Movement of molecules in and out of cells Flashcards
Dissolved substances can move how?
By diffusion and active transport.
Water moves across boundaries by…
…osmosis.
Osmosis is what?
The diffusion of water down the concentration gradient through a partially permeable membrane.
What causes osmosis?
Differences in concentration inside and outside of a cell.
Most soft drinks contain what?
Water, sugar and ions.
Sports drinks contain sugars to what?
Replace sugars used in exercise.
Sports drinks contain water and ions to what?
To replace water and ions lots during sweating.
What happens if water and ions aren’t replaced?
The body’s water/ion balance is disturbed and the cells do not work as efficiently.
What is active transport?
The absorption of material against the concentration gradient. It requires energy from respiration.
Active transport allows cells to absorb what from dilute solutions?
Ions.
Effectiveness of exchange surfaces is increased by…
…a larger surface area.
…being thin (shorter distance).
…efficient blood supply (animals).
…ventilated (animals for gaseous exchange).
Gas and solute exchange surfaces are adapted for what?
To provide maximum effectiveness.
Difficulty of exchanging of materials is increased with what?
size and complexity of the organism.
In humans the surface area of the lungs is increased by…
…the alveoli.
In humans the surface area of the small intestine is increased by…
…the villi.
What do villi do?
Provide a large surface area with an extensive network of capillaries to absorb products of digestion by diffusion and active transport.
The breathing systems are in the body, why?
So that oxygen from the air can diffuse into the bloodstream and carbon dioxide can diffuse out of the bloodstream into the air.
How does air move into the lungs?
The ribcage moves out and the diaphragm downwards which increases the volume of the lungs. This decreases the pressure and air from the higher pressure surroundings moves in.
How does air move out of the lungs?
The ribcage contracts and the diaphragm relaxes causing a decrease in volume in the lungs. This means the pressure is increased and air moves to the lower pressured surroundings.
The action of breathing in and out is known as what?
Ventilation.
Plants obtain carbon dioxide how?
Through diffusion in their leaves.
Plants absorb water and mineral ions mostly through what?
Their roots.
How is the surface area of roots increased?
With root hair cells.
How is the surface area of leaves increased?
With internal air spaces and flattened shape.
