Active Transport: Definition, Examples, and Differences

📚 Active Transport: Quick Study Guide

• 🧬 Active transport requires energy, usually in the form of ATP (adenosine triphosphate).
• 📦 It moves molecules *against* their concentration gradient (from low to high concentration).
• ➡️ There are two main types: primary active transport (using ATP directly) and secondary active transport (using an electrochemical gradient).
• 🔑 Key examples include the sodium-potassium pump and transport of glucose in the intestines.
• 🔬 Unlike passive transport, active transport requires specific carrier proteins or pumps embedded in the cell membrane.

🧪 Practice Quiz

1. Which of the following is a defining characteristic of active transport?
   1. A) Movement of molecules down the concentration gradient
   2. B) Requirement of energy input
   3. C) Reliance on membrane fluidity
   4. D) No involvement of transport proteins
2. What molecule is most commonly used as the energy source in primary active transport?
   1. A) Glucose
   2. B) ATP
   3. C) Water
   4. D) Oxygen
3. The sodium-potassium pump is an example of which type of transport?
   1. A) Facilitated diffusion
   2. B) Osmosis
   3. C) Active transport
   4. D) Simple diffusion
4. In which direction does the sodium-potassium pump move sodium ions ($Na^+$)?
   1. A) From high to low concentration
   2. B) From low to high concentration
   3. C) Only into the cell
   4. D) Only out of the cell
5. What is the main difference between primary and secondary active transport?
   1. A) Primary uses ATP; secondary uses an electrochemical gradient.
   2. B) Primary transports ions; secondary transports sugars.
   3. C) Primary occurs in animals; secondary occurs in plants.
   4. D) Primary is faster than secondary.
6. Which of the following is an example of a molecule transported via active transport in the human body?
   1. A) Oxygen
   2. B) Carbon dioxide
   3. C) Glucose in the intestines
   4. D) Water
7. Active transport is crucial for maintaining:
   1. A) Cell size
   2. B) Membrane fluidity
   3. C) Ion gradients across cell membranes
   4. D) Protein structure