CH-03 movement in and out of the cells Flashcards Preview

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What is diffusion?- DEFINITION

Diffusion is the movement of molecules from a region of its higher concentration to a region of its lower concentration down a concentration gradient.
Molecules move down a concentration gradient, as a result of their random movement that
The energy for diffusion comes from the kinetic energy of random movement of molecules and ion.


What does diffusion helps organisms to -

1. Obtain many of their requirements
2.get rid of many of their waste products
3.carry out gas exchange for respiration


Three factors that affect the rate of diffusion.

1. Distance- smaller the distance, faster the rate of diffusion.
2. Temperature- higher the temperature, faster the molecules move.
3.Concentration gradient- greater the concentration difference, faster the diffusion.


What is OSMOSIS?

Osmosis is the diffusion of water molecules from a dilute solution to a more concentrated solution across a partially permeable membrane down its concentration gradient.


What happens to animal cells in pure water?

Osmosis takes place. Water diffuses into the cell through the partially permeable cell membrane. The cell swells, and as the cell membrane has to stretch- it eventually strains and bursts.


What happens to animal cells in concentrated solution?

Water molecules diffuse out of the cell, cytoplasm shrinks. The cell shrivels up.


What happens to plant cells in pure water?

As the water diffuses into the cell, cytoplasm and vacuole swells. However, the plant cell has very strong cell wall around it-- which is stronger than cell membrane-preventing the cell from bursting.
It becomes turgid.


What does turgidity helps plants with?

turgidity helps plants having no wood to stay upright and keeps the leaves firm. supports and strengthens the plant


What happens to plant cells in concentrated solution?

It becomes flaccid. Alot of water diffuses out- cytoplasm and vacuole shrinks . As it shrinks and shrinks towards the center of the cell-- cell wall is left behind and cell membrane is tears away from the cell wall. And the cell becomes plasmolysed.


What is Active transport?

Active transport is the movement of molecules and ions through the cell membrane from a region of lower concentration to a region of higher concentration using energy from respiration against the concentration gradient.


Examples of active transport-

1. Uptake of glucose by epithelial cells in the villi of the small intestine and by kidney tubules in nephrons.
2. Uptake of ions- from soil water by root hair cells.


How does Active transport works?

1. Substance combines with carrier protein molecule in the cell membrane
2. Carrier transports substances across membrane using energy from respiration to give them the kinetic energy needed to change shape and move the substance through the cell membrane
3. Substance released into cell