Uploaded by Jihad Mokhtari

Study Guide Lecture Exam 1

The content of this study guide has been provided by Dr. Graeme Lindbeck, who heads the Biology Program at Valencia
College West Campus. Some questions have been slightly modified by me to make them into multiple choice questions, or to
add additional contextual information. Content is organized by chapters and should be used for reference purposes. You
should complement this study guide by reviewing your Mastering Biology assignments, recommended videos and your
classroom and laboratory notes.
Chapters 1 and 2
1. One day you are watching a wasp drag a grasshopper down a hole in the ground. A friend sees you and asks what you
are doing. You reply, “I am watching the wasp store grasshoppers in her nest to feed her offspring.” Which of the
following is the best word to describe your statement?
a. observation
b. hypothesis
c. theory
d. assumption
e. prediction
2. In order to test your hypothesis, you plan an experiment. Which of the following experimental results would provide
the best support for your hypothesis?
a. Follow the wasp and see that she digs a similar hole in another place.
b. Watch the first hole for a while and see that the wasp brings in another grasshopper.
c. Dig into the hole and see the wasp eating a grasshopper.
d. Dig into the hole and find a grasshopper buried with wasp eggs on its side.
e. Come back to the hole three weeks later and see several adult wasps come out of it.
3. You and your friend wait until the wasp flies away; then you dig into the hole. You find three grasshoppers, each with
a small white egg on its side. You claim that this observation supports your hypothesis. Which of the following
assumptions are you most likely making?
a. The wasp stored the grasshopper to feed her offspring.
b. The eggs are grasshopper eggs.
c. The wasp laid the eggs.
d. The wasp dug the hole.
e. The wasp will not return.
4. Identify the level of biological organization (Atom, Molecule, Organelle, Cell, Tissue, Organ, Organ System, Organism,
Population, Community, Ecosystem, Biome, Biosphere) for each of the following:
a. The kidney of a bat.
b. An oak tree outside a cave in upstate New York.
c. Bats in a cave in upstate New York.
d. The physical and biological components of a cave in upstate New York.
e. The respiratory system of a bat.
f. All the species living and interacting within a cave in upstate New York.
5. Cat DNA is much more similar to dog DNA than to tortoise DNA. Why is that?
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a. Cats and dogs are both carnivores and take in similar nutrients
b. Cats and dogs have lived together with humans for a long time, so they have grown more alike.
c. Cats and dogs have more offspring during their lifetime than tortoises have, so their DNA changes less
d. Cats and dogs have a common ancestor that is more recent than the common ancestor of cats and tortoises.
6. In a population, which individuals are most likely to survive and reproduce?
a. The individuals that are most different from the others in the population.
b. The individuals that are best adapted to the environment.
c. The largest individuals in the group.
d. The individuals that can catch the most prey.
7. Global warming is causing more and more ice to melt each year in the Arctic, resulting in more areas of exposed bare
ground than before. These brown areas make polar bears (which are white) much more obvious to their prey.
Recently, an infant polar bear was born with brown fur. The polar bear survived to adulthood and fathered several
offspring with brown fur. Which of the following is a plausible explanation of how the brown fur trait appeared in
these polar bears?
a. A polar bear realized it would be better to be brown in order to hide more effectively. It triggered mutations
in its fur pigment gene, changed the fur color from white to brown.
b. One or more random mutations occurred in the fur pigment gene of an individual polar bear embryo, which
resulted in a change from white fur to brown fur.
c. Increased temperature due to global warming caused targeted mutations in the fur pigment gene in an
individual polar bear embryo, which resulted in a change in pigment from white to brown.
d. A female polar bear realized it would be better for her offspring to be brown and mated with a grizzly bear to
get this result.
8. A chemical element cannot be broken down to other forms by chemical reactions. Each element has a specific
number of protons, neutrons and electrons.
a. What is the name of the following element, and how many protons, neutrons and electrons does it have?
Number of Protons
Number of Neutrons
Number of electrons
b. What are the atomic number, mass number, and weight in Daltons of the element shown in part a?
