1.3.9

Required Practical - Osmosis in Plant Tissue

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Concentrations of Salt or Sugar Solutions on Plant Tissue

The aim of this practical is to investigate the effect of a range of concentrations of salt or sugar solutions on the mass of plant tissue using osmosis theory.

Calculate the results

Calculate the results

  • Using the recorded results, calculate the change in mass and percentage change.
  • To find the percentage change in mass =

    • FinalMassInitialMassInitialMass×100\dfrac{Final Mass - Initial Mass}{Initial Mass} \times 100
Plot the results

Plot the results

  • Plot a graph of percentage change in mass (y-axis) against concentration of solution (x-axis).
    • The point where the curve crosses 0% indicates the isotonic concentration of the potato cells.
Variables

Variables

  • Independent variable:
    • Concentration of salt or sugar solution (mol dm-3)
  • Dependent variable:
    • Change in mass (and length) of potato cylinders
  • Control variables:
    • Type of plant tissue, temperature, volume of solution, time left in solution, size and shape of potato pieces
Explanation

Explanation

  • In pure water (0.0M), potato gains mass → water moves into the cells by osmosis.
  • In strong solutions (1.0M), potato loses mass → water moves out of the cells.
  • The concentration where no change occurs is isotonic – equal concentration inside and outside the cells.
Evaluation and Improvements

Evaluation and Improvements

  • Possible errors:
    • Unequal potato size or surface area
    • Inaccurate drying before weighing
    • Evaporation of the solution
  • Improvements:
    • Use more concentration points for accuracy
    • Repeat each concentration at least 3 times and calculate a mean
    • Use a more precise balance
Jump to other topics
1

Cell Biology

1.1

What's in Cells?

1.2

Cell Division

1.3

Transport in Cells

2

Organisation

2.1

Principles of Organisation

2.2

Enzymes

2.3

Circulatory System

2.4

Non-Communicable Diseases

2.5

Plant Tissues, Organs & Systems

3

Infection & Response

4

Bioenergetics

5

Homeostasis & Response

5.1

Homeostasis

5.2

The Human Nervous System

5.3

Hormonal Coordination in Humans

5.4

Plant Hormones

6

Inheritance, Variation & Evolution

6.1

Reproduction

6.2

Variation & Evolution

6.3

Genetics & Evolution

6.4

Classification

7

Ecology

7.1

Adaptations & Interdependence

7.2

Organisation of Ecosystems

7.3

Biodiversity

7.4

Trophic Levels

7.5

Food Production

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