module 2 - biological elements and water

Question 1

what are the 4 key elements that make up all living things?

Answer 1

C (carbon)
H (hydrogen)
O (oxygen)
N (nitrogen)

Question 2

what are the other 2 imporant elements involved in the composition of biologican world?

Answer 2

P (phosphorous)
S (sulpher)

Question 3

what are the 5 cations that play an important role in the composition of biological world?

Answer 3

Ca2+
Na+
k+
H+
NH4+

Question 4

what is the role of Ca2+?

Answer 4

nerve impulse transmission and muscle contraction

Question 5

what is the role of Na2+?

Answer 5

nerve impulse transmission and kidney function

Question 6

what is the role of K+?

Answer 6

nerve impulse transmission and stomatal opening

Question 7

what is the role of H+?

Answer 7

catalysis of reactions
proton pump in photosynthesis
pH determination

Question 8

what is the role of NH4+?

Answer 8

production of nitrate ions (NO3-)

Question 9

what are the 5 anions that play an important role in the composition of biological world?

Answer 9

NO3-
HCO3-
Cl-
PO4*3-
OH-

Question 10

what is the role of Nitrate ions (NO3-) ?

Answer 10

Nitrogen supply to plants for amino acid and protein formation

Question 11

what is the role of Hydrogen carbonate ions (HCO3-) ?

Answer 11

Maintenance of blood pH

Question 12

what is the role of Chloride ions (Cl-)?

Answer 12

Balance positive charge of sodium and potassium ions in cells

Question 13

what is the role of Phosphate ions (PO43-)?

Answer 13

Cell membrane formation
nucleic acid and ATP formation and bone formation

Question 14

what is the role of Hydroxide ions (OH-)?

Answer 14

Catalysis of reactions, pH determination

Question 15

which elements are in a carbohydrates?

Answer 15

carbon, hydrogen and oxygen

Question 16

what elements are present in lipids?

Answer 16

carbon, hydrogen and oxygen

Question 17

Which elements are found in proteins?

Answer 17

Carbon, hydrogen, oxygen, nitrogen and sulphur.

Question 18

Which elements are found in nucleic acids?

Answer 18

Carbon, hydrogen, oxygen, nitrogen and phosphorus

Question 19

Define the term ‘polar’ in relation to molecules.

Answer 19

Molecules that have regions or negativity and regions of positivity

This is due to the way in which electrons are distributed between elements joined by a covalent bond.

Question 20

Explain how polar molecules like water interact with each other

Answer 20

The positive and negative regions of the molecules attract each other and form hydrogen bonds.

These bonds give water its cohesive properties - it moves as one body because the molecules are attracted to each other.

These bonds also give water its adhesive properties - it molecules are attracted to other surfaces

Question 21

properties of hydrogen bonds?

Answer 21

relativly weak interactions between R groups of different partial chages e.g O and H in different H2O molecules

Question 22

What are the unique characteristics of water that are essential for life on Earth?

Answer 22

Unusually high specific heat capacity (boiling point).
Becomes less dense when it freezes.
Cohesive properties
Adhesive properties
‘Skin’ of surface tension

habitat
solvent
transport
temp control

Question 23

Why is it good that water has a high specific heat capacity?

Answer 23

Keeps habitats stable for living things as a lot of energy is needed to change it by a degree.

Question 24

Because ice is less dense than water what two things does this allow it to do?

Answer 24

create a stable environment for aquatic animals to live in throughout the winter
acts as an isulating layer for bodies of water against extreme cold

Question 25

Because water is a good solvent it can do what two things?

Answer 25

Molecules and ions can move around and react together in water
Molecules and ions can be transported around living things while dissolved in water

Question 26

what makes water a good transport medium?

Answer 26

cohesion between water molecules means that when water is transported theough the body, molecules will stick together
adhesion occurs between water and another polar molecule
the effects of both cohesion and adhesion = cappilary action

water can rise up narrow tubes against gravity

Question 27

why is it good that water is stable?

Answer 27

because water isnt easily innfluenced by temp or evapourate easily it provides a constant environment

Question 28

what does surface tension allow?

Answer 28

some insects such as pond skaters live on the surface of the water
surafe tension is strong enough to allow this to happen

Question 29

what does it mean if water acts as a coolant?

Answer 29

Water acts as a coolant, helping to buffer temperature changes during chemical reactions in prokaryotic and eukaroytic cells because of the large amounts of energy required to overcome hydrogen bonding. Maintaining constant temperatures in cellular environments is important as enzymes are often only active in a narrow temperature range.