Movement into and out cells diffusion Flashcards
What is diffusion?
Net movement of particles from a region of higher concentration to a region of lower concentration as a result of random movement.
Where does diffusion occur and what does it allow?
Occurs in plants and animals both and allows substances to diffuse in and out of the cell membrane.
Where does the energy for diffusion come from?
Energy for diffusion comes from kinetic energy from the random movement of particles.
How does diffusion relate to the concentration gradient?
Diffusion occurs down a concentration gradient, meaning particles move from a higher to a lower concentration until they are evenly spread out.
Why is diffusion important in animals?
Diffusion allows gas exchange (oxygen in, carbon dioxide out) and the absorption of dissolved food materials into cells.
How does diffusion help in gas exchange in animals?
Oxygen diffuses into the bloodstream from the lungs, and carbon dioxide diffuses out of the blood to be exhaled.
Why is diffusion important in plants?
Diffusion helps plants take in carbon dioxide and release oxygen during photosynthesis.
What role does diffusion play in root hair cells?
Dissolved minerals and salts diffuse from the soil into the root hair cells of plants.
What are the factors that influence the rate of diffusion?
The rate of diffusion is influenced by:
Surface area - Larger surface area allows faster diffusion.
Temperature - Higher temperature increases particle movement, speeding up diffusion.
Concentration gradient - A steeper gradient (greater difference) increases the diffusion rate.
Distance - Shorter distances across the membrane make diffusion faster.
How does surface area influence the rate of diffusion?
A larger surface area of the exchange membrane allows particles to diffuse faster.
How does temperature affect the rate of diffusion?
Increasing temperature increases the kinetic energy of particles, causing them to move faster and increasing the rate of diffusion.
How does concentration gradient impact diffusion?
The steeper the concentration gradient (the bigger the difference between high and low concentration), the faster the rate of diffusion.
How does the distance affect the rate of diffusion?
The shorter the distance across the exchange membrane, the easier it is for particles to diffuse, increasing the rate of diffusion.
What is osmosis?
Osmosis is the net movement of water molecules from a region of high water potential (dilute solution) to a region of lower water potential (concentrated solution) through a partially permeable membrane.
Through what does osmosis occur?
Osmosis occurs through a partially permeable membrane that allows water molecules to pass but not larger solute molecules.
What happens to a plant cell placed in distilled (pure) water?
Water moves into the cell by osmosis. The cell swells and becomes turgid but doesn’t burst due to the elastic cell wall.
What causes turgor pressure in a plant cell?
The vacuole fills with water and exerts turgor pressure against the cell wall, helping the plant remain firm and upright.
What happens to a plant cell placed in a salt solution (low water potential)?
Water moves out of the cell by osmosis. The cell becomes plasmolysed — the cytoplasm and cell membrane shrink away from the cell wall.
What happens when an animal cell is placed in pure water?
Water enters the cell by osmosis. If too much water enters and isn’t removed, the cell may burst. This is called hemolysis.
What happens when an animal cell is placed in a salt (concentrated) solution?
Water leaves the cell by osmosis. The cell shrinks and becomes crinkled or crenated due to water loss.
Why is osmosis important in plants?
Plants absorb water from soil into roots by osmosis. This water keeps cells turgid, giving the plant structure and support.
What happens if plant cell vacuoles aren’t full of water?
Cells become flaccid. If many cells become flaccid, the leaf wilts and droops.
Why do animal cells not burst or shrink under normal conditions?
They are surrounded by tissue fluid with the same concentration as inside the cell, so no net osmosis occurs.
What is active transport?
Active transport is the movement of particles from a lower to a higher concentration using energy from respiration.
