Biology 101

Cells are ____

characteristic of prokaryotic and eukaryotic organisms

In comparison to eukaryotes, prokaryotes

are smaller

A localized group of organisms that belong to the same species is called a

population

When a person gets dehydrated while exercising on a hot day, their pituitary gland releases ADH, a hormone that signals the kidneys to retain more water. This is an example of:

Negative feedback regulation

Which of these provides evidence of the common ancestry of all life?

near universality of the genetic code

You find yourself standing next to a beautiful rose bush. Which of the following do you and the rose have in common?

You both are multicellular.

Charles Darwin proposed a mechanism for descent with modification that stated that organisms of a particular species are adapted to their environment when they posses____.

heritable traits that enhance their survival and reproductive success in the local environment

How does a scientific theory differ from a scientific hypothesis?

Theories are usually an explanation for a more general phenomenon; hypotheses typically address more specific issues.

A friend of yours calls to say that his car would not start this morning. He asks for your help. You say that you think the battery must be dead. If so, then jump-starting the car from a good battery will solve the problem. In doing so, you are ____.

stating a hypothesis and using that hypothesis to make a testable prediction

The best experimental design ____.

includes a large sample size and a control, and alters only one condition between the controls and the experimental condition

In the process of science, which of these is tested?

a hypothesis

A controlled experiment

includes at least two groups, one of which does not receive the experimental treatment

About twenty-five of the ninety-two natural elements are known to be essential to life. Which four of these twenty-five elements make up approximately 96 percent of living matter?

carbon, hydrogen, nitrogen, oxygen

Trace elements are those required by an organism in only minute quantities. Which of the following is a trace element that is required by humans and other vertebrates, but not by other organisms such as bacteria or plants?

iodine

Knowing the atomic mass of an element allows inferences about which of the following?

the number of protons plus neutrons in the element

From its atomic number of 15, it is possible to predict that the phosphorus atom has

15 protons and 15 electrons`

Fluorine has an atomic number of 9. Which of the following would you do to a neutral fluorine atom to complete its valence shell?

add 1 electron

How many electrons will a single atom of sulfur with no charge and no bonds have in its valence shell (see the figure above)?

6

Oxygen has an atomic number of 8 and most commonly, a mass number of 16. Thus, what is the atomic mass of an oxygen atom?

approximately 16 daltons

A covalent chemical bond is one in which

outer-shell electrons of two atoms are shared so as to satisfactorily fill their respective orbitals

What results from an unequal sharing of electrons between atoms?

a polar covalent bond

What is the difference between covalent bonds and ionic bonds?

Covalent bonds involve the sharing of electrons between atoms; ionic bonds involve the electrical attraction between charged atoms.

Water molecules are attracted to one another by

hydrogen bonds

What results from the chemical reaction illustrated above? The reactants have no charge.

a cation with a net charge of +1 and an anion with a net charge of -1

When are atoms most stable?

when all of the electron orbitals in the valence shell are filled

In a single molecule of water, two hydrogen atoms are bonded to a single oxygen atom by

polar covalent bonds

Water molecules can form hydrogen bonds with

compounds that have polar covalent bonds

Which of the following is a property of liquid water? Liquid water

has a heat of vaporization that is higher than that for most other substances

The cities of Portland, Oregon, and Minneapolis, Minnesota, are at about the same latitude, but Minneapolis has much hotter summers and much colder winters than Portland. Why?

The ocean near Portland moderates the temperature.

Water has many exceptional and useful properties. Which is the rarest property among compounds?

Solid water is less dense than liquid water.

Which of the following effects can occur because of the high surface tension of water?

A raft spider can walk across the surface of a small pond

A dietary Calorie equals 1 kilocalorie. Which of the following statements correctly defines 1 kilocalorie? One kilocalorie equals

1000 calories, or the amount of heat required to raise the temperature of 1 kg of water by 1°C

Why does ice float in liquid water?

Stable hydrogen bonds keep water molecules of ice farther apart than water molecules of liquid water.

Rank, from low to high, the pH of blood, stomach acid, and urine.

stomach acid, urine, blood

Which of the following solutions would require the addition of the greatest amount of base to bring the solution to neutral pH?

gastric juice at pH 2

Increased atmospheric COz concentrations might have what effect on seawater?

Seawater will become more acidic, and carbonate concentrations will decrease.

The element present in all organic molecules is

carbon

Stanley Miller's 1953 experiments supported the hypothesis that

organic molecules can be synthesized abiotically under conditions that may have existed on early Earth

How many electron pairs does carbon share to complete its valence shell?

4

A carbon atom is most likely to form what kind of bond(s) with other atoms?

covalent

Thalidomide and L-dopa, shown below, are examples of pharmaceutical drugs that occur as enantiomers, or molecules that

are mirror images of one another

The complexity and variety of organic molecules is due to

the chemical versatility of carbon atoms

Differences among organisms are caused by differences in the

types and relative amounts of organic molecules synthesized by each organism

When Stanley Miller applied heat and electrical sparks to a mixture of simple inorganic compounds such as methane, hydrogen gas, ammonia, and water vapor, what compounds were produced?

simple organic compounds, amino acids, and hydrocarbons

Which of the following is true of carbon?

It can form both polar and nonpolar bonds.

Why is carbon so important in biology?

It can form a variety of carbon skeletons and host functional groups.

Research indicates that ibuprofen, a drug used to relieve inflammation and pain, is a mixture of two enantiomers; that is, molecules that

are mirror images of each other

The two molecules shown in the figure below are best described as

cis-trans isomers

Which of the functional groups below acts most like an acid in water?

carboxyl

Which functional group shown above is characteristic of alcohols?

-OH

Which of these classes of biological molecules does NOT include polymers?

lipids.

