Movement of Substances Into & Out of Cells Practice Questions

Question 1

5 marks

A teacher put one drop of blue food colouring into a beaker of still water at $20\ ^{\circ}\mathrm{C}$ . She did not stir the water. After 30 minutes all of the water in the beaker was pale blue.

(a)

Name the process that caused the food colouring to spread through the water.

/ 1

(b)

Describe the movement of the food colouring particles in the beaker.

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(c)

The teacher repeated the demonstration using water at $60\ ^{\circ}\mathrm{C}$ . The colour spread through the water in a much shorter time.

Explain why.

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Question 2

4 marks

Substances move into and out of cells by diffusion, osmosis and active transport.

Complete the table by writing an answer in each of the four empty boxes.

Process	Example of substance moved	Down or against the concentration gradient	Energy from respiration needed?
diffusion	oxygen	down	(i)
osmosis	(ii)	down	no
active transport	mineral ions	(iii)	(iv)

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Question 3

5 marks

A student cut a cylinder from a fresh beetroot and left it in distilled water for one hour. The mass of the cylinder before and after is shown.

	mass in grams
at the start	2.50
after one hour	2.87

(a)

State what is meant by osmosis.

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(b)

Calculate the percentage change in mass of the beetroot cylinder.

Give your answer to 1 decimal place.

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(c)

State the direction in which water moved during the hour.

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Question 0

6 marks

A student investigated osmosis in potato tissue. She cut cylinders of potato using a cork borer, weighed each one, and placed each cylinder into a different concentration of sucrose solution for 30 minutes. She then removed the cylinders and reweighed them.

(a)

Give two variables the student should control in this investigation.

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(b)

Explain why each potato cylinder should be blotted with paper towel before it is reweighed.

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(c)

Explain why the student calculated the percentage change in mass rather than simply the change in mass.

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Question 0

5 marks

A student placed one potato cylinder in each of five sucrose solutions for 30 minutes. Her results are shown in the table.

Concentration of sucrose solution in $\mathrm{mol/dm^3}$	Mass at start in grams	Mass at end in grams	Percentage change in mass
0.0	3.20	3.58	$+11.9$
0.2	3.15	3.34	$+6.0$
0.4	3.24	3.27
0.6	3.18	3.02	$-5.0$
0.8	3.10	2.79	$-10.0$

(a)

Calculate the percentage change in mass of the potato cylinder in the $0.4\ \mathrm{mol/dm^3}$ sucrose solution.

Give your answer to 1 decimal place.

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(b)

The student plotted a graph of percentage change in mass against concentration of sucrose solution.

Using the results in the table, estimate the concentration of sucrose solution at which there would be no change in the mass of the potato cylinder.

/ 1

(c)

Explain what this concentration tells the student about the cells in the potato.

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Question 0

6 marks

Root hair cells absorb water and mineral ions from the soil. The concentration of nitrate ions in the soil water is much lower than the concentration of nitrate ions in the cytoplasm of a root hair cell.

(a)

Name the process by which water is absorbed into a root hair cell.

/ 1

(b)

Explain how nitrate ions are absorbed into the root hair cell.

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(c)

Root hair cells contain large numbers of mitochondria.

Explain why.

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Question 0

6 marks

A gardener watered a healthy pot plant with a fertiliser solution that was much more concentrated than the instructions said it should be. Two hours later the leaves of the plant had wilted (gone floppy).

(a)

When a plant cell is placed in pure water it takes in water but does not burst.

Give the reason for this.

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(b)

Explain why the leaves of the plant wilted after it was watered with the concentrated fertiliser solution.

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(c)

An animal cell placed in pure water will burst.

Explain why.

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Question 0

6 marks

A student investigated the rate of diffusion of ammonia gas. She placed cotton wool soaked in ammonia solution at one end of a dry glass tube and a piece of damp red litmus paper $30\ \mathrm{cm}$ away at the other end. She timed how long it took for the litmus paper to turn blue. She repeated the experiment at different temperatures using the same ammonia solution.

Her results are shown in the table.

Temperature in $^{\circ}\mathrm{C}$	Time for litmus to turn blue in seconds
20	120
30	95
40	72
50	55

(a)

Describe the relationship between temperature and the time taken for the litmus paper to turn blue.

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(b)

Explain, in terms of particles, why temperature has this effect.

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(c)

The student repeated the experiment at $20\ ^{\circ}\mathrm{C}$ using a more concentrated ammonia solution. The litmus paper turned blue in less time.

Explain why.

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Question 0

6 marks

Scientists investigated how barley roots take up chloride ions. They measured the rate of chloride ion uptake by the roots in air containing different percentages of oxygen. The concentration of chloride ions in the solution around the roots was always lower than the concentration inside the root cells.

They then repeated the investigation at $21\%$ oxygen after adding cyanide, a chemical that stops respiration.

Oxygen concentration in %	Rate of chloride ion uptake in arbitrary units per hour
0	2
5	12
10	22
21	30
21 (with cyanide added)	3

(a)

Calculate the percentage increase in the rate of chloride ion uptake when the oxygen concentration is increased from $5\%$ to $21\%$ .

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(b)

Explain how these results provide evidence that chloride ions are taken up by the barley roots by active transport.

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Question 0

6 marks

Visking tubing is a partially permeable material. A student filled a piece of visking tubing with concentrated sucrose solution, tied both ends and placed it in a beaker of distilled water, as shown.

Every 10 minutes the student removed the tubing, dried it with paper towel, weighed it and returned it to the beaker. Her results are shown.

Time in minutes	Mass of visking tubing in grams
0	20.0
10	22.5
20	24.4
30	25.6
40	26.0
50	26.0

(a)

Calculate the rate of increase in mass, in $\mathrm{g/min}$ , during the first 10 minutes.

/ 1

(b)

Explain the results shown in the table.

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(c)

Give one way in which the visking tubing is different from a real plant cell.

/ 1

Key Concepts in Biology

Cells & Control

Genetics

Natural Selection & Genetic Modification

Health, Disease & the Development of Medicines

Plant Structures & their Functions

Animal Coordination, Control & Homeostasis

Exchange & Transport in Animals

Ecosystems & Material Cycles

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