Bio 212 Exam 3

Which of the following terms describes the DNA-protein complexes that look like beads on a string? A. Chromatin B. Histones C. Nucleosome D. 30-nanometer fiber

Which of the following regulatory elements is not composed of DNA sequences? A. Enhancers B. Promoter-proximal elements C. Activators D. Silencers

True or false? Regulatory and basal transcription factors regulate transcription by binding to the promoter.

Which of the following regulatory DNA sequences might be located thousands of nucleotides away from the transcription start site of a gene? A. Enhancer B. Promoter-proximal C. element D. Promoter E. TATA box

Which of the following events in transcription initiation likely occurs last? A. Regulatory transcription factors bind to enhancers. B. TBP is recruited to the promoter. C. Basal transcription factors form a basal transcription complex. D. RNA polymerase binds to the promoter of the gene.

True or false? One possible way to alter chromatin structure such that genes could be transcribed would be to make histone proteins more positively charged.

If cells of an individual contain the same set of genes, how do these cells become different from each other during development? A. Different cell type-specific regulatory elements in DNA are created during development. B. Different cell type-specific regulatory elements in DNA are selectively lost during development. C. Differences in extracellular signals received by each cell lead to differences in the types of regulatory proteins present in each cell. D. Differences develop in promoter sequences that lead to different signals being produced by each type of cell.

An example of a basal transcription factor is _____. A. a silencer-binding transcription factor B. a promoter-proximal-binding transcription factor C. the TATA-binding protein D. an enhancer-binding transcription factor E. RNA polymerase

Which statement is most accurate concerning how gene expression in eukaryotes compares with that in bacteria? A. Proteins that control transcription perform fundamentally different roles in eukaryotes versus prokaryotes. B. The tight packaging of eukaryotic DNA provides a mechanism of positive control nonexistent in bacteria. C. Coordinated control of functionally related genes by a single promoter is common in both. D. The number of proteins that controls transcription is much greater in eukaryotes.

Muscle cells differ from nerve cells mainly because they _____. A. have unique ribosomes B. use different genetic codes C. have different chromosomes D. contain different genes E. express different genes

Which answer best explains how certain patterns of histone acetylation or DNA methylation could influence whether a cell became a muscle cell or a brain cell? A. They could produce differences in the DNA sequences of genes found in different cell types. B. They could determine what sets of genes are found in different cell types. C. They could affect which sets of genes are transcribed in different cell types. D. They could produce different patterns of post-translational control in different cell types.

If a cell were unable to produce histone proteins, which of the following would be a likely effect? A. There would be an increase in the amount of "satellite" DNA produced during centrifugation. B. Spindle fibers would not form during prophase. C. Amplification of other genes would compensate for the lack of histones. D. The cell's DNA couldn't be packed into its nucleus

What level of transcription would you predict for a gene whose promoter is heavily methylated? A. High transcription B. Low transcription C. Moderate transcription D. There is no correlation between methylation and transcription levels.

Predict how a drug that inhibits histone deacetylase will alter gene expression. A. chromatin would stay decondensed; transcription would stop; amount of protein would decrease B. chromatin would stay decondensed; transcription would be prolonged; amount of protein would increase C. chromatin would stay condensed; transcription would be prolonged; amount of protein would increase D. chromatin would stay condensed; transcription would stop; amount of protein would decrease

The phenomenon in which RNA molecules in a cell are destroyed if they have a sequence complementary to an introduced double-stranded RNA is called _____. A. RNA interference B. RNA blocking C. RNA obstruction D. RNA disposal E. RNA targeting

Which statements about the modification of chromatin structure in eukaryotes is false? A. Some forms of chromatin modification can be passed on to future generations of cells. B. DNA is not transcribed when chromatin is packaged tightly in a condensed form. C. Deacetylation of histone tails in chromatin loosens the association between nucleosomes and DNA. D. Acetylation of histone tails in chromatin allows access to DNA for transcription. E. Methylation of histone tails in chromatin can promote condensation of the chromatin. F. Acetylation of histone tails is a reversible process.

