Biology 113 Exam 1 (Chapters 1-3)

Excited about the fungus chemical's promise for treating cancer, you write up your experimental results and send the paper to a prestigious scientific journal, hoping it will be published. The journal sends your paper out to several scientists for evaluation--a process known as peer review. The reviewers identify several issues with the experimental design and data presented in your paper. Which of the following criticisms are valid issues of concern that peer reviewers might identify?

- The effect may not be real because we don't know if the results are reproducible. - The treatment kills cancer cells, but it might simply be a poison that kills all cells—even normal cells. - Cell samples were taken from too few patients.

Which of the following is a carboxyl group?

-COOH

Which of the following is an amino group?

-NH2

Fluorine's atomic number is 9 and its atomic mass is 19. How many neutrons does fluorine have?

10

Compared to a solution of pH 3, a solution of pH 1 is

100 times more acidic.

Grapefruit juice is approximately pH 3, and tomato juice is approximately pH 4. A glass of grapefruit juice contains _____ H+ as a glass of tomato juice.

10X as much

What is the atomic mass of an atom that has 6 protons, 6 neutrons, and 6 electrons?

12

How many different kinds of amino acids are there in most proteins?

20

This atom can form up to _____ single covalent bond(s). There is an atom with 2 electron shells. The inner electron shell contains a pair of electrons. The outer electron shell contains 4 electrons.

4

An uncharged atom of boron has an atomic number of 5 and an atomic mass of 11. How many electrons does boron have?

5

An uncharged atom of boron has an atomic number of 5 and an atomic mass of 11. How many protons does boron have?

5

What is the atomic number of an atom that has 6 protons, 6 neutrons, and 6 electrons?

6

How are cohesion and surface tension related to the chemical properties of water?

All are properties related to hydrogen bonding.

Kingdom ___________ consists of multicellular eukaryotes that obtain their food by ingesting (eating) other organisms.

Animalia

Part complete The four most common elements in living organisms are

C, H, O, N.

Select the hydrocarbon from the following choices.

C3H8

All organisms with eukaryotic cells are grouped in domain __________.

Eukarya

Kingdom _________ includes eukaryotic organisms that mostly decompose organic wastes and absorb nutrients into their cells.

Fungi

Part complete What is the fundamental difference between covalent and ionic bonding?

In a covalent bond, the partners share a pair of electrons; in an ionic bond, one partner accepts electrons from the other.

Generally, animals cannot digest the linkages between the glucose molecules in cellulose. How then do cows get enough nutrients from eating grass?

Microorganisms in their digestive tracts hydrolyze the cellulose to glucose.

_______________ are a major component of cell membranes. They form a bilayer with their hydrophobic tails mingling together and their hydrophilic heads facing the watery environment on both sides of the membrane.

Phospholipids

Kingdom __________ consists of multicellular eukaryotes that produce their food by photosynthesis.

Plantae

____________ are a diverse collection of mostly single-celled eukaryotes, which are sorted into several kingdoms to reflect their evolutionary relationships.

Protists

What structural difference accounts for the functional differences between starch and cellulose?

Starch and cellulose differ in the glycosidic linkages between their glucose monomers.

Imagine that you are a scientist hard at work in a cancer research lab. You and many of your colleagues are hoping to discover new powerful drugs that could prevent deaths from cancer. Your research team has observed that cancer cells have a lower survival rate when exposed to samples of a certain species of fungus. To study this further, your team isolated several chemicals from the fungus, including one known to affect cell metabolism. You hypothesize that it is that chemical that lowers the survival rate of cancer cells.

Statement(s) supported by the data - Cancer cells treated with the chemical have a lower survival rate than cells that are not treated. - .After 5 days of chemical treatment, less than 50% of the cancer cells are alive. Statement(s) NOT supported by the data - Cancer cells treated with the chemical have a higher survival rate than cells that are not treated. - After 10 days without chemical treatment, more than 90% of the cancer cells are alive. - This chemical will be useful for treating colon cancer, but not necessarily for other types of cancers. - This chemical will be useful for treating all types of cancers.

__________ are lipids with a structure consisting of four fused rings. Many sex hormones are made from this type of lipid.

Steroids

Why isn't this insect drowning? There is a photo of a pond skater floating on the surface of the water.

