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[O] Pure Biology Smart Guides

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  1. I. PRINCIPLES OF BIOLOGY

    2. Cells
    2 Topics
  2. 3. Movement of Substances
    1 Topic
  3. 4. Nutrients
    4 Topics
  4. 5. Enzymes
    2 Topics
  5. II. MAINTENANCE AND REGULATION OF LIFE PROCESSES
    6. Nutrition in Humans
    4 Topics
  6. 7. Nutrition in Plants
    2 Topics
  7. 8. Transport in Humans
    5 Topics
  8. 9. Transport in Plants
    4 Topics
  9. 10. Respiration in Humans
    5 Topics
  10. 11. Excretion in Humans
    4 Topics
  11. 12. Homeostasis
    3 Topics
  12. 13. Nervous System
    2 Topics
  13. 14. Human Eye
    2 Topics
  14. 15. Hormones
    2 Topics
  15. III. CONTINUITY OF LIFE
    16. Cell Division
    3 Topics
  16. 17. Reproduction in Plants
    3 Topics
  17. 18. Reproduction in Humans
    5 Topics
  18. 19. Heredity
    6 Topics
  19. 20. Molecular Genetics
    2 Topics
  20. IV. MAN AND HIS ENVIRONMENT
    21. Ecology
    5 Topics
  21. 22. Our Impact on the Ecosystem
    2 Topics
[O] Pure Biology Smart Guides 3. Movement of Substances Diffusion & Osmosis
Chapter 2, Topic 1
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Diffusion & Osmosis

FortisLearn June 13, 2020
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Concentration gradient: It is the difference in concentration between two regions.

Diffusion

Diffusion: it is the net movement of particles from a region where they are of higher concentration to a region where they are of lower concentration, that is, down a concentration gradient without the need of energy.

Osmosis

Osmosis: It is the net movement of water molecules from a solution of higher water potential to a solution of lower water potential, through a partially permeable membrane, a passive type of transport without the need for energy.

Active transport: It is the process in which energy from cell respiration is used to move the particles of a substance across a partially permeable membrane against its concentration gradient, that is, from a region where the particles are of lower concentration to a region where they are of higher concentration.

Factors affecting diffusion

  • Temperature (higher temperature, higher rate of diffusion)
  • Size of Particles (smaller size of particle, higher rate of diffusion)
  • Thickness of the barrier (thicker the barrier, the slower the rate of diffusion)
  • Concentration Gradient (higher concentration gradient, higher rate of diffusion)
  • Surface Area (larger surface area, higher rate of diffusion)
 How water movesPlant cell becomesAnimal cell becomes
In a solution of higher water potentialWater molecules enter cell by osmosisTurgidHaemolysed (RBC) Burst (all other cells)
In a solution of lower water potentialWater molecules leave cell by osmosisPlasmolysed (for single cell) Flaccid (for tissues/one strip cell)Crenated
DiffusionOsmosis
Involves only the movement of solute particlesInvolves only the movement of water molecules
Take place in gaseous or liquid or solid statesOnly take place in solution media
Can take place in the presence or absence of a membraneMust take place in the presence of partially permeable membrane
Both involve the movement of molecules down a concentration gradient.
Both are passive processes in which no energy is required.