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Q1-3: The diagram shows an animal cell.
This cell contains molecules of carbon dioxide and oxygen:
Using the diagram complete the following sentences:
4. In the soil, water and mineral ions enter the plant through the root hairs. Plant roots have many root hairs:
Water enters the root hair by the process of ..
5. The statements below describe conditions required for some molecules to be moved into the root hair cell.
1. A concentration gradient 2. Use of ATP
1. A concentration gradient
2. Use of ATP
Which of these statements is correct for the process of osmosis?
On the hot day the uptake of magnesium ions would ..
8 - 10: A student cut some potato chips and placed them in different concentrations of sucrose solution. The chips were 50 mm long at the start. After 60 minutes she remeasured the chips and plotted a graph of her results:
9. How much was the increase in length of the potato chips placed in pure water?
Question 1:
There is a higher concentration of oxygen molecules outside the cell compared with within the cell.
In the diagram, you can see many more red dots (oxygen) outside the cell than inside. In biology, "concentration" just refers to how crowded molecules are in a specific area.
* Outside: High concentration (very crowded). * Inside: Low concentration (less crowded).
*These A.I. responses have been individually checked to ensure they match the accepted answer, but explanations may still be incorrect. Responses may give guidance but the A.I. might not be able to answer the question! This is particularly the case for questions based on diagrams, which the A.I. typically cannot interpret. Grade Gorilla uses Gemini, Deepseek and a range of other A.I. chatbots to generate the saved responses. Some answers have had human intervention for clarity or where the A.I. has not been able to answer the question.
Question 2:
Oxygen will therefore enter the cell by diffusion.
Diffusion is the natural movement of particles from an area where they are crowded (high concentration) to an area where they are less crowded (low concentration). It’s a "passive" process, meaning it doesn't require the cell to use any energy—it happens naturally, much like how the scent of perfume eventually spreads across a whole room.
Question 3:
The oxygen molecules pass through the plasma membrane to enter the cell.
The "border" of the animal cell is the plasma membrane (also called the cell membrane). It acts like a gatekeeper. It is semi-permeable, which is a fancy way of saying it has tiny gaps that allow small molecules like oxygen and carbon dioxide to slip right through, while keeping larger, potentially harmful things out.
Question 4:
The correct answer is B. Osmosis.
Reasoning:
Water moves from the soil (where water concentration is higher) into the root hair cell (where water concentration is lower due to dissolved minerals and sugars in the cell sap).
This movement across a semipermeable membrane is osmosis (the net movement of water from a region of higher water potential to lower water potential).
Diffusion (A) refers to movement of solutes, not specifically water. Active uptake (C) requires energy and is used for moving mineral ions, not water.
Question 5:
Answer: B. 1 only
Explanation:
Osmosis is the movement of water across a membrane from high water concentration to low water concentration.
This requires a concentration gradient (statement 1 is correct).
Osmosis is a passive process, so it does not need ATP (statement 2 is incorrect).
Thus, only statement 1 is correct.
Question 6:
The correct answer is B. Active Uptake.
Magnesium ions are moving from low concentration (soil) to high concentration (inside vacuole).
Moving against a concentration gradient requires energy (ATP) and carrier proteins — this is active uptake (active transport).
Diffusion and osmosis move substances down a concentration gradient, so they do not apply here.
Phagocytosis is the engulfing of large particles, not ions.
Answer: B
Question 7:
The correct answer is B. increase.
Magnesium ions enter root hair cells by active transport (moving from low to high concentration).
Active transport requires energy from respiration.
On a hot day, the rate of respiration increases (within limits), providing more ATP.
This increases the rate of active transport, so magnesium uptake increases.
Question 8:
Answer: C. 1.2%
Reasoning: The point where final length equals starting length (50 mm) occurs at 1.2% sucrose concentration on the graph.
Question 9:
Answer: B. 3.0 mm
Reasoning: At 0.0% sucrose (pure water), final length = 53.0 mm. Increase = 53.0 - 50.0 = 3.0 mm.
Question 10:
Answer: C. flaccid
Reasoning: In 2% sucrose solution, the chip length decreased to 47.0 mm, meaning water left the cells by osmosis. The cells lost water and became limp (flaccid).