Nitrogen fixation is a process that_____.
A) recycles nitrogen compounds from dead and decaying materials
B) converts ammonia to ammonium
C) releases nitrate from the rock substrate
D) converts nitrogen gas into ammonia
Looking at the data in the figure above, what can be said about survival and clutch size?
A) Animals with low survival tend to have smaller clutch sizes.
B) Large clutch size correlates with low survival.
C) Animals with high survival tend to have larger clutch sizes.
D) Probability of survivorship does not correlate with clutch size.
Animals that help other animals of the same species _____.
A) have excess energy reserves
B) are bigger and stronger than the other animals
C) are usually related to the other animals helped
D) are always male
Upon activation by stomach acidity, the secretions of the parietal cells _____.
A) initiate the chemical digestion of protein in the stomach
B) initiate the mechanical digestion of lipids in the stomach
C) initiate the chemical digestion of lipids in the stomach
D) delay digestion until the food arrives in the small intestine
The following questions are based on the drawings of root or stem cross sections shown
in the figure.
Refer to the figure above. A plant that is at least three years old is represented by _____.
A) I only
B) II only
C) III only
D) IV only
What is gene annotation in bioinformatics?
A) finding transcriptional start and stop sites, RNA splice sites, and ESTs in DNA
sequences
B) assigning names to newly discovered genes
C) describing the functions of noncoding regions of the genome
D) matching the corresponding phenotypes of different species
Eukaryotic sexual life cycles show tremendous variation. Of the following elements,
which do all sexual life cycles have in common?
I. Alternation of generations
II. Meiosis
III. Fertilization
IV. Gametes
V. Spores
A) I, II, and IV
B) II, III, and IV
C) II, IV, and V
D) I, II, III, IV, and V
Which of the following best reflects what we know about how the flu virus moves
between species?
A) The flu virus in a pig is mutated and replicated in alternate arrangements so that
humans who eat the pig products can be infected.
B) A flu virus from a human epidemic or pandemic infects birds; the birds replicate the
virus differently and then pass it back to humans.
C) An influenza virus gains new sequences of DNA from another virus, such as a
herpesvirus; this enables it to be transmitted to a human host.
D) An animal such as a pig is infected with more than one virus, genetic recombination
occurs, the new virus mutates, the virus is passed to a new species such as a bird, and
the virus mutates again and can now be transmitted to humans.
Use the paragraph and accompanying figure to answer the following questions.
Human immunodeficiency virus (HIV) infects cells that have both CD4 and CCR5 cell
surface molecules. The viral nucleic acid molecules are enclosed in a protein capsid,
and the protein capsid is itself contained inside an envelope consisting of a lipid bilayer
membrane and viral glycoproteins. One hypothesis for viral entry into cells is that
binding of HIV membrane glycoproteins to CD4 and CCR5 initiates fusion of the HIV
membrane with the plasma membrane, releasing the viral capsid into the cytoplasm. An
alternative hypothesis is that HIV gains entry into the cell via receptor-mediated
endocytosis, and membrane fusion occurs in the endocytotic vesicle. To test these
alternative hypotheses for HIV entry, researchers labeled the lipids on the HIV
membrane with a red fluorescent dye.
What would be observed by live-cell fluorescence microscopy immediately after HIV
entry if HIV is endocytosed first, and then later fuses with the endocytotic vesicle
membrane?
A) A spot of red fluorescence will be visible on the infected cell’s plasma membrane,
marking the site of membrane fusion and HIV entry.
B) The red fluorescent dye-labeled lipids will appear in the infected cell’s interior.
C) A spot of red fluorescence will diffuse in the infected cell’s cytoplasm.
D) A spot of red fluorescence will remain outside the cell after delivering the viral
capsid.
High levels of citric acid inhibit the enzyme phosphofructokinase, a key enzyme in
glycolysis. Citric acid binds to the enzyme at a different location from the active site.
This is an example of _____.
A) competitive inhibition
B) allosteric regulation
C) the specificity of enzymes for their substrates
D) positive feedback regulation
Several epidemic microbial diseases of earlier centuries incurred high death rates
because they resulted in severe dehydration due to vomiting and diarrhea. Today they
are usually not fatal because we have developed which of the following?
A) antiviral medications that are efficient and work well with most viruses
B) intravenous feeding techniques
C) medications to slow blood loss
D) hydrating drinks with high concentrations of salts and glucose
Swine are vulnerable to infection by bird flu virus and human flu virus, which can both
be present in an individual pig at the same time. When this occurs, it is possible for
genes from bird flu virus and human flu virus to be combined. If the human flu virus
contributes a gene for Tamiflu resistance (Tamiflu is an antiviral drug) to the new virus,
and if the new virus is introduced to an environment lacking Tamiflu, then what is most
likely to occur?
A) The new virus will maintain its Tamiflu-resistance gene, in case of future exposure
to Tamiflu.
B) The Tamiflu-resistance gene will undergo mutations that convert it into a gene that
has a useful function in this environment.
C) If the Tamiflu-resistance gene involves a cost, it will experience directional selection
leading to reduction in its frequency.
D) If the Tamiflu-resistance gene confers no benefit in the current environment, and has
no cost, the virus will increase in frequency.
