Core component 1 - Water Flashcards
Describe the structure of a water molecule and how they can join together
The water molecule is a dipole (polar molecule) - has a positively charged end and a negatively charged end. Hydrogen bonds can form between the positive charge on a hydrogen and the negative charge on the oxygen atom of another water molecule.
How can water act as a solvent?
Because water molecules are dipoles, they attract charged particulars such as ions and other polar molecules, such as glucose. However, non- polar molecules such as lipids do not dissolve in water.
Why is it useful that water can act as a solvent?
1) Living organisms can obtain their key elements from aqueous solution.
2) Water can act as a transport medium
3) Substanes can dissolve in water, so chemical reactions can take place in solution.
How does water act as a metabolite?
1) Reactant in photosynthesis and hydrolysis
2) Product of aerobic respiration and condensation reactions
What is a high specific heat capacity?
This means a large amount of heat energy is needed to raise its temperature.
Why is it useful that water have a high specific heat capacity?
1) This prevents large fluctuations in water temperature
2) Important to keep aquatic habitats stable - so organisms do not have to adapt to extremes of temperature and enzymes within cells can work efficiently
What does high latent heat of vaporisation mean?
This means a lot of heat energy is needed to change it from a liquid to a vapour
Why is high latent heat of vaporisation an important feature of water?
1) It’s important in temperature control - heat is used to vaporise water from sweat on the skin or from a leaf’s surface. As the water evaporates, the body cools.
2) So much energy would be required to vaporise all the water that aquatic habitats rarely evaporate away.
What is cohesion ?
When the water molecules attract each other forming hydrogen bonds. There are so many molecules and they stick together in a lattice - this is called cohesion.
Why is cohesion an important feature of water?
It allows columns of water to be drawn up xylem vessels in plants.
How does water have a high surface tension at normal temperatures?
In a pond, for example, cohesion between water molecules molecules at the surface produces surface tension.
Why is high surface tension an important feature of water?
Insects, such as the pond skater, can live on the top of the water providing support
What else does water provide which is useful?
Buoyancy
