Transport Triathlon
Three transport processes, one finish line: race diffusion, osmosis and active transport head-to-head and never mix them up again.
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Transport Triathlon 🏁
Three ways substances cross a membrane — **diffusion**, **osmosis** and **active transport** — are about to race head-to-head. The exam almost never asks about them one at a time; it asks you to **tell them apart**. This is the sprint that makes the differences stick.
Line them up 📊
The whole topic comes down to three questions about each process: • **Energy?** Diffusion — no. Osmosis — no. Active transport — **yes** (from respiration). • **What moves?** Diffusion — any particle. Osmosis — **water only**. Active transport — dissolved substances. • **Direction?** Diffusion & osmosis go **down** the gradient (high → low). Active transport goes **against** it (low → high).
Spot the passive two
Pick the TWO processes that are **passive** — they need **no** energy from respiration.
- Diffusion
- Osmosis
- Active transport
- Respiration
Define the odd one out
Active transport moves substances _____ the concentration gradient, so it needs _____ released by _____.
Why active transport costs energy ⚡
Diffusion and osmosis are like rolling **downhill** — particles spread from where there are lots to where there are few, all on their own. Active transport goes **uphill**: it drags substances from a **low** concentration to a **higher** one, against the natural flow. Working against the gradient is why it **must** use energy from **respiration**.
True of active transport?
Pick the TWO statements that are true of **active transport**.
- It moves substances against the concentration gradient
- It needs energy from respiration
- It moves substances down the concentration gradient
- It happens without any energy
Match the real example
- Root hair cells absorbing mineral ions from dilute soil water
- Oxygen moving from the lungs into the blood
- Water entering a plant root
- Active transport
- Diffusion
- Osmosis
The mineral puzzle
Soil water is very **dilute** in mineral ions, yet root hair cells still pull those ions **in** — building up an even higher concentration inside. Which process must the root hair cell be using?
- Active transport
- Diffusion
- Osmosis
- No process can do that
Finish line 🎓
Triathlon done. Carry these three lines into the exam: • **Diffusion** — any particle, **down** the gradient, **passive**. • **Osmosis** — **water** only, across a partially permeable membrane, **down** the gradient, **passive**. • **Active transport** — **against** the gradient, so it **needs energy** from respiration (root-hair mineral uptake, gut sugar absorption).