AEHBY Task 2 Cheatsheet
09/12/2025
AEHBY Task 2 Cheatsheet
1. Chapter 2: Cells Make Up the Human Body
1.1 The Cell Theory & Hierarchy
Hierarchy of Structure: Cells → Tissues → Organs → Organ Systems → Organism.
Cell Theory Principles:
- All living things are made of cells (and the materials cells produce).
- The cell is the smallest living unit of structure and function of all organisms.
- All cells arise from pre-existing cells.
1.2 Cell Structure & Organelles
Common Traits: All cells are microscopic, require oxygen/glucose, require waste removal, and naturally cannot live outside the body.
Organelle Master List:
| Organelle | Structure | Function |
|---|---|---|
| Cell Membrane | Phospholipid bilayer | Separates cell from environment; regulates entry/exit. |
| Cytoplasm/Cytosol | Jelly-like liquid | Suspends organelles; site of metabolic reactions. |
| Nucleus | Double membrane (Nuclear Envelope) with Nuclear Pores | Stores DNA (as Chromatin/Chromosomes); controls cell function. Contains Nucleoplasm. |
| Nucleolus | Inside nucleus | Site of RNA production for protein synthesis. |
| Ribosomes | Small spheres (free or on ER) | Site of Protein Synthesis (amino acid joining). |
| Rough ER | Channels + Ribosomes | Surface for chemical reactions; transports proteins. |
| Smooth ER | Channels (No Ribosomes) | Transports materials; lipid synthesis. |
| Golgi Body | Stacked flattened sacs | Modifies & packages proteins into vesicles for secretion. |
| Mitochondria | Double membrane (inner folds) | Site of Aerobic Respiration (Powerhouse). |
| Lysosomes | Spheres with enzymes | Garbage disposal; digests worn-out organelles. |
| Centrioles | Cylindrical pairs | Involved in cell division (mitosis). |
| Cilia/Flagella | Hair-like projections | Cilia: Move substances (mucus) across surface. Flagella: Move the cell. |
Note: Cytoskeleton and Inclusions are structural components but excluded from detailed study for this task.
1.3 The Cell Membrane (Fluid Mosaic Model)
- Fluid: Molecules are constantly moving (like oil).
- Mosaic: Composed of many different molecules (lipids, proteins, cholesterol).
- Why “Bilayer”? It consists of two layers of phospholipids arranged tail-to-tail.
- Structure:
- Phospholipid Bilayer: Hydrophilic (water-loving) phosphate heads face out; Hydrophobic (water-fearing) lipid tails face in.
- Cholesterol: Maintains membrane integrity/stability (prevents freezing/melting).
- Proteins: Channel, Carrier, Receptor, Cell-identity markers.
- Components Check:
- Inside Membrane Structure: Proteins, Cholesterol, Phospholipids.
- NOT Inside Membrane Structure: Nucleic Acids (DNA/RNA), Cytosol (these are inside the cell, not the membrane itself).
1.4 Transport Mechanisms (SA:V Ratio)
Cells are small to maintain a High Surface Area to Volume Ratio (SA:V). This allows materials (Oxygen/Glucose) to diffuse to the center of the cell quickly enough to sustain life.
| Transport | Type | Description |
|---|---|---|
| Simple Diffusion | Passive | Movement from High to Low Conc. (e.g., O2, CO2, Alcohol, Steroids). |
| Osmosis | Passive | Diffusion of water across semi-permeable membrane (Low Solute → High Solute). |
| Facilitated Diffusion | Passive | Uses Channel Proteins (ions/water) or Carrier Proteins (glucose) to move High → Low. |
| Active Transport | Active (ATP) | Uses Carrier Proteins to move substances AGAINST gradient (Low → High). |
| Vesicular Transport | Active (ATP) | Endocytosis: Entering (Phagocytosis=Solids, Pinocytosis=Liquids). Exocytosis: Exiting. |
1.5 Tissues
- Epithelial: Covering/Lining. Cells packed close together (e.g., Skin, lining of heart/stomach/intestines).
- Connective: Support. Cells separated by Matrix.
- Tendons: Connect Muscle to Bone [4, 20].
- Ligaments: Connect Bone to Bone [4, 20].
