Flashcards in 3.1 Chemical Elements And Water Deck (18):
State the four most frequently occurring chemical elements in living things.
State 5 other elements needed by living organisms
State one role of calcium
Mineral component of animal bones and teeth
State one role of iron
Found in haemoglobin in animals, allowing for oxygen transport.
State one role of sodium
Needed for nerve impulses to be sent.
State one role of phosphorous
Constituent of ATP and nucleic acids.
State one role of sulphur
Found in some amino acids.
Outline the structure of a water molecule
Water molecules consist of two hydrogen atoms covalently bonded to one oxygen atom.
Outline the polarity of a water molecule
The hydrogen atoms have a slightly positive charge, while the oxygen atom has a slightly negative charge. This gives water polarity (it has positive and negative poles).
State the type of bond between the hydrogen atom of one water molecule, and the oxygen atom of another
Outline the thermal properties of water
Water has a high specific heat capacity (can absorb much heat energy before changing temperature).
Water has a high heat of vaporisation.
Water is able to evaporate at temperatures below boiling.
Outline the cohesive properties of water
Stick together due to the hydrogen bonds between them.
Attract other nearby water molecule.
Tend to stick to other charged or polar molecules (adhesion).
State a property of water which makes it important for photosynthesis
Outline the solvent properties of water
Small size of water molecules allows them to surround small molecules and break them apart.
Water can dissolve other polar molecules.
Water can disassociate ionic compounds into their positive and negative ions.
Explain how water is used as a coolant in living organisms.
Both plants and animals use the evaporation of water from the surfaces of their bodies to facilitate cooling. Blood (mainly composed of water) is able to carry heat from warmer parts of the body to cooler parts.
Explain how water is used as a medium for metabolic reaction in living organisms
Nearly everywhere on earth, water is in a liquid state, and liquid water is he medium for metabolic reactions. Water can dissolve many organic and inorganic substances to facilitate chemical reactions. Water can absorb thermal energy released at a by-product of chemical reactions.
Explain how water is used as a transport medium in living organisms
Water is an effective transport medium for dissolved substances. In animals, water in the blood is used to transport oxygen, glucose, and urea. In plants, minerals from the soil ad sugars from leaves are transported in water through the xylem of plants.