D2.3 - osmosis (3i) Flashcards
what occurs in the solvation of ions and a polar molecules with water as the solvent?
in solvation there are attractions between the polar water molecules and the solute molecules, leading to hydrogen bond formation
- postively charged ions form hydrogen bonds with the partial negative charge on the oxygen atoms of water molecules e.g) Na+
- negatively charged ions form hydrogen bonds with the partial positive charge on the hydrogen atoms of water molecules e.g) Cl-
- polar molecules form hydrogen bonds between the partial positive charges on the solute molecules and partial negative charges of the oxygen atoms of water molecules, and between partial negative charges on the solute molecules and partial positive charges on the hydrogen atoms of water molecules e.g) glucose
what is the direction of movement of osmosis?
in osmosis, water movement occurs from a hypotonic solution (less concentrated) to a hypertonic solution (more concentrated)
what does cell osmolarity depend on?
- species
- level of hydration
- tissue type or age
- soil type
what happens in a hypotonic solution?
if the environment surrounding a cell is hypotonic (less concentrated than the cell’s cytoplasm) then net movement of water will occur into the cell by osmosis
what happens in a hypertonic solution?
if the environment surrounding a cell is hypertonic (more concentrated than the cell’s cytoplasm) then net movement of water will occur out of the cell by osmosis
what happens in an isotonic solution?
if the environment surrounding a cell is isotonic (the same solute concentration as the cell’s cytoplasm) then dynamic equilibrium occurs
what occurs during dynamic equilibrium?
in dynamic equilibrium there is no net movement of water, however water molecules continue to pass in both directions across the membrane
what is the impact of water movement on cells that lack a cell wall for a hypertonic medium?
in hypertonic medium, net movement of water occurs out of cells by osmosis, causing shrinkage and crenation
what are the effects of water movement on cells that lack a cell wall for a hypotonic medium?
in hypotonic medium, net movement of water occurs into cells by osmosis, causing swelling and bursting
what are the effects of water movement on cells that lack a cell wall for a isotonic solution?
in isotonic medium, there is no net movement of water into or out of cells by osmosis and so there is no effect on the cell structure
what are the effects of water movement on cells with a cell wall for a hypertonic medium?
in hypertonic medium, net movement of water occurs out of cells by osmosis, causing plasmolysis, where the plasma membrane pulls away from the inside of the cell wall
what are the effects of water movement on cells with a cell wall for a hypotonic medium?
in hypotonic medium, net movement of water occurs into cells by osmosis
- the presence of the cell wall prevents bursting, instead turgor pressure is generated
what are the effects of water movement on cells with a cell wall for a isotonic medium?
in isotonic medium, there is no net movement of water into or out of cells by osmosis and so there is no effect on the cell structure
how do multicellular and some unicellular organisms prevent harmful cell changes due to the effects of water movement?
multicellular organisms prevent harmful cell changes by maintaining an isotonic tissue fluid that surrounds the cells
why do freshwater unicellular organisms absorb water?
why do freshwater unicellular organisms absorb water?