Surface tension.

Household ammonia has a pH of 12; household bleach has a pH of 13. Which of the following statements about these substances is true?

The ammonia has 10 times as many H+ ions as the bleach.

The pH of human blood is maintained at around pH 7.4. Why does a buffer system need to be present in blood to protect against changes in pH due to increases in acids?

The metabolic processes of the body produce more acids than bases.

How does the pH of the solution on the right compare with that of the solution on the left? There are 2 pictures of ions and molecules forming water solution. In the right picture, the negatively charged ions of 2 different bound atoms are prevailing. In the left picture, positively charged single atoms are prevailing.

The solution on the right is basic relative to the solution on the left.

The hydrogen bonds in liquid water are less stable than in ice. Why?

There is less movement of molecules in colder conditions.

Which of these refers to atoms with the same atomic number but different atomic masses?

These atoms are isotopes.

Which of the following describes a covalent bond?

Two or more atoms share electron pairs.

____________ have one or more double bonds in their hydrocarbon chains and are usually found in vegetable oils.

Unsaturated fatty acids

You've made a hot drink by dissolving a teaspoon of instant coffee and a teaspoon of sugar in a cup of hot water. Which of the following statements is true?

You've just prepared an aqueous solution.

All cells have _____.

a cell membrane

In a hydrolysis reaction, __________. In this process, water is __________.

a polymer breaks up to form monomers ... consumed

Proteins are an important class of molecules because of the functions they perform. Proteins can _____.

act as signal receptors to receive signals in cell communication

Manufacturers make vegetable oils solid or semisolid by _____.

adding hydrogens

Human proteins, such as insulin, can be produced by bacterial cells. This is possible because _____.

all organisms share a common genetic code

Protein polymers are made up of ___________ monomers.

amino acid

An ionic bond involves _____.

an attraction between ions of opposite charge

Most of the prokaryotes known as __________ live in extreme environments, such as salty lakes.

archaea

Atoms with the same number of protons but with different electrical charges _____.

are different ions

Lipids differ from other large biological molecules in that they _____.

are not truly polymers

___________ are the most diverse and widespread prokaryotes.

bacteria

How do isotopes of an element differ?

by atomic mass number

A fatty acid consists of a _______ and a long hydrocarbon chain.

carboxyl group

At which level of interaction does life first appear?

cell

Plant cell walls consist mainly of _____.

cellulose

The equation shows a _________ --the breaking and forming of chemical bonds that leads to a change in the composition of matter.

chemical reaction

What type of bond is joining the two hydrogen atoms? There are 2 hydrogen atoms with a pair of electrons shared between these 2 atoms.

covalent

What is another name for a condensation reaction?

dehydration

The reaction that joins two monomers to form a polymer is known as a _____ reaction. The molecule of water formed is due to the interaction between _____ and a hydrogen ion.

dehydration ... a hydroxyl group

A DNA nucleotide is composed of a __________.

deoxyribose sugar, which is bonded to a phosphate group and a nitrogenous base

You work for a company that manufactures food products. A new "wonder food" is being distributed by a rival company. The researchers in your company determine that the "wonder food" contains only carbon, oxygen, and hydrogen. At this point, your researchers can say with certainty that the food

does not include proteins or nucleic acids.

Organisms with prokaryotic cells are separated into two ________, Bacteria and Archaea.

domains

A(n) _____ bond joins these two oxygen atoms. There are 2 oxygen atoms with 2 shared electron pairs. Also, each of the atoms has a pair of electrons in the inner electron shell. In the outer electron shell, each atom has 2 pairs of electrons in addition to those 2 which are shared.

double covalent

The tendency of an atom to pull electrons toward itself is referred to as its _____.

electronegativity

A substance that cannot be broken down into other substances by ordinary chemical procedures is known as a(n) _____.

element

The number of oxygen atoms on the left side of the equation is _______ the number of oxygen atoms on the right side.

equal to

Each water molecule is joined to _____ other water molecules by ____ bonds.

four ... hydrogen

Which of the following organisms contain the polysaccharide chitin?

fungi and insects

A fat molecule is composed of two types of smaller molecules: __________ and fatty acids.

glycerol

Sucrose is formed when glucose is joined to fructose by a(n) __________.

glycosidic linkage

As ice melts,

hydrogen bonds are broken.

