Unit 02 - Chemical and Cellular Basis of Life (1) Flashcards
(24 cards)
What percentage of elements are essential for healthy life and reproduction?
20-25% of elements
Which four elements make up 96% of living matter?
Oxygen (O), Carbon (C), Hydrogen (H), Nitrogen (N)
What elements make up the remaining 4% of the mass of organisms?
Calcium (Ca), Phosphorous (P), Potassium (K), Sulphur (S)
Name some trace elements found in living matter.
- Sodium (Na)
- Chlorine (Cl)
- Magnesium (Mg)
- Boron (B)
- Cobalt (Co)
- Copper (Cu)
- Chromium (Cr)
- Fluorine (F)
- Iodine (I)
- Iron (Fe)
Why is water considered a vital inorganic molecule?
Life could not exist on this planet without water.
What are the two main reasons why water is important for life?
- Vital chemical constituent of living cells
- Provides a biological medium for all organisms
What type of molecule is water?
Small, polar, and angular molecule
What is polarity in the context of the water molecule?
Uneven charge distribution within a molecule
What are hydrogen bonds in water?
Weak attractions between the slightly polar hydrogen atom of one water molecule and the slightly polar oxygen atom of adjacent water molecules.
List the four major properties of water that maintain life on Earth.
- Cohesive behavior
- Ability to moderate temperature
- Expansion upon freezing
- Versatility as a solvent
Define cohesion as it relates to water.
Attraction between water molecules due to hydrogen bonding.
What is adhesion in relation to water?
Attraction between water molecules and other substances.
How does cohesion help in the transport of water in plants?
Water and dissolved substances are transported as a continuous column through xylem against gravity.
What property of water allows small insects to walk on the surface of a pond?
High surface tension due to cohesion between water molecules.
What is the significance of water’s ability to moderate temperature?
Water can absorb or release a relatively high amount of heat energy with slight temperature changes.
How does water function as a thermal buffer?
Due to its high specific heat.
What role does evaporation of sweat play in thermoregulation?
Helps maintain body temperature at a constant level.
What happens to water when its temperature falls below 4°C?
It begins to freeze and forms a crystalline lattice called ice.
Why does ice float on water?
Water has maximum density at 4°C; ice is less dense.
What is the importance of ice floating in polar regions?
It allows organisms in aquatic bodies to survive during winter.
What gives water its versatility as a solvent?
Polarity of water molecules.
What types of substances can dissolve in water?
- Polar molecules (e.g., Glucose)
- Ionic compounds (e.g., NaCl)
- Molecules with both polar and ionic regions (e.g., lysozymes)
Fill in the blank: Water molecules surround each of the solute molecules and form hydrogen bonds with them, making water a versatile _______.
solvent
