Which structure in this figure shows one complete nucleosome?
A) structure A
B) structure B
C) structure C
D) structure D
Which of the following statements regarding behavior is true?
A) Innate behaviors are performed the same way in all members of a genus.
B) Fixed action patterns are learned behavior sequences.
C) A learned behavior triggers a fixed action pattern.
D) A fixed action pattern is under strong genetic control.
Which arrow shows nitrogen fixation?
A) arrow A
B) arrow B
C) arrow C
D) arrow D
Mitochondria transfer ________ energy from ________ to ATP; chloroplasts transform
________ energy into the chemical energy of ATP.
A) chemical; food; light
B) food; light; chemical
C) light; food; kinetic
D) food; light; nuclear
Tay-Sachs is inherited as an autosomal recessive allele. Homozygous individuals die
within the first few years of life. However, there is some evidence that heterozygous
individuals are more resistant to tuberculosis. Which of the following statements about
Tay-Sachs is true?
A) The allele for Tay-Sachs is selected against.
B) This situation is an example of heterozygote advantage if tuberculosis is present in a
population.
C) This situation is an example of disruptive selection.
D) Heterozygotes will be more fit than either homozygote regardless of environmental
conditions.
Which of the following is a good way to ripen a green, unripe fruit?
A) putting it in a darkened area such as a drawer or box
B) placing it in a sealed plastic bag with an overripe banana
C) placing it in a microwave, on low power, for 5 minutes
D) placing it under a bright light for 24 hours
Which of the following objects is most like a hydrostatic skeleton?
A) a water balloon
B) a hot air balloon
C) a piece of M&M candy
D) a bowling ball
You find the frozen remains of a woolly mammoth in an Alaskan glacier. You analyze a
bit of the tusk and find that its 14C:12C ratio is about one-fourth (25%) of the baseline
level typically found in living organisms. Given that the half-life of 14C is 5,730 years,
when did the mammoth die?
A) 5,730 years ago
B) almost 12,000 years ago
C) at least 25,000 years ago
D) approximately 75,000 years ago
The pupil of the eye is similar to what part of a camera?
A) lens
B) aperture (light opener)
C) film
D) flash
Consider the following food label and then answer the questions that follow.
Krispy Krackers 100-Calorie Pouches
You are trying to cut down on the number of dessert foods that you eat as one effort
toward losing weight. You don’t feel ready to cut all sweets from your diet, so you
decide to buy a dessert snack item that comes in small packages (hoping that the
smaller amount will satisfy your cravings for sweet foods). In the grocery store, you
study the label above for 100-calorie pouches of Krispy Krackers.
In weighing the benefits of eating one serving of this item, you conclude that
A) it contributes to the recommended amount of dietary fiber.
B) it contributes to the recommended amount of iron.
C) it contributes to the recommended amount of calcium.
D) it contributes to the recommended amount of vitamin C.
A thick filament consists of
A) actin.
B) actin and regulatory proteins.
C) myosin.
D) actin and myosin.
California condors, large, predatory birds that were previously on the edge of
extinction, have benefited from a program that raises birds in captivity and then releases
them into the wild. The reintroduction program, however, is having variable success.
Which of the following provides the best evidence to help develop a hypothesis about
what is causing the difficulties faced by a coastal condor population?
A) Sea lions, food for condors along the coast, live near an old dumping ground for a
chemical manufacturing plant and have a significant amount of DDT in their blubber.
B) Air currents along the coast are stronger, allowing coastal condors to cover more
area in their search for prey.
C) California bans ammunition containing lead (Pb) to prevent lead ingestion by
condors feeding on carcasses of animals shot by hunters but not retrieved.
D) Hatching success in birds farther from the coast was greater than that in birds along
the coast.
A radioactive isotope is an isotope that
A) is stable.
B) decays.
C) has more protons than the common variant of the element.
D) has the same atomic mass but a different atomic number than the common variant of
the element.
Which of the following statements about temperate broadleaf forests is true?
A) Temperate broadleaf forests have a narrow range of temperatures over the course of
a year.
B) Oak, hickory, birch, beech, and maple are common trees in temperate broadleaf
forests.
C) Temperate broadleaf forests have very poor soil.
