Chapter 2- Biochemistry- chemical elements and water Flashcards Preview

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Flashcards in Chapter 2- Biochemistry- chemical elements and water Deck (38):
0

What are the 4 most frequently occurring chemical elements?

Carbon
Hydrogen
Oxygen
Nitrogen

1

Most frequent element- carbon, what it its percentage?

19%

2

Most frequent chemical, hydrogen, what is its percentage?

10%

3

Most frequent chemical, oxygen, what is its percentage?

65%

4

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

3%

5

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

Sulphur
Calcium
Phosphorus
Iron
Sodium

6

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

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

7

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

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

8

What is phosphorus (1%) a component of?

Nucleic acids and cell membranes.

9

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

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

10

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

Generation of nerve impulses in neurones.

11

What is chemical polarity?

Describes how equally bonding electrons are shared between atoms.

12

What is cell polarity?

Differences in shape, structure and functions of cells.

13

What does oxygen atoms have more of?

More protons (+ve)

14

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

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

15

Covalent bonded molecules that have slightly potential charge are what?

Polar

16

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

Weak hydrogen bonds

17

What are the 3 thermal properties of water?

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

18

What does specific heat capacity measure?

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

19

What does heat of vaporisation measure?

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

20

What does heat of fusion measure?

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

21

Why do all these thermal properties of water occur?

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)

22

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

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

23

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

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

24

What are waters solvent properties?

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

25

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

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.

26

What are the 2 other properties water has?

Is transparent- allowing light to pass through it
Expands when frozen become less dense

27

What is a coolant?

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

28

What do animals and plants do
to facilitate cooling?

Evaporation of water from surface of bodies

29

How do animals and plants facilitate cooling?

Animals- sweating and panting
Plants- transpiration from leaves in plants

30

Water is a medium for what?

Metabolic reactions.

31

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

Dissolve many inorganic and organic substances

32

What can water absorb in a metabolic reaction?

Thermal energy released as a by product of chemical reactions.

33

Is Water is a transport medium?

Yes

34

How is water transported up xylem of plant?

Forces of attraction between water molecules help facilitate

35

How is water effectively transported for dissolved substances in plants?

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

36

How is water effectively transported in dissolved substances in animals?

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

37

How is the surface tension useful in water?

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

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