2.5.3Inquiry Process
Specialised Cells — IB Biology HL Revision Notes & Topical Questions
5 min read 6 parts Lesson 61 of 160
Curriculum Equation Key قوانين الرقم الهيدروجيني والاتزان الأيوني - pH & Acid-Base Equilibrium FormulasFast Exam Solution
pH = -log[H⁺] | pOH = -log[OH⁻] | pH + pOH = 14 | [H⁺][OH⁻] = 10⁻¹⁴
Word Equation & Conditions: الرقم الهيدروجيني = -لوغاريتم تركيز أيون الهيدروجين | pH + pOH = 14
Location & Specifications: الاتزان الأيوني، كيمياء 3 ثانوي، التحصيلي، و AP Chemistry.
Section 1 of 6Animal Cells
Differentiated cells have structures that suit their jobs.
Red blood cell
- Red blood cell Biconcave shape with no nucleus gives a high surface area and room for haemoglobin to carry oxygen.
Neurone
- Neurone Long axon carries impulses over distance, and branched dendrites receive signals from many cells.
Sperm cell
- Sperm cell Flagellum for swimming, many mitochondria for energy and an acrosome with enzymes to penetrate the egg.
Egg cell
- Egg cell Large size with a store of food and cortical granules that help block entry of more than one sperm.
| Cell | Feature | Function |
|---|---|---|
| Red blood cell | No nucleus, biconcave | Carry oxygen |
| Neurone | Long axon | Transmit impulses |
| Sperm | Flagellum, acrosome | Reach and penetrate egg |
| Ciliated cell | Cilia | Move mucus |
Section 2 of 6Plant Cells
Plant Cells
Palisade cell
- Palisade cell Contains many chloroplasts and is tall and tightly packed to absorb light for photosynthesis.
Root hair cell
- Root hair cell A long extension increases surface area for absorbing water and mineral ions.
Xylem vessel
- Xylem vessel Dead cells with lignified walls and no end walls form hollow tubes for water transport.
Guard cell
- Guard cell Pairs of cells that change shape to open and close stomata and control gas exchange.
Section 3 of 6Connecting Structure and Function
1
Identify what job the cell has to perform.
2
Look at which organelles are abundant, such as mitochondria for energy-demanding cells.
3
Note shape features such as extensions and folds that raise the surface area.
4
Link each feature to a specific advantage.
5
Check that the explanation uses the structure and the function.
Section 4 of 6Surface Area and Efficiency
Larger surface
- Larger surface Microvilli and root hairs increase the surface through which substances are absorbed.
Short diffusion distance
- Short diffusion distance Thin cells such as alveolar cells allow fast gas exchange.
More organelles
- More organelles Cells with high energy needs have large numbers of mitochondria.
Missing organelles
- Missing organelles Red blood cells lose the nucleus to make room for haemoglobin.
Section 5 of 6Worked Example
Question
- A scanning micrograph shows a red blood cell as 56 mm across at a magnification of ×8000.
- Calculate its real diameter in micrometres.
- Actual size = image size ÷ magnification.
- 56 mm ÷ 8000 = 0.007 mm.
- 1 mm = 1000 µm, so 0.007 mm = 7 µm.
Answer The red blood cell has a diameter of 7 µm.
Section 6 of 6Exam Checklist & Tips
2.5.3 – Key Points for the Exam
- Specialised cell A cell with a structure that suits a particular function.
- Differentiation The process by which a cell becomes specialised.
- Acrosome A vesicle at the sperm tip containing digestive enzymes.
- Biconcave Shaped like a disc with a dip in the centre on both sides.
Common Mistakes
- Giving a function without linking it to structure.
- Saying specialised cells have different DNA.
- Stating that red blood cells have mitochondria.
- Describing xylem vessels as living cells.
Last updated:
Cambridge 9700 AS Biology
Core Formula
Magnification Triangle & Unit Conversion
Formula: M = I / A ⇔ A = I / M ⇔ I = M × A
Units: 1 mm = 1,000 μm = 1,000,000 nm.
Rule: Convert Image size (ruler mm) to μm by ×1,000 before dividing by Actual size.