Water Details

Question 1

How water contributed the evolution of cells

Answer 1

-The first cells evolved in a watery environment
-This is believed to have been in the deep oceans, close to hydrothermal vents in the Earth’s crust
-Some water and solutes got trapped within a membrane
-Chemical reactions began occurring within the membrane-bound structure
-This led to the evolution of cells

Question 2

Types of bonds in water molecules

Answer 2

Covalent bonds(between oxygen and hydrogen atoms)

Question 3

Why are the bonds in water molecules polar?

Answer 3

The sharing of electrons in the bonds are unequal

Question 4

Charge of the hydrogen atoms in a water molecule

Answer 4

Positive charge(partial)

Question 5

Charge of the oxygen atom in a water molecule

Answer 5

Negative charge(partial)

Question 6

The cause of water’s unique properties

Answer 6

The large number of hydrogen bonds between the water molecules

NB: Even though hydrogen bonds are weak, there are many water molecules per unit volume of water since they are so small

Question 7

Chemical properties of water

Answer 7

-Cohesion
-Adhesion
-Solubility
-Polarity

Question 8

Physical properties of water

Answer 8

-Specific feat capacity
-Thermal conductivity
-Buoyancy
-Viscosity

Question 9

Cause of cohesion between water molecules

Answer 9

the mutual attraction between water molecules(because of the hydrogen bonds between them)

Question 10

(Regarding their interaction with water)Biological molecules can either be…

Answer 10

-Hydrophilic(water-loving)
-Hydrophobic(water-hating)

Question 11

Features of hydrophilic molecules

Answer 11

Polar

Question 12

Features of hydrophobic molecules

Answer 12

Non-polar

Question 13

Why water is regarded as the universal solvent

Answer 13

Most biological molecules are hydrophillic and can be dissolved in it

Question 14

Substances that water adheres to but cannot dissolve are hydrophilic(T/F)

Answer 14

True

Question 15

Examples of hydrophillic substances

Answer 15

-Glucose
-Cellulose
-Starch
-Sodium ions
-Chloride ions

Question 16

Examples of hydrophobic substances

Answer 16

-Lipids
-Alkanes

Question 17

Examples of highly solube molecules(in water)

Answer 17

-Urea
-Glucose
-Salts
-Amino acids

Question 18

Reasons most enzymes require water

Answer 18

Water helps enzymes to hold their shape and improve their stability(which is needed for catalysing reactions)

Question 19

Water has a high specific heat capacity(4200J/kg/°C), so…

Answer 19

a relatively large amount of energy is required to raise its temperature

Question 20

Advantages of water’s high specific heat capacity

Answer 20

-Provides suitable acquatic habitats(since water temperatures change more slowly than air temperatures)
-Is able to maintain a constant temperature(since water can absorb a lot of heat without wide temperature fluctuations), which is vital for optimising enzyme activity

Question 21

The density of water is higher than the density of ice(T/F)

Answer 21

True