Which of the following is NOT a polymer?

glucose

Which of the following best summarizes the relationship between dehydration reactions and hydrolysis?

Dehydration reactions assemble polymers; hydrolysis reactions break polymers apart.

What does the term insoluble fiber refer to on food packages?

Cellulose

Lactose, a sugar in milk, is composed of one glucose molecule joined by a glycosidic linkage to one galactose molecule. How is lactose classified?

as a disaccharide

How do phospholipids interact with water molecules?

1. The polar heads interact with water; the nopolar tails

Which of the following is the best explanation for why vegetable oil is a liquid at room temperature while animal fats are solid?

Vegetable oil has more double bonds than animal fats.

The molecule shown below is a

steroid

Which of the following is the stroegest evidence that protein structure and function are coralated?

Denatured (unfolded) proteins do not function normally

Which level of protein structure do the a helix and the b-pleated sheet represent?

Secondary

Misfolding of polypeptides is a serious problem in cells. Which of the following diseases are
associated with an accumulation of misiolded polypeptides?

Alzheimer's and Parkinson's only

Nucleic acids are polymers made up of which of the following monomers?

Nucleotides

One of the primary functions of RNA molecules is to

function in the synthesis of proteins

Which of the following descriptions best fits the class of molecules known as nucleotides?

A nitrogenous base, a phosphate group, and a sugar

If one strand of a DNA molecule has the sequence of bases ATTGCA, the other complementary strand would have the sequence

TAACGT

A new organism is discovered in the forests of Costa Rica. Scientists there determine that the polypeptide sequence of hemoglobin from the new organism has 72 amino acid differences from humans, 65 differences from a gibbon, 49 differences from a rat, and 5 differences from a frog.
These data suggest that the new organism is more closely related to

frogs than to humans,

Which of the following is a major difference between prokaryotic cells and eukaryotic cells?

Eukaryotic cells have more intracellular organelles than prokaryotes.

Which structure is common to plant and animal cells?

mitochondrion

In a bacterium, we will find DNA in

the nucleoid

Which of the following macromolecules leaves the nucleus of a eukaryotic cell through pores in the nuclear membrane?

mRNA

Large numbers of ribosomes are present in cells that specialize in producing which of the following molecules?

proteins

A cell with a predominance of free ribosomes is most likely

primarily producing proteins in the cytosol

A cell with an extensive area of smooth endoplasmic reticulum is specialized to

synthesize large quantities of lipids

Which structure is the site of the synthesis of proteins that may be exported from the cell?

rough ER

Which organelle is the primary site of ATP synthesis in eukaryotic cells?

mitochondrion

In a plant cell, DNA may be found

in the nucleus, mitochondria, and chloroplasts

Where are proteins produced other than on ribosomes free in the cytosol or ribosomes attached to the ER?

in mitochondria

Suppose a young boy is always tired and fatigued, suffering from a metabolic disease. Which of the following organelles is most likely involved in this disease?

mitochondria

Which of the following contain the 9 + 2 arrangement of microtubules, consisting of nine doublets of microtubules surrounding a pair of single microtubules?

flagella and motile cilia

Spherocytosis is a human blood disorder associated with a defective cytoskeletal protein in the red blood cells (RBCs). What do you suspect is the consequence of such a defect?

abnormally shaped RBCs

Plasmodesmata in plant cells are most similar in function to which of the following structures in animal cells?

gap junctions

Ions can travel directly from the cytoplasm of one animal cell to the cytoplasm of an adjacent cell through

gap junctions

In plant cells, the middle lamella

allows adjacent cells to adhere to one another

According to the fluid mosaic model of cell membranes, phospholipids

can move laterally along the plane of the membrane

An animal cell lacking oligosaccharides on the external surface of its plasma membrane would likely be impaired in which function?

cell-cell recognition

What kinds of molecules pass through a cell membrane most easily?

small and hydrophobic

Which of the following most accurately describes selective permeability?

Only certain molecules can cross a cell membrane.

Which of the following allows water to move much faster across cell membranes?

aquaporins

Diffusion ___

is a passive process in which molecules move from a region of higher concentration to a region of lower concentration

Which of the following processes includes all others?

passive transport

Which of the following is true of osmosis?

In osmosis, water moves across a membrane from areas of lower solute concentration to areas of higher solute concentration.

A patient was involved in a serious accident and lost a large quantity of blood. In an attempt to replenish body fluids, distilled water —equal to the volume of blood lost —is added to the blood directly via one of his veins. What will be the most probable result of this transfusion?

The patient's red blood cells will swell and possibly burst because the blood has become hypotonic compared to the cells.

What will happen to a red blood cell (RBC), which has an internal ion concentration of about 0.9 percent, if it is placed into a beaker of pure water?

The cell would swell because the water in the beaker is hypotonic relative to the cytoplasm of the RBC.

When a plant cell, such as one from a rose stem, is submerged in a very hypotonic solution, what is likely to occur?

The cell will become turgia.

A sodium-potassium pump ___

move three sodium ions out of a cell and two potassium ions into a cell while consuming an ATP for each cycle

Which of the following membrane activities requires energy from ATP?

movement of Na+ions from a lower concentration in a mammalian cell to a higher concentration in the extracellular fluid

White blood cells engulf bacteria using.

phagocytosis

The difference between pinocytosis and receptor-mediated endocytosis is that

pinocytosis is nonselective in the molecules it brings into the cell, whereas receptor-mediated endocytosis offers more selectivity.

In receptor-mediated endocytosis, receptor molecules initially project to the outside of the cell. Where do they end up after endocytosis?

on the inside surface of the vesicle

A bacterium engulfed by a white blood cell through phagocytosis will be digested by enzymes contained in _

lysosomes