IGCSE Biology Extended (0610) Study Notes

IGCSE Biology (0610) Study Notes

1. Characteristics and Classification of Living Organisms

1.1. Characteristics of Living Organisms

• Acronym: MRS GREN

  • Movement: Action causing a change of position or place

  • Respiration: Chemical reactions in cells break down nutrients to release energy for metabolism

  • Sensitivity: Ability to detect and respond to internal/external changes

  • Growth: Permanent increase in size and dry mass

  • Reproduction: Producing genetically identical or different offspring

  • Excretion: Removal of metabolic waste and excess substances

  • Nutrition: Take in materials for energy, growth, and development

1.2. Concept and Uses of the Classification System

• Classification Importance: Groups organisms by shared features, showing evolutionary relationships.

• Levels of Classification:

  • Species: A group of organisms that can reproduce fertile offspring

  • Hierarchy Sequence: Kingdom → Phylum → Class → Order → Family → Genus → Species

  • Acronym: King Philip Came Over For Good Soup

• Binomial Nomenclature:

  • Two-part scientific name: Genus species (e.g., Homo sapiens)

  • Genus capitalized, species lowercase, italicized or underlined

• Dichotomous Keys: Utilizes visible features to classify organisms. Follows a series of choices leading to identification.

1.3. Types of Vertebrates Features

1.4. Five Kingdoms of Life

• Animals: Multicellular ingestive heterotrophs (e.g., cats, newts)

• Plants: Multicellular photosynthetic autotrophic organisms (e.g., cacti, oaks)

• Fungi: Heterotrophic and saprotrophic organisms; cell walls not cellulose (e.g., yeast, mushrooms)

• Prokaryotes: Unicellular, lacking nucleus/membrane-bound organelles (e.g., E. coli)

• Protists: Single-celled, eukaryotic organisms (e.g., Amoeba)

1.5. Classification of Plants

• Ferns: Non-flowering plants; reproduce by spores

• Flowering Plants: Reproduce through flowers/seeds

  • Monocotyledons: One seed leaf, long narrow leaves, parallel veins, multiples of 3 petals

  • Dicotyledons: Two seed leaves, broad leaves, branching veins, multiples of 4 or 5 petals

1.7. Viruses

• Characteristics: Not classified as living organisms; cannot perform life's seven processes independently.

• Structure: Composed solely of genetic material (RNA or DNA) encased in a protein coat.

• Replication: Takes over a host cell’s metabolic processes to replicate itself.

2. Organization of the Organism

2.1. Cell Structure

• All living things are cellular. Cells arise from existing cells.

• Basic structures in Eukaryotic cells:

  • Cell Membrane: Controls substance movement

  • Cytoplasm: Site of metabolic reactions

  • Nucleus: Contains DNA and controls cellular activity

  • Mitochondria: Site of aerobic respiration

  • Ribosomes: Protein synthesis locations

  • Endoplasmic Reticulum: Rough ER has ribosomes; assists in protein synthesis.

• Plant Cell Specifics:

  • Vacuole: Maintains turgidity

  • Cell Wall: Provides rigidity

  • Chloroplasts: Site of photosynthesis

• Prokaryotic Cells: Lacktrue nuclei and membrane-bound organelles; Example: Bacterial cells contain ribosomes, plasmids, and a peptidoglycan cell wall.

2.4. Levels of Organization

• Cells: Building blocks of life

• Tissues: Groups of similar cells performing a shared function

• Organs: Groups of tissues performing specific functions

• Organ Systems: Groups of organs working together

• Organism: Entire living entity.

2.5. Magnification

• Formula:

  • Actual Size = Image Size ÷ Magnification

  • Image Size = Magnification × Actual Size

• Unit Conversions:

  • 1 cm = 10 mm

  • 1 mm = 1000 μm

  • 1 μm = 0.001 mm

3. Movement Into and Out of Cells

3.1. Diffusion

• Definition: Net movement of particles from high to low concentration

• Factors Influencing Diffusion:

  • Concentration gradient

  • Temperature

  • Surface area to volume ratio

  • Distance

• Importance: Essential for delivering vital molecules like glucose and oxygen.

3.2. Osmosis

• Definition: Net movement of water molecules through a partially permeable membrane from a higher water potential to a lower water potential.

• Cell Conditions:

  • Hypertonic: Cell shrinks

  • Hypotonic: Cell becomes turgid

  • Isotonic: Cell remains unchanged

3.4. Active Transport

• Definition: Movement of particles against a concentration gradient, requiring energy (ATP).

• Key Components: Carrier proteins facilitate the transport across the membrane.

3.5. Comparisons

3.6. Dialysis Tubing Experiment

• Concept: Demonstrates osmosis and diffusion with a non-living semi-permeable membrane; allows passage of small molecules and not larger ones.

