Biochemistry

Question 1

How much of an average human’s body weight is composed of water?
Entire body:

Answer 1

60%

Question 2

How much of an average human’s body weight is composed of water?
Brain:

Answer 2

70%

Question 3

How much of an average human’s body weight is composed of water?
Lungs:

Answer 3

90%

Question 4

How much of an average human’s body weight is composed of water?
Bone tissue:

Answer 4

22%

Question 5

How many hydrogen bonds does the average water molecule make with neighbouring water molecules?

Answer 5

An average of 3.4 hydrogen bonds with its neighbouring water molecules

Question 6

How does the lattice structure of liquid water make it unique compared to the molecules of similar size and polarity?

Answer 6

In liquid water, the hydrogen bonds that hold the lattice together constantly breaks and reforms, allowing the water molecules to slip past one another and reform the lattice in new positions.

Question 7

How does the lattice structure of solid water provides ice with a unique property as it changes state from liquid to solid?

Answer 7

• Each water molecule forms 4 hydrogen bonds with its neighbouring water molecules
• Ice water lattice spaces the water molecules farther apart than they are in liquid water lattice
• 10% less dense in its solid state than liquid state

Question 8

3 Unique properties of water are:

Answer 8

• Water clinges
• Water absorbs thermal energy
• Solid water is less dense than liquid water

Question 9

Adhesion

Answer 9

Water molecules stick to other substances

Question 10

Cohesion

Answer 10

Attraction between molecules of the same substance

Question 11

High Specific Heat Capacity

Answer 11

• Hydrogen bonding causes water to absorb large amounts of thermal energy
  
  • Temperature increases or lose large amounts of
    thermal energy
    - Temperature decreases

Question 12

High Specific Heat of Vapouization

Answer 12

Hydrogen bonding causes water to absorb large amounts of thermal energy and become vapour(gas)

Question 13

Highest Density at 4 degree C

Answer 13

• As water molecules cool below 0 degree C, they form an ice water lattice
• The hydrogen bonds keept water molecules spread apart, reducing the density so that it is below the density of liquid water

Question 14

Effect of Adhesion

Answer 14

High surface tension

Question 15

Effect of Cohesion

Answer 15

Cappilary action and solubility of polar compounds

Question 16

Effect of High Specific Heat Capacity

Answer 16

Temperature moderation

Question 17

Effect of High Specific Heat of Vapourization

Answer 17

Evapouration and cooling

Question 18

Effect of Highest Density at 4 degree C

Answer 18

Ice floats on water

Question 19

Example of Adhesion

Answer 19

A water strider walks on the surface of a pond

Question 20

Example of Cohesion

Answer 20

Polar substance such as sugars, are highly soluble in water

Question 21

Example of High Specific Heat Capacity

Answer 21

High specific capacity helps organisms maintain a constant body temperature

Question 22

Example of High Specific Heat of Vapourization

Answer 22

Humans dissipate body heat by evapouration of water from surface of body by sweating

Question 23

Example of Highest Density at 4 degree C

Answer 23

Fish and other organisms survive in winter because water freezes from the top bottom

Question 24

The concept of ‘hydration shell’ as ionic or polar compounds dissolve in water

Answer 24

• Reduces the attraction between molecules or ions of another substance and promotes their separation
  - Seperation allows the substance to go into solution
• As the molecules and ions dissociate, water molecules surround them forming a hydration shell
• Tends to prevent the ions from re-associating

Question 25

Hydrophilic vs Hydrophobic

Answer 25

Hydophilic loves water molecules(polar) whereas hydrophobic are afraid of water molecules (non-polar)

Question 26

Example of Hydrophilic

Answer 26

O, N, S contain polar bonds

Question 27

Example of Hydrophobic

Answer 27

Hydrocarbons

- H + C

Question 28

Why does even a small variation in pH affect enzyme function?

Answer 28

A small change in pH surrounding some proteins causes a structural change that can alter or destroy the functions the protein.
- ie. scientists have noticed that if the ocean water
becomes too acidic it would threaten the health of
Earth’s ocean and its ecosystems.

Question 29

Buffer

Answer 29

A chemical that compensates for pH changes in a solution by accepting or donating H+ ions
- Important for stabilizing pH levels

Question 30

Which ion is an important biological buffer?

Answer 30

Carbonic acid Bicarbonate

Question 31

Briefly describe why water molecules attract so well to other molecules?

Answer 31

Water is highly cohesive. The positive and negative charges of the hydrogen and oxygen atoms make up water molecules makes them attracted to each other. It gives them a high surface tension.

Question 32

Why is adhesion and cohesion properties essential for plant growth?

Answer 32

Adhesion allows water to stick to the organic tissues of plants and cohesion keeps the water molecules together making a chain of water molecules which helps with plant growth.

Question 33

Why is solid water less dense than liquid water and why is this property crucial for aquatic organisms?

Answer 33

Water is less dense than liquid water because they way hydrogen bonds are oriented as it freezes. The water molecules are pushed farther apart compared to liquid water. This property is crucial for aquatic organisms because