Part 1

1. Nitrogen fixation is a natural process by which inert or unreactive forms of nitrogen are transformed into usable nitrogen. Why is this process important to life?

2. Given what you have learned about the hydrogen bonding shared between nucleic acids in DNA, which pair is more stable under increasing heat: adenine and thymine, or cytosine and guanine? Explain why.

3. Which of the following is not an organic molecule; methane (CH4), fructose (C6H12O6), rosane (C20H36), or ammonia (NH3)? How do you know?

Part 2

• Record your hypothesis about what will happen when Biuret solution is mixed with the solutions from test tubes 1, 2, 3, and 4 here. Be sure to use scientific reasoning to support your hypothesis.

• Write a statement to explain the molecular composition of the unknown solution based on the results obtained during testing with the Biuret solution and each sample solution.

• Diet and nutrition are closely linked to the study of biomolecules. How should you monitor your food intake to insure the cells in your body have the materials necessary to function?

There are other types of reagents used to determine what type of biomolecule a substance is. For example, copper ions present in Benedict’s reagent reacts with the

Part 3

• At what magnification do you first notice the ragweed pollen?

• Which is bigger, a rhinovirus or E. Coli?

• Based on the magnification, how many of the E. Coli can fit into the same space as the head of a pin?

• About how many red blood cells could fit across the diameter of a human hair (again, look at the magnification scale)?

Part 4

• What is the highest objective lens you can use to see the entire letter e?

• The nuclei (the structure inside a cell that contains DNA) of the cheek cells have been stained using a special dye so that they appear purple. What shape are they?

• At high magnification, you may notice that not all of the nuclei in the onion root tip slide appear as the shape you described in the question above. What do they look like?

• What is the first step normally taken when you look through the ocular lenses?

Part 5

• State your hypothesis (developed in Step 8) here. Be sure to include what you think the pH will be, and why.

• What is a neutralization reaction?

• When might neutralization reactions be used in a laboratory setting?

• At what point was the solution in beaker “B” neutralized?

• What do you think would have been the results if a stronger solution of sodium bicarbonate was used? Would it take more or less to neutralize? What about a weaker concentration of sodium bicarbonate?

Part 6

• State your hypothesis (developed in Step 8) here. Be sure to include what you think the pH will be, and why.

• What is a neutralization reaction?

• When might neutralization reactions be used in a laboratory setting?

• At what point was the solution in beaker “B” neutralized?

• What do you think would have been the results if a stronger solution of sodium bicarbonate was used? Would it take more or less to neutralize? What about a weaker concentration of sodium bicarbonate?