What is the arrow pointing to? There are ions and molecules forming water solution. A single atom which is positively charged is highlighted with an arrow.

hydrogen ion

In a neutral solution the concentration of _____.

hydrogen ions is equal to the concentration of hydroxide ions

What is the name of the process during which a bond between two monomers is broken?

hydrolysis

Lipids are diverse compounds that are grouped together because they are ___________.

hydrophobic

The oil and vinegar in your salad dressing remain separate from one another due to the _____ properties of the oil.

hydrophobic

What is the arrow pointing to? There are ions and molecules forming water solution. The structure of 2 different bound atoms, the larger of which is negatively charged and highlighted with an arrow.

hydroxide ion

In salt, what is the nature of the bond between sodium and chlorine?

ionic

Polymers that contain sugars ...

may store hereditary information, may store energy, and may protect cells.

A(n) _____ refers to two or more atoms held together by covalent bonds.

molecule

Your first big biology exam is coming up in a few days, and in order to prepare for late-night study sessions, you buy a box of Yummies, a delicious type of snack cake. After checking out the nutrition facts label on the side of the box, you discover that a single Yummie cake contains 4.5 grams of total fat, 27 grams of carbohydrate, 0 grams of fiber, and 1 gram of protein. After eating a Yummie cake, what molecule do you expect to be most abundant in your digestive system?

monosaccharides

In O2, the type of bond that holds the two oxygen atoms together is a __________________.

nonpolar covalent bond

Nucleic acid polymers are made up of _________ monomers.

nucleotide

A property of life known as energy processing refers to the fact that living things _____.

obtain energy from their environment and use it to power their own activities and chemical reactions

Ionic bonds form when _____.

one atom transfers an electron to another atom

A covalent bond is likely to be polar if _____.

one of the atoms sharing electrons is much more electronegative

The most widely effective solvent for organisms is a material that is _____.

polar

The unequal sharing of electrons within a water molecule makes the water molecule _____.

polar

In this molecule, what type of bond is found between the oxygen and hydrogens? There is a molecule of water. It is shown that in this molecule, the oxygen atom is negatively charged on one side of the molecule and hydrogen atoms are positively charged on the opposite side of the molecule.

polar covalent

In H2O, the type of bond that holds one of the hydrogen atoms to the oxygen atom is a _______________.

polar covalent bond

DNA carries the instructions for building _____, and these instructions are found in informational units called _____.

polypeptides ... genes

In the equation, C6H12O6 is a ________.

product

In the equation, CO2 is a __________.

reactant

In the equation 2 H2 + O2 → 2 H2O, the H2 molecules are ________ and the H2O molecules are ________.

reactants; products

Scientific experimentation is important in that it allows the experimenter to __________.

reject some alternative hypotheses

Part complete A polar covalent bond _____.

results in an unequal sharing of electrons

The hydrocarbon chains of _____________ are not kinked, and thus pack closely together, making animal fats solid at room temperature.

saturated fatty acids

Carbohydrate polymers are made up of ____________ monomers.

simple sugar

A company was testing a new drug they thought would help decrease the risk of transmitting viruses from mother to fetus. In an experiment to test the compound, a worker gave 400 pregnant female rats a small dose of the experimental drug and inoculated each with a type of virus known to cause disease in rats. An additional 400 pregnant rats were given only the virus. Of the rat pups born to the females that received both the virus and the drug, 203 showed symptoms of the disease; of the rat pups born to the females that received only the virus, 207 showed symptoms. From this test, we can best conclude __________.

that the drug seems to have little effect on viral transmission at the dosage given

When you add acid to a solution, _____.

the hydrogen ion concentration increases and lowers the pH

Generally, what determines the number and kinds of chemical bonds an element can make and the chemical reactivity of an element?

the number of electrons in its outer shell

In a group of water molecules, hydrogen bonds form between _____.

the oxygen atom in one molecule and a hydrogen atom in another molecule

Proteins differ from one another because

the sequence of amino acids in the polypeptide chain differs from protein to protein.

The chemical energy used by most organisms for metabolism and growth ultimately comes from __________.

the sun

A single water molecule (H − O − H) is held together by

two polar covalent bonds.