Natural Selection

Natural selection was proposed by Charles Darwin in 1859. He theorised that all species evolved from simple life forms that first appeared on Earth more than three billion years ago. Natural selection happens like this:

Genetic variation

Within a biological population, different individuals have genetic variation (differences in characteristics).

Survival of the fittest

Individuals possessing genes that make them better adapted to the environment will have a greater chance of survival.

Breeding

Individuals with the best chances of survival are the most likely to breed successfully (because they survive).

Best characteristics survive

The characteristics responsible for the increase in the likelihood of survival are more likely to be passed on to the next generation.

1Cell Biology

1.1What's in Cells?

1.1.1Types of Cells

1.1.2Properties of Prokaryotes

1.1.3Standard Form

1.1.4Standard Form - Calculations

1.1.5Addition in Standard Form - Calculations

1.1.6Subtraction in Standard Form - Calculations

1.1.7Multiplication in Standard Form - Calculations

1.1.8Division in Standard Form - Calculations

1.1.9Animal Cells

1.1.10Plant Cells

1.1.11Differences Between Animal & Plant Cells

1.1.12Bacterial Cells

1.1.13Types of Cells HyperLearning

1.1.14Cell Specialisation in Animals

1.1.15Sperm Cells

1.1.16Nerve Cells

1.1.17Muscle Cells

1.1.18Cell Specialisation in Plants - Root Hair Cells

1.1.19Cell Specialisation in Plants - Xylem

1.1.20Cell Specialisation in Plants - Phloem

1.1.21Microscopy

1.1.22Magnification

1.1.23Developments in Microscopy

1.1.24Microscope Practical

1.1.25Microscopy - Calculations

1.1.26Culturing Microorganisms

1.1.27Contamination

1.1.28Avoiding Contamination

1.1.29Calculating Bacteria

1.1.30Calculating Bacteria - Calculations

1.1.31End of Topic Test - What's in Cells?

