Start with adenosine triphosphate and bioenergetics, then connect membrane transport to homeostasis. Bacterial cell structure offers a useful comparison when reviewing cell organisation.
Independent practice • ATP and membrane transport
Review how cells transfer energy and move substances across membranes. Focus on the mechanism, rather than memorising an answer letter.
This page contains eight practice questions. They are learning exercises, not official exam questions or a complete syllabus guide.
How to use this set
- Answer all eight questions before opening the solutions.
- For calculations, write the equation, substitute values and include units.
- Check the explanation even when your answer is correct. Record the concept behind each mistake.
Practice questions
Question 1
Which combination describes ATP?
- Adenine, ribose and three phosphate groups
- Adenine, deoxyribose and two phosphates
- Glucose and three amino acids
- Ribose and four nitrogenous bases
Show answer and explanation
Answer: A. ATP contains adenine, the sugar ribose and three phosphate groups.
Question 2
Which reaction shows ATP hydrolysis to ADP?
- ADP + phosphate → ATP with no energy input
- ATP + water → ADP + inorganic phosphate
- ATP → glucose + oxygen
- ADP → DNA
Show answer and explanation
Answer: B. Water participates in hydrolysis. The overall reaction has a favourable free-energy change under typical cellular conditions.
Question 3
Which statement about ATP is most accurate?
- Breaking a bond by itself releases energy.
- The overall hydrolysis reaction can be coupled to cellular work.
- ATP never needs regeneration.
- ATP is a permanent store of all cellular energy.
Show answer and explanation
Answer: B. Bond breaking requires energy. The energy change of the complete reaction, including product formation, allows useful coupling.
Question 4
In simple diffusion, net movement occurs:
- Down a concentration gradient
- Only against a gradient
- Only when ATP is consumed directly
- Only through a pump
Show answer and explanation
Answer: A. Random molecular motion produces net movement from a region of higher concentration to one of lower concentration.
Question 5
Facilitated diffusion differs from simple diffusion because it:
- Always moves uphill
- Uses membrane transport proteins
- Always directly hydrolyses ATP
- Cannot occur in living cells
Show answer and explanation
Answer: B. Channels or carriers help substances cross the membrane while movement remains down the relevant gradient.
Question 6
At diffusion equilibrium, what happens?
- Molecules stop moving.
- All molecules move only one way.
- Molecules still move, but there is no net movement.
- The membrane disappears.
Show answer and explanation
Answer: C. Equilibrium is dynamic: movements continue in both directions with no net concentration-driven transfer.
Question 7
An animal cell is placed in a sufficiently hypotonic solution. What is expected?
- Net water movement into the cell
- Net water movement out only
- No possible water movement
- A new cell wall forms
Show answer and explanation
Answer: A. A hypotonic external solution promotes net water entry by osmosis; the cell may swell.
Question 8
Why can a membrane protein be involved in passive transport?
- All proteins consume ATP directly.
- Protein assistance does not necessarily mean movement against a gradient.
- Passive transport cannot use proteins.
- Proteins remove the membrane.
Show answer and explanation
Answer: B. Transport mechanism and energy requirement are separate questions. Facilitated diffusion uses proteins without moving uphill.
Review your work
Score one point for each correct answer. Use the score to identify what to revise, rather than to predict an examination result. Rework any missed question without looking at the solution, then explain your reasoning aloud.
For exam preparation, compare your topic list with the current syllabus issued by your examination authority. This short set makes no claim of full syllabus coverage.
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