Atomic number
Mass number
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Weight in Daltons
9. If two or more elements are in the same row (period) of the periodic table, what do they have in common?
a. Atomic Number
b. Number of Atomic Orbitals
c. Number of electrons in the outer orbital (valence electrons)
d. Weight in Daltons
10. If two or more elements are in the same column of the periodic table, what do they have in common?
a. Atomic Number
b. Number of Atomic Orbitals
c. Number of electrons in the outer orbital (valence electrons)
d. Weight in Daltons
11. Acetic acid (vinegar) has the chemical formula CH3COOH, as shown in the figure. When vinegar and water are mixed,
the two react to create hydronium ions and acetate ions. Refer to pages 36-39 in the text book, which describe the
following types of chemical bonds: nonpolar and polar covalent bonds, ionic bonds, hydrogen bonds, and van der
Waals interactions. From all the information provided, match the type of bond with the correct letter in the figure.
Acetic acid (vinegar) dissociation
Acetic Acid in Water
From all the information provided, determine which of the bonds between elements in this molecule are:
covalent bonds d
ionic bonds
hydrogen bonds
van der Waal interactions g
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Chapters 3 and 4
12. Compounds that have the capacity to form hydrogen bonds with water are said to be hydrophilic (water loving).
Those without this capacity are hydrophobic (water fearing). Is acetic acid (see the figure in question 11) hydrophilic
or hydrophobic? Explain your answer.
13. The molecule shown in figure 11 is acetic based molecule. The COOH group is polar, that allows it to make the
molecule hydrophilic.
14. In addition to being polar, water molecules can dissociate into hydronium ions (H3O+ or simply H+) and hydroxide
ions (OH). The concentration of each of these ions in pure water is 10-7 M, or one out of every 10 million molecules.
The H+ concentration of a solution is given by its pH value. The pH of a solution is defined as the negative log10 of the
hydrogen ion concentration. What is the pH of pure water?
Water is 10e-7 M, so the [H+] is 7.
15. The molecule in question 1 is acetic acid. The COOH group can release an H+ into solution. - concentration at this pH?
If you add acetic acid to water and raise the concentration of H+ to 10-4, what is the pH of the solution? What would
be the OH
 The concentration of water is 10e-4 [H+], so the pH of it is 4.
 The OH of the solution is 10. [PoH+oH=14]
16. Life as we know it could not exist without water. All the chemical reactions of life occur in aqueous solutions. Water
molecules are polar and are capable of forming hydrogen bonds with other polar or charged molecules. As a result,
water has the following properties:
A. H2O molecules are cohesive; they form hydrogen bonds with each other.
B. H2O molecules are adhesive; they form hydrogen bonds with polar surfaces.
C. Water is a liquid at normal body temperatures.
D. Water has a high specific heat.
E. Water has a high heat of vaporization.
F. Water’s density is greatest at 4oC.
Explain how these properties of water (A through F) are related to the phenomena described below. More than one
property may be used to explain a given phenomenon.
a. During winter, air temperatures in the northern US and Canada can be below 0oC for months, yet fish and
other animals living in the lakes survive.
b. The ice on top of the lake acts like insulation and as a result most deep lakes do not freeze. {Water expands
when it freezes, and it becomes less dense when it freezes resulting in floating ice}
c. Many substances like salt and sucrose dissolve quickly in water.
d. the attraction of polar water molecules for the Na and Cl of NaCl is strong enough to allow them to dissociate
and interact with water molecules.
e. When you pour water into a container a meniscus forms at the top of the water.
f. Water is attracted to the polar molecules that make up the container. As a result, some of the water
molecules associate with the polar molecules of the container and climb up due to adhesion. {this is called
capillary action}
g. Sweating and evaporation of sweat from the body surface help lower a human’s body temperature.
h. Water has very high heat capacity, the heat excites the water molecules of the body causing the break of
hydrogen bonds and then evaporate away. When they escape away, they take that heat energy with them
leaving the body temperature cooler.
