Homeostasis and The Plasma Membrane

Agriculture Biology

Goals

I can explain passive transport I can explain how diffusion occurs I can identify how water moves in and out of

a cell through osmosis.

Passive Transport

Movement across the cell membrane that does not require energy from the cell.

Process of Diffusion

Diffusion - Movement of particles from higher concentration to low concentration (people move from big city to country for more space!!)

Equilibrium

Diffusion is due to random movement of particles

Colored ions evenly distributed in beaker, but ions still move and collide

Dynamic Equilibrium- (movement balanced) – continuous movement but no overall change in concentrations in beaker

What happened here? Diffusion in action!

Diffusion

Fertile eggs are injected at day 19 with pure dye into the opposite end of the air cell.

The dye then diffuses into the yolk sac which is absorbed by the chick and becomes systemic.

When they hatch…voila…Easter Chicks!! Who needs to dye eggs when you have

dyed chicks!

STOP

Write a summary of diffusion in your notes.

Osmosis- the diffusion of water Diffusion of water molecules

through a selectively permeable membrane from high concentration to low concentration (passive transport)

Cell will lose or gain water by osmosis depending on the water concentration outside of the cell versus inside of the cell

Osmosis in Action

Osmosis in Action

Concentration Gradients

Difference in concentration of substance is concentration gradient

Isotonic Solutions

Amount of water going in= amount of water leaving

Hypotonic Solutions

Amount of water going into the cell > amount of water going out of the cell

CELL SWELLS

STOP

Draw a picture of a hypotonic solution. IN>OUT CELL SWELLS

Hypertonic Solutions

Amount of water going OUT> amount of water leaving the cell

CELL SHRINKS

STOP

DRAW A PICTURE OF HYPERTONIC SOLUTION

OUT>IN CELL SHRINKS

Effects on Agriculture: Why is this important?

The floral industry relies on osmosis to help carry dye up the stems of carnations and roses

Growing plants, both ornamental and crops, is a science itself. Making sure that plants are irrigated properly will ensure more product which equals=====$$$$$$$

If the livestock and pet industries do not provide adequate fresh water for animals what happens to the cells? They shrink! This can be detrimental to the livestock industry with regards to “shrinkage” when selling cattle, etc.

Ticket out the Door

1. Explain passive transport.

2. What occurs during diffusion?

3. During osmosis, water is being passively diffused through what?

4. There are three outcomes of osmosis. Explain what happens to the cell when water moves out, moves in, or remains constant.