BIO - T2 SCIENCE

B2 Cells

B2.1 Cell structure

  • Comparison of Plant and Animal Cells:
    • Plant Cells: Cell Wall, Cell Membrane, Nucleus, Cytoplasm, Chloroplasts, Ribosomes, Mitochondria, Vacuoles
    • Animal Cells: Cell Membrane, Nucleus, Cytoplasm, Ribosomes, Mitochondria, Smaller Vacuoles
  • Bacterial Cell Structure:
    • Cell Wall, Cell Membrane, Cytoplasm, Ribosomes, Circular DNA, Plasmids
  • Functions of Cell Structures:
    • Cell Wall: Protects and gives shape to the cell (plant only).
    • Cell Membrane: Controls entry and exit of substances.
    • Nucleus: Contains genetic material.
    • Cytoplasm: Site of metabolic reactions.
    • Chloroplasts: Site of photosynthesis (plant only).
    • Ribosomes: Protein synthesis.
    • Mitochondria: Site of aerobic respiration.
    • Vacuoles: Storage of substances, maintaining turgor pressure (plant only).
  • New cells arise from cell division.

Specialized Cells:

  • Ciliated Cells: Movement of mucus.
  • Root Hair Cells: Absorption.
  • Palisade Mesophyll Cells: Photosynthesis.
  • Neurones: Electrical impulse conduction.
  • Red Blood Cells: Oxygen transport.
  • Gametes (Sperm and Egg): Reproduction.
  • Terminology Definitions: Cell, Tissue, Organ, Organ System, Organism.

B2.2 Size of Specimens

  • Magnification Formula:
    • \text{Magnification} = \frac{\text{Image size}}{\text{Actual size}}
  • Calculate magnification and specimen size using millimeters (mm).
  • Convert between mm and micrometers (μm).

B1 Characteristics of Living Organisms

B1.1 Characteristics Definition:

  1. Movement: Action causing change in position.
  2. Respiration: Chemical reactions that release energy.
  3. Sensitivity: Ability to detect changes in environment.
  4. Growth: Permanent increase in size or mass.
  5. Reproduction: Processes that produce more organisms.
  6. Excretion: Removal of metabolic waste.
  7. Nutrition: Intake of materials for energy and growth.

B4 Biological Molecules

B4.1 Composition of Biological Molecules:

  • Chemical Elements: Identify elements in carbohydrates, fats, proteins.
  • Large Molecule Formation:
    • Starch, Glycogen, Cellulose from Glucose.
    • Proteins from Amino Acids.
    • Fats from Fatty Acids and Glycerol.
  • Tests for Biological Molecules:
    • Iodine for Starch.
    • Benedict's for Reducing Sugars.
    • Biuret for Proteins.
    • Ethanol Emulsion for Fats.

B5 Enzymes

B5.1 Enzyme Functionality:

  • Enzymes are proteins acting as biological catalysts.

Enzyme Action and Specificity:

  • Active Site: Where substrate binds.
  • Enzyme-Substrate Complex: Formation during reaction.
  • Specificity: Enzyme shape must complement substrate shape.

Factors Affecting Enzyme Activity:

  • Temperature and pH: Affects kinetic energy, shape, fit, and can lead to denaturation.

B3 Movement Into and Out of Cells

B3.1 Diffusion:

  • Definition: Net movement of particles from high to low concentration (down concentration gradient).

Importance in Cells:

  • Some substances move via diffusion through membranes.

Factors Influencing Diffusion:

  • Surface area, temperature, concentration gradient, distance.

B3.2 Osmosis:

  • Definition: Water movement through partially permeable membranes.
  • Effects in Plant Cells: Turgidity, turgor pressure, plasmolysis, flaccidity.

B3.3 Active Transport:

  • Description: Movement against concentration gradient, requiring energy from respiration.

B7 Human Nutrition

B7.1 Diet:

  • Balanced Diet Components:
    • Carbohydrates, Fats, Proteins, Vitamins (C & D), Minerals (Calcium & Iron), Fibre, Water.
    • Causes of Scurvy (Vitamin C deficiency) and Rickets (Vitamin D deficiency).

B7.2 Digestive System:

  • Organ Identification: Alimentary canal: Mouth, Oesophagus, Stomach, Intestines; Associated organs: Salivary glands, Pancreas, Liver, Gall bladder.
  • Functions: Ingestion, Digestion, Absorption, Assimilation, Egestion.

B7.3 Digestion:

  • Physical vs Chemical Digestion:
    • Physical: Breakdown without chemical change.
    • Chemical: Breakdown into smaller soluble molecules. Enzyme roles: Amylase, Proteases, Lipase.

B8 Transport in Plants

B8.1 Xylem and Phloem:

  • Functions:
    • Xylem: Transport of water & minerals, support.
    • Phloem: Transport of sucrose & amino acids.

B8.2 Water Uptake:

  • Root hair cells: large surface area for uptake.

B8.3 Transpiration:

  • Loss of water vapour from leaves through stomata.

B9 Transport in Animals

B9.1 Circulatory System:

  • Description: Blood vessels, pump, and valves ensuring one-way flow.

B9.2 Heart Structure:

  • Identifying Structures: Atria, Ventricles, Valves, Coronary arteries.

B9.3 Blood Vessels:

- Structure Description: Arteries (thick walls, no valves), Veins (thinner walls, valves), Capillaries (thin walls, exchange function).

B10 Diseases and Immunity

B10.1 Pathogens:

  • Definition: Disease-causing organisms; modes of transmission include direct contact, environmental.

Body Defenses:

  • Skin, Mucus, White blood cells.

Immunity:

  • Active immunity through antibody production; Vaccination process.

B11 Gas Exchange in Humans

B11.1 Gas Exchange Structures:

  • Identification: Lungs, diaphragm, trachea, alveoli.

Composition of Air:

  • Differences between inspired and expired air.

B12 Respiration

B12.1 Uses of Energy:

  • Muscle contraction, growth, metabolism.

Aerobic vs Anaerobic:

  • Equations:
    • Aerobic: \text{glucose} + \text{oxygen} \rightarrow \text{carbon dioxide} + \text{water}
    • Anaerobic: \text{glucose} \rightarrow \text{lactic acid}

B13 Coordination and Response

B13.1 Nervous System:

  • Description: CNS (Brain, Spinal cord) & PNS (Nerves).

Reflex Arc Components:

  • Receptor, sensory neurone, relay neurone, effector.

B14 Drugs

Drug Characteristics:

  • The effect of drugs on chemical reactions. Antibiotics vs viruses.

B15 Reproduction

B15.1 Asexual vs Sexual Reproduction:

  • Asexual: identical offspring, Sexual: genetically different.

Flower Structures:

  • Pollination: Transfer of pollen, Fertilization process.

B16 Inheritance

Chromosomes and Genes:

  • Structure of DNA and definition of genes.

Mendelian Genetics:

  • Dominant and recessive traits.

B18 Organisms and Their Environment

Energy Flow:

  • Role of the Sun; food chains and webs; producers and consumers.

Carbon Cycle:

  • Photosynthesis, respiration, decomposition.

B19 Human Influences on Ecosystems

Ecosystem Definition:

  • Biodiversity and habitat destruction impacts.