Topic 1- Water

Question 1

Where do all metabolic reactions take place in cells?

Answer 1

In water

Question 2

As 71% of the Earth’s surface is covered in water it is a major 1._____ for organisms

Answer 2

1.habitat

Question 3

70% to 95% of the 1._____ of a cell is water

Answer 3

1.mass

Question 4

What is water composed of?

Answer 4

Hydrogen and oxygen atoms

Question 5

One atom of oxygen combines with two atoms of hydrogen by sharing 1.______ (covalent bonding)

Answer 5

1.electrons

Question 6

The oxygen atom attracts the electrons more strongly than the hydrogen atoms resulting in what?

Answer 6

A weak negatively charged region on the oxygen atom and a weak positively charged region on the hydrogen atoms

Question 7

What is a dipole?

Answer 7

separation of charge due to the electrons in the covalent bonds being unevenly shared

Question 8

What is a polar molecule?

Answer 8

When a molecule has one end that is negatively charged and one end that is positively charged

Question 9

Is water a polar molecule?

Answer 9

Yes

Question 10

Why do hydrogen bonds form between water molecules?

Answer 10

Because they are polar

Question 11

Why do hydrogen bonds only form a strong structure when they are in large numbers?

Answer 11

As they are weak

Question 12

What are some properties of water?

Answer 12

-An excellent solvent – many substances can dissolve in water
-A relatively high specific heat capacity
-A relatively high latent heat of vaporisation
-Water is less dense when a solid
-Water has high surface tension and cohesion
-It acts as a reagent
-Polar
-presence and number of hydrogen bonds between water molecules

Question 13

Why is water a good solvent?

Answer 13

-Polar molecule
-Ions and covalently bonded polar substances will dissolve in it
-Metabolites can be transported efficiently

Question 14

What is specific heat capacity?

Answer 14

he amount of thermal energy required to raise the temperature of 1kg of that substance by 1°C

Question 15

What is waters specific heat capacity?

Answer 15

4200 J/kg°C

Question 16

Does water have a high or low specific heat capacity?

Answer 16

High

Question 17

Why dos water have a high specific heat capacity?

Answer 17

-Many hydrogen bonds
-Takes a lot of thermal energy to break these bonds

Question 18

High specific heat capacity is useful for living organisms, why?

Answer 18

-Provides suitable habitats
-Able to maintain a constant temperature as it is able to absorb a lot of water without fluxuating in temp
-Temps are maintained for enzyme activity

Question 19

Water in 1.____ _____ is also vital in transferring heat around the body, helping to maintain a fairly constant temperature

Water in 2.___ ____ also plays an important regulatory role in maintaining a constant body temperature

Answer 19

1.blood plasma
2.tissue fluid

Question 20

What needs to be broken for water to change state?

Answer 20

Hydrogen bonds

Question 21

Why is latent heat of vaporisation an advantage?

Answer 21

-only a little water is required to evaporate for the organism to lose a great amount of heat
-This provides a cooling effect for living organisms

Question 22

Hydrogen bonds between molecules allow for what?

Answer 22

strong cohesion between water molecules

Question 23

Why is strong cohension useful?

Answer 23

-allows columns of water to move through the xylem of plants and through blood vessels in animals
-Enables tension

Question 24

What is meant by adhesion? What does this allow for?

Answer 24

Water is also able to hydrogen bond to other molecules, such as cellulose- Allowing for transpiration