For a species with a haploid number of 23 chromosomes, how many different
combinations of maternal and paternal chromosomes are possible for the gametes?
A) 23
B) 46
C) about 1000
D) about 8 million
Use the following figure to answer the questions below.
Which of the following statements is true concerning the accompanying figure?
A) It represents a C4 photosynthetic system.
B) It represents an adaptation that maximizes photorespiration.
C) It represents a C3 photosynthetic system.
D) It represents a CAM photosynthetic system.
A young farmer purchases some land in a relatively arid area and is interested in
earning a reasonable profit for many years. Which of the following strategies would
best allow the farmer to achieve such a goal?
A) establishing an extensive irrigation system
B) using plenty of the best fertilizers
C) finding a way to sell all parts of crop plants
D) selecting crops adapted to arid areas
Ecologists often build models to depict the relationships between organisms. In such
models, an arrow is used to link two organisms in a relationship. The arrowhead is next
to the organism that is affected. If the effect is positive, the arrow is labeled with (+),
and if negative, then the label is (-). Which of the following models best illustrates the
relationship of the Brazil nut tree and the other organisms associated with it?
A)
B)
C)
D)
When imbalances occur in the sex ratio of sexual species that have two sexes (that is,
other than a 50:50 ratio), the members of the minority sex often receive a greater
proportion of care and resources from parents than do the offspring of the majority sex.
This is most clearly an example of _____.
A) sexual selection
B) balancing selection
C) stabilizing selection
D) frequency-dependent selection
Red-green color blindness is a sex-linked recessive trait in humans. Two people with
normal color vision have a color-blind son. What are the genotypes of the parents?
A) XnXn and XnY
B) XNXN and XnY
C) XNXN and XNY
D) XNXn and XNY
Which of the following would be the most problematic for the natural environment in
the development of genetically engineered crops?
A) the introduction of male sterility into crops
B) the creation of transgenic crops with apomictic seeds
C) the creation of crops with flowers that develop normally, but fail to open
D) the creation of transgenic crops that hybridize more easily
Positive feedback differs from negative feedback in that _____.
A) positive feedback benefits the organism, whereas negative feedback is detrimental
B) the positive feedback’s effector responses are in the same direction as the initiating
stimulus rather than opposite of it
C) the effector’s response increases some parameter (such as body temperature),
whereas in negative feedback it can only decrease the parameter
D) positive feedback systems have only effectors, whereas negative feedback systems
have only receptors
Suppose a cell has the following molecules and structures: enzymes, DNA, ribosomes,
plasma membrane, and mitochondria. It could be a cell from _____.
A) a bacterium
B) an animal but not a plant
C) nearly any eukaryotic organism
D) a plant but not an animal
As cytokinins are primarily produced in roots, what route would they travel to influence
lateral shoot formation in a recently topped tree?
A) symplastic
B) trachieds/vessels
C) phloem
D) apoplastic
The production of red blood cells is stimulated by _____.
A) low-density lipoproteins
B) immunoglobulins
C) erythropoietin
D) epinephrine
Lipid-soluble signaling molecules, such as testosterone, cross the membranes of all
cells but affect only target cells because _____.
A) only target cells retain the appropriate DNA segments
B) intracellular receptors are present only in target cells
C) only target cells possess the cytosolic enzymes that transduce the testosterone
D) only in target cells is testosterone able to initiate the phosphorylation cascade
leading to activated transcription factor
Which of the following have unevenly thickened primary walls that support young,
growing parts of the plant?
A) parenchyma cells
B) collenchyma cells
C) sclerenchyma cells
D) tracheids and vessel elements
The following questions are based on the accompanying figure.
In the figure above, which number represents DNA synthesis?
A) I
B) II
C) III
D) IV
Use the following information to answer the question(s) below.
Paulinella chromatophora is one of the few cercozoans that is autotrophic, carrying out
aerobic photosynthesis with its two elongated “chromatophores.” The chromatophores
are contained within vesicles of the host cell, and each is derived from a
cyanobacterium, though not the same type of cyanobacterium that gave rise to the
chloroplasts of algae and plants.
Similar to most amoebozoans, the forams and the radiolarians also have pseudopods, as
do some of the white blood cells of animals (monocytes). If one were to erect a taxon
that included all organisms that have cells with pseudopods, the taxon would _____.
A) be polyphyletic
B) be paraphyletic
C) be monophyletic
D) include all eukaryotes
If you experimentally reduce the concentration of K+ in the extracellular fluid
surrounding hair cells in the inner ear, the result would be like which of the following?
A) decreasing the volume of sound reaching the hair cells
B) increasing the volume of sound reaching the hair cells
C) decreasing the frequency of sound reaching the hair cells
D) increasing the frequency of sound reaching the hair cells
The figure below shows the pedigree for a family. Dark-shaded symbols represent
individuals with one of the two major types of colon cancer. Numbers under the
symbols are the individual’s age at the time of diagnosis. Males are represented by
squares, females by circles.
From this pedigree, this trait seems to be inherited _____.
A) from mothers
B) as an autosomal recessive
C) as a result of epistasis
D) as an autosomal dominant
Transcription factors _____.
A) regulate the synthesis of DNA in response to a signal
B) transcribe ATP into cAMP
C) control gene expression
D) regulate the synthesis of lipids in the cytoplasm