Biological Importance of Water

Question 1

criteria for something to be alive

Answer 1

1. made out of cells (basic unit of life)
2. has some nucleic acids
   -has some nucleic acids: self replicating molecules that control function of cell
3. capture + transform matter + energy - metabolism
4. homeostasis: maintain favorable internal environment
5. reproduction: sexual or asexual

Question 2

Why is water important for cells

Answer 2

• cells are 75% water
• cells have to maintain water balance
• water is required for the chemical reactions that take place in cells

Question 3

all living things are…

Answer 3

made up one one or more then one cell

Question 4

What are the two different types of cells

Answer 4

Prokaryotic and Eukaryotic cells

Question 5

Prokaryotic cells have

Answer 5

• a cell membrane and a cell wall
• have no membrane bound organelles
  ex. bacteria + archaea

Question 6

Eukaryotic cells have

Answer 6

• have a cell membrane
  -maybe a cell wall
• have membrane bound organelles
  ex. chloroplasts, mitochondria, nucleus
  -includes fungi, plants, animals, Protista

Question 7

What does the cell membrane form?

Answer 7

a phospholipid bilayer

Question 8

What does a phospholipid bilayer consist of

Answer 8

hydrophilic heads face inwards towards each other, allowing the hydophobic
tails (fatty acid chains to face each other) to face each other with the heads facing outwards

Question 9

the cell membrane also includes

Answer 9

cholesterol molecules which functions as chemical signaling
protein molecules which function as gates or channels

Question 10

What is the fluid mosaic model of membranes

Answer 10

Fluid: phospholipids can move around; they are not attached to adjacent molecules
Mosaic: two heterogeneous layers; proteins and other molecules are scattered across surface

Question 11

What is the Cell Membranes structure

Answer 11

• composed of phospholipid molecules, cholesterol, proteins
  Have phosphate “heads” that are polar (hydrophilic or water-loving)
  Have lipid “tails” that are nonpolar (hydrophobic or water-hating)

Question 12

What is the function of the cell membrane

Answer 12

• act as a protective barrier and regulates what comes in and out of the cell: selective permeability
• send and receives chemical messages
• provides shape and structure

Question 13

Diffusion

Answer 13

• The movement of any substance from a region of high concentration to a region of low concentration (no energy required because you are following a concentration gradient

Question 14

Osmosis

Answer 14

A specialized type of diffusion. Osmosis is the movement of WATER across a semi-permeable membrane in response to a concentration gradient. (from a region of more pure water to a region of less pure water)
- important for maintaining cellular water balance

Question 15

Terms to describe solute conditions

Answer 15

-Hypotonic solution– contains LESS solute than whatever you are comparing it to (higher water, lower solute)
-Hypertonic solution- contains MORE solute than whatever you are comparing it to (lower water, higher solute)
-Isotonic – same concentration of solute (solute = solute)