A keystone species that is a predator will
A) maintain the species diversity in a community.
B) harvest prey species down to extinction.
C) help many of its prey reproduce.
D) reduce the diversity of the community.
Which of the following statements about the humoral immune response is true?
A) The humoral immune response defends against bacteria and viruses by activating T
cells.
B) The humoral immune response defends primarily against bacteria and viruses
present in body fluids.
C) The humoral immune response plays a major role in protecting the body from
cancerous cells.
D) The humoral immune response is the result of macrophages producing antibodies.
A target cell that is affected by a particular steroid hormone would be expected to have
A) an intracellular receptor protein that binds the hormone.
B) a cell-surface receptor protein that binds the hormone.
C) enzymes that are activated or inactivated by the intracellular hormone-receptor
complex.
D) enzymes that are activated or inactivated by the hormone’s second messenger.
Which step in this figure portraying lipid-soluble hormone action shows transcription in
response to the bound hormone-receptor complex?
A) step 1
B) step 2
C) step 3
D) step 4
How would the shape of a DNA molecule change if adenine paired with guanine and
cytosine paired with thymine?
A) The DNA molecule would be longer.
B) The DNA molecule would be shorter.
C) The DNA molecule would be circular.
D) The DNA molecule would have irregular widths along its length.
Which of the following human activities has contributed to an increase in the number of
bacteria having R plasmids?
A) nitrogen fixation by genetically engineered plants
B) improper use of restriction enzymes in research and medical facilities
C) increased carcinogen exposure from excessive fossil fuel burning
D) heavy use of antibiotics in medicine and in agriculture
A small seed may grow into a very large tree. As the tree grows, it adds a great deal of
mass. Where does most of this mass come from?
A) something in the air
B) something in the soil
C) something in the water
D) sunlight
Which of the following are products of cellular respiration?
A) oxygen and carbon dioxide
B) energy to make ATP and carbon dioxide
C) oxygen and glucose
D) oxygen and energy to make ATP
Many amphibians (including many frogs, toads, and salamanders) spend the early part
of their lives in water but live on land as adults. The adults of many species return to
water to breed and lay their eggs. Frogs have small lungs and supplement their oxygen
intake by breathing through the skin. Although large frogs have more total surface area
than smaller frogs, the larger frogs have a lower surface area/volume ratio (less skin
surface relative to their total body volume). To keep their respiratory surfaces moist,
frogs are generally found in wet or very moist locations.
In an experiment designed to investigate oxygen consumption in relation to body size,
frogs from five different species were weighed and placed in a respirometer (a machine
that measures oxygen consumption) for 1 hour. The table shows the results of the
experiment.
From the data in the table, it is reasonable to conclude that
A) smaller frogs consume less oxygen per gram of body weight.
B) each tested species consumes a different amount of oxygen per gram of body weight.
C) oxygen consumption per gram of body weight is the same for all tested species.
D) oxygen consumption per gram of body weight for the largest species is much higher
than that for the smallest species.
In the electron transport chain, the final electron acceptor is
A) an oxygen atom.
B) a molecule of carbon dioxide.
C) a molecule of water.
D) ADP.
Fatty acids with double bonds between some of their carbons are said to be
A) unsaturated.
B) saturated.
C) completely hydrogenated.
D) monoglycerides.
What evidence is used to determine the branching sequence of an evolutionary tree?
A) experiments in artificial selection
B) anatomical or molecular homologous structures
C) the genetic code
D) an overall assessment of general similarities between organisms
Which of the following are produced during the light reactions of photosynthesis?
A) glucose, ADP, NADP+
B) glucose, ADP, NADP+, CO2
C) ADP, NADP+, O2
D) ATP, NADPH, O2
The biological species concept is
A) applicable to all forms of life, past and present.
B) applicable to all present life-forms but not to fossil organisms whose reproductive
behavior cannot be observed.
C) easy to apply to all present sexually reproducing organisms but harder to apply to
asexual organisms and fossils.
D) sometimes difficult to put into practice even for present sexual organisms and
useless for asexual organisms and fossils.
When observing a chicken skin cell in G2 under a microscope, you count 156 total
chromatids. How many chromosomes does a male chicken have in its sperm cells?
