Chapter 2- Biochemistry- chemical elements and water

Question 0

Most frequent element- carbon, what it its percentage?

Answer 0

19%

Question 1

What are the 4 most frequently occurring chemical elements?

Answer 1

Carbon
Hydrogen
Oxygen
Nitrogen

Question 2

Most frequent chemical, hydrogen, what is its percentage?

Answer 2

10%

Question 3

Most frequent chemical, oxygen, what is its percentage?

Answer 3

65%

Question 4

Most frequent chemical, nitrogen, what’s its percentage?

Answer 4

3%

Question 5

What are the 5 other main elements needed by living organisms?

Answer 5

Sulphur
Calcium
Phosphorus 
Iron
Sodium

Question 6

Where is sulphur (0.25%) found and what does this allow?

Answer 6

Found in certain amino acids (cysteine and methionine) - allowing for proteins to form disulphides bonds.

Question 7

Where is calcium (1.5%) found and what’s its involved with ?

Answer 7

Found in bones and teeth and involved in neurotransmitter release in synapses.

Question 8

What is phosphorus (1%) a component of?

Answer 8

Nucleic acids and cell membranes.

Question 9

Where is iron (0.7%) found and what’s its purpose?

Answer 9

Found in haemoglobin (red protein responsible for transporting oxygen) and allows oxygen transport.

Question 10

What is sodium (0.15%) involved in the generation of?

Answer 10

Generation of nerve impulses in neurones.

Question 11

What is chemical polarity?

Answer 11

Describes how equally bonding electrons are shared between atoms.

Question 12

What is cell polarity?

Answer 12

Differences in shape, structure and functions of cells.

Question 13

What does oxygen atoms have more of?

Answer 13

More protons (+ve)

Question 14

If oxygen has more protons what does it attract more of and what does this equal too?

Answer 14

Attracts more electrons (-ve) which equals it to become slightly negative while hydrogen becomes slightly positive.

Question 15

Covalent bonded molecules that have slightly potential charge are what?

Answer 15

Polar

Question 16

Slightly charged regions of water can attract other polar or charged compounds therefore water molecules can associate with what?

Answer 16

Weak hydrogen bonds

Question 17

What are the 3 thermal properties of water?

Answer 17

High specific heat capacity
High heat of vaporisation
High heat of fusion

Question 18

What does specific heat capacity measure?

Answer 18

Measure of energy required to raise the temp of 1g of substance by 1•C

Question 19

What does heat of vaporisation measure?

Answer 19

amount of energy absorbed per gram as it changes from a liquid to a gas/vapour

Question 20

What does heat of fusion measure?

Answer 20

amount of energy required to be lost to change 1g of solid at 0•C

Question 21

Why do all these thermal properties of water occur?

Answer 21

Result of extensive hydrogen bonding between water molecules

Allows water to absorb considerable amounts of energy with little change ( hydrogen bonds need to be broken first)

Question 22

Is water strongly cohesive (stick to one another)? If so what do they stick too?

Answer 22

Yes- tend to stick to other molecules that are charged or polar (adhesion)

Question 23

Why is water strongly cohesive (stick to one another)?

Answer 23

Result of polarity of a water molecule and its ability to form hydrogen bonds with appropriate molecules.

Question 24

What are waters solvent properties?

Answer 24

Can dissolve organic and inorganic substances that contain electronegative atoms (fluorine,oxygen and nitrogen)

Question 25

Why does water have the solvent properties it does and what does it result in?

Answer 25

Polar attraction of large quantities of water can sufficiently weaken intramolecular forces (such as ionic bonds) and result in the dissociation (split into smaller particles) of the atoms.

Question 26

What are the 2 other properties water has?

Answer 26

Is transparent- allowing light to pass through it

Expands when frozen become less dense

Question 27

What is a coolant?

Answer 27

A liquid or a gas which is used to remove hear from something

Question 28

What do animals and plants do

to facilitate cooling?

Answer 28

Evaporation of water from surface of bodies

Question 29

How do animals and plants facilitate cooling?

Answer 29

Animals- sweating and panting

Plants- transpiration from leaves in plants

Question 30

Water is a medium for what?

Answer 30

Metabolic reactions.

Question 31

What can water do to facilitate chemical reactions in metabolic reactions?

Answer 31

Dissolve many inorganic and organic substances

Question 32

What can water absorb in a metabolic reaction?

Answer 32

Thermal energy released as a by product of chemical reactions.

Question 33

Is Water is a transport medium?

Answer 33

Yes

Question 34

How is water transported up xylem of plant?

Answer 34

Forces of attraction between water molecules help facilitate

Question 35

How is water effectively transported for dissolved substances in plants?

Answer 35

In plants minerals from soils and sugars from leaves can be transported in water through xylem.

Question 36

How is water effectively transported in dissolved substances in animals?

Answer 36

In animals- water in blood is used to transport oxygen,glucose and urea.

Question 37

How is the surface tension useful in water?

Answer 37

Force of attraction between water molecules makes water sufficiently dense for some smaller organisms to move along its surface.