.9 End of Topic Test - Food and Trophic Levels
    • 19.3 Nutrient Cycles

      • 19.3.1 Importance of Cycling
      • 19.3.2 Carbon Cycle
      • 19.3.3 Peat Bog
      • 19.3.4 Water Cycle
      • 19.3.5 Nitrogen Cycle
      • 19.3.6 Nitrogen Cycle & Microorganisms
    • 19.4 Populations

      • 19.4.1 Ecosystems
      • 19.4.2 Population Growth Factors
      • 19.4.3 Population Growth
      • 19.4.4 Human Population
      • 19.4.5 Grade 9 - Ecosystems
      • 19.4.6 End of Topic Test - Ecosystems
  20. 20 Human Influence on Ecosystems

    • 20.1 Food Supply

      • 20.1.1 Food Supply & Modern Technology
      • 20.1.2 Food Supply & Modern Technology Drawbacks
      • 20.1.3 Food Supply & Populations
      • 20.1.4 Causes of Famine
      • 20.1.5 Declining Fish Stock
    • 20.2 Habitat Destruction

      • 20.2.1 Habitat Destruction
      • 20.2.2 Deforestation
      • 20.2.3 Exam-Style Questions - Deforestation
    • 20.3 Pollution

      • 20.3.1 Humans & Waste
      • 20.3.2 Nuclear Waste
      • 20.3.3 Land Pollution
      • 20.3.4 Waste Production - Plastics
      • 20.3.5 Air Pollution
      • 20.3.6 Greenhouse Effect
      • 20.3.7 Global Warming
      • 20.3.8 Eutrophication
    • 20.4 Conservation

      • 20.4.1 Conservation
      • 20.4.2 Reasons to Conserve Biodiversity
      • 20.4.3 Renewable Resources
      • 20.4.4 Recycling
      • 20.4.5 Sustainability
      • 20.4.6 Sewage Treatment
      • 20.4.7 Sustainable Fishing
      • 20.4.8 Sustainable Forest
      • 20.4.9 Endangered Species
      • 20.4.10 Causes of Endangering
  21. 21 Biotechnology & Genetic Modification

    • 21.1 Biotechnology & Genetic Modification

      • 21.1.1 Bacteria in Biotechnology
    • 21.2 Biotechnology

      • 21.2.1 Yeast in Biotechnology
      • 21.2.2 Enzymes in Biotechnology
      • 21.2.3 Penicillin
    • 21.3 Genetic Modification

      • 21.3.1 Genetic Modification
      • 21.3.2 Genetic Modification - Process
      • 21.3.3 Genetic Modification - Controversy
      • 21.3.4 Pros & Cons of Genetic Modification

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