Chapter 5 Homeostasis and Cell Transport Flashcards
How does the cell membrane help organisms maintain homeostasis?
by being selectively permeable and controlling which substances enter and leave the cell
What is passive transport?
substances crossing the cell membrane without the cell having to use any energy
What type of molecules are involved with passive transport?
water, carbon dioxide, oxygen, glucose
In what direction do the small molecules move during passive transport?
down the concentration gradient from an area where they are in high concentration to an area where they are in low concentration
What is a concentration gradient?
the difference in the concentration of molecules across a distance
What type of energy is passive transport driven by/
kinetic energy of the molecules themselves, so the cell does not use any energy
How long does diffusion continue?
until equilibrium is reached and the concentration gradient no longer exists
What happens to the molecules after equilibrium?
they continue to move equally in all directions
What are the three types of passive transport?
diffusion, osmosis, and facilitated diffusion
What is diffusion?
the type of passive transport which describes the movement of any molecule down its concentration gradient from an area of high concentration to low concentration
What is osmosis?
the type of passive transport which describes the diffusion of water across a selectively permeable membrane
What is selectively permeable?
when only certain molecules are allowed to pass through the membrane
What is the solute of a solution?
the molecules being dissolved
What is the solvent of the solution?
the fluid the molecules are being dissolved in
What is the direction of osmosis determined by?
the solute concentrations on the two sides of a membrane. if the solute concentration is high the solvent concentration will be low and vice versa
How is water the same as all molecules that move by diffusion?
they will move from an area of high concentration to an area of low concentration of water
How do cells respond to the increase or decrease in water concentration in their cytosol?
by either shrinking or swelling
What are the terms hypertonic, hypotonic, and isotonic used to describe?
the difference in concentration of solute from one side of a membrane to another
How is something hypertonic?
when is has less solute than the other side of the membrane
In what direction will water move if a cell is placed in a hypotonic solution?
the water will move into the cell
What happens to the cells in hypotonic solutions?
they swell and may burst
What is the bursting of cells called?
cytolysis
How is something hypertonic?
when it has more solute than the other side of the membrane
In what direction will water move if a cell is placed in a hypertonic solution?
water will move out of the cell
What happens to a cell placed in a hypertonic solution?
the cell shrinks
What is the shrinking of cells called?
plasmolysis
How does something become isotonic?
at equilibrium the % of solute is the % on both sides of the membrane
What type of environments do most single celled organisms live in?
hypotonic environments in which water is constantly entering
How do single cell organisms compensate for the water constantly entering?
they have a specialized organelle called a contractle vacuole that removes excess water
What do the cell walls of plant cells do?
they limit the amount of water that can enter plant cells
What is turgor pressure?
the pressure that water molecules exert during the cell wall
What will plants look like with low turgor pressure?
wilted
What is facilitated diffusion?
a type of passive transport in which a molecule utilizes a carrier/transport protein to pass through the cell membrane
What does a carrier protein do when a specific molecule binds to it?
the carrier proteins changes shape and transports the molecules down its concentration gradient (high to low) Ex. Glucose
