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the process in which CO2 in the atmosphere intercepts and absorbs reflected infrared radiation and reflects it back to Earth is known as

greenhouse effect

when one species was removed from a tidepool, the species richness became significantly reduced. the removed species was probably a

keystone species

which of the following is the major primary producer in a savanna ecosystem?


which of the following is an example of an ecosystem?

zebras, cheetahs, and antelope living on the African savanna

carrying capacity is

the number of animals or people a given area of land or water can support over time

which of the following is a likely graphic outcome of a population of deer introduced to an island with an adequate herbivory and without natural predators, parasites, or disease?

grows at first, then makes a straight vertical line on time

an ecological footprint is a construct that is useful

for a person living in a developed nation to consider to make better choices when using global food and energy resources

which of the following is density-independent factor limiting human population growth?


the greatest cause of the biodiversity crisis that includes all of the others is

overpopulation by humans

how is habitat fragmentation related to biodiversity loss?

populations of organisms in fragments are smaller and, thus, more susceptible to extinction

which of the following is the most direct threat to biodiversity?

overexploitation of species

what is the term for a top predator that contributes to the maintenance of species diversity among its animal prey?

keystone species

extinction is a natural phenomenon. it is estimated that 99% of all species that ever lived are now extinct. why then do we say that we are now in a biodiversity crisis?

the current rate of extinction is high and human activities threaten biodiversity at all levels

which of the following describes carbon dioxide, methan, and water vapor re-reflecting infrared radiation back toward earth?

greenhouse effect

which of the following causes an increase in the intensity of UV radiation reaching the earth?

a depletion of the atmospheric ozone

the high levels of pesticides found in birds of prey is an example of

biological magnification

trophic efficiency is

the percentage of production transferred from one trophic level to the next

which of these ecosystems has the highest net primary productivity per square meter?

open ocean

subtraction of which of the following will convert gross primary productivity into net primary productivity?

the energy used by autotrophs in respiration

which of the following is true of detrivores?

they convert organic materials from all trophic levels to inorganic compounds usable by primary producers

How are matter and energy used in ecosystems?

Matter is cycled through ecosystems; energy is not

Which of the following describes the relationship between ants and acacia trees?


In a tide pool, 15 species of invertebrates were reduced to eight after one species was removed. The species removed was likely a(n)

Keystone species

Dwarf mistletoes are flowering plants that grow on certain forest trees. They obtain nutrients and water from the vascular tissues of the trees. The trees derive no known benefits from the dwarf mistletoes. Which of the following best describes the interactions between dwarf mistletoes and trees?


Use the surviorship curves in Figure 53.1 to answer the following questions. Which curve best describes survivorship in elephants?

Curve A

Use the survivorship curves in Figure 53.1 to answer the following questions. Which curve best describes survivorship in marine mollusks?

Curve E

You are observing a population of lizards when you notice that the number of adults has increased and is higher than previously observed. One explanation for such observation would include

Increased immigration

Trees are not usually found in the tundra biome because of


In which of the following terrestrial biome pairs are both dependent upon periodic burning?

Chaparral and savanna

Probably the most important factor(s) affecting the distribution of biomes is (are)


Where would an ecologist find the most phytoplankton in a lake?

Photic zone

Generalized global air circulation and precipitation patterns are caused by

Rising, warm, moist air masses cool and release precipitation as they rise and then at high altitude, cool and sink back to the surface as dry air masses after moving north or south of the tropics

The main reason polar regions are cooler than the equator is because

Sunlight strikes the poles at a lower angle

Which of the following are important biotic factors that can affect the structure and organization of biological communities?

Predation, competition

Sow bugs become more active in dry areas and less active in humid areas. This is an example of


A chemical produced by an animal that serves as a communication to another animal of the same species is called


Most amphibians and land-dwelling invertebrates

Are ectothermic organisms

Humans can lose, but cannot gain, heat through the process of


Tissues are composed of cells, and tissues functioning together make up


To increase the effectiveness of exchange surfaces in the lungs and in the intestine, evolutionary pressures have

Increased surface area

Which of these is not considered an amniote?


Which of the following is a shared characteristic of all chordates?


Deuterostomes that have an endoskeleton are part of which phylum?


The heartworms that can accumulate with the hearts of dogs and other mammals have a pseudocoelom, an alimentary canal, and an outer covering that is occasionally shed. To which phylum does the heartworm belong?