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A bottle contains equal parts water and oil. After vigorous shaking, the mixture separates into layers of oil
over water.
j. Oil is hydrophobic, while water is hydrophilic. Therefore, they are being pushed out of the water as a result of
the water’s cohesive forces.
k. Water drops on a surface tend to form rounded drops or beads.
l. Water molecules are cohesive and form hydrogen bonds with each other. As a result, a drop of water tends
to bead up or become rounded.
m. Water drops on the surface of a freshly waxed car tend to round up or bead more after waxing than before
n. The wax is hydrophobic and less polar therefore, adhesion between the surface and the water molecules is
lower; the cohesion of the water molecules for each other looks livelier.
o. If you touch the edge of a paper towel to a drop of colored water, the water will be absorbed by the paper
p. Water molecules are adhesive, they form hydrogen bonds with polar surfaces. {paper towels are made up of
cellulose fiber}
q. One mole of an element or compound contains 6.023 x 1023 atoms or molecules of the element or
compound. One mole of an element or compound has a mass equal to the mass number, or molecular
weight, in grams. For example, 1 mole of hydrogen gas (H2) contains 6.023 x 1023 molecules and weighs 2g
[ you have two hydrogens, each hydrogen has 1 for mass number or molecular weight so you add them and
you get 2g].
How would you determine how many grams are in a mole of any chemical element or compound?
To get the number of grams, you will need to multiply the mole value by the molar mass of the element or
r. What is the weight of 1 mole of pure sodium (Na)?
1 mole of sodium (Na) is equal to the mass number which is 23 moles.
s. How many atoms of sodium are in one mole of sodium?
1 mole = 6.02x10e23 atoms/ things/ molecules, so 1 mole (6.02x10e23)=6.02x10e23 atoms.
One Na+ ion and one Cl ion can combine to form NaCl (table salt).
a. If Cl has 17 electrons, 17 protons, and 18 neutrons, what is its mass number?
To get the mass number you add the number of protons and neutrons, so it is 34.
b. What is the molecular mass of NaCl?
To find the molecular mass of NaCl, you look up each of their mass number then you are them, so
c. How many grams of NaCl equal a mole of NaCl?
58.44g x 1mole divided by 58.44g. cross out the grams, and after you divide you will get 1 mole=58.4g of
If you wanted to combine equal numbers of Na+ and Cl- ions in a flask, how much Cl- would you have to add if you
added 23 g of Na+? (Explain your answer).
To make a one molar (1 M) solution of NaCl, you need to add 1 mole of NaCl to sufficient distilled water to make a
final volume of 1 liter (1 L or 1,000 ml). A 1 M solution is said to have a molarity of 1. If you add 2 moles of NaCl to 1 L
of distilled water, you have a 2 M solution and its molarity is
a. How many NaCl units are in the 1 M NaCl solution?
b. How many units of NaCl are there per ml of the solution?
Next, you divide this 1 M solution of NaCl into four separate flasks, putting 250 ml into each flask.
a. How many grams of NaCl are in each flask?
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b. How many units of NaCl are in each flask?
c. How many units of NaCl are there per ml of distilled water?
d. What is the molarity of NaCl in each of the four flasks?
A solution at pH 6 contains ______________ H+ than the same amount of a solution at pH 8.
a. 20 times more.
b. 100 times more.
c. 2 times less.
d. 100 times less.
The answer: pH6 =10e-6[H+] and pH8= 10e-8, the difference between them is 10e-2= 100. pH6 os 100 times more
than because it is closest to 0 therefore, more acidic (containing more H+).
Most of the unique properties of water result from the fact that water molecules
a. Are the most abundant molecules on the Earth’s surface?
b. Are held together by covalent bonds. c.
c. Are constantly in motion.
d. Are polar and form hydrogen bonds.
A can of cola consists mostly of sugar dissolved in water, with some carbon dioxide gas that makes it fizzy and makes
the pH less than 7=neutral.
In chemical terms, you could say that cola is an aqueous solution where water is the _________, sugar is a
___________, and carbon dioxide makes the solution _________.
a. solvent … solute … basic
b. solute … solvent … basic
c. solvent … solute … acidic
d. solute … solvent … acidic
Functional groups can modify the properties of organic molecules. In the following table, name each functional group,
indicate whether each functional group is polar or nonpolar, and hydrophobic or hydrophilic, and give an example of
a molecule which contains the functional group (draw the molecule, highlighting the functional group).
