Biology text book 9th fbise Chp.No.4 Cells and tissues

1. Chapter No.4 Cells and tissues
Topic : Passage of molecules into and
out of cells

2. Objective
• Describe the different methods for the passage of
molecules into and out of cells.
1. Passive transport
• Diffusion
• Facilitated diffusion
• Osmosis
2. Filtration
3. Active transport
4. Endocytosis
5. Exocytosis

3. Introduction

5. Passive
transport
Simple
diffusion
Facilitated
diffusion
Osmosis

12. Water balance problems

13. Osmosis and guard cells
During day, guard cells make more glucose and so are
hypertonic than near by cells. so, water from neighboring
cells enter them. They swell and stoma becomes open.
During night, guard cells donot photosynthesize so amount of
glucose decreases. Guard cells become hypotonic and
water moves out of them.They become flaccid and stoma is
closed.

15. Application of knowledge about semi-
permeable membranes
• Artificially synthesized semi-permeable
membranes are used for the separation of
bacteria from virses, because bacteria cannot
cross a semi-permeable membrane.
• In advaced water-treatment technologies,
membrane based filtration systems are used.
In this process, membranes separate salts
from water by reverse osmosis.

19. Sodium-Potassium Pump in nerve cells

22. Filtration
Filtration is method by which small molecules are
forced to move across semi-permeable
membrane with the aid of hydrostatic (water)
pressure or blood pressure.
For example,in the body of an animal ,blood
pressure forces water and dissolved molecules to
move through the semi-permeable membranes
of the capillaries walls cells.In filtration the
pressure cannot force large molecules,such as
proteins, to pass through the membrane pores.

23. Capillary Filtration