A terrestrial mollusc without a shell belongs to which class?


A radially symmetrical animal that has two embryonic tissue layers probably belongs to which phylum?


You are trying to identify an organism. It is an animal, but it does not have nerve or muscle tissue. It is neither diploblastic nor triploblastic. It is probably a


In addition to seeds, which of the following characteristics are unique to the seed-producing plants?


Green algae often differ from land plants in that some green algae

Are unicellular

The largest seaweeds belong to which group?

Brown algae

Which of these taxa contains species that produce potent toxins that can cause extensive fish kills, contaminate shellfish, and poison humans?


Cyanobacteria are

Photosynthetic autotrophs

Which of these is the most common compound in the cell walls of gram-positive bacteria?


Members of which kingdom have cell wals and are all heterotrophs?


Which of the following pairs are the best examples of homologous structures?

Bat wing and human hand

Which gas was least abundant in Earth's early atmosphere, prior to 2 billion years ago?

Oxygen (O2)

One species mates at the season when daylight is increasing from 13 hours to 13 hours, 15 minutes; another species mates at the season when daylight is increasing from 14 hours to 14 hours, 15 minutes.


What is generally true of two very closely related species that have diverged from each other quite recently?

They share a common ancestor recently in evolutionary time

Fossil evidence indicates that horses have gradually increased in size over geologic time. Which of the following terms best describes this?

Directional selection

Which of the following statements best summarizes evolution as it is viewed today?

It is the differential survival and reproduction of the most-fit phenotypes

In a Hardy-Weinberg population with two alleles, A and a, that are in equilibrium, the frequency of the allele a is 0.4. What is the percentage of the population that is homozygous for this allele?


Each of the following has a better chance of influencing gene frequencies in small populations than in large populations, but which one most consistently requires a small population as a precondition for its occurrence?

Genetic drift

Which of these is the smallest unit that natural selection can change?

A population's gene frequency

Which statement best describes the evolution of pesticide resistance in a population of insects?

Offspring of insects that are genetically resistant to the pesticide become more abundant as the susceptible insects die off

Natural selection is based on all of the following except

Individuals adapt to their environments and, thereby, evolve

Charles Darwin was the first to propose

A mechanism for evolution that was supported by evidence

Darwin's mechanism of natural selection required long time spans in order to modify species. From whom did Darwin get the concept of Earth's ancient age?

Charles Lyell

What was the prevailing notion prior to the time of Lyell and Darwin?

Earth is 6,000 years old and populations are unchanging

Which enzyme was used to produce the molecule in Figure 20.1?

A restriction enzyme

Why are viruses referred to as obligate parasites?

They cannot reproduce outside of a host cell

What does the operon model attempt to explain?

The coordinated control of gene expression in bacteria

Once transcribed, eukaryotic mRNA typically undergoes substantial alteration that includes

Excision of introns

A particular triplet of bases in the template strand of DNA is 5' AGT 3'. The corresponding codon for the mRNA transcribed is

3' UCA 5'

Which of the following separates the DNA strands during replication?


What is meant by the description "antiparallel" regrarding the strands that make up DNA?

The 5' to 3' direction of one strand runs counter to the 5' to 3' direction of the other strand

Why does the DNA double helix have a uniform diameter?

Purines pair with pyrimidines

Cytosine makes up 38% of the nucleotides in a sample of DNA from an organism. Approximately what percentage of the nucleotides in this sample will be thymine?


What is the mechanism for the production of genetic recombinants?

Crossing over and independent assortment

Males are more often affected by sex-linked traits than females because

Males are hemizygous for the X chromosome

Huntington's disease is a dominant condition with late age of onset in humans. If one parent has the disease, what is the probability that his or her child will have the disease?


A sexually reproducing animal has two unlinked genes, one for head shape (H) and one for tail length (T). Its genotype is HhTt. Which of the following genotypes is possible in a gamete from this organism?


The F1 offspring of Mendel's classic pea cross always looked like one of the two parental varieties because

One allele was completely dominant over another

Chiasmata are what we see under a microscope that let us know which of the following is occuring?

Anaphase II

Which of the following occurs in meiosis but not in mitosis?

Synapsis and allignment of tetrads at metaphase plate

Which of the following is true of a species that has a chromosome number of 2n = 16?

