Movement of Substances in & out of Cells Flashcards
Define diffusion and describe the process
Diffusion is the net movement of molecules and ions from an area of higher concentration to an area of lower concentration down a concentration gradient due to their random movement.
Explain the importance of diffusion in gases for both animals and plants
Animals: Essential for gas exchange (O2 in, CO2 out).
Plants: Necessary for obtaining carbon dioxide and releasing oxygen during photosynthesis.
How is diffusion involved in the movement of solutes in organisms?
Dissolved salts diffuse through root hair cells, and the absorption of dissolved food materials in various organisms, such as amoeba, bacteria, and fungi, occurs through diffusion.
Where does the energy for diffusion come from, and what molecules utilize this energy?
The energy for diffusion comes from the kinetic energy of the random movement of molecules and ions.
Why is water considered a crucial solvent, and what processes are hindered without it?
Plants can’t obtain minerals without them being dissolved in water, and enzymes, hormones, and excretory products require water for proper functioning.
Name the factors that influence the rate of diffusion and explain their impact.
Surface area: A larger surface area facilitates faster diffusion.
Temperature: Higher temperature increases kinetic energy, speeding up diffusion.
Concentration gradient: Steeper gradients result in faster diffusion.
Distance (thickness of exchange membrane): Thinner membranes enhance diffusion rate.
Define osmosis and describe the movement of water molecules.
Osmosis is the net movement of water molecules from a region of higher water potential to a region of lower water potential through a partially permeable membrane.
Differentiate between dilute and concentrated solutions in terms of water potential
Dilute solutions have high water potential with lots of water molecules, while concentrated solutions have low water potential with few water molecules
How does water move in and out of cells, and why is it crucial for cells in animals and plants to be surrounded by an isotonic solution?
Water moves through the cell membrane by osmosis, and it’s crucial for cells to be surrounded by a liquid with the same concentration as the cell’s contents. In animals, this is tissue fluid, and in plants, it helps support the cell wall.
Describe the behavior of a plant cell placed in distilled water and explain the outcome.
Water molecules move into the plant cell, causing it to swell and become turgid due to the presence of the cell wall. The cell will not burst because of the cell wall.
What exerts pressure on the elastic cell wall, and what is the result of this pressure?
The vacuole exerts turgor pressure on the elastic cell wall, making the cell turgid and preventing it from bursting.
What happens to a plant cell when placed in a salt solution with low water potential, and what term describes this process?
Water moves out of the plant cell into the concentrated salt solution, causing the cell to become plasmolyzed.
Why is osmosis important for plants, and what happens if water potential gradients are absent?
Plants gain water through osmosis in their roots. Without a water potential gradient, water loss from the roots can occur. If plant cells are not full of water, they become flaccid, emphasizing the need for water to maintain turgor and firmness.
Explain the consequences of osmosis in animal cells surrounded by high or low water potential.
High water potential: Osmosis causes the cell to burst (hemolysis in RBCs) since animal cells lack a cell wall to provide strength.
Low water potential: Water in the cytoplasm diffuses outwards, leading to cell shrinkage (crenation).
What is the process called when osmosis causes a cell to burst, especially in red blood cells (RBCs)?
The process is called hemolysis, and it occurs when RBCs are surrounded by a high water potential.
