CIE iGCSE Co-ordinated Sciences-B3.3 Active transport- Study Notes- New Syllabus
CIE iGCSE Co-ordinated Sciences-B3.3 Active transport – Study Notes
CIE iGCSE Co-ordinated Sciences-B3.3 Active transport – Study Notes -CIE iGCSE Co-ordinated Sciences – per latest Syllabus.
Key Concepts:
Core
- Describe active transport as the movement of particles through a cell membrane from a region of lower concentration to a region of higher concentration (i.e. against a concentration gradient), using energy from respiration
Supplement
- Explain the importance of active transport as a process for movement of molecules or ions across membranes, including ion uptake by root hairs
CIE iGCSE Co-Ordinated Sciences-Concise Summary Notes- All Topics
Active Transport
📌 Introduction
Cells sometimes need to move substances against the concentration gradient (low → high). This process requires energy from respiration (ATP).
🔑 Definition
Active transport: movement of particles from lower concentration → higher concentration across a cell membrane, using energy released from ATP.
⚙️ Key Features
- Moves against concentration gradient (opposite of diffusion & osmosis).
- Needs carrier proteins in the membrane.
- Requires energy (ATP) from cellular respiration.
- Selective process → only specific molecules/ions transported.
🌱Examples
- Plants: Root hair cells absorb mineral ions (e.g., nitrates, phosphates) from soil water even when soil concentration is lower than inside roots.
- Animals: – Absorption of glucose in small intestine (when gut conc. < blood conc.) – Re-absorption of useful substances (e.g., glucose, amino acids) in kidney tubules
📊 Comparison Table
| Feature | Diffusion | Osmosis | Active Transport |
|---|---|---|---|
| Energy needed? | No | No | Yes (ATP) |
| Gradient | High → Low | High WP → Low WP | Low → High |
| Membrane needed? | Sometimes | Partially permeable | Always (carrier proteins) |
🔑 Quick Recap
Active transport: moves particles low → high conc.
Needs ATP + carrier proteins
Examples: ion uptake in roots, glucose absorption in gut, kidney reabsorption
Opposite of diffusion & osmosis
Importance of Active Transport
📌 Why it matters
Active transport enables cells to absorb essential substances even when they are in lower concentration outside the cell. Without it, many vital processes in plants and animals would fail.
🔑 Key Points
- Against concentration gradient: Moves particles from low → high conc. (diffusion & osmosis cannot do this).
- Energy use (ATP): Uptake is independent of external concentrations.
- Selective uptake: Specific ions/molecules transported as required.
🌱 Example: Ion Uptake by Root Hair Cells
- Soil often contains very low conc. of mineral ions (e.g., nitrates, magnesium, potassium).
- Root hair cells use active transport to absorb them against the gradient.
- Minerals are vital for: – Nitrates → protein synthesis, growth – Magnesium → chlorophyll formation, photosynthesis
- Without active transport: Plants show poor growth + yellow leaves (deficiency).
🧬 Other Examples (Animals)
- Small intestine: Absorption of glucose into blood even when gut conc. is lower.
- Kidneys: Reabsorption of glucose and ions from urine into blood.
📊 Summary Table
| Importance | Example |
|---|---|
| Supplies minerals essential for plant growth | Root hair cells absorb nitrates & magnesium |
| Maintains nutrient absorption in low concentration environments | Small intestine glucose uptake |
| Prevents loss of useful substances | Kidney reabsorption |
📝 Quick Recap
Active transport = low → high conc., needs ATP
Essential when outside conc. < inside conc.
Plants: mineral ion uptake by root hairs
Animals: glucose absorption & kidney reabsorption