Term
| State that the most frequently occurring chemical elements in living things are... |
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Definition
| carbon, hydrogen, oxygen and nitrogen. |
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Term
| State that a variety of other elements are needed by living organisms, including: |
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Definition
- sulfur
- calcium
- phosphorus
- iron
- sodium |
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Term
| State one role for each of the elements mentioned in 3.1.2 in both plants and animals. |
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Definition
- Sulfur: essential element in variable group of some amino acids (therefore proteins)
- Calcium: essential element in bones, teeth, shells, nerve function
- Phosphorus: essential element in nucleotides, including ATP
- Iron: essential element in heme group of hemoglobin, oxygen transport molecule
- Sodium: essential ion in neuron membrane potential, required for nerve impulse transmission |
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Term
Outline the thermal, cohesive and solvent properties of water.
Thermal properties |
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Definition
- hydrogen bonds between polar water molecules cause water to resist change
- high specific heat (energy required to change water temperature)
- high heat of vaporization (energy required to boil water)
- high heat of fusion (loss of energy required to freeze water)
- thus, water produces a stable environment for aquatic organisms |
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Term
Outline the thermal, cohesive and solvent properties of water.
Cohesion |
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Definition
- hydrogen bonds between polar water molecules cause them to cohere
- allowing for transpiration in plants moving water against gravity
- surface tension between cohering water molecules
- allowing for animals such as water striders to walk over the surface of ponds even though they are denser than water |
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Term
Outline the thermal, cohesive and solvent properties of water.
Solvent properties |
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Definition
- the polarity of water attracts, or dissolves, any other polar or charged particles by forming hydrogen bonds with them
- proteins, glucose, or ions, such as sodium or calcium are all soluble |
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Term
Explain the relationship between the properties of water and its uses in living organisms as a coolant, medium for metabolic reactions and transport medium.
Coolant |
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Definition
- hydrogen bonds between polar water molecules cause water to resist change
- high heat of vaporization (energy required to change liquid water into vapor) because hydrogen bonds must be broken
- thus, evaporation from plant leaves (transpiration) or from human skin (sweat) removes heat, acting as a coolant |
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Term
Explain the relationship between the properties of water and its uses in living organisms as a coolant, medium for metabolic reactions and transport medium.
Medium for metabolic reactions |
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Definition
- cytoplasm is primarily water, providing a polar medium in which other polar or charged molecules dissolve
- many enzymes are globular proteins that are water soluble so they dissolve in cytoplasm where they control metabolic reactions |
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Term
Explain the relationship between the properties of water and its uses in living organisms as a coolant, medium for metabolic reactions and transport medium.
Transport medium |
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Definition
- hydrogen bonds between polar water molecules cause them to cohere
- as water is lost by transpiration/evaporation from plant leaves, hydrogen bonds between adjacant water molecules pull water up columns of xylem
- thus, plants move water against the force of gravity, by as much as 100 meters |
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