Unit 2: The Chemistry of Life
Week #3
2-1
The Nature of Matter Pgs 35-39
Questions
1. Describe the structure of an atom.
Atoms have a nucleus made up of protons and neutrons. Electrons are in constant motion in the
space around the nucleus.
2.
Why do all isotopes of an element have the same chemical properties? In what way do isotopes of an
element differ?
They have the same number of electrons. They differ in number of neutrons.
3.
What is a covalent bond? An ionic bond?
A covalent bond forms when electrons are shared between atoms. An ionic bond forms when
electrons are transferred.
4.
What is a compound? How are compounds related to molecules?
A compound is a substance formed by the chemical combination of two or more elements in definite
proportions. A molecule is the smallest unit of most compounds.
5.
How do van der Waals forces hold molecules together?
When the sharing of electrons is unequal, a molecule has regions that are charged. An attraction can
occur between oppositely charged regions of nearby molecules.
6.
How are ionic bonds and van der Waals forces similar? How are they different?
In both cases, particles are held together by attractions between opposite charges, but the attractions
are stronger between the ions than they are between the molecules.
Writing an Article
Write an article for your school newspaper on forensic science as a career. Assume that you have
already interviewed a forensic scientist who works for a law enforcement agency. The article should
be about 500 words long. Hint: Consider the interests of your readers.
2-2
1.
The Properties of Water
Pgs 40-43
Questions
Use the structure of a water molecule to explain why it is polar.
The hydrogen atoms form covalent bonds with the oxygen atom. Because of oxygen’s greater
attraction for electrons, there is an unequal distribution of electrons. The oxygen end of the bent
water molecule is negative; the hydrogen end is positive.
2.
Compare acidic and basic solutions in terms of their H+ ions than OH- ion concentrations.
Per volume, there are more H+ ions than OH- in an acidic solution and more OH- ions than H+ ions in a
basic solution.
3.
What is the difference between a solution and a suspension?
In a solution, all components are evenly distributed. In a suspension, undissolved particles are
suspended in the mixture and can settle out over time.
4.
What does pH measure?
The pH scale measures the concentration of H+ ions in a solution.
5.
The strong acid hydrogen fluoride (HF) can be dissolved in pure water. Will the pH of the solution be
greater or less than 7?
The pH will be less than 7.0.
Creating a Concept Map
Draw a concept map on the properties of water. Include the following terms in your concept map:
hydrogen bonds, polarity, cohesion, adhesion, capillary action, and solvent.
Week 4
2-3
Carbon Compounds
Pgs 44-48
1. Name four groups of organic compounds found in living things.
Carbohydrates, lipids, nucleic acids and proteins
Questions
2.
Describe at least one function of each group of organic compounds.
A typical response might mention that living things use carbohydrates as their main source of energy,
fats can be used to store energy, and nucleic acids transmit hereditary information and proteins form
tissues.
3.
What properties of carbon explain carbon’s ability to form many different macromolecules?
Each carbon atom can form four covalent bonds, and carbon atoms can bond with other carbon
atoms.
4.
Explain why proteins are considered polymers but lipids are not.
Proteins are made up of amino acid monomers joined in long chains. Although fatty acid chains may
be mistaken for monomers, only three fatty acids can attach to a glycerol molecule.
5.
Compare the structures and functions of the biomolecules lipids and starches.
Lipids are made mostly from carbon and hydrogen atoms; starch is a carbohydrate made up of
carbon, hydrogen and oxygen atoms. Both can be used to store energy.
Science as a Way of Knowing
Use what you learned about levels of organization in Section 1-3 to discuss the levels of organization
in macromolecules. Begin your discussion with the smallest structure.
2-4
1.
Chemical Reactions/Enzymes Pgs 49-53
Questions
What happens to chemical bonds during chemical reactions?
Bonds are broken in reactants and new bonds are formed in products.
2.
Describe the role of energy in chemical reactions.
Some chemical reactions release energy, and other chemical reactions absorb energy. Energy
changes determine how easily a chemical reaction will occur.
3.
What are enzymes, and how are they important to living things?
Enzymes are biological catalysts. Living cells use enzymes to speed up virtually every important
chemical reaction that takes place in cells.
4.
Describe how enzymes work, including the role of the enzyme-substrate complex.
Substrates, the reactants of an enzyme-catalyzed reaction, attach to the enzyme at an active site and
form an enzyme-substrate complex. Once the complex is formed, the enzyme helps convert substrate
into product.
5.
A change in pH can change the shape of a protein. How might a change in pH affect the function of an
enzyme such as hexokinase? Hint: Think about the analogy of the lock and key.
A change in pH could change the shape of hexokinase. This change would diminish or possibly
eliminate the ability of glucose and ATP to bind to the active site on the enzyme.
Modeling
Make a model that demonstrates how an active site and a substrate are like a lock and a key. Give a
brief talk in which you refer to your model as you explain how enzymes work.
38-1
1.
Food and Nutrition
Pgs 971-977
Questions
List the six nutrients needed by the body.
Water, carbohydrates, fats, proteins, vitamins and minerals
2.
What is the importance of water in the body?
Some body tissues, such as blood, are mostly water, and water is needed for many vital body
processes, including chemical reactions, elimination of wastes, and keeping the body cool through
evaporation.
3.
Why is fiber an important part of your diet?
Fiber adds bulk to the material moving through the digestive system, helping it to process food more
effectively.
4.
How are vitamins and minerals similar? How are they different?
Both vitamins and minerals are nutrients that are needed in small amounts for good health, but
vitamins are organic molecules, whereas minerals are inorganic.
5.
Which vitamins and minerals promote healthy bones?
Vitamins C and D, calcium, phosphorus, and fluorine
Designing a Brochure
Design and create a brochure that explains how the body uses the six nutrients necessary for normal
function. Use images from magazines or from the Internet to illustrate your brochure.
