1.3 cell transport

diffusion

Movement of molecules from an area of higher concentration to an area of lower concentration.

substances moved in diffusion

oxygen

glucose

amino acids

water

factors affecting rate of diffusion

Concentration gradient, temperature, surface area

diffusion in humans

-oxygen diffuses from the air in the lungs, into the capillaries' blood; carbon dioxide diffuses from the blood in the capillaries into the air in the lungs

osmosis

Diffusion of water molecules in a higher concentration to a lower concentration through a partially permeable membrane

Osmosis across living cells

Cells contain dilute solutions of ions, sugars and amino acids.

The cell membrane is partially permeable. Water will move into and out of cells by osmosis.

how do root hair cells take up water

osmosis

what stops plant cells from bursting

cell wall

Plant cell in pure water

Gains water, becomes turgid and firm.

Plant cell in concentrated solution

cell contents lose water via osmosis, shrink and pull away from cell wall.

cell becomes flaccid

when does a plant undergo plasymosis

in a highly concentrated solution

Animal cell in concentrated solution

water moves out by osmosis, the cell shrinks

animal cell in distilled water

gains water and bursts

osmosis in plants

Water moves from soil to plant

Supports stems and leaves

Osmosis practical independent variable:

Concentration of sugar solution

Osmosis practical dependent variable:

mass of potato cylinders after experiment

Osmosis practical control variable:

time that each cylinder is left in sucrose solution and size of cylinders

Osmosis practical

1)Set up 6 boiling tubes, each containing the same volume of one of the sucrose solutions. The 0.0 mol/dm-3 sucrose solution is distilled water. Label the boiling tubes.

2)Prepare 6 potato cylinders using a borer and cut the cylinders to the same length. Gently dry each potato cylinder using a paper towel to remove excess liquid and record its mass before placing it into one of the boiling tubes.

3)Leave the potato cylinders in the boiling tubes for 40 minutes.

4)Remove each potato cylinder from its boiling tube, gently remove excess liquid from the surface of the cylinder with a paper towel and record its mass.

5)repeat and calculate the mean

rate of water loss

mass/time(in hours)

active transport

movement of particles from area of low concentration to higher concentration against concentration gradient

active transport in plants

uptake of mineral ions via root hair cells

What is required for active transport in root hairs to work?

Energy from respiration

active transport in animals

glucose molecules move from gut wall into the blood.

The process requires energy produced by respiration.