Videos

• What is one of the very important molecular components of life?

  Water
• Why is water considered the main medium for life processes?

  Because all life processes occur in and with water
• What are the three atoms that make up a water molecule?

  One oxygen and two hydrogen
• What is the consequence of the asymmetrical structure of water molecules?

  Water molecules are polar
• What causes the partial charges in a water molecule?

  The unequal distribution of electrons between hydrogen and oxygen
• How can you determine if a molecule is polar?

  If you can draw a straight line through the molecule separating positive and negative charges
• What type of bond forms between water molecules due to their polarity?

  A hydrogen bond
• Why is cohesion important for water molecules?

  It allows water molecules to stick together
• How does cohesion help plants transport water?

  It allows water to move up through the xylem against gravity
• What is transpiration in plants?

  The process of plants giving off water vapor through stomata
• How does cohesion contribute to the movement of water in plants?

  It pulls water molecules up together through the xylem
• What is surface tension in water?

  The cohesive force that allows insects to walk on water
• What is adhesion in relation to water molecules?

  Water molecules can stick to other surfaces
• How does adhesion benefit plants in soil?

  It allows water to move through soil and stick to its particles
• What is capillary action?

  The movement of water through porous spaces in soil
• How does adhesion help in the function of plant xylem?

  Water molecules are attracted to the polar walls of the xylem
• What is the solvent property of water?

  Water can dissolve many substances due to its polarity
• What happens when salt is added to water?

  The sodium and chloride ions separate and dissolve
• What are hydrophilic substances?

  Substances that are attracted to water
• What are hydrophobic substances?

  Substances that do not dissolve in water
• What role do phospholipids play in cell membranes?

  They create a barrier that separates the inside of the cell from the outside
• What is specific heat?

  The amount of energy needed to raise the temperature of a substance by one degree Celsius
• Why does water have a high specific heat?

  Because of the hydrogen bonds that hold water molecules together
• What is thermal conductivity?

  The rate at which heat passes through a material
• How does thermal conductivity benefit organisms?

  It allows for efficient heat transfer within their bodies
• What is buoyancy?

  The ability of a substance to float in water
• How does density relate to buoyancy?

  If an object is less dense than water, it will float
• What is the density of water?

  997 kilograms per meter cubed
• How do green algae utilize buoyancy?

  They trap oxygen produced during photosynthesis to float
• What does viscosity describe?

  The ability of a substance to flow based on internal friction
• How does viscosity affect the flow of substances?

  A high viscosity means the substance flows slowly
• How does the viscosity of blood compare to pure water?

  Blood has a higher viscosity than pure water
• What are the two specific organisms to compare for the IB exam regarding water properties?

  Gavia arctica (black-throated loon) and Pusa hispida (ringed seal)
• How do the physical properties of water impact the seal compared to the loon?

  The seal expends more energy moving through viscous water than the loon does in air
• How do adaptations help the seal regulate its body temperature in cold water?

  It has a thick coat of fur to retain body heat
• What are the key properties of water that are important for life?

  • Polarity
  • Cohesion
  • Adhesion
  • Solvent properties
  • High specific heat
  • Thermal conductivity
  • Buoyancy
  • Viscosity
• How do the properties of water support biological systems?

  • Cohesion aids in water transport in plants
  • Adhesion helps water move through soil
  • Solvent properties facilitate metabolic reactions
  • High specific heat stabilizes internal temperatures
  • Buoyancy allows organisms to float
  • Viscosity affects movement in fluids
• Compare the impact of water properties on Gavia arctica and Pusa hispida.

  • Gavia arctica (loon):
  • Flies through air, less energy spent
  • Pusa hispida (seal):
  • Moves through viscous water, more energy spent
  • Thick fur for heat retention