1B Water

Question 1

How are water molecules form?

Answer 1

HYDROGEN BONDS form between a POSITIVELY CHARGED HYDROGEN atom and a NEGATIVELY CHARGED OXYGEN atom

Question 2

What are the five key properties of water?

Answer 2

1) Important metabolite
2) Good solvent
3) High latent heat of vapourisation
4) Can buffer changes in temperature
5) Very cohesive

Question 3

Explain why water is an important metabolite.

Answer 3

Metabolic reactions requir CONDENSATION and HYDROLYSIS reactions that use water molecules

Question 4

Explain how molecules can dissolve in water.

Answer 4

> IONIC molecules have 1 POSITIVE and 1 NEGATIVE ion
The POSITIVE side of water molecules is attracted to the NEGATIVE ION of ionic molecules so they become SURROUNDED by water molecules (DISSOLVE)

Question 5

Explain what is meant by water having a high latent heat of vapourisation and how it is advantageous to organisms.

Answer 5

> A HIGH amound of HEAT is required to turn it from a LIQUID to a GAS
This means organisms can use EVAPORATION without losing too much water

Question 6

Explain how water buffers changes in temperature and how that is advantageous to organisms.

Answer 6

> HYDROGEN BONDS give water a HIGH SPECIFIC HEAT CAPACITY as when water is heated, MORE ENERGY is needed to BREAK hydrogen bonds than to increase the temperature so temperature changes AREN’T RAPID
This makes it a GOOD HABITAT
Water inside organisms remains STABLE so maintaning body temperature is easier

Question 7

Explain what makes water cohesive and the importance of this property.

Answer 7

> It is the POLARITY of water is what makes it cohesive
This aids FLOW making it good at TRANSPORTING substances
It also means it has a HIGH SURFACE TENSION when in contact with air