AP Bio Ch. 1-5 Review questions

Iron, (Fe), is a trace element required for the proper functioning of hemoglobin, the molecule that carries oxygen in red blood cells. What might be the effects of an iron deficiency?

A person with an iron deficiency will probably show effects of low oxygen in the blood, such as fatigue.

Acetic acid, (CH3 COOH), can be a buffer, similar to carbonic acid. Write the dissociation reaction, identifying the acid, base, H+ acceptor, and H+ donor.

CH3 COOH -->CH3 COO- + H+ CH3 COOH is the acid (the H+ donor) CH3 COO- is the base (the H+ acceptor)

Draw a structural formula for C2 H4

H-C=C-H H H

Why are human sex hormones considered lipids?

Human sex hormones are steroids, a type of hydrophobic compound.

If a genetic mutation changes primary structure, how might it destroy the protein's function?

Primary structure, the amino acid sequence, affects the secondary structure, which affects the tertiary structure, which affects the quaternary structure (if any). in short, the amino acid sequence affects the shape of the protein. Because the function of a protein depends on its shape, a change in primary structure can destroy a protein's function.

Many mammals control their body temperature by sweating. Which property of water is most directly responsible for the ability of sweat to lower body temeperature?

The absorption of heat by the breaking of hydrogen bonds.

Which of the following statements concerning unsaturated fats is true?

They have double bonds in the carbon chains of their fatty acids.

The radioactivity of an atom arises from

the existence of unpaired electrons in the valence shell

Organic chemistry is currently defined as

the study of carbon compounds

Which of the following is a hydrophobic material?

wax

Some scientists believe that life elsewhere in the universe might be based ont eh element silicon, rather than on carbon, as on Earth. Look at the electron distribution diagram for silicon and draw the Lewis dot structure for silicon. What properties does silicon share with carbon that would make silicon-based life more likely than say, neon-based life or aluminum-based life?

˚ ˚S˚ ˚ Si has four valence electrons, the same number as carbon. Therefore, silicon would be able to form long chains, including branches, that could act as skeletons for organic molecules. It would clearly do this much better than neon (with no valence electrons) or aluminum (with three valence electrons).

What are the four main classes of large biological molecules?

-Proteins -Carbohydrates -Lipids -Nucleic Acids

How can the freezing of water crack boulders?

As water freezes, it expands because water molecules move farther apart in forming ice crystals. When there is water in a crevice of a boulder, expansion due to freezing may crack the rock.

Which of the following pairs of base sequences could form a short stretch of a normal double helix of DNA?

5'-ATGC-3' with 5'-GCAT-3'

What defines a chemical reaction at equilibrium?

At equilibrium, the forwards and reverse reactions occur at the same rate.

What is the smallest double-bonded molecule C can make?

C2 H4

What does the term amino acid signify about the structure of such a molecule?

It has both an amino group (-NH2), which makes it an amine, and a carboxyl group (-COOH), which makes it a carboxylic acid.

Why does a denatured protein no longer function normally?

The function of a protein is a consequence of its specific shape, which is lost when a protein becomes denatured.

Which action could produce a carbonyl group?

The replacement of the -OH of a carboxyl group with hydrogen

Is a trace element an essential element? Explain.

Yes, because an organism requires trace elements, even though only in small amounts.

Which chemical group is most likely to be responsible for an organic molecule behaving as a base?

amino

The enzyme amylase can break glycosidic linkages between glucose monomers only if the monomers are the a form. Which of the following could amylase break down?

glycogen, starch, and amylopectin

Identify the asymmetric carbon in this molecule O OH H H H C--C--C--C--C--H H H H H H

o oh h h h c--C--c--c--c--h h h h h h

Compared with P-31, the radioactive isotope P-32 has ________

one more neutron

The structural level of a protein least affected by a disruption in hydrogen

primary level

A Lithium atom has 3 protons and 4 neutrons. What is its atomic mass in daltons?

7

Write the formula for a monosaccharide that has three carbons

C3 H6 O3

The atomic number of sulfur is 16. Sulfur combines with hydrogen by covalent bonding to form a compound, hydrogen sulfide. Based on the number of valence electrons in a sulfur atom, predict the molecular formula of the compound.

H2S

Construct a table that organized the following terms, and label the columns and rows.

Monomers or Polymer or Type of Components Larger Linkage Molecule Sugars Monosacch. Polysacch. Glycosidic Links Lipids Fatty Acids Triacylglycerols Ester Proteins Amino Acids Polypeptides Peptide Bonds Nucleic Nucleotides Polynucleotides Phosphodiester Acids

Explain what holds together the atoms in a crystal or magnesium chloride (MgCl2).

The attractions between oppositely charged ions forms ionic bonds.

Why is it unlikely that two neighboring water molecules would be arranged like this? O=HH=O HH (The oxygens are each attached to two hydrogens)

The hydrogen atoms of one molecule, with their partial positive charges, would repel the hydrogen atoms of the adjacent molecules.

Enzymes that break down DNA catalyze the hydrolysis of the covalent bonds that join nucleotides together. What would happen to DNA molecules treated with these enzymes?

