Dissolved Substances Flashcards
How does water often move across boundaries?
By osmosis
What is osmosis?
The diffusion of water from a high water concentration to a low water concentration through a partially permeable membrane
What causes water to move into or out of the cell by osmosis?
Differences In the concentrations of the solutions inside and outside a cell
What do most soft drinks contain?
Water, sugar, ions
Why do sports drinks contain sugar ?
To replace the sugar used in energy release during the activity
Why do sports drinks contain water and ions?
To replace the water and ions lost during sweating
What happens if water and ions are not replaced?
The ion/water balance of the body is disturbed and the cells don’t work as efficiently
What is active transport?
The process by which dissolved molecules move across a cell membrane from a lower to a higher concentration against a concentration gradient
What does active transport enable?
Cells to absorb ions from very dilute solutions
What two things increase the difficulty of exchanging materials ?
The size and complexity of an organism
In humans what happens?
The surface area of the lungs is increased by the alveoli
The surface area of the small intestine is increased by villi
What makes diffusion and osmosis faster?
A large surface area
A short distance for the molecules to travel
What does active transport require?
Energy from respiration
Mitochondria
What do dissolved substances move by?
Diffusion and active transport
