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Which of the following statements best describes the molecular basis of muscle
shortening?
A) Individual filamentous proteins contract.
B) Individual filamentous proteins shorten by coiling.
C) Rod-shaped protein polymers shorten by losing subunits from their ends.
D) Protein filaments crawl along other protein filaments.
A steer must eat at least 100 pounds of grain to gain less than 10 pounds of muscle
tissue. This illustrates
A) the first law of thermodynamics.
B) the second law of thermodynamics.
C) that some energy is destroyed in every energy conversion.
D) that energy transformations are typically 100% efficient.
Recent studies have shown that the onset of puberty in American girls has decreased
from an average of 12-13 years of age to as young as 8-10. Many scientists who study
premature puberty suggest that steroids in our food and in the environment may be
contributing factors, since steroids are known to cross cell membranes and bind to
receptors inside cells.
Why are hormones present in our foods? Synthetic testosterone compounds (similar to
those used by some athletes) make young animals gain weight faster so they are ready
for market sooner. Female animals receive synthetic estrogen to inhibit the reproductive
cycle and divert all energy into weight gain. In the United States, up to two-thirds of
meat animals are raised using hormones. In addition, hormones are used to increase
milk production in dairy cattle.
Scientific investigation of the exact effects of environmental steroids on humans is
extremely difficult since there are multiple sources of hormones in the environment. A
valid study would require a control group who hasn't been exposed to the chemicals
being studied. Since everyone has had some exposure to environmental hormones, no
control group is available to use as a reference.
How are steroids able to cross cell membranes and enter cells?
A) Steroids and cell membranes both contain receptor proteins.
B) Steroids are able to pass through the phospholipid bilayer and bind to receptors
inside the cell.
C) Steroids can diffuse through open channel proteins in the membrane.
D) Steroids move through cell membranes, such as water, by osmosis.
Which of the following statements regarding breathing and circulation in insects is
false?
A) Insects lose very little water by using a tracheal system to breathe.
B) The tracheal system of insects consists of a series of branching air tubes that extend
from the surface to deep inside the body.
C) Terrestrial animals such as insects spend much more energy than aquatic animals to
ventilate their respiratory surfaces.
D) The circulatory system of insects is not involved in transporting oxygen.
In which of the following human blood vessels is the blood pressure lowest?
A) arteries in the head
B) arterioles in the legs
C) capillaries in the feet
D) veins in the head
Which of the following statements regarding the brain is true?
A) Ventricles in the brain are filled with interstitial fluid.
B) The blood-brain barrier helps to maintain a stable chemical environment for the
brain.
C) Layers of connective tissue, called epithelium, surround and protect the brain and
spinal cord.
D) White matter is mainly dendrites.
Which of the following pieces of evidence would be considered the best for establishing
biological relatedness?
A) birth certificates
B) pictures from family reunions
C) testimony from relatives
D) a very close match in the DNA profile
The ________ represents the sporophyte generation of a conifer, and the ________
produces gametophytes.
A) cone; tree
B) tree; cone
C) tree; pollen
D) seed; tree
Which of the following is most likely to be an epiphyte?
A) a plant growing on the branches of another plant
B) a plant that captures insects
C) a plant with a very deep root system
D) a plant that parasitizes another plant
Biological control is defined as
A) the use of chemicals, such as pesticides, to control pests.
B) the intentional release of a natural enemy of a pest population.
C) the exploitation of coevolutionary principles to produce pesticides.
D) an intentional attempt to increase the numbers of specific prey populations.
Which of the following is a disadvantage of cloning as a propagation technique?
A) Cloning produces monocultures that can potentially be wiped out by a single
disease.
B) Cloning is more expensive and more difficult than growing from seeds.
C) Cloning is time-consuming, with slow results.
D) Cloned organisms are dangerous and unpredictable.
The directions for each amino acid in a polypeptide are indicated by a codon that
consists of ________ nucleotides in an RNA molecule.
A) five
B) four
C) three
D) two
What prompts a newborn baby to start to breathe?
A) an increase in the concentration of carbon dioxide in the baby's blood
B) a decrease in the concentration of oxygen in the baby's blood
C) a change in the temperature on the surface of the skin
D) exposure to air
A hot, dry summer will reduce crop yields in part because
A) the stomata of the plants stay open to help cool the leaves.
B) carbon dioxide uptake is reduced by the stomata closing to prevent excessive water
loss.
C) oxygen uptake is reduced by the stomata closing to prevent excessive water loss.
D) carbon dioxide release is reduced by the stomata closing to prevent excessive water
loss.
Marine animals that have body fluids with a solute concentration equal to that of the
surrounding seawater are
A) osmoregulators.
B) osmoconformers.
C) hypotonic.
D) hypertonic.
When did the level of oxygen in Earth's atmosphere become high enough to sustain
aerobic respiration?