1.1.32Exam-Style Questions - Cell Structure & Microscopy

1.2Cell Division

1.2.1Chromosomes

1.2.2The Cell Cycle

1.2.3Mitosis

1.2.4Exam-Style Questions - Mitosis & Cell Cycle

1.2.5Stem Cells

1.2.6Use of Stem Cells

1.2.7Disadvantages of Stem Cells

1.3Transport in Cells

1.3.1Diffusion

1.3.2Factors Affecting Diffusion

1.3.3Surface Area : Volume

1.3.4Surface Area : Volume - Calculations

1.3.5Exchange Surfaces

1.3.6Examples of Exchange Surfaces

1.3.7Osmosis

1.3.8Required Practical - Osmosis

1.3.9Active Transport

1.3.10Transport in Cells

1.3.11End of Topic Test - Cell Division & Transport

1.3.12Grade 9 - Cell Transport

2Organisation

2.1Principles of Organisation

2.1.1Cells & Tissues

2.1.2Organs

2.1.3Organ Systems

2.1.4Organisms

2.2Enzymes

2.2.1Enzymes

2.2.2Enzymes HyperFlashcards

2.2.3Rate of Reaction

2.2.4Calculating Rate of Reaction

2.2.5Rate of Reaction - Calculations

2.2.6Digestion

2.2.7Bile

2.2.8Examples of Digestive Enzymes - Amylase

2.2.9Examples of Digestive Enzymes - Protease

2.2.10Examples of Digestive Enzymes - Lipase

2.2.11Testing for Biological Molecules

2.2.12End of Topic Test - Organisation & Enzymes

2.2.13Grade 9 - Enzymes

2.2.14Exam-Style Questions - Enzymes

2.3Circulatory System

2.3.1Types of Blood Vessel

2.3.2Blood Vessels - Arteries

2.3.3Blood Vessels - Capillaries

2.3.4Blood Vessels - Veins

2.3.5The Heart - Structure

2.3.6The Heart - Function

2.3.7Important Blood Vessels

2.3.8Double Circulatory System

2.3.9Gas Exchange

2.3.10Gas Exchange - Calculations

2.3.11Alveoli

2.3.12Blood Components

2.3.13Platelets

2.3.14Red Blood Cells

2.3.15White Blood Cells

2.3.16End of Topic Test - Circulatory System

2.4Non-Communicable Diseases

2.4.1Health Issues

2.4.2Disease Interactions

2.4.3Sampling

2.4.4Sampling - Calculations

2.4.5Risk Factors

2.4.6Examples of Risk Factors

2.4.7Risk Factor Graphs

2.4.8Coronary Heart Disease

2.4.9Heart Valve Disease

2.4.10Heart Failure

2.4.11Treating Heart Disease

2.4.12Comparing Treatments of Heart Disease

2.4.13Cancer

2.4.14Cancer Risk Factors

2.4.15End of Topic Test - Non-Communicable Diseases

2.4.16Exam-Style Questions - Coronary Heart Disease

2.5Plant Tissues, Organs & Systems

2.5.1Plant Tissues

2.5.2Leaves

2.5.3Transpiration

2.5.4Rate of Transpiration

2.5.5Measuring Transpiration

2.5.6Translocation

2.5.7Transpiration Tissues - Xylem Cells

2.5.8Transpiration Tissues - Root Hair Cells

2.5.9Stomata

2.5.10Stages of Stomata

2.5.11Premium Knowledge - Transpiration

2.5.12End of Topic Test - Plants

2.5.13Exam-Style Questions - Plant Tissues

3Infection & Response

3.1Communicable Disease

3.2Monoclonal Antibodies

3.2.1Monoclonal Antibodies

3.2.2Producing Monoclonal Antibodies

3.2.3Uses of Monoclonal Antibodies

3.2.4Grade 9 - Monoclonal Antibodies

3.3Plant Diseases

3.3.1Ion Deficiencies

3.3.2Other Plant Diseases

3.3.3Plant Defences

3.3.4Signs of Plant Disease

3.3.5Identifying Disease

3.3.6End of Topic Test - Antibodies & Plant Disease

4Bioenergetics

4.1Photosynthesis

4.1.1Photosynthesis

4.1.2Photosynthesis Equation

4.1.3Rate of Photosynthesis

4.1.4Limiting Factors

4.1.5Photosynthesis in Farming

4.1.6Uses of Glucose

4.1.7Photosynthesis - Calculations

4.1.8Photosynthesis Experiments

4.1.9Grade 9 - Photosynthesis Experiment

4.1.10Exam-Style Questions - Rate of Photosynthesis

4.2Respiration

4.2.1Organisms and Energy

4.2.2Respiration

4.2.3Metabolism

4.2.4Respiration - Calculations

4.2.5Respiration During Exercise

4.2.6Oxygen Debt

4.2.7Respiration HyperLearning

4.2.8End of Topic Test - Photosynthesis and Respiration

4.2.9Exam-Style Questions - Anaerobic Respiration

5Homeostasis & Response

5.1Homeostasis

5.1.1Homeostasis

5.1.2Regulating Internal Conditions

5.1.3Homeostasis & Negative Feedback

5.1.4The Body's Negative Feedback Loop

5.1.5Exam-Style Questions - Exercise & Homeostasis

5.2The Human Nervous System

5.2.1The Nervous System

5.2.2The Nervous System HyperFlashcards

5.2.3Synapses

5.2.4Reflexes

5.2.5Reflexes Practical

5.2.6Exam-Style Questions - Nervous System

5.2.7The Brain: Key Facts

5.2.8The Brain: Brain Areas

5.2.9The Brain: Neuro Techniques

5.2.10Eye Anatomy

5.2.11Eye Function

5.2.12Eye Defects

5.2.13Control of Body Temperature

5.2.14Thermoregulation - Sweating & Shivering

5.2.15Thermoregulation - Body Hair

5.2.16Thermoregulation - Blood Vessels

5.2.17Body Temperature HyperLearning

5.2.18End of Topic Test - Human Nervous System

5.3Hormonal Coordination in Humans

5.3.1Endocrine Glands

5.3.2The Endocrine System

5.3.3Thyroxine

5.3.4Adrenaline

5.3.5Blood Glucose

5.3.6Detecting Glucose

5.3.7Type 1 Diabetes

5.3.8Type 2 Diabetes

5.3.9Water Balance

5.3.10Kidneys

5.3.11Urea

5.3.12Urine Production

5.3.13Urine

5.3.14Dialysis

5.3.15Dialysis - Pros & Cons

5.3.16Transplants

5.3.17Transplants - Pros & Cons

5.3.18Puberty

5.3.19Menstruation

5.3.20Menstrual Hormones

5.3.21Menstrual Cycle

5.3.22Female Contraception - The Pill

5.3.23Female Contraception - Other Options

5.3.24Female Contraception - Diaphragm & IUDs

5.3.25Male Contraception - Condoms

5.3.26Male Contraception - Sterilisation

5.3.27Male Contraception - 'Natural Methods'