The phosphodiester linkages between deoxyribose sugars would be broken.

What would be the effects on the properties of the water molecule if oxygen and hydrogen had equal electronegativity?

Water molecules would not be polar, and they would not form hydrogen bonds with each other.

How are gasoline and fat chemically similar?

Both consist largely of hydrocarbon chains.

Describe how properties of water contribute to the upward movement of water in a tree.

Hydrogen bonds hold neghboringi water molecules together. This cohesion helps the water molecules resist gravity. Adhesion between water molecules and the walls of water-conducting cells also counters gravity. As water evaporates form leaves, the chain of water molecules in water-conducting cells moves upward.

Can propane (C3 H8) form isomers?

No. There is not enough diversity in the atoms. It can't form structural isomers because there is only one way for three carbons to attach to each other (in a line). There are no double bonds, so geometric isomers are not possible. Each carbon has at least two hydrogens attached to it so the molecule is symmetrical and cannot have enantiometric isomers.

HCl is a strong acid that dissociates in water. HCl-->H+ + Cl- What is the pH of 0.01 M HCl?

[H+] = 0.01 M = 10^-2, so pH = 2

Choose the term that correctly describes the relationship between these two sugar molecules. OH O OH H-C-C-C-H H H and O OH OH C-C-C-H H H H

structural isomers

What is the hydroxide ion concentration of the lake described in the question above?

10^-10 M

Measurements show that the pH of a particular lake is 4.0. What is the hydrogen ion concentration of the lake?

10^-4 M

Compared with a basic solution at pH 9, the same volume of an acidic solution at pH 4 has ___ times as many hydrogen ions (H+).

10^5, or 100,000

A slice of pizza has 500 kcal. If we could burn the pizza and use all the hear to warm a 50-L container of cold water, what would be the appropriate increase in the temperature of the water? (Note: a liter of cold water weights about 1 kg)

10˚C

A nitrogen atom has 7 protons, and the most common isotope of nitrogen has 7 neutrons. A radioactive isotope of nitrogen has 8 neutrons. Write the atomic number and mass number of this radioactive nitrogen as a chemical symbol with a subscript and superscript.

15N 7

What coefficients must be placed in the following blanks so that all atoms are accounted for in the products? C6 H12 O6 --> ___ C2 H6 O + ____ CO2

2;2

In a DNA double helix, a region along one DNA strand has this sequence of nitrogenous bases: 5'-TAGGCCT-3'. Write down this strand and its complementary strand, clearly indicating the 5' and 3' ends of the complementary strand.

5'-TAGGCCT-3' 3'-ATCCGGA-5'

How many grams of acetic acid (C2 H4 O2) would you use to make 10 L of a 0.1 M aqueous solution of acetic acid? (Note: the atomic masses in daltons are approximately 12 for carbon, 1 for hydrogen, and 16 for oxygen.)

60.0 grams

Atoms can be represented by simply listing the number of protons, neutrons, and electrons - for example, 2p+; 2n0 (neutron); 2e- for helium. What are the numbers of protons, electrons, protons and neutrons in the O-18 isotope of oxygen?

8p+ 10n0 8e-

How many electrons does flourine have? How many electron shells? Name the orbitals that are occupied. How many electrons are needed to fill the valence shell?

9 electrons 2 electron shells 1s, 2s, 2p (3 orbitals) 1 electron needed to fill the valence shell

Suppose you had an inorganic molecule such as glycine and you chemically remove the -NH2 group and replaced it with -COOH. Draw the structural formula for this molecule and speculate about its chemical properties.

A chemical group that can act as a base has been replaced with a group that can act as an acid, increasing the acidic properties of the molecule. The shape of the molecule would also change, likely changing the molecules with which it can interact.

What conclusion did Stanley Miller draw when he formed amino acids int eh products of his experiments?

Amino acids are essential molecules for living organisms. Their synthesis from gases of the primitive atmosphere on Earth demonstrated that life's molecules could initially have been synthesized from nonliving molecules.

Compare the structure of a fat (triglyceride) with that of a phospholipid.

Both have a glycerol molecule attached to fatty acids. The glycerol of a fat has three fatty acids attached, where as glycerol of a phospholipid is attached to two fatty acids and one phosphate group.

A dehydration reaction joins two glucose molecules to form maltose. The formula for glucose is C6 H12 O6. What is the formula for maltose?

C12 H24 O11

Write an equation that uses the products of photosynthesis as reactants and that uses the reactants as products. Add energy as another product. This new equation describes a process that occurs in your cells. Describe this equation in words. How does this equation relate to breathing?

C6 H12 O6 + 6O2 --> 6CO2 + 6 H2O + Energy. Glucose and oxygen react to form carbon dioxide, water, and energy. We breathe in oxygen because we need it for this reaction to occur, and we breathe out carbon dioxide because it is a by-product of this reaction.

The molecular formula for glucose is C6 H12 O6. What would be the molecular formula for a polymer made by linking ten glucose molecules together by dehydration reactions?

