2.1.2 Biological molecules Flashcards
What molecules is water composed of?
Hydrogen
Oxygen
Why is water polar?
the oxygen atom has a slight negative charge and the 2 hydrogen atoms have a slight positive charge
What type of bonds join water molecules?
Hydrogen
What type of reaction joins water molecules?
Condensation
List some properties of water
- high surface tension
-cohesion
-adhesion
-high density
-ice less dense than water
-transparency
-solvent
-high specific heat capacity
-high latent heat of vaporisation
Why does water have a high surface tension?
Water molecules at the surface have fewer water molecules to hydrogen bond to so they cohere to the water molecules next to them. This creates a high surface tension.
Why is water cohesive?
Like molecules of water will hydrogen bond to each other.
Why is waters cohesion beneficial?
Helps plants to take up water as the water molecules cohere together to create a continuous stream of water.
What is adhesion in water?
The attraction of different molecules to each other via hydrogen bonding.
What is the benefit of waters adhesion?
Allows water to stick to plant tissues e.g droplets on leaves which creates a ready source of drinking water for organisms.
How is waters high density beneficial?
Things can float on water and will exert less energy when floating.
Why does water have a high density?
Water molecules are packed more closely together than in some liquids of the same volume.
Why is ice less dense than water?
Hydrogen bonds in ice hold water molecules further apart than when water is a liquid.
Why is ice being less dense than water beneficial?
Means that ice can provide habitats for organisms.
Why is water transparent?
Light can be transmitted through it.
Why is waters transparency beneficial?
-Predators can see their prey through the water
-Light is needed for photosynthesis.
Why is water a solvent?
Due to waters polarity and strong attraction to other molecules it can destroy the forces of attraction holding the muscles together causing it to dissolve.
Why is water being a solvent beneficial?
-Can transport a wide range of compounds
-Valuable to all living things
Why does water have a high specific heat capacity?
Due to the many hydrogen bonds present.
Why is waters specific heat capacity beneficial?
temperature of water does not fluctuate which means it can be a good habitat.
Why is waters high latent heat of vapourisation important?
Provides a cooling effect on organisms.
What does waters high latent heat of vapourisation mean?
Only little water is required to evaporate to lose a great amount of heat.
How does waters high surface tension benefit organisms?
Helps creatures to walk on water e.g water striders.
What molecules make up carbohydrates?
-Carbon
-Hydrogen
-Oxygen
