Movement of substances in and out of cells Flashcards
What is diffusion?
The net movement of particles from an area of high concentration to an area of low concentration down a concentration gradient.
Diffusion is a passive process, so it doesn’t require energy.
How does diffusion occur across a cell membrane?
Diffusion allows substances to pass through a partially permeable cell membrane.
For example, during respiration, oxygen moves into the cell due to a concentration gradient.
What types of particles can move across a semipermeable membrane?
Relatively small particles like oxygen, glucose, and carbon dioxide can move across, but larger particles like starch cannot.
Does diffusion require a membrane?
No, diffusion does not require a membrane to occur.
For example, gases can diffuse in a room.
What factors affect the rate of diffusion?
Factors include temperature, concentration gradient, surface area:volume ratio, and distance particles have to travel.
How does temperature affect diffusion?
Increased temperature means that the substance has more kinetic energy, moving faster and increasing the rate of diffusion.
How does concentration gradient affect diffusion?
The steeper the concentration gradient, the greater the difference between the two concentrations, leading to a faster rate of diffusion.
How does surface area affect diffusion?
A greater surface area provides more space for the substance to move through, increasing the rate of diffusion.
How does distance affect diffusion?
The further the particles have to travel, the longer it will take, decreasing the rate of diffusion.
What is osmosis?
The net movement of water molecules from a region of high water potential to low water potential through a partially permeable membrane.
Is osmosis an active or passive process?
Passive
What type of membrane allows osmosis to occur?
Partially permeable membrane
In osmosis, what direction does water move?
From high concentration of water to low concentration of water.
What characterizes a concentrated solution in terms of water potential?
Low water potential (more solute, less water)
What characterizes a dilute solution in terms of water potential?
High water potential (more water, less solute)
What is an isotonic solution?
A solution where the concentration of solute is the same as in the cell, resulting in no net water movement.
What is a hypertonic solution?
A solution with a higher concentration of solute than the cell, causing water to move out of the cell.
What is a hypotonic solution?
A solution with a lower concentration of solute than the cell, causing water to move into the cell.
What happens to an animal cell in a hypotonic solution?
Water moves into the cell, potentially causing it to burst.
What happens to an animal cell in a hypertonic solution?
It loses water and becomes shrivelled.