C60 H102 O51

Why does the following structure fail to make sense chemically? H-C=C-H

Each carbon atom has only 3 covalent bonds instead of the required 4

What is electronegativity, and how does it affect interactions between water molecules?

Electronegativity is the attraction of an atom for the electron of a covalent bond. Because oxygen is more electronegative than hydrogen, the oxygen atom in H2O pulls electrons towards itself, resulting in a partial negative charge on the oxygen atom and a partial positive charge on the hydrogen atoms. Oppositely charged ends of water molecules are attracted to each other, forming a hydrogen bond.

Explain the saying, it's not the heat, it's the humidity.

High humidity hampers cooling by suppressing the evaporation of sweat.

If you were a pharmaceutical researcher, why would you want to learn the three dimensional shapes of naturally occurring signaling molecules?

If researchers can synthesize molecules that mimic these shapes, they may be able to treat diseases or conditions caused by the inability of affected individuals to synthesize such molecules.

How many molecules of water are needed to completely hydrolyze a polymer that is ten monomers long?

Nine, with one water required to hydrolyze each connected pair of monomers.

What parts of a polypeptide chain participate in the bonds that hold together secondary structure? What parts participate in tertiary structure?

Secondary structure involves hydrogen bonds between atoms of the polypeptide backbone. Tertiary structure involves bonding between atoms of the R groups of the amino acid subunits.

Explain how table salt has emergent properties.

Table salt is made up of sodium and chlorine. We are able to eat the compound, showing that it has different properties from those of a metal and a poisonous gas.

What chemical change occurs when ATP reacts with water and releases energy?

The ATP molecule loses a phosphate, becoming ADP.

What would happen if a cow were given antibiotics that killed all the prokaryotes in its stomach?

The absence of these prokaryotes would hamper the cow's ability to obtain energy from food and could lead to weight loss and possible death.

Suppose you eat a serving of green beans. What reactions must occur for the amino acid monomers in the protein of the beans to be converted to proteins in your body?

The amino acids in the green beans' proteins are released in hydrolysis reactions and incorporated into other proteins in dehydration reactions.

Which statement is true of all atoms that are anion?

The atoms has more electrons than protons, and has a negative charge.

In the term TRACE element, the modifier TRACE means

The element is required in very small amounts

If two or more elements are in the same row (of the periodic table), what do they have in common? If two or more elements are in the same column, what do they have in common?

The elements in a row all have the same number of electron shells. In a column, all the elements have the same number of electrons in their valence shells.

A water strider's legs are coated with a hydrophobic substance. What might be the benefit? What would happen if the substance were hydrophilic?

The hydrophobic substance repels water, perhaps helping to keep the ends of the legs from becoming coated with water and breaking through the surface. If the legs were coated with a hyrophilic substance, water would be drawn up them, possibly making it more difficult for the water strider to walk on water.

If you were a pharmacist, how would you make a 0.5 molar solution of sodium chloride (NaCl)? (The atomic mass of Na is 23 daltons and that of Cl is 35.5 daltons.)

The molecular mass of NaCl is 58.5 daltons. A mole would have a mass of 58.5 grams, so you would measure out 0.5 moles, or 29.3 grams, of NaCl and gradually add water, stirring until it is dissolved. You would add water to bring the final volume to 1 liter.

Suppose a membrane surrounded an oil droplet, as it does in the cells of plant seeds. Describe and explain the form it might take.

The oil droplet membrane could consist of a single layer of phospholipids rather than a bilayer, because an arrangement in which the hydrophobic tails of the membrane phospholipids were in contact with the hydrocarbon regions of the oil molecules would be more stable.

Given a liter of pure water and a liter solution of acetic acid, what would happen to the pH if you added 0.01 mol of a strong acid to each? Use the reaction equation to explain the result.

The pH of the water should go from 7 to about 2; the pH of the acetic acid solution will only decrease a small amount, because the reaction shown in the question above will shift to the left, with CH3 COO- accepting the influx of H+ and becoming CH3 COOH.

Which of the following statements correctly describes any chemical reaction that has reached equilibrium?

The rates of the forward and reverse reactions are equal

When Miller tried the experiment without the electrical discharge, no organic compounds were found. What might explain this result?

The spark provides energy needed for the inorganic molecules in the atmosphere to react with each other.

a) Suppose a substitution occurred in one DNA strand of the double helix, resulting in 5'-TAAGCCT-3' 3'-ATCCGGA-5' Draw the two strands; circle and label the mismatched bases. b) If the modified top strand is replicated, what would its matching strand be?

a) 5'-taAgcct-3' 3'-atCcgga-5' b) 3'-ATTCGGA-5'

Which term includes all others in the list? a) monosaccharide b) disaccharide c) starch d) carbohydrate e) polysaccharide

d) carbohydrate

The bonds that are broken when water vaporizes are

hydrogen bonds between water molecules

We can be sure that a mole of table sugar and a mole of vitamin C are equal in their

number of molecules

Which functional group is not present inthis molecule? OH O--H--C--H H C -----C-------N HO H H

sulfhydryl