D) Temperate broadleaf forests are less open than tropical rain forests.
Exposure to the HIV virus doesn’t necessarily mean that a person will develop AIDS.
Some people have genetic resistance to infection by HIV. Dr. Stephen O’Brien from the
U.S. National Cancer Institute has recently identified a mutant form of a gene, called
CCR5, that can protect against HIV infection. The mutation probably originated in
Europe among survivors of the bubonic plague. The mutated gene prevents the plague
bacteria from attaching to cell membranes and, therefore, from entering and infecting
body cells.
Although the HIV virus is very different from the bacteria that causes the plague, both
diseases affect the exact same cells and use the same method of infection. The presence
of the mutated gene in descendants of plague survivors helps prevent them from
contracting AIDS. Pharmaceutical companies are using this information as the basis for
a new approach to AIDS prevention. This could be very important in areas of the world
where the mutation is scarce or absent, such as Africa.
Imagine that a pharmaceutical company was successful at producing a drug based on
the CCR5 gene product that is effective at preventing the contraction of AIDS.
However, shortly after the drug has been in use, patients and doctors report that the drug
is not as effective as it once was. What is the most likely explanation for this result?
A) The people taking the drug have built up a tolerance to the drug.
B) Some HIV viruses have genetic variations in the RNA genome that provide
resistance to the actions of the drug.
C) The HIV virus gained mutations in its DNA genome in order to become resistant to
the actions of the drug.
D) The DNA of white blood cells of the people taking the drug have mutated to become
resistant to the drug.
Why is a newly molted crab unusually slow and clumsy?
A) Its new exoskeleton cannot support the forces that its muscles generate.
B) It temporarily lacks an exoskeleton.
C) Its muscles are still forming their connections with the new exoskeleton.
D) Its neurons are still forming their connections with the new muscles.
Clots in our blood can lead to a heart attack or stroke by blocking blood flow. If a clot
were made up of a mass of proteins, what changed in the proteins to cause them to form
the clot?
A) The proteins became more polar.
B) The blood became saturated with proteins.
C) The proteins were no longer soluble in the blood.
D) The proteins became more soluble in the blood.
Which of the following statements about tunicates indicates that these animals are
chordates?
A) Larvae show segmentation, radial symmetry, and a pseudocoelom.
B) Larvae have a dorsal hollow nerve cord, a post-anal tail, pharyngeal slits, and a
notochord.
C) Larvae and adults both have a true coelom.
D) Tunicates have tube feet and a water vascular system.
Introduced species are a problem all over the world, and there are many examples in the
United States. Several years ago, a fisherman caught a northern snakehead fish in a
pond in Crofton, Maryland (a suburb of Washington, DC). Snakeheads are a favorite
food of immigrants from China, and live fish can frequently be found in Asian markets.
It was suspected that the fish in the Crofton pond were purchased locally and then
intentionally released.
Snakeheads are top predators, and 90% of the northern snakeheads’ diet consists of
other fishes. The northern snakehead can breathe out of water and travel short distances
(about 100 feet) across land. They also breed rapidly. Females can lay more than
100,000 eggs per year. Juveniles have also been identified in the Potomac River and
other rivers in Pennsylvania.
Based on the characteristics of the snakehead described, which of the following is most
likely to be a productive strategy to reduce the spread of this species?
A) extending the fishing season for prey fishes
B) introducing a natural predator to feed on juvenile snakeheads
C) capturing breeding snakeheads and sterilizing them so that they cannot breed any
longer
D) introducing algae and photosynthetic bacteria to reduce nutrient levels in the water
Figure A. Changes in permeability of tubules in the kidney in response to the hormone
vasopressin (AVP), which aids in osmoregulation.
Figure B. Density of aquaporins in kidney tubule cells before, during, and after
administration of vasopressin.
Figure C. Permeability of tissues to water before, during, and after administration of
vasopressin.
The following questions relate to these data indicating how the tubules in the kidney
respond to the administration of the hormone vasopressin.
Using the data from the graphs and what you know about membranes and metabolic
pathways, predict which of the following is the likely reason why actions of aquaporins
in a membrane can change so rapidly.