Week 5
8-1
Energy and Life
Pgs 201-203
1. What is the ultimate source of energy for plants?
The sun
Questions
2.
What is ATP and what is its role in the cell?
ATP stands for adenosine triphosphate, which is one of the principal chemical compounds that living
things use to store energy and release it for cell work to be done.
3.
Describe one cellular activity that uses the energy released by ATP.
A typical answer might mention active transport, movements within the cell, synthesis of proteins
and nucleic acids, or responses to chemical signals.
4.
How do autotrophs obtain energy? How do heterotrophs obtain energy?
Autotrophs obtain energy by making their own food. Heterotrophs obtain energy from the foods
they consume.
5.
With respect to energy, how are ATP and glucose similar? How are they different?
Similar: both store chemical energy for a cell. Different: A single molecule of glucose stores more
than 90 times the chemical energy of an ATP molecule.
Interdependence in Nature
Recall that energy flows and that nutrients cycle through the biosphere. How does the process of
photosynthesis impact the flow of energy and the cycling of nutrients? You may wish to refer to
Chapter 3 to help you answer this question.
8-2
1.
2.
Photosynthesis
Pgs 204-207
Questions
What did van Helmont, Priestly and Ingenhousz discover about plants?
Van Helmont discovered that water was involved in increasing the mass of a plant. Priestly
discovered that a plant produces the substance in air required for burning. Ingenhousz discovered
that light is necessary for plants to produce oxygen.
Describe the process of photosynthesis, including the reactants and products.
Photosynthesis uses the energy of sunlight to convert water and carbon dioxide into oxygen and
high-energy sugars.
3.
Why are light and chlorophyll needed for photosynthesis?
Light provides the energy needed to produce high-energy sugars. Chlorophyll absorbs light, and the
energy of that absorbed light makes photosynthesis work.
4.
Describe the relationship between chlorophyll and the color of plants.
Plants are green because green light is reflected by the chlorophyll in leaves.
5.
How well would a plant grow under pure yellow light? Explain your answer.
The plant would not grow well because chlorophyll does not absorb much light in the yellow region
of visible light.
Descriptive Writing
Write a summary paragraph describing either van Helmont’s, Priestley’s, or Ingenhousz’s
experiments with plants and light. Hint: Use the first boldface key sentence on page 206 to give you
an idea for the topic sentence.
8-3
Photosynthesis
Pgs 208-214
Questions
1. Summarize the light-dependent reactions.
The light-dependent reactions produce oxygen gas and convert ADP and NADP+ into the energy
carriers ATP and NADPH.
2.
What reactions make up the Calvin cycle?
The Calvin cycle uses ATP and NADPH from the light-dependent reactions to produce high-energy
sugars.
3.
How is light energy converted into chemical energy during photosynthesis?
Light energy is converted into chemical energy by the pigments in the chloroplast.
4.
What is the function of NADPH?
The main function of NADPH is to carry high-energy electrons produced by light absorption in
chlorophyll to chemical reactions elsewhere in the cell.
5.
Why are the light-dependent reactions important to the Calvin cycle?
The light-dependent reactions provide the Calvin cycle with ATP and NADPH. The Calvin cycle uses
the energy in ATP and NADPH to produce high-energy sugars.
Making a Flowchart
Construct a flowchart that illustrates the steps of photosynthesis. Begin with the energy of sunlight
and end with the production of sugars. Include as much detail as possible in the numerous steps.
Week 6
9-1
Chemical Pathways
Pgs 221-225
Questions
1. Describe the process of cellular respiration.
Cellular respiration is the process that releases energy by breaking down molecules in food in the
presence of oxygen.
2.
What are the products of glycolysis?
Glycolysis produces 2 molecules of pyruvic acid, 2 molecules of ATP, and 2 molecules of NADH.
3.
Name the two main types of fermentation.
Alcoholic fermentation and lactic acid fermentation.
4.
What is a calorie? A Calorie?
A calorie is the amount of energy required to raise the temperature of 1 gram of water 1 degree
Celsius. A Calorie is 1000 calories.
5.
How is the function of NAD+ similar to that of NADP+?
Both are electron carriers.
6.
How are lactic acid fermentation and alcoholic fermentation similar? How are they different?
Similar: Both provide energy to cells in the absence of oxygen. Different: Alcoholic fermentation
produces alcohol, carbon dioxide, and NAD+, while lactic acid fermentation produces lactic acid and
NAD+.
Matter and Energy
Write the conversion of ADP to ATP as a chemical equation. What are the reactants and the product?
You may wish to refer back to Chapter 2 to review chemical equations.
9-2
1.
Krebs Cycle/Electron Carrier Pgs 226-232
Questions
What happens to pyruvic acid during the Krebs cycle?
Pyruvic acid is broken down into carbon dioxide in a series of energy-extracting reactions.
2.
How does the electron transport chain use the high-energy electrons from the Krebs cycle?
The electron transport chain uses the high-energy electrons from the Krebs cycle to convert ADP and
ATP.
3.
Why is cellular respiration considered to be much more efficient than glycolysis alone?
Cellular respiration enables the cell to produce 34 more ATP molecules per glucose molecule in
addition to the 2 ATP molecules obtained from glycolysis.
4.
How many molecules of ATP are produced in the entire breakdown of glucose?
36
5.
Compare the energy flow in photosynthesis to the energy flow in cellular respiration.
The energy flows in photosynthesis and cellular respiration take place in opposite directions.
Photosynthesis is the process that “deposits” energy, while cellular respiration is the process that
“withdraws” energy.
6.
How is the chemical energy in glucose similar to money in a savings account?
The energy in glucose is “saved” and can be “withdrawn” when the body needs it.