5.3.28Hormones for Infertility

5.3.29In Vitro Fertilisation

5.3.30Fertility Treatments - Pros & Cons

5.3.31End of Topic Test - Homeostasis & Hormones

5.3.32Grade 9 - Hormonal Coordination

5.3.33Exam-Style Questions - Hormones & Contraception

5.4Plant Hormones

5.4.1Plant Hormones

5.4.2Types of Tropisms

5.4.3Auxins and Tropisms

5.4.4Required Practical - Plant Hormones

5.4.5End of Topic Test - Hormones

6Inheritance, Variation & Evolution

6.1Reproduction

6.2Variation & Evolution

6.2.1Variation

6.2.2Evolution

6.2.3Natural Selection

6.2.4Selective Breeding

6.2.5Uses of Selective Breeding

6.2.6Dangers of Selective Breeding

6.2.7Genetic Engineering

6.2.8Uses of Genetic Modification

6.2.9Advantages of Genetic Modification

6.2.10Disadvantages of Genetic Modification

6.2.11Cloning

6.2.12Cloning Plants

6.2.13Cloning Animals

6.2.14Adult Cell Cloning

6.2.15End of Topic Test - Variation & Evolution

6.2.16Exam-Style Questions - Selective Breeding

6.3Genetics & Evolution

6.3.1Natural Selection

6.3.2Controversy Around Natural Selection

6.3.3Darwin's Theory of Evolution

6.3.4Inheritance Theory

6.3.5Speciation

6.3.6Alfred Russel Wallace

6.3.7Evidence for Evolution

6.3.8Fossils

6.3.9Resistant Bacteria

6.3.10Genetics

6.3.11Extinctions

6.3.12Grade 9 - Evolution

6.4Classification

6.4.1Classification of Living Organisms

6.4.2Traditional System

6.4.3Classification of Living Organisms: Updated System

6.4.4Evolutionary Trees

6.4.5End of Topic Test - Genetics & Classification

7Ecology

7.1Adaptations & Interdependence

7.1.1Communities: Ecosystems

7.1.2Communities: Resources

7.1.3Species Interdependence

7.1.4Stable Communities

7.2Organisation of Ecosystems

7.2.1Population Dynamics

7.2.2Impact of Environmental Change

7.2.3Causes of Environmental Change

7.2.4Assessing Ecosystems

7.2.5Organism Abundance

7.2.6Required Practical - Using Quadrats

7.2.7Assessing Ecosystems - Calculations

7.2.8The Carbon Cycle

7.2.9The Water Cycle

7.2.10The Cycling of Materials

7.2.11Decay

7.2.12Anaerobic Decay

7.2.13Biogas Generators

7.2.14Required Practical - Decay

7.2.15End of Topic Test - Organisation of Ecosystems

7.2.16Grade 9 - Ecosystems

7.2.17Exam-Style Questions - Decomposition

7.3Biodiversity

7.3.1Humans & Biodiversity

7.3.2Waste Management

7.3.3Human Activities

7.3.4Land Use

7.3.5Deforestation

7.3.6Carbon Dioxide

7.3.7The Greenhouse Effect

7.3.8Global Warming

7.3.9Maintaining Biodiversity

7.3.10End of Topic Test - Adaptations & Biodiversity

7.4Trophic Levels

7.4.1Trophic Levels

7.4.2Trophic Levels: Food Chains

7.4.3Trophic Levels: Decomposers

7.4.4Pyramids of Biomass

7.4.5Transfer Efficiency

7.4.6Reasons for Energy Wastage

7.4.7Transfer Efficiency - Calculations

7.4.8Premium Knowledge - Trophic Levels & Food Chains

7.4.9Exam-Style Questions - Food Chains

7.5Food Production

7.5.1Food Security

7.5.2Food Production: Biotechnology

7.5.3Declining Fish Stock

7.5.4Sustainable Fishing

7.5.5Farming

7.5.6Food Production - Calculations

7.5.7End of Topic Test - Food & Trophic Levels

Jump to other topics