A) The number of aquaporins in the membrane is constant, but the pores have to be
activated.
B) Aquaporins are inserted into the membrane as needed.
C) Aquaporins are only in cells that need to be permeable to water.
D) Aquaporins use ATP to pump water across the membrane, and their action is limited
by the metabolic pathways that produce ATP.
When an organism such as a yeast lives by fermentation, it converts the pyruvate from
glycolysis into a different compound, such as alcohol. Why doesn’t it secrete the
pyruvate directly?
A) The conversion yields 32 ATP per pyruvate molecule.
B) The conversion yields one NADH per pyruvate molecule.
C) The conversion is needed to regenerate the molecules needed for glycolysis.
D) A buildup of pyruvate in the surrounding environment would be too toxic.
Which of the following statements regarding stem cells is false?
A) Embryonic stem cells can give rise to all the different specialized cells in the body.
B) Adult, but not embryonic, stem cells can be grown in laboratory culture.
C) Adult stem cells are present in adult tissues.
D) Adult stem cells are partway along the road to differentiation.
All animals must obtain ________ from outside sources.
A) preformed ATP
B) fuel to power body activities
C) enzymes
D) chyme
Removing the terminal bud of a plant that shows apical dominance will cause
A) an increase in the growth of the root system.
B) increased growth of the terminal bud.
C) increased growth of the axillary buds.
D) an immediate flowering of the plant.
Which of the following statements about insecticides is true?
A) To control agricultural pests, pest management uses biological controls, chemicals,
or cultural methods, but never a combination of these.
B) Simply killing many individuals is often the best way to reduce the size of a pest
population.
C) Most insecticides kill the pest but not the pest’s natural predators.
D) Prey species often have a higher reproductive rate than do predators.
A stomach cell is producing pepsin, an enzyme that hydrolyzes proteins. Which of the
following events suggests that gene expression of pepsin has been turned off in the cell?
A) The pepsin protein is folded properly in the cytoplasm.
B) The chromosome with the pepsin gene is tightly coiled.
C) The pepsin mRNA leaves the nucleus and enters the cytoplasm.
D) Activators and RNA polymerases are abundant in the nucleus.
Cilia differ from flagella in that
A) cilia contain nine microtubule doublets surrounding a central pair of microtubules,
whereas flagella contain only nine microtubule doublets.
B) the protein filaments of cilia are “naked,” whereas those of flagella are wrapped in
an extension of the cell membrane.
C) cilia are typically more numerous and shorter than flagella.
D) cilia are anchored only in the proteins of the cell membrane, whereas flagella are
anchored in a special structure called the basal body.
The mitochondrial cristae are an adaptation that
A) permits the expansion of mitochondria as oxygen accumulates in the mitochondrial
matrix.
B) helps mitochondria divide during times of greatest cellular respiration.
C) increases the space for more copies of the electron transport chain and ATP synthase
complexes.
D) carefully encloses the DNA housed within the mitochondrial matrix.
Which type of plant hormone generally acts as a growth inhibitor?
A) auxins
B) gibberellins
C) cytokinins
D) abscisic acid
What is the name given to the starch-digesting enzyme secreted by salivary glands?
A) bile salts
B) lipase
C) pepsin
D) amylase
Much of the intracellular structure of a eukaryote cell is involved in protein synthesis.
The figure shows the amounts of protein in cells at different parts of the cell cycle
between two cell divisions. G1 is a stage just after the cell has divided, and G2 is the
stage just before the cell divides again. S is a stage when the cell is synthesizing
material such as DNA, mitochondria, and other organelles.
Most of the protein measured in the cells was likely synthesized by
A) mitochondria.
B) nucleolus.
C) smooth endoplasmic reticulum.
D) ribosomes.
During the Cambrian explosion approximately 535 to 525 million years ago,
A) all modern species of animals suddenly appeared.
B) animals rapidly diversified in the oceans.
C) a massive volcanic eruption nearly wiped out life on Earth.
D) great forests produced peat layers that were later transformed into coal.
The polymerase chain reaction relies upon unusual, heat-resistant ________ that were
isolated from bacteria living in hot springs.
A) DNA polymerases
B) phages
C) restriction enzymes
D) plasmids