Exchange of Materials Flashcards
What is Osmosis?
The movement of water
From an area of high concentration to an area of low concentration along a concentration gradient
From more dilute solution to higher concentration
What does osmosis occur across?
A partially permiable membrane
What is the movement of water molecules performing osmosis like?
Random
What does osmosis not require from the cell?
Energy
Cells may need to absorb substances in short supply. To do this, they may have to absorb susbtances…
…against the concentration gradient
What is active transport?
The movement of susbtances across either a cell membrane or against a concentration gradient
It requires energy because of this
Where does the energy for active transport come from?
Respiration
How do root cells use active transport?
They absorb mineral ions from dilute solutions in the soil
How do the kidneys use active transport?
Glucose can be reabsorbed in kidney tubes
What specific substance dos active transport use?
A transport protein
It rotates, using energy
What happens if you sweat a lot or do not drink enough water? (Or eat a lot of salty food)
You may become dehydrated
What do sports drinks contain and why?
- Water to replace water lost by sweating
- Sugar to replace sugar used for respiration in exercise
- Mineral ions to replace those lost by sweating
What does isotonic?
Having the same concentration of solutes as another solution
What does it mean if a sports drink is isotonic?
The concentration of sugar, water, and mineral ions in the drink matches those in the body
For normal levels of exercise, what might be just as effective as a sports drink?
A drink of water
What do large organisms need and why?
Exchange surfaces
They need these to obtain all the food and oxygen they require
What makes an exchange surface efficient?
- Large surface area
- Thin walls or short diffusion path
- Efficient transport system - bloody supply in animals
What form of exchange takes place in the lungs?
The gaseous exchange