- Examples: Bone, Cartilage, Blood, Fat.
- Nervous: Communication. Made of Neurons.
- Muscular: Contraction.
- Skeletal: Voluntary, Striated, attached to bone.
- Smooth: Involuntary, Non-striated, organs.
- Cardiac: Involuntary, Striated, Heart only.
2. Chapter 3: Metabolism & Biochemistry
2.1 Biochemistry Classifications
Inorganic Compounds: Small molecules, usually no Carbon chain.
- Examples: Water, Minerals, Vitamins [3, 14].
Organic Compounds: Contain Carbon chain; large molecules.
- Carbohydrates:
- Monosaccharides: Glucose, Fructose, Galactose.
- Disaccharides: Sucrose, Maltose, Lactose.
- Polysaccharides: Starch, Glycogen, Cellulose.
- Lipids (Fats): Common form: Triglyceride. Structure: 1 Glycerol + 3 Fatty Acid tails.
- Proteins:
- Elements: C, H, O, N (often S, P).
- Building Blocks: Amino Acids joined by Peptide Bonds.
- Dipeptide: 2 amino acids joined. Polypeptide: 10+ amino acids. Protein: 100+ amino acids.
- Nucleic Acids (Comparison):
| Feature | DNA | RNA | | :--- | :--- | :--- | | Strands | Double stranded | Single stranded | | Sugar | Deoxyribose | Ribose | | Bases | Thymine (T) | Uracil (U) | | Length | Longer | Shorter |
2.2 Metabolic Reactions & Enzymes
- Catabolism: Breaking down, releases energy (e.g., Respiration).
- Anabolism: Building up, requires energy (e.g., Protein synthesis).
- Enzymes: Biological catalysts (proteins) that lower Activation Energy.
- Lock & Key Model: Active site is rigid; precise fit with substrate.
- Induced Fit Model: Enzyme shape changes slightly when substrate binds to create a complementary fit.
- Factors: Concentration, Temperature (optimal 37°C), pH, Co-factors (ions), Co-enzymes (vitamins), Inhibitors.
2.3 Cellular Respiration & Energy
Equation: C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + Energy (ATP + Heat)
Energy Efficiency:
- ~40% captured as ATP.
- ~60% lost as HEAT (maintains body temp) [3, 25].
ATP Structure:
- Adenine (base) + Ribose (sugar) + 3 Phosphate groups.
- Energy is stored in the bond of the last phosphate.
| Stage | Location | Oxygen? | Process | ATP Yield |
|---|---|---|---|---|
| Glycolysis | Cytosol | No | Glucose → 2 Pyruvic Acid | 2 ATP |
| Anaerobic | Cytosol | No | Pyruvate → Lactic Acid. Creating “Oxygen Debt”. | 0 extra |
| Aerobic | Mitochondria | Yes | 1. Krebs Cycle (Citric Acid Cycle) 2. Electronic Transport Chain (ETC) | 2 (Krebs) ~34 (ETC) Total: ~38 |
- Oxygen Debt: Extra oxygen needed post-exercise to convert Lactic Acid back to Glucose in the liver.
3. Chapter 4: The Respiratory System
3.1 Structure & Specifics
Primary Function: Supply oxygen to blood and remove carbon dioxide.
Upper Respiratory:
- Nasal Cavity: Warms, moistens, and filters air.
- Pharynx: Throat; passage for air and food.
- Epiglottis: Flap of cartilage that closes off trachea during swallowing to prevent food entering lungs.
- Larynx: The “voice box” containing vocal cords that vibrate to make sound.
Lower Respiratory:
- Trachea: C-shaped cartilage holds it open; lined with cilia/mucus.
- Bronchi: Have C-shaped cartilage rings (like trachea).
- Bronchioles: Made of smooth muscle and elastin (no cartilage). Allows expansion/constriction to control airflow [18, 22].
- Alveoli: Grape-like clusters, one cell thick, surrounded by capillaries.
- Pleura (Membranes):
- Visceral Pleura: Covers the surface of the lungs.
- Parietal Pleura: Lines the inside of the chest cavity.
- Pleural fluid: Between layers to reduce friction.