4. Biological Molecules

4.1. Carbohydrates, Proteins, and Fats

• Carbohydrates: Composed of C, H, O; includes sugars and starches.

• Proteins: Composed of C, H, O, N, and sometimes S; formed by amino acids.

• Fats and Oils: Made from C, H, O; fatty acids and glycerol.

4.2. Food Tests

• For various biomolecules, using chemical indicators (e.g., Benedict’s for reducing sugars).

4.3. DNA Structure

• Chromosomes: Composed of DNA, forming a double helix with base pairs: A-T, C-G.

5. Enzymes

5.1. Enzyme Function

• Definition: Biological catalysts that speed up metabolic reactions and lower activation energy.

• Reusability: Unchanged after reactions.

5.2. Factors Affecting Enzymes

• Temperature: Each enzyme has an optimum temperature. High temperatures denature enzymes.

• pH: Enzymes have an optimal pH; extreme pH denatures enzymes.

5.3. Common Enzymes

6. Plant Nutrition

6.1. Photosynthesis

• Definition: Process where plants convert light energy into chemical energy (glucose) from CO2 and H2O.

• Equation:
  $6CO<em>2 + 6H</em>2O <br>ightarrow C<em>6H</em>{12}O<em>6 + 6O</em>2$

6.2. Mineral Requirements

• Essential nutrients (e.g., nitrogen for amino acids, magnesium for chlorophyll).

6.3. Investigations on Photosynthesis

• Various experiments investigating the effects of light intensity and CO2 on photosynthesis rates.

6.4. Leaf Structure and Adaptations for Photosynthesis

• Features: Stomata for gas exchange, chloroplasts for photosynthesis, and structures optimizing light capture.

7. Human Nutrition

7.1. Balanced Diet

• Essential macronutrients: carbohydrates, proteins, fats, vitamins, minerals, and water.

7.2. Digestive System Functions

• Breakdown of food, nutrient absorption, waste removal through the alimentary canal.

7.3. Enzymes in Digestion

• Role of different digestive enzymes at various pH levels from saliva to stomach and intestines.

7.4. Chemical Digestion Process

• Mechanics: Breakdown of large food molecules into smaller, absorbable units.

8. Transport in Plants

8.1. Xylem and Phloem Functions

• Xylem: Water/mineral transport and structural support.

• Phloem: Transports sucrose and nutrients produced in photosynthesis.

8.2. Transpiration

• Water loss through stomata; vital for nutrient distribution and temperature control.

8.3. Water Uptake and Pathway Investigation

• Root hair cells absorb water via osmosis; pathway traced using food dyes in experimental setups.

9. Transport in Animals

9.1. Circulatory Systems

• Single vs Double Circulation: Differences in blood flow and heart structure between fish and mammals.

9.2. Heart Structure and Function

• Detailed dynamics of blood circulation; identifying chambers, valves, and their roles.

9.3. Blood Vessel Types and Functions

• Differences and characteristics of arteries, veins, and capillaries.

10. Diseases and Immunity

10.1. Pathogens and Body Defenses

• Mechanisms of pathogens, human defenses (skin, immune response).

10.2. Immunity Types

• Active: Immunity by antigen exposure through infection or vaccines.

• Passive: Short-term immunity from another source (mother to child).

11. Gas Exchange in Humans

11.1. Gas Exchange Structures

• Lungs: Functional components for oxygen and CO2 exchange through alveolar structures.

11.2. Breathing Process

• Mechanics of inhalation/exhalation involving diaphragm and intercostal muscles.

12. Respiration

12.1. Aerobic vs Anaerobic Respiration

• Breakdown of glucose with or without oxygen, including energy yield differences.

13. Excretion in Humans

13.1. Kidney Functions and Structure

• Nephron structure and processes: ultrafiltration and selective reabsorption.

14. Coordination and Response

14.1. Nervous System Structure

• CNS vs PNS: Coordinating body responses through nerve signal transmission.

15. Drugs

15.1. Antibiotics and Resistance

• Mechanism and implications of antibiotic use in bacteria; emergence of resistant strains.

16. Reproduction

16.1. Asexual vs Sexual Reproduction

• Genetic implications and methods in organisms.

17. Inheritance

17.1. Chromosomes, Genes, and Traits

• Understanding Mendelian genetics and mechanisms of gene expression.

18. Variation and Selection

18.1. Natural Selection Principles

• Mechanisms driving evolution and species adaptation.

19. Organisms and their Environment

19.1. Energy Flow in Ecosystems

• Trophic levels, energy transfer, and implications for biodiversity.

20. Human Influences on Ecosystems

20.1. Pollution and Conservation Strategies

• Environmental impacts of human activity and methods for sustainable management.

21. Biotechnology and Genetic Modification

21.1. Gene Editing Techniques

• Applications of genetic modification in agriculture and medicine.