Functional Group
(Hydroxyl) alcohol
(carbonyl) ketone(within)
(carboxyl) -carboxylic
(amino) Amin
(Sulfhydryl) thiol
Org. Phosphate
(methyl) methylated
Polar/Non Polar
Example (Where you find it?)
Polar, Releases
Polar, Picks up
26. The diagrams below are examples of isomers – organic molecules that share the same chemical formula but have
different structures and different chemical properties. Identify which type of isomer is illustrated in each case.
Organic Molecules
Type of Isomer
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Structural isomer: have covalent bonds in
different arrangements.
Trans-isomers: have double bonds with CH3 on
opposite sides. ?
trans-isomer: have double bonds. ?
Enantiomer isomer: are mirror image of each
other. (asymmetric)
Structural isomer: covalent bonds but different
Chapter Five
Some Rules for Identifying carbohydrates, lipids, proteins and nucleic acids.
27. What are the approximate C:H:O ratio in each of the following types of macromolecules?
Nucleic acids
28. Which of the compounds listed in question 1 are often composed of C, H, and O only?
Nucleic acids
29. Which of the compounds can be identified by looking at the C:H:O ratios only?
Nucleic acids
30. What other elements are commonly associated with each of these four types of macromolecules?
Always contain P
Generally contain no P
Always contain N
Generally contain no N
Frequently contain S
Generally contain no S
Contain OH
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Nucleic acids
31. Functional groups can modify the chemical properties of carbon backbones of organic molecules. In the following
table, indicate whether each functional group is polar or nonpolar and hydrophobic or hydrophilic. Indicate which of
these functional groups are found in proteins and lipids.
Functional group
Polar or nonpolar
Hydrophobic or
Found in all
Found in many
Found in many
32. You want to use a radioactive isotope as a trace that will label only the protein in an RNA virus. Assume the virus is
made of only a protein coat and an RNA core. Which of the following would you use? Explain your answer.
a. Radioactive P
b. Radioactive N
c. Radioactive S
d. Radioactive C
33. Closely related macromolecules often have many characteristics in common, like the same chemical elements and
functional groups. To be able to distinguish between closely related macromolecules, you need to determine how
they differ and label that difference.
a. What makes RNA different from DNA?
b. If you wanted use a radioactive or fluorescent tag to label only the RNA in a cell and not the DNA, what
compound(s) could you label that is/are specific for RNA?
c. If you wanted to label only the DNA, what compound(s) could you label?
34. Refer to your answers to questions 26-32 and list the simple rule(s) you can use to identify the following
Nucleic acids
DNA versus RNA
35. What molecule/structure is that? Identify the compounds illustrated below as carbohydrates, lipids, amino acids, or
nucleic acids. Indicate whether each is polar or nonpolar and hydrophobic or hydrophilic.
Molecule type
Polar or Nonpolar
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Hydrophobic or hydrophilic
36. Predicting the behavior of macromolecules. The twenty amino acids that are commonly used in proteins differ in their
chemical properties of their side chains, or R groups. What properties does each of the following R groups have?
(Each may have more than one)
R Group
Basic, acidic or neutral
Polar or nonpolar
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Hydrophobic or hydrophilic
37. Polypeptides and proteins are made up of linear sequences of amino acids. Each protein has a specific three-dimensional
shape and interactions between the amino acids and their R groups play a significant role in determining the shape. How
are amino acids linked together to form polypeptides and proteins? What is this type of bond called?
38. Describe the four structural levels of a protein. What kinds of bonds hold each of these structural levels together?
Structural Level Kind of Bonds
39. Lipids are hydrophobic and are insoluble in water. A wide range of compounds are included in this group, including fats,
oils, waxes, and steroids like cholesterol.
a. How are fatty acids and glycerol linked together to form fats (triglycerides or triacylglycerols)?
b. What function do fats serve in living organisms?
c. How do phospholipids differ from triglycerides?
d. What characteristics do phospholipids have that triglycerides do not have?
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