There are 8 homologous pairs

What is a karyotype?

A visual diagram of a person's chromosomes

Cells that are in a nondividing state are in which phase?


The formation of a cell plate is beginning across the middle of a cell and nuclei are re-forming at opposite ends of the cell. What kind of cell is this?

A plant cell undergoing cytokinesis

A cell containing 92 chromatids at metaphase of mitosis would, at its completion, produce two nuclei each containing how many chromosomes?


Which term describes centromeres uncoupling, sister chromatids separating, and the two new chromosomes moving to opposite poles of the cell?


From the perspective of the cell receiving a message, the three stages of cell signaling are

Signal reception, signal transduction, and cellular response

Assume a thylakoid is somehow punctured so that the interior of the thylakoid is no longer separated from the stroma. This damage will have the most direct effect on which of the following processes?

The synthesis of ATP

When oxygen is releaed as a result of photosynthesis, it is a by-product of which of the following?

Splitting the water molecules

In any ecosystem, terrestrial or aquatic, what group(s) is (are) always necessary?

Producers and primary consumers

Which of the following are products of the light reactions of photosynthesis that are utilized in the Calvin cycle?


For each molecule of glucose that is metabolized by glycolysis and the citic acid cycle, what is the total number of NADH + FADH2 molecules produced?


In addition to ATP, what are the end products of glycolysis?

NADH and pyruvate

The oxygen consumed during cellular respiration is involved directly in which process or event?

Accepting electrons at the end of the electron transport chain

When a molecule of NAD+ (nicotinamide adenine dinucleotide) gains a hydrogen atom (not a hydrogen ion) the molecule becomes


When you have a severe fever, what may be a grave consequence if this is not controlled?

Change in the folding of enzymes

Which of the following is true of enzymes?

They accelerate the rate of chemical reactions and many activities in living organisms require multiple enzymes

Why is ATP an important molecule in metabolism?

It provides energy coupling between exergonic and endergonic reactions

White blood cells engulf bacteria through what process?


Ions diffuse across membranes down their

Electrochemical gradients

The sodium-potassium pump is called an electrogenic pump because it

Contributes to the membrane potential

A patient has had a serious accident and lost a lot of blood. In an attempt to replenish body fluids, distilled water, equal to the volume of blood lost, is transferred directly into one of his veins. What will be the most probable result of this transfusion?

The patient's red blood cells will swell because the blood fluid is hypotonic compared to the cells

Which of the following types of molecules are the major structural components of the cell membrane?

Phospholipids and proteins

Which of the following relationships between cell structures and their respective functions is NOT correct?

Chloroplasts: Chief sites of cellular respiration

Which of the following are capable of converting light energy to chemical energy?


Which of the following contains hydrolytic enzymes?


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


All of the following are part of a prokaryotic cell except

Endoplasmic reticulum

What maintains the secondary structure of a protein?

Hydrogen bonds

At which bond would water need to be added to achieve hydrolysis of the peptide back to its component amino acid? Refer to Figure 5.6 to answer the following questions.

Bond C

All of the following statements concerning saturated fats are true except

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

Which is the following is true of both starch and cellulose?

They are both polymers of glucose

What is the chemical mechanism by which cells make polymers from monomers?

Dehydration synthesis

Which of the following is not a polymer?


Which two functional groups are always found in amino acids?

Carboxyl and amino

Which of the following solutions has the greatest concentration of hydrogen ions [H+]?

Gastric juice pH 2

The slight negative charge at one end of one water molecule is attracted to the slight positive charge of another water molecule. What is this attraction called?

Hydrogen bond

What is the difference between covalent bonds and ionic bonds?

Covalent bonds involve the sharing of electrons between atoms, and ionic bonds involve the electrical attraction between atoms

How do isotopes of the same element differ from each other?

Number of neutrons

About 25 of the 92 natural elements are known to be essential to life. Which four of these 25 elements make up approximately 96% of living matter?

Carbon, hydrogen, nitrogen, and oxygen

For most ecosystems, _________ is (are) the ultimate source of energy, and energy leaves the ecosystem in the form of _________.

Sunlight; heat

Which of the following sequences represents the hierarchy of biological organization from the least to the most complex level?

Molecule, cell, organ system, population, ecosystem, biosphere

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