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Topic 3.1 Review Book
Chemical Elements and Water
Name ___________________
Topic 3 The chemistry of life
Topic 3.1 Chemical Elements and Water (Textbook pages 37-43)
Key facts
1. The most commonly occurring elements in organisms are carbon, hydrogen, oxygen and nitrogen.
2. Sulfur, calcium, phosphorus, iron and sodium are also in organisms in significant amounts.
3. Sulfur is a component of several amino acids.
4. Phosphorus is essential to ATP and nucleic acids.
5. Iron is present in a group of compounds called cytochromes. These are important in the electron
transport chains of respiration and photosynthesis.
6. Sodium is involved in nerve impulse transmission as well as to help maintain solute concentrations
within cells.
7. Calcium is essential to muscle contraction as well as acting as a coenzyme or a messenger.
8. Water has a high specific heat which allows it to absorb or give off a great deal of energy before it
allows a temperature change. Thus, this thermal property of water allows temperature regulation
within organisms as most organisms are made of a significant amount of water.
9. Water has cohesive properties. This results in attraction between water molecules. Cohesion of
water molecules allows water to move as a column of water in the vascular tissues of plants.
10. Water is a polar molecule, and because of this, it is able to dissolve any other polar substance.
Because most molecules have polar properties, water is often referred as the universal solvent.
However, it can not dissolve non-polar substances. This is especially important in the transport of
substances in the blood of humans. Blood is mostly made up of water.
11. Water is the medium for metabolic reactions.
12. When animals perspire or when plants transpire water is acting as a coolant.
Draw assessment statements from this topic
1. Draw and label a diagram showing the structure of a water molecule. Be certain to show polar regions
and areas where hydrogen bonding would occur.
Complete the following.
1. Name the four most common occurring chemical elements in organisms.
2. What chemical element may be deficient if a person shows low levels of energy?
Name ______________________________
Section _____________
3. What element is found in some amino acids and vitamins?
4. Name two compounds that always contain phosphorus.
5. What causes water to be a polar molecule?
6. Describe or diagram how two water molecules could produce a weak hydrogen bond between
them.
7. A phrase to remember is “like dissolves like.” Use this phrase to explain why water is called the
universal solvent when in actuality it is not.
8. Explain how water helps to maintain body temperature in humans.
9. How does evaporation from animals and transpiration from plants bring about cooling?
10. Explain the cohesive properties of water.
11. Give an example of water being used as a transport medium in animals.
12. Give an example of water being used as a transport medium in plants.
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