Human Biology - Cells

Year 11 ATAR Human Biology – Notes

1. Describe the structural organization within the body.

The human body is organized in a hierarchy of increasing complexity:

  1. Cells – Basic functional unit of life (e.g., muscle cell, nerve cell).

  2. Tissues – Groups of similar cells performing a function (e.g., epithelial tissue).

  3. Organs – Structures composed of multiple tissue types (e.g., heart, lungs).

  4. Organ Systems – Groups of organs working together (e.g., circulatory system).

  5. Organism – The complete living being.

🖼 Diagram Suggestion: A pyramid or flowchart representing the levels of organization.

2. Label the following structures of a cell on a diagram and know their functions.

🖼 Diagram Suggestion: A labeled animal cell diagram including:

  • Cell Membrane – Controls entry/exit of substances.

  • Cytoplasm – Fluid in which organelles are suspended.

  • Nucleus – Contains genetic material (DNA), controls cell function.

  • Nucleolus – Produces ribosomes.

  • Nuclear Membrane – Encloses nucleus, controls exchange with cytoplasm.

  • Nuclear Pores – Allow material exchange between nucleus & cytoplasm.

  • Chromosomes (DNA) – Carry genetic instructions.

  • Endoplasmic Reticulum (ER)

    • Rough ER – Synthesizes proteins.

    • Smooth ER – Synthesizes lipids.

  • Ribosomes – Protein synthesis.

  • Golgi Body – Modifies and packages proteins.

  • Mitochondria – Energy production (ATP).

  • Centrioles – Cell division.

  • Vesicles – Transport substances.

  • Lysosomes – Digestive enzymes for breakdown of waste.

  • Cilia & Flagella – Movement.

 

3. Describe the structure of the cell membrane (phospholipid bilayer). Label and discuss how it works (function).

The cell membrane consists of:

  • Phospholipid bilayer: Hydrophilic heads (water-attracting) & hydrophobic tails (water-repelling).

  • Proteins: Embedded for transport & communication.

  • Cholesterol: Maintains fluidity.

  • Carbohydrates: Cell recognition.

Function:

  • Controls movement of substances.

  • Provides protection & support.

  • Allows communication between cells.

🖼 Diagram Suggestion: Fluid Mosaic Model of the membrane with labeled components.

4. Define and compare diffusion and osmosis.

  • Diffusion: Movement of molecules from high to low concentration (passive transport).

  • Osmosis: Diffusion of water across a semi-permeable membrane.

🖼 Diagram Suggestion:

  1. Particles moving from high to low concentration (diffusion).

  2. Water moving toward a more concentrated solution (osmosis).

5. Outline the differences between passive and active transport.

Transport Type

Energy Required?

Examples

Passive

❌ No

Diffusion, Osmosis, Facilitated Diffusion

Active

✅ Yes (ATP)

Sodium-Potassium Pump, Endocytosis, Exocytosis

 

 

6. Explain endocytosis and exocytosis (phagocytosis & pinocytosis).

  • Endocytosis: Cell engulfs material.

    • Phagocytosis – "Cell eating" (solid particles).

    • Pinocytosis – "Cell drinking" (liquids).

  • Exocytosis: Cell expels materials (e.g., hormones, waste).

🖼 Diagram Suggestion: Show a cell engulfing (endocytosis) and expelling (exocytosis) materials.

7. Give examples of materials transported by each method.

  • Diffusion – Oxygen, carbon dioxide.

  • Osmosis – Water movement.

  • Facilitated diffusion – Glucose (via carrier proteins).

  • Active transport – Ions (Na⁺, K⁺).

  • Endocytosis – Bacteria engulfed by white blood cells.

  • Exocytosis – Hormone secretion.

8. Describe how surface area to volume ratio affects material exchange.

  • Higher SA:V ratio = Faster exchange.

  • Smaller cells = More efficient diffusion.

🖼 Diagram Suggestion: Show a large cell vs. small cell with different SA:V ratios.

 

 

 

 

 

9. Name, describe functions of, and sketch examples of four tissue types.

Tissue Type

Function

Example

Epithelial

Covers/protects

Skin, stomach lining

Connective

Supports

Bone, blood, fat

Muscle

Movement

Skeletal, cardiac, smooth muscle

Nervous

Sends signals

Brain, spinal cord

🖼 Diagram Suggestion: Simple labeled tissue diagrams.

10. Define metabolism.

Metabolism = All chemical reactions in the body that maintain life.

11. Define and distinguish between catabolism and anabolism with examples.

  • Catabolism – Breaks molecules, releases energy (e.g., respiration).

  • Anabolism – Builds molecules, uses energy (e.g., protein synthesis).

🖼 Diagram Suggestion: Flowchart of catabolic vs. anabolic reactions.

12. Write the word and chemical equation for cellular respiration.

  • Word Equation:
    Glucose + Oxygen → Carbon Dioxide + Water + ATP

  • Chemical Equation:
    C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + ATP

 

 

13. Compare aerobic and anaerobic respiration.

Feature

Aerobic

Anaerobic

Oxygen Required?

✅ Yes

❌ No

ATP Produced

High (36-38)

Low (2)

End Products

CO₂, H₂O

Lactic acid (animals) / ethanol (yeast)

14. Explain the importance of ATP in the body.

ATP = Cellular energy currency, powers:

  • Active transport.

  • Muscle contraction.

  • Synthesis of molecules.

15. Give five reasons cells require nutrients.

  1. Energy production.

  2. Growth & repair.

  3. Cell division.

  4. Enzyme production.

  5. Communication between cells.

 

 

 

 

 

 

 

 

16-20. Enzymes and Metabolism

16. Describe why cells need nutrients.

Nutrients = Essential for energy, cell growth, and repair.

17. Explain that all metabolic processes are controlled by enzymes.

Enzymes = Biological catalysts speeding up reactions.

18. Describe the characteristics and functions of enzymes.

  • Specificity – One enzyme for one reaction.

  • Reusable – Not consumed in reactions.

19. Explain enzyme action (Lock & Key + Induced Fit Models).

🖼 Diagram Suggestion:

  • Lock & Key: Perfect fit between enzyme & substrate.

  • Induced Fit: Enzyme slightly changes shape.

20. Factors affecting enzyme activity.

  • pH, Temperature, Substrate Concentration, Inhibitors.