A1.1 Water

Question 1

Define cohesion

Answer 1

Hydrogen bonds hold water together- Cohesion among water molecules plays a key role in the transport of water and dissolved nutrients against gravity in plants.

Question 2

Special properties of water.

Answer 2

Cohesion, Adhesion, Buoyancy, Viscosity, Thermal conductivity, Specific heat capacity, useful as a solvent.

Question 3

Define adhesion

Answer 3

The force by which individual molecules stick to surrounding materials and surfaces.

Question 4

How are hydrogen bonds drawn?

Answer 4

Dashed lines

Question 5

Define hydrogen bond

Answer 5

A type of weak attractive intermolecular force; a hydrogen atom in a molecule is attracted to an electronegative atom, such as oxygen, in a different molecule.

Question 6

What is water?

Answer 6

Water is the medium of life.

Question 7

Define covalent bond

Answer 7

A bond formed by the sharing of electrons between atoms

Question 8

Define hydrophilic

Answer 8

Attracted to water. Polar substances that are attracted by water. Have an affinity for water and are soluble in water.

Question 9

What allows plant roots to draw up water?

Answer 9

Adhesion forces

Question 10

Describe how the black-throated loon (Gavia arctica) interacts with the physical properties of water in their habitat.

Answer 10

Buoyancy in water allows the bird to stay afloat without expending a lot of energy, however when flying through air the bird must expend energy to stay aloft. Air is not viscous, so the loon can easily move through it when flying. The loon doesn’t lose as much body heat to the air because air has low thermal conductivity. However, because the air has a low specific heat, its temperature changes as rapidly.

Question 11

Define hydrophobic

Answer 11

Non-polar substances that are repelled by water. They lack affinity for water and are insoluble in water.

Question 12

What are substances that like water called?

Answer 12

Hydrophilic.

Question 13

What are substances that don’t like water called?

Answer 13

Hydrophobic.

Question 14

Define solvent

Answer 14

A liquid in which another substance can be dissolved.

Question 15

Is water essential to life and why?

Answer 15

Yes. It serves a s a medium for metabolic reactions.

Question 16

What properties of water allows it to be used as a medium of life?

Answer 16

Water has high buoyancy and high heat capacity.

Question 17

Define solute

Answer 17

Dissolved molecule or ion in a solution

Question 19

Describe how the ringed seal (Pusa hispida) interacts with the physical properties of water in their habitat.

Answer 19

Buoyancy in water allows the seal to stay afloat without expending a lot of energy. However, the water is viscous, so the seal has adaptations for streamlining as it swims through it. Water has a greater thermal conductivity than air, so the seal needs to insulate itself with blubber to maintain body temperatures. However, because the water has a high specific heat, the temperature of the water does not change as rapidly as the air around it, providing habitat stability for the seal.

Question 20

State two reasons why water was retained on early Earth.

Answer 20

1. The distance of the Earth from the Sun keeps temperature on Earth below that needed to vaporize water.
2. Earth’s gravity keeps water from escaping the planet.