cell transport Flashcards
(23 cards)
factors affecting rate of diffusion and explain - concentration gradient
Concentration Gradient: Diffusion occurs down a concentration gradient from an area of high concentration to an area of low concentration.
The greater the difference in concentration, the faster diffusion occurs.
factors affecting rate of diffusion and explain - temp
Temperature: At higher temperatures, particles gain energy and move faster. Therefore, diffusion occurs faster.
factors affecting rate of diffusion and explain - surface area
Surface Area: Volume the greater the surface area: volume ratio, the faster the rate of diffusion.
factors affecting rate of diffusion and explain - distance
Distance: Diffusion occurs faster over a shorter distance than a longer distance
define diffusion
the net movement of molecules and ions from a region of their higher movement to a region of their lower concentration down a concentration gradient as a result of their random movement
fill in the missing words: many living ____ get most of their requirements from _____
organisms, diffusion
what is diffusion important for?
important for gas exchange for respiration animals & plants
give examples of diffusion
-plants need co2 for photosynthesis, this diffuses from the air through the stomata
-respiration in animals and plants
define osmosis
the diffusion of water molecules from a region of higher water potential (dilute solution) to a region of lower water potential (concentrated solution) through a partially permeable membrane
fill in the missing words: _____ molecules are _______ than ______ molecules
water, smaller, sugar
define partially permeable membrane
a membrane that lets some molecules through but not others
give examples of a partially permeable membrane
visking tube, cell membrane
state: a solution that has a high concentration of water molecules is a ________ ____________ or has a ______ ______ __________
dilute solution, high water potential
define turgid
tight and firm
define flaccid
when a cell becomes wilted/limp (floppy) and loses its firmness
what happens to an animal cell in pure water?
as more water enters the cell, it swells. The cell membrane must stretch until the strain is too much and the cell bursts
what happens to plant cells in pure water?
does not burst in water, surrounded by a permeable cell wall, cytoplasm and vacuole begin to swell, however the cell wall is very turgid and keeps it from bursting
is a cell membrane fully permeable or a cell wall fully permeable? state why
cell wall is fully permeable as the cell membrane is partially permeable
explain plasmolysis in plant cells
when a solution is very concentrated, a lot of water diffuses out of the cell, the cytoplasm and vacuole shrink. The cell wall is unable to shrink due to its stiffness, as the cytoplasm keeps shrinking to the centre, the cell membrane tears away from the cell wall
what usually happens to a plasmolysed cell?
it usually kills a plant cell because the cell membrane is damaged as it tears away from the cell wall
define active transport
the movement of molecules and ions in or out of a cell through the cell membrane against a concentration gradient, using energy for respiration
when does active transport occur?
when cells need to absorb substances that are only present in small quantities in their surroundings
define water potential
the measure of the ability of water to move from one location to another