What role does a transcription factor play in a signal transduction pathway? A. By binding to a plasma membrane receptor it initiates a cascade. B. It relays a signal from the cytoplasm to the plasma membrane. C. It activates relay proteins. D. By binding to DNA it triggers the transcription of a specific gene. E. It is a plasma membrane protein that binds signal molecules.

A signal transduction pathway is initiated when a _____ binds to a receptor. A. G protein B. tyrosine kinase C. calmodulin D. signal molecule E. cyclic AMP

Which of these acts as a second messenger? A. protein kinase B. G-protein-linked receptor C. G protein D. cyclic AMP E. adenylyl kinase

Calcium ions that act as second messengers are stored in _____. A. lysosomes B. endoplasmic reticula C. peroxisomes D. mitochondria E. chloroplasts

_____ catalyzes the production of _____, which then opens an ion channel that releases _____ into the cell's cytoplasm. A. Phospholipase C ... cyclic AMP ... Ca2+ B. Adenylyl cyclase ... cyclic AMP ... Ca2+ C. Protein kinase ... PIP2 ... Na+ D. Phospholipase C ... IP3 .... Ca2+ E. Adenylyl cyclase ... IP3 .... Ca2+

A protein kinase activating many other protein kinases is an example of _____. A. mutualism B. deactivation C. sensitization D. amplification E. a cellular response

Why does a hormone act only on specific cell types in an organism and not others? A. A cell must have the appropriate receptor before it can bind to the hormone. B. Hormones only act on cells that are adjacent to the releasing cell. C. All cells will bind to the hormone and process it, but not all cells will produce a response. D. Hormones are prevented from entering the bloodstream, and thus only act on the releasing cell itself.

The product of the bicoid gene in Drosophila provides essential information about ________. A. the dorsalventral axis B. lethal genes C. the anteriorposterior axis D. segmentation E. the leftright axis

Fill in the blank: Differentiation is triggered by the production of regulatory __________ factors, which _________ other ______________ factors, and so on−a sequence that constitutes a regulatory cascade−as development progresses. At each step in the cascade, a new subset of genes is ___________−resulting in a step-by-step process to _________________ cells. Options: transcription fully differentiated inhibited undifferentiated translation activated repress induce

Muscle cells differ from nerve cells mainly because they _____. A. express different genes B. have unique ribosomes C. contain different genes D. have different chromosomes E. use different genetic codes

Why is Caenorhabditis elegans an appropriate model organism for studying developmental processes? A. C. elegans has genes that are completely unique from mice and humans. B. C. elegans does not undergo programmed cell death. C. C. elegans has millions of cells but can be easily mutated to have no gastrulation. D. C. elegans have meristems, regions that contain many stem cells. E. C. elegans is transparent and has only about 1000 cells, allowing the cells to be followed during development.

Which of the following is not a body segment of the fruit fly embryo? A. Head B. Antenna C. Abdomen D. Thorax

Which of the following statements about a gene that shows maternal effect inheritance is true? A. Embryonic cells transcribe the gene. B. Offspring will show a mutant phenotype if the mother has a mutant genotype. C. Offspring will always show a mutant phenotype if they have a mutant genotype. D. Offspring will have a mutant phenotype if the father has a mutant genotype.

True or False? Pattern formation refers to events that organize embryonic cells in space

Where is bicoid mRNA translated? A. Sperm cells B. Nurse cells C. Fertilized egg D. Follicle cells

Which body part develops in regions with a low concentration of Bicoid protein? A. Head B. Thorax C. Abdomen

Which of the following statements about the Bicoid protein is true? A. The Bicoid protein is a regulatory transcription factor. B. The Bicoid protein is a cytoplasmic determinant. C. The Bicoid protein establishes the dorsal-ventral body axis. D. The Bicoid protein is diffused evenly throughout the fertilized egg.