A) 312
B) 156
C) 78
D) 39
Natural killer cells
A) are phagocytes that attack and kill pathogenic microorganisms.
B) attack virus-infected cells by releasing chemicals that lead to cell death.
C) tag pathogenic microorganisms with antibodies.
D) “eat” microorganisms that have been tagged with antibodies.
Miller-type experiments have shown that
A) simple cells could be produced in the laboratory using a ‘soup” of small organic
molecules.
B) complex organic molecules can be produced by physical processes from inorganic
components.
C) living cells could survive in primitive Earth’s atmosphere.
D) given the conditions of early Earth, the formation of life would still require
additional materials from meteorites and asteroids.
How many sex chromosomes are in a human gamete?
A) one
B) two
C) three
D) four
Which of the following structures contributes to the structure of the placenta as well as
completely surrounding the embryo?
A) chorion
B) amnion
C) yolk sac
D) allantois
Which of the following statements regarding infertility and fertilization procedures is
true?
A) Embryos fertilized through assisted reproductive technologies cannot be frozen for
later use, as they degrade rapidly.
B) In GIFT, sperm are injected into an embryo in vitro, and the embryo is placed into
the oviducts.
C) In IVF, fertilization occurs in a dish. The embryo is allowed to develop for several
days, and then the embryo is placed into the uterus.
D) Children conceived using reproductive technologies such as IVF and ICSI display a
high rate of abnormalities resulting from these procedures.
The signal that crosses a synapse is stopped when
A) a second action potential traveling down the signaling cell ‘sounds a retreat,” and the
neurotransmitters return to the signaling cell.
B) the responding cell runs out of sodium and is no longer able to respond to the
stimulus.
C) the responding cell runs out of potassium and is no longer able to respond to the
stimulus.
D) the neurotransmitter is enzymatically broken down or transported back to the
signaling cell.
It is essential for heart muscle cells to beat in a coordinated fashion. The cell junctions
that would best facilitate this are
A) occluding junctions.
B) anchoring junctions.
C) tight junctions.
D) gap junctions.
The end products of glycolysis include
A) NADH.
B) acetyl CoA.
C) citric acid.
D) O2.
Bacteria that are unable to survive in the presence of oxygen are called
A) obligate anaerobes.
B) obligate aerobes.
C) facultative anaerobes.
D) aerotolerant anaerobes.
Allopatric speciation is not likely to occur when
A) there is no disruption in gene flow between two populations.
B) a geographic barrier forms between two populations.
C) several populations become isolated from one another as drying conditions cause a
large body of water to become separate smaller bodies of water.
D) separated populations adapt to different environmental conditions.
What is the complementary sequence to the DNA strand TCGATGG?
A) TCGATGG
B) GGTAGCT
C) AGCUACC
D) AGCTACC
Which of the following statements is true?
A) A line of lobe-finned fishes gave rise to tetrapods, and a line of tetrapods gave rise to
modern amphibians.
B) A line of tetrapods gave rise to chordates, and a line of lobe-finned fishes gave rise
to tetrapods.
C) A line of amphibians gave rise to tetrapods, and a line of lobe-finned fishes gave rise
to modern amphibians.
D) Tetrapods and amphibians evolved at approximately the same time, while
lobe-finned fishes evolved 2 million years later.
Natural selection is nature’s mechanism for selecting characteristics that best adapt the
animal to its environment. Mammals have evolved a sophisticated mechanism for
eliminating nitrogenous wastes that involves
A) secretion through cell membranes.
B) forming urea and storing it in concentrated solution.
C) producing uric acid and excreting it with feces.
D) recycling urea and using it as an energy source.
Some of your DNA may not code for any protein and has no known function in gene
regulation; it is sometimes referred to as “junk” DNA. How do nucleotide sequences of
“junk DNA” evolve?
A) They evolve through natural selection.
B) They evolve through genetic drift and other chance processes.
C) They evolve to be more useful by taking on new functions.
D) They evolve by gradually being eliminated from the gene pool.
The human embryo’s first blood cells arise in the
A) developing liver.
B) developing bone marrow.
C) yolk sac.
D) allantois.
The human population on Earth is expected to reach 9.5 billion people by
A) 2015.
B) 2050.
C) 2093.
D) 3150.