A) 1.0 billion years ago
B) 1.5 billion years ago
C) 2.7 billion years ago
D) 3.5 billion years ago
Wood frogs freeze solid during the winter and then thaw in the spring. As the freezing
progresses, blood circulation stops. How would you expect cells not being served by the
circulatory system to produce ATP during this time, and what by-product would you
expect to build up in the cells?
A) aerobic respiration and CO2
B) fermentation and lactate
C) fermentation and alcohol
D) photosynthesis and O2
You notice that over the past month, many students on campus have started wearing a
new style of school sweatshirt. You think to yourself that perhaps the bookstore has
recently started selling this new sweatshirt style. This is an example of
A) an experimental question.
B) a type of observation.
C) a hypothesis.
D) an experiment.
Action potentials normally travel along an axon
A) toward the cell body.
B) away from the cell body.
C) either toward or away from the cell body.
D) away from the synapse.
The simplest animals to display cephalization and centralization of the nervous system
are
A) sponges.
B) flatworms.
C) cnidarians.
D) echinoderms.
According to this figure, which pair of organisms shares the most recent common
ancestor?
A) lungfishes and amphibians
B) amphibians and lizards
C) mammals and crocodiles
D) lizards and ostriches
The yolk sac of humans
A) stores nutrients to support the developing embryo.
B) is evidence of humans' relationships with egg-laying vertebrates.
C) secretes HCG.
D) absorbs nutrients from, and releases waste to, the mother's blood.
Compared to conventional agriculture, organic farming
A) uses fewer synthetic pesticides.
B) increases crop yields.
C) guarantees the safety and extra health benefits of food.
D) requires much less hands-on work.
HIV is a virus that is particularly difficult to eradicate
A) because of its DNA genome.
B) because it rarely mutates.
C) because it mutates to produce new drug-resistant strains.
D) due to its small size.
Which of the following results from stimulation by the parasympathetic nervous
system?
A) increased heart rate
B) inhibition of the digestive organs
C) inhibition of urination
D) stimulation of saliva secretion
Textile mills often release dye color and toxic by-products into rivers and streams,
which may then taint groundwater. Fungi associated with mangrove trees have been
shown to reduce both colors and toxicity in tainted groundwater.
The fungi are being used as a form of
A) endosymbiosis.
B) bioremediation.
C) phagocytosis.
D) mixotrophy.
Nondisjunction occurs when
A) a portion of a chromosome breaks off and is lost.
B) two chromosomes fuse into one.
C) members of a chromosome pair fail to separate.
D) an entire pair of chromosomes is lost during meiosis I.
Which of the following statements correctly describes the behavior of a tetrad during
anaphase I of meiosis?
A) It goes intact to one pole of the dividing cell.
B) It splits into two pairs of sister chromatids, and one pair goes to each pole of the
dividing cell.
C) It splits into two pairs of homologous, nonsister chromatids, and one pair goes to
each pole of the dividing cell.
D) It splits into four chromosomes, which distribute in random pairs to the two poles of
the dividing cell.
According to this graph of changes in Earth's atmosphere, which of the following took
place between the years 1800 and 2000?
A) Nitrous oxide (N2O) levels increased from 270 ppb to 390 ppb.
B) Carbon dioxide (CO2) levels increased from 950 ppb to 1,800 ppb.
C) Carbon dioxide (CO2) levels increased from 290 ppm to 380 ppm.
D) Methane (CH4) levels increased from 270 ppm to almost 2,000 ppm.
Organic compounds
A) always contain nitrogen.
B) are synthesized only by animal cells.
C) always contain carbon.
D) always contain oxygen.
Home pregnancy test kits can detect whether a woman is pregnant within one to three
weeks of her egg being fertilized. The test kits include a short strip of paper that extends
from a plastic case. After a woman urinates on the strip of paper and waits three to five
minutes, a symbol is displayed on a small window in the plastic case. Some tests show
a single line to indicate the woman is not pregnant (negative result) and two lines to
indicate she is pregnant (positive result). Others show a minus or plus sign (or some
other variation) to indicate negative and positive results.
The test reports a positive symbol if it detects the presence of HCG in the woman's
urine. In order for HCG to be detected, it must be present in the urine at a concentration
of at least 10 to 100 units per milliliter. Even though home pregnancy tests are well
designed and have been tested extensively, false negative and false positive results do
occur. A false positive occurs when a test tells a woman that she is pregnant when she
really is not, and a false negative occurs when a test tells a woman that she is not
pregnant when she really is. Most home pregnancy test kit manufacturers claim that
their tests are over 99% accurate.
What would be the best experiment for a manufacturer to conduct in order to determine
the false positive rate of their test kits?
A) Have a group of women who are less than five weeks pregnant use the test and count
the number of false positive results.
B) Have a woman use the test before she is pregnant and again after she is pregnant and
determine whether the tests were positive or negative.
C) Have a group of women who are 32 weeks pregnant use the test and count the
number of false positive results.
D) Have a group of women who are not pregnant use the test and count the number of
false positive results.
