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Biology Test 1 2


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Compared to 31P, the radioactive isotope 32P has:

A. A different atomic number
B. One more neutron
C. One more proton
D. One more electron
E. A different charge
B is correct. All isotopes of an element have the same atomic number. They have the same number of protons in the nucleus of the atom; the same number of electrons orbiting the atom and differ only in the number of neutrons in the nucleus of the atom.
An element is to a(an) _________________ as a tissue is to a(an) __________.

A. Atom, organism
B. Compound, organ
C. Molecule, cell
D. Atom, organ
E. Compound, organelle
B is the correct answer. Remember compounds are substances composed of one or more elements. Organs are composed of one or more types of tissues. In this answer the relationships in both halves of this statement are stated correctly.
In the term “trace element,” the modifier “trace” means:

A. The element is required in very small amounts.
B. The element can be used as a label to trace atoms through an organismÂ’s metabolism.
C. The element is very rare on ear
A is the correct answer. Trace means that this element is required in very minute quantities – in the human body it makes up less than 0.01% by weight of the naturally occurring elements. Compare the recommended daily intake of 1000 to 1500 milligrams for calcium which is not a trace element to the 100 micrograms per day for the trace element selenium. (And even the “experts” don’t completely agree on the recommended amount of selenium. Some think that 100 mg is too high.)
Atoms can be represented by simply listing the number of protons, neutrons and electrons - for example, 2p+; 2n0; 2e- for helium. Which atom represents the 18O isotope of oxygen?

A. 6p+; 8n0; 6e-
B. 8p+; 10n0; 8e-
C. 9p+; 9n0; 9e-
The atomic number of oxygen is 8. You know this means that an oxygen atom has 8 protons in the nucleus. You also know that a neutral atom of oxygen has an equal number of electrons as protons – 8 electrons. You know this because the opposite electrical attraction between the positively charged protons and negatively charged electrons is the “glue” that holds an atom together. You also know that the atomic mass number (the isotope number) of 18 is the sum of the total number of protons plus the total number of neutrons in the nucleus. 18 – 8 = 10 neutrons in the nucleus. The only possible correct answer is B. (D is not correct because the number of neutrons is not correct. D represents the isotope 16O.)
The atomic number of sulfur is 16. Sulfur combines with hydrogen by covalent bonding to form a compound, hydrogen sulfide. Based on the electron configuration of sulfur, we can predict that the molecular formula of the compound will be:

A. HS<
C is correct. Each atom of hydrogen would have a “filled” valence shell and the atom of sulfur would have a “filled” shell as shown in the graphic above.Neither D nor E are possible with the chemical structures of sulfur and hydrogen.
The reactivity of an atom arises from:

A. The average distance of the outermost electron shell from the nucleus
B. The existence of unpaired electrons in the valence shell.
C. The sum of the potential energies of all the electron she
B. The existence of unpaired electrons in the valence shell.
Which of these statements is true of all anionic atoms?

A. The atom has more electrons than protons.
B. The atom has more protons than electrons.
C. The atom has fewer protons than does a neutral atom of the same element.
D. The
A is the correct answer. With a transfer of an electron or electrons, the anion has more electrons than protons in the nucleus and now has a net negative charge.
What coefficients must be placed in the blanks to balance this chemical reaction?

C6H12O6 ® ____C2H6O + ____CO2

A. 1, 2
B. 2,2
C. 1,3
D. 1,1
E. 3,1
B. 2,2
Which of the following statements correctly describes any chemical reaction that has reached equilibrium?

A. The concentration of products equals the concentration of reactants.
B. The rate of the forward reaction equals the rate of the r
B is correct. This is the definition of chemical equilibrium.
The main thesis of Lawrence HendersonÂ’s The Fitness of the Environment is:

A. EarthÂ’s environment is constant.
B. It is the physical environment, not life, that has evolved.
C. The environment of Earth has adapted to life.
D is correct. To quote Henderson, “For life to exist at all in a particular location, the environment must first be a suitable abode.” Life depends on certain environmental conditions on Earth. Water is abundant in all three of its forms. The temperature of the planet occurs in a range that is compatible with life and water is the reason this is true. Simply stated, life on Earth is water-based. Cells in living organisms are between 65-90% water and living organisms cannot
survive without a source of water.
Air temperature often increases slightly as clouds begin to drop rain or snow.

which behavior of water is most directly responsible for this phenomenon?

