A1.1 Water

Question 1

List reasons why water is a substance on which life depends

Answer 1

life needs to interact with each other in a liquid solvent – water

Question 2

what is the structure of an atom

Answer 2

Electrons on the valence shells, protons and neutrons inside the nucleus

Question 3

What is a covalent bond

Answer 3

A sharing of electrons between two non-metals

Question 4

What is an ionic bond

Answer 4

A transfer of electrons between a nonmetal and a metal

Question 5

Explain how the sharing of electrons between atoms in a
noncovalent bond

Answer 5

They share their electrons unevenly, one side has a slightly negative charge and another side has a slightly positive charge.

Question 6

State the location of the polar covalent bond within a water molecule

Answer 6

The oxygen atom has a slightly negative charge while the 2 hydrogens have a slightly positive charge

Question 7

What makes an atom more electronegative

Answer 7

The smaller the atom and the more positive it is (opposites attract)

Question 8

Explain why a smaller atom + more positive atom is more electronegative

Answer 8

A more positive atom means it has more protons = attracts more electrons
smaller means less shells = a stronger pull on the other electrons

Question 9

what is a hydrogen bond

Answer 9

a weak attraction between polar molecules (slight positive hydrogen atom and slight negative charged atom)

Question 10

Are covalent bonds stronger or hydrogen bonds

Answer 10

covalent bonds (hydrogen bonds are weaker because they are an intermolecular bond)

Question 11

The cause of the formation of hydrogen bonds between water molecules

Answer 11

When water atoms are near each other hydrogen bonds start to form. A dotted line is drawn to show the attraction between the Slightly positive Hydrogen and the slightly negative oxygen

Question 11

what is the importance of hydrogen bonds in water molecules

Answer 11

made and broken very easily, the large amount of bonds contribute to the stability of the earth

Question 12

What is cohesion

Answer 12

cohesion is an attraction between water molecules due to hydrogen bonding

Question 13

what is adhesion

Answer 13

adhesion is an attraction between water and other substances due to hydrogen bonding and different substances

Question 14

what is surface tension

Answer 14

how difficult it is to break or stretch apart the surface due to cohesion

Question 15

How does water move through the Xylem in a vascular plant

Answer 15

Root Absorption: Roots take in water from the soil.
Xylem Transport: Water moves up the plant through the xylem tubes.
Transpiration Pull: Water evaporates from leaves, pulling more water up.
Cohesion & Adhesion: Water sticks to itself and xylem walls, helping it move upward.

Question 16

what is the cause of surface tension

Answer 16

there is a strong cohesive force (hydrogen bond) between water molecules that needs to be overcome

Question 17

Benefit to living things that result from surface tension

Answer 17

Allows small insects to walk on water.
Helps plants draw water through roots.
Supports water movement in cells.

Question 18

polar meaning

Answer 18

one part is slightly positive and one part is slightly negative

Question 19

Outline the cause of capillary action

Answer 19

Liquid moves through narrow tubes.
Driven by adhesion, cohesion, & surface tension.
Works against gravity.
Adhesive forces > cohesive forces.

Question 20

Capillary action in the plant xylem

Answer 20

Adhesion: Keeps water attached to xylem walls, preventing it from falling.
Cohesion: Allows water to move up in a continuous stream.
Surface Tension: Maintains water’s structure in the xylem.

Question 21

capillary action in soil

Answer 21

Porous Soil: Has spaces for water.
Attraction: Water sticks to polar substances in soil.
Capillary Action: Pulls water up, even against gravity.

Question 22

what is a solvent

Answer 22

the liquid in which a solute dissolves

Question 23

What is a solute

Answer 23

the substance that dissolves in a solvent

Question 24

What is solution

Answer 24

a mixture of one or more solutes dissolved in a solvent

Question 25

what is solvation

Answer 25

The process of the solute dissolving in the solvent

Question 26

Why is water able to dissolve charged and polar molecules

Answer 26

It’s a universal solvent
Polarity: Water has a positive and negative end.
Hydrogen Bonds: Attracts positive and negative ions

Question 27

What does the term hydrophilic mean

Answer 27

Dissolves in water, and forms strong bonds with water (hydrogen bonds, ion-dipole).

Question 28

What does the term hydrophobic mean?

Answer 28

Does not dissolve, clusters in water due to weak or no interactions.

Question 29

What is an example of a function of a hydrophobic and insoluble molecule?

Answer 29

-Steroid hormones
-Plasma membrane and nuclear membrane
-Certain parts of proteins

Because steroids are hydrophobic, they can pass straight through the nuclear membrane and interact with DNA

Question 30

What is an example of a function of a hydrophilic and soluble molecule?

