3.1-Chemical Elements of Water State that the most frequently occurring chemical elements in living things are carbon, hydrogen, oxygen, and nitrogen State that a variety of other elements are needed by living organisms, including sulfur, calcium, phosphorus, iron and sodium.

3.1.3-State one role for each of the elements mentioned in –Nitrogen is part of amine groups in amino acids, and thus proteins –Calcium is needed to make the mineral that strengthens bones and teeth –Phosphorus is part of phosphate groups in DNA and ATP –Iron is needed to make hemoglobin and thus carry oxygen to the blood –Sodium is used in neurons for the transmission of nerve impulses Hemoglobin, including iron, is the material that makes up red blood cells, above. – Sulfur, found in the hair, nails and skin, assists the immune system

3.1.4-Draw and label a diagram showing the structure of water molecules to show their polarity and hydrogen bond formation OO H H H H Oxygen pole is slightly negative Hydrogen pole is slightly positive Hydrogen bond IIVIIV

3.1.5-Outline the thermal, cohesive, and solvent properties of water Thermal (Campbell book pg.43)~ Water has a large heat capacity because of the hydrogen bonds that form between its molecules. It takes lots of energy to break these bonds. Water also has high boiling and freezing points. Additionally, water can evaporate at temperatures below its boiling point, taking the required heat energy to break the hydrogen bonds from the liquid water, which gives it a cooling effect. Cohesive (Campbell book pg.42)~ Water molecules stick to each other because of the hydrogen bonds that form between them. Solvent (Campbell book pg.45)~ Many different substances can dissolve in water because of its polarity.

3.1.6-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~ Evaporation of water from plant leaves (transpiration) and from human skin (sweat) has cooling effects Medium for metabolic reactions~ cohesive properties of water allow strong pulling forces to be exerted to suck columns of water to the tops of trees without breaking. Transport~ The solvent properties of water allow many substances to be carried dissolved in water in the blood of animals and the sap of trees. The properties of water allow water to enter, pass through, and exit a plant.

Key Terms (pg.41-46) polar molecule cohesion adhesion surface tension specific heat solution solvent solute aqueous solution hydrophilic hydrophobic