Water

Question 1

What are the key functions of water in the body?

Answer 1

It is a metabolite in many reactions such as condensation and hydrolysis (metabolite = involved in the reactions)

It is a solve so some substances dissolve in it and most metabolic reactions take place in solutions

Its high latent heat of vaporisation means water is good at controlling a body’s temperature

Its molecules are cohesive (stick together) which helps water transport in plants

Question 2

Describe the structure of water

Answer 2

One oxygen atom, two hydrogen atoms covalently bonded

Water is a polar molecule

Since the H electrons are pulled more to the more massive O atom, the H side has a slight positive charge while the O atom exhibits a slight negativity

Question 3

Explain a hydrolysis reaction

Answer 3

A water molecule breaks a bond in metabolic reactions

Question 4

Explain a condensation reaction

Answer 4

A water molecule is released by a new bond in a metabolic reaction

Question 5

Why is water’s high latent heat of vaporisation useful?

Answer 5

Water molecules are attracted to each other by their polarity which requires a lot of energy to break

This means a lot of energy is used up when water evaporates (its bonds break)

For organisms heating up, that means water sweated out can cool the body - which is a critical homeostatic principle keeping the body’s temperature stable

Question 6

What does it mean that water is a good buffer?

Answer 6

The hydrogen bonds between water molecules can absorb a lot of energy

This means that water doesn’t undergo rapid temperature changes which again helps to maintain constant body temperature (connect to why this may good for enzymes)

Question 7

Explain why water is a good solvent

Answer 7

Water is a polar molecule, so it attracts other ions

these ions become surrounded by water molecules which means in effect they dissolve

which is deployed in many metabolic ionic reactions in the body.

Question 8

What does it mean that water is cohesive?

Answer 8

Again, water’s polarity means that water molecules are attracted to one another - they’re cohesive

This helps water to flow which is useful in transporting substances

And water has a high surface tension when it comes into contact with air - allowing pondskaters to walk on water, but also to allow sweat to form in droplets to reduce body temperature.

And why this hurts…