A. The change in the density of water when water condenses.

B. The
C is the correct answer. When water changes from the gaseous to the liquid and from

liquid to solid state (vapor to rain; rain to snow), hydrogen bonds are forming. When

hydrogen bonds form, heat is released to the atmosphere.
For two bodies of matter in contact, heat always flows from:

A. The body with greater heat to the one with less heat

B. The body of higher temperature to the one of lower temperature

C. The more dense body to the less den
B is correct. Heat always flows from the body of higher temperature to the one of

lower temperature until both are approximately the same temperature. The

cooler body of matter increases in temperature (molecules speed up) at the

expense of the kinetic energy of the warmer body of matter. Ice cools your coke

by absorbing heat from the coke. This is why the ice melts. (As hydrogen bonds

break, heat is absorbed!)
A slice of pizza has 500 kcal. If we could burn the pizza and use all the heat to

warm a 50 L container of cold water, what would be the approximate

increase in the temperature? (Note: A liter of cold water weighs about 1
It requires 1cal to raise 1 gm of water 10C in temperature.

The 50 L of water weigh 50 kg. Since 1 kg is = to 1000 gm, the total weight of the water

expressed in grams is 50,000 gm.

Since 1 kcal = 1000 cal, the energy in calories in the pizza is 500,000 cal.

500,000 cal/50,000 gm (1cal/gm/0C) = 100C Answer choice C
The bonds that are broken when water vaporizes are:

A. Ionic bonds

B. Bonds between water molecules

C. Bonds between atoms of individual water molecules

D. Polar covalent bonds

E. Nonpolar covalent b
B is correct. When water changes from the liquid to the gaseous state, enough

hydrogen bonds between individual water molecules are broken so that individual

water molecules can speed up fast enough to escape as water vapor.
6. Which of the following is an example of a hydrophobic material?

A. Paper D. Sugar

B. Table salt E. Pasta

C. Wax
C is correct. Wax is a substance classified as a lipid and put into the same

general category of lipids as fats and oils. There are no polar regions on

this molecule to interact with water molecules. Therefore it is insoluble in

water or “hydrophobic”.
We can be sure that a mole of table sugar and a mole of vitamin C are equal in their:

A. Weight in Daltons

B. Weight in grams

C. Number of molecules

D. Number of atoms

E. Volume
C is correct. A mole of any substance always contains 6.02 x 1023 molecules.
How many grams of acetic acid (C2H4O2) would you use to make 10L of a 0.1 M

aqueous solution of acetic acid? (Note the atomic weights in daltons are

approximately 12 for carbon, 1 for hydrogen and 16 for oxygen)

A. 10g
D. 60g

Molecular weight of acetic acid in grams (1 mole): 60 grams

2C x 12 = 24 0.1M = 0.1 moles/liter of acetic acid

4H x 1 = 4 0.lM = (0.1moles/liter) (60 g/mole) = 6g/liter

2O x 16 = 32 To make 10 liters of solution: 10liters x 6g/liter = 60 grams

60 needed
Acid precipitation has lowered the pH of a particular lake to 4.0. What is the

hydrogen ion concentration of the lake?

A. 4.0M C. 10-4 M E. 4%

B. 10-10 M D. 104 M
C is correct. The pH scale goes from 0 – 14. A pH of 7 is neutral. Any value

below 7 is acidic and any value above 7 is basic. The scale is a

logarithmic scale and each step is a 10 fold change. pH is the negative

log to the base 10 of the hydrogen ion concentration. A pH of 4 would be

a hydrogen ion concentration of 10-4.
Organic chemistry is currently defined as:

A. The study of compounds that can be made only by living cells

B. The study of carbon compounds

C. The study of vital forces

D. The study of natural (as opposed to s
By the definition given in class, only one of the above is correct: B – the study of carbon

Which of the following hydrocarbons has a double bond in the carbon skeleton.

A. C3H8
B. C2H6
C. CH4
D. C2H4
E. C2H2
D is correct. With a carbon atom sharing two pairs of electrons with another carbon

atom, each carbon can covalently bond with only two hydrogens.
Which functional group is most responsible for some organic molecules behaving as


A. Hydroxyl D. Amino

B. Carbonyl E. Phosphate

C. Carboxyl
D is correct. The amino group ( –NH2) can act as a base by accepting another

hydrogen ion (--NH3+)
Temperature moderation
Expansion upon freezing
How is water able to moderate the temperature of the planet?
1) High specific heat

2) High heat of vaporization
How do Cells make macromolecules?
1. Hooking one atom to another

- Autotrophs can do this!

2. Assembly from “preformed” subunits

-Heterotrophs and autotrophs do this

-More energy efficient

1. CONDENSATION: (also called

“Dehydration Synthesis”)

Assembly of a polymer –Anabolism!!

As each two monomers are joined together to form

the polymer chain, a molecule of water is removed.

2. HYDROLYSIS: (hydro-“water”

lysis-“break apart”)

Disassembly of large polymers back into monomers

(reverse of condensation!)




-CARBONYL group is located on

the terminal carbon in the chain


-CARBONYL group is located on a

carbon that is not on the end of the chain

Look at the sugars: they are all

6 carbon sugars with the chemical

formula: C6H12O6

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