The Cell and Its Environment Flashcards
What is homeostasis?
Biological balance
Balance that every organism, organ, and cell must maintain in face of constant changing conditions
What is an example of homeostasis at the organism level?
When humans are hot, they sweat, drink cold liquids, turn on AC
Pike (fish) seek cold water at the bottom of the pond
What is an example of homeostasis at the organ level?
Heart with exercise beats faster. Weakened heart will beat faster causing growth.
If one kidney fails, the other will take over and increase in size.
If both fail, dialysis will filter waste from the blood.
What are the three types of membranes?
Semi-permeable membrane: regulates what enters and leaves the cell
Permeable membrane: all molecules can enter and leave
Nonpermeable membrane: no molecules
What determines if a molecule enters a cell or not?
Size of molecule
Size of pores
Concentration of molecules inside and outside cell
What are the two types of transport in a cell?
Active transport: molecules move in and out of a cell due to energy within the cell
Passive transport: molecules move in and out of a cell and the cell has no control
What is diffusion?
Movement of molecules from an area of higher concentration to an area of lower concentration
What is equilibrium?
Concentration of molecules is equal inside and outside the cell
What two factors affect diffusion?
Temperature- with increased temperature, rate of diffusion increases
Pressure- molecules move from an area of greater pressure to an area of lesser pressure
What is osmosis?
Water molecules move from an area of greater concentration to an area of lesser concentration
What is turgor?
Internal water pressure
What results from too much turgor in an animal cell?
Cytolysis- the bursting of a cell
How do some single celled organisms regulate water intake?
Using a contractile vacuole “sump pump”
How do fish regulate water intake?
Gills rid of water
Urinate
How do humans regulate water intake?
Urinate
Sweat
Cry
Breathe
What is a hypotonic solution?
Greater concentration of solutes inside the cell so water enters the cell
What is a hypertonic solution?
Concentration of solutes is greater outside the cell, water leaves the cell
What is an isotonic solution?
When the concentration of solutes and water is equal both inside and outside the cell (strive toward isotonic solution)
What happens when a paramecium is placed in distilled water as opposed to pond water?
Distilled water creates a hypotonic solution, so water enters the cell through osmosis causing cytolysis. Pond water creates a hypertonic solution so water exits the cell through osmosis to dissolve other particles.
What is the difference between equilibrium and an isotonic solution?
In equilibrium, one molecule is equal. In an isotonic solution, all molecules are equal.
What is plasmolysis?
Loss of turgor
Causes plants to wilt and die
What are two possible causes of plasmolysis?
Lack of water
Over-fertilization
What is an example of active transport?
Iodine molecules entering algae cells
What would probably happen to an animal cell if we inject it with chloroform?
If injected with a little, it would lose cytoplasm but will repair itself.
If injected with a lot, cell will die.