3.2 Gas Exchange & Transport
- Gas Exchange: Occurs via diffusion along concentration gradients (Alveoli ↔ Capillary).
- Features Assisting Diffusion (Alveoli Suitability):
- Large Surface Area: Millions of alveoli create a huge area for gas exchange.
- Thin Walls: Alveoli are one cell thick (simple squamous epithelium) for short diffusion distance.
- Moist Surface: Gases dissolve in moisture to diffuse easier.
- Rich Blood Supply: Surrounded by network of capillaries to maintain concentration gradient.
- Oxygen Transport:
- Most (approx 97%) attached to Haemoglobin in Red Blood Cells (HbO₂).
- Small amount dissolved in Calcium/plasma.
- Carbon Dioxide Transport:
- Most caried in plasma as Bicarbonate Ions (HCO₃⁻).
- Some attached to Haemoglobin.
- Small amount dissolved in plasma.
3.3 Ventilation Mechanics
Intrapulmonary Pressure: Pressure inside the lungs. Air flows from High Pressure → Low Pressure.
| Phase | Diaphragm | Intercostals | Chest Volume | Intrapulmonary Pressure | Air Flow |
|---|---|---|---|---|---|
| Inspiration | Contracts (Flattens) | Contract (Ribs Up/Out) | Increases | Decreases (becomes < atmos) | IN |
| Expiration | Relaxes (Domes) | Relax (Ribs Down/In) | Decreases | Increases (becomes > atmos) | OUT |
Extended Response: Process of Inhalation (Step-by-Step):
- Intercostal muscles contract, pulling the ribcage upwards and outwards.
- Diaphragm contracts and flattens (moves downwards).
- These movements increase the volume of the thoracic cavity.
- As volume increases, the intrapulmonary pressure decreases (becomes lower than atmospheric pressure).
- Air flows from high pressure (outside) to low pressure (inside lungs) until pressures equalize.
3.4 Respiratory Diseases
- Emphysema: Breakdown of alveoli; replaced by fibrous tissue. Loss of elasticity and SA.
- Cause: Long-term exposure to irritants (smoking).
- Symptoms: Shortness of breath, constant struggle for air.
- Bronchitis:
- Acute: Infection (viral/bacterial). Inflammation of bronchi, mucus production. Short term.
- Chronic: Long-term inflammation/mucus. Part of COPD.
- Symptoms: Persistent cough with mucus, wheezing, breathlessness.
- Asthma: Allergic response causing constriction of bronchioles (muscle spasm), inflammation, and mucus.
- Triggers: Allergens, smoke, exercise.
- Symptoms: Difficulty breathing, wheezing, tight chest, coughing.
- Pneumonia:
- Cause: Infection by bacteria, virus, or fungus.
- Effect: Inflammation causes secretion of fluid and mucus into alveoli, reducing air capacity and surface area for gas exchange.
- Symptoms: Fever, breathing difficulty, chest pain.
- Lung Cancer: Uncontrolled tumour growth.
- Causes: Smoking (20-90x risk), Asbestos fibres.
- Symptoms: Chronic cough, coughing blood, chest pain, weight loss.
4. Verified Booklet Answers (Direct from Text)
- Q: Principles of Cell Theory?
- All living things made of cells. 2. Cell is smallest unit of life. 3. Cells arise from pre-existing cells.
- Q: What is a concentration gradient? The difference in concentration that brings about the diffusion of solute molecules.
- Q: Why are cells small? To have a large Surface Area to Volume ratio, allowing substances (O2) to reach the center of the cell quickly enough to sustain life.
- Q: Define Tissue. A group of cells similar in structure working together to carry out a particular task.
- Q: Relationship between Cellular Respiration and Breathing? Breathing (Ventilation) supplies the Oxygen needed for cellular respiration and removes the CO2 produced as waste.
- Q: What is “Oxygen Debt”? Extra oxygen required to turn lactic acid molecules back into glucose in the liver after anaerobic respiration.
- Q: Function of the Liver in respiration? Stores glucose as glycogen; converts lactic acid back to glucose.
- Q: Difference between DNA and RNA? DNA: Double stranded, Deoxyribose, Thymine. RNA: Single stranded, Ribose, Uracil.