Answer 30

Glucose
Ions
Amino acids
Proteins e.g. enzymes

This ensures they can be transported easily. Making water an excellent transport medium.

Question 31

what is the role of water as a medium for metabolism

Answer 31

• cytosol is a liquid found in the cytoplasm
• It contains water and dissolved salts, fatty acids, sugars, amino acids, and proteins such as enzymes
• the substances are needed to fulfill the metabolic process, if they aren’t hydrophilic it wouldn’t be possible.
  -water is needed to dissolve the reactants and enzymes so they can react

Question 32

What is the role of water as a medium for transport in vascular plants

Answer 32

-Dissolved solutes can be transported in solution around the body of an organism.
-the dissolved mineral ions are transported in the xylem from the roots to the leaves
-Dissolved sugars produced in photosynthesis are transported in the phloem from source to sink

Question 33

What is the role of water as a medium for transport in animal blood

Answer 33

• Dissolves Nutrients and Gases like glucose, amino acids, ions) and respiratory gases (oxygen, carbon dioxide) for easy transport in blood.
  -Transport of Waste: Waste products (urea, carbon dioxide) dissolve in water, enabling their removal from the body.

Question 34

what is High specific capacity

Answer 34

require a greater change in energy to change their temperature

Question 35

Water has a high specific capacity. Think back to your chemistry, what does this mean?

Answer 35

hydrogen bonds between water molecules, it takes a lot of energy to raise the temperature of water, as the H-bonds can absorb a lot of the energy.

Question 36

Why do you think this makes water a good habitat for animals?

Answer 36

This means water doesn’t experience rapid changes in temperature.

Question 37

list physical properties of water that are consequential for animals in aquatic habitats

Answer 37

-High Specific Heat Capacity
-High Surface Tension
-density and buoyancy
High Thermal conductivity

Question 38

what is buoyancy

Answer 38

• Buoyancy is an upward force applied to an object that is immersed in a fluid. If the buoyant force of the fluid is greater than the object’s weight, the object will float.

Question 39

Physical properties of buoyancy

Answer 39

An object with a lower density than the fluid experiences a buoyant force greater than gravity, causing it to float.
An object with a higher density than the fluid experiences a buoyant force weaker than gravity, causing it to sink.

Question 40

What is viscosity

Answer 40

-Viscosity is a measure of a fluid’s tendency to flow.
-Viscosity is due to the amount of friction the molecules of a liquid experience as they flow over each other.
-A thick fluid is more viscous and a thin fluid is less viscous.

Question 41

Compare the viscosity of air to water to blood

Answer 41

Air: Lowest viscosity; allows fast, easy movement.
Water: Moderate viscosity; provides some resistance but supports aquatic life.
Blood: Highest viscosity; enables effective circulation for nutrient and oxygen delivery in animals.

Question 42

What is thermal conductivity

Answer 42

Thermal conductivity is a material’s ability to conduct heat.

-High Thermal Conductivity: Good heat conductors (e.g., metals) transfer heat quickly.
-Low Thermal Conductivity: Poor conductors (e.g., wood, rubber) insulate by slowing heat transfer.

Question 43

What are some low-conductive materials

Answer 43

styrofoam and air

Question 44

what are some high-conductive materials

Answer 44

water and copper

Question 45

How does the ringed seal use the physical properties of water to live

Answer 45

-Buoyancy in water helps the seal stay afloat with minimal energy use.
-Water’s viscosity creates resistance, so the seal has streamlined adaptations for efficient swimming.
-Water has higher thermal conductivity than air, so the seal insulates itself with blubber to maintain body temperature.
-Water’s high specific heat means it changes temperature slowly, providing a stable habitat for the seal.

Question 46

How does the black-throated loon use the physical properties of water to live

Answer 46

-Buoyancy in water enables the bird to float with minimal energy expenditure.
-When flying, the bird must expend energy to stay aloft.
-Air’s low viscosity allows the bird to move easily through it.
-The bird loses less body heat to the air due to its low thermal conductivity.
-However, air’s low specific heat means its temperature can change rapidly.

Question 47

What is the specific heat capacity

Answer 47

Specific heat capacity is the quantity of heat needed to raise the temperature of a chemical per unit mass.

Question 48

what is the benefit to the life of the high specific heat capacity of water

Answer 48

As a result of its high specific heat capacity, water heats up or cools down very slowly. This provides for a stable internal environment and habitat of living things.