BIOLOGY - Movement in and out of cell

Diffusion

1. Passive Transport (doesn’t require energy from the cell)
2. The net movement of particles from an area of higher concentration to an area of lower concentration.
3. Happens in both gases and particles of dissolved substances
4. Diffuses evenly until equilibrium is reached 5. faster in gases, slower in solids

3 factors affecting rate of diffusion:

1. Concentration Gradient -The difference in concentration between two places. The Larger the Concentration Gradient > Higher the rate of diffusion
2. Temperature - Higher temperature give particles more energy; move around faster; diffuse more quickly. Higher Temp > Higher Rate of diffusion
3. Distance: Shorter Distance > Higher rate of diffusion

Examples of Diffusion:

1. Carbon dioxide moves from the air into the leaves through stomata down the concentration gradient finally to diffuse into the mesophyll cells of leaf, the site of photosynthesis.
2. Gas exchange: oxygen enters air sacs. oxygen concern. higher in air sac than blood. oxygen diffuses into blood stream

Importance of Diffusion: GPAP

1. Gas exchange in lungs
2. Photosynthesis
3. Absorption of amino acids from small intestines into the blood stream
4. Pollination

Osmosis

(Diffusion of water molecules) 1. The net movement of water molecules across a partially permeable membrane from a region of higher water concentration to a region of lower water concentration
2. Water concentration: The amount of water compared to other molecules, like solutes (sugars or salts), that are dissolved in the water. Proportion of water compared to solutes determines concentration

Pure Water>Dilute>Concentrated

Dilute Solution has small amount of solute and large amount of solvent.
Concentrated has large amount of solute and small amount of solvent

Examples of osmosis

1. The absorption of water by plant roots
2. The absorption of water in small intestine

Animal Cell

Concentrated: Crenation: Water is lost from the cell thru osmosis, it shrinks
Dilute: Haemolysis: animal cell takes in water through osmosis, bulges and bursts because no cell wall

Plant Cell

Concentrated: Plasmolysis: Water is lost from cell. becomes flaccid.
Dilute: Hypotonic: water is taken into plant cell, bulges but doesn’t burst due to cell wall

Active Transport

1. Requires energy from Cell.
2. The Movement of molecules across a cell membrane, from a region of lower concentration to a region of higher concentration and requiring energy from cellular respiration
3. Protein carriers are involved
4. allows absorption of substances from dilute solutions

Passive Transport

Movement of particles down a concentration gradient without requiring energy from the cell.

Cellular Respiration

Energy for active transport. Mitochondria breaks down glucose to release energy. Stores energy as ATP which takes energy to the parts of cell that needs it. Responsible for all energy that the cell uses

Importance of Active Transport: SSD

1. Absorption of ions from soil into roots
2. Absoprtion of glucose/amino acids from Small Intestine to cells
3. absorption of glucose from kidney tubules into blood

Example of Active Transport

Root hair cells use active transport to absorb mineral ions, so adapt by having large surface are and lots mitochondria.
1. Plants need to absorb water and mineral ions, so networks of roots into ground.
2. They have root hair cells which absorb by long hair protrusions which gives large surface area for absorptions.
3. Magnesium ions or nitrates are in High Concentration inside the hairs so cannot diffusion. so use active transport. that’s way many mitochondria in root hairs