When we compare animal development to plant development, we find that _____. A. animal cells, but not plant cells, migrate during morphogenesis B. plant cells, but not animal cells, migrate during morphogenesis C. plant cells and animal cells migrate extensively during morphogenesis D. neither plant cells nor animal cells migrate during morphogenesis

Meristematic tissue cells in plants are most similar to which kind of cells in animals? A. somite cells B. embryonic stem cells C. mesodermal cells D. ectodermal cells

From earliest to latest, the overall sequence of early development proceeds in which of the following sequences? A. preformation → morphogenesis → neurulation B. gastrulation → organogenesis → cleavage C. gastrulation → blastulation → neurulation D. cleavage → gastrulation → organogenesis E. ovulation → gastrulation → fertilization

Which one of the following processes in a developing embryo is a prerequisite for all of the other processes? A. germ layer formation B. organogenesis C. cell differentiation D. mitosis

Which observation is evidence for genetic equivalence in plants or animals? A. A single root or shoot cell from an adult carrot can grow into an entire carrot plant. B. A tobacco embryo can produce an entire tobacco plant. C. A sheep embryo can produce a fertile adult. D. A single sheep embryo transplanted to a black-faced surrogate mother can produce a fertile white-faced adult.

Mechanoreceptors that react to changes in pressure are part of the _____. A. lateral line systems in fish B. pain receptors in birds C. human sense of taste D. eyes in arthropods E. human sense of smell

Considering that sounds and odors both trigger changes in the patterns of action potentials in sensory neurons, how does the brain perceive which sense is which when the action potentials reach the brain? A. The action potentials stimulated by sounds are different in size and shape from those stimulated by odors. B. Chemoreception is not consciously perceived by the brain, whereas mechanoreception is. C. The axons from different sensory neurons go to different areas of the brain. D. Mechanoreception is not consciously perceived by the brain, whereas chemoreception is.

Which of the following sensory receptors is correctly paired with its category? A. hair cell: mechanoreceptor B. rod: chemoreceptor C. taste receptor: mechanoreceptor D. olfactory receptor: electromagnetic receptor E. muscle spindle: electromagnetic receptor

How does the ear allow humans to distinguish the volume of different sounds? A. Louder sounds cause larger action potentials than do softer sounds, and louder sounds induce a higher frequency of action potentials than do softer sounds. B. Louder sounds induce a higher frequency of action potentials than do softer sounds. C. Louder sounds cause smaller action potentials than do softer sounds. D. Louder sounds cause larger action potentials than do softer sounds. E. Louder sounds induce a lower frequency of action potentials than do softer sounds.

Hair cells in the vertebrate ear are responsible for transducing sound pressure waves. Ion channels in the hair cell membrane open when _____. A. the membrane is distorted mechanically B. a chemical ligand binds to the ion channel C. the cell membrane reaches a threshold voltage D. light is absorbed by a molecule in the membrane

Which part of the eye is the opening through which light initially passes? A. Retina. B. Pupil. C. Fovea. D. Sclera.

Which of the following statements does not describe a vertebrate eye? A. It contains photoreceptors that are either rod- or cone-shaped. B. It contains many light-sensing columns called ommatidia. C. It acquires images by focusing light on receptor cells. D. It contains cells that are sensitive to either dim light or color.

True or false? The "blind spot" in vertebrate eyes is a region of the retina that contains no photoreceptors.

Which part of the eye contains the densest concentration of cone cells? A. Lens. B. Fovea. C. Opsin. D. Cornea.

Which part of the eye bends light to focus it on the retina? A. Fovea. B. Optic nerve. C. Sclera. D. Lens

Which of the following statements about photoreception is true? A. Rhodopsin is found in cone cells. B. Rod cells are responsible for color vision. C. The retinal molecule changes shape when it absorbs light. D. Cone cells are sensitive to dim light

True or false? Cone cells are color photoreceptors that use different retinal molecules to absorb different wavelengths of light.

Why is the inflow of sodium ions into a photoreceptor cell called "the dark current"? A. The inflow of ions occurs when the receptor is not receiving light. B. It only occurs with wavelengths outside of the visible spectrum. C. It causes blindness. D. It causes photocells to stop working.

What structures would neurobiologists look for if they are interested in determining if an animal can see in color? A. pupil B. electroreceptors C. lens D. opsins

Odorant molecules activate sensory neurons by ________. A. deflecting the cilia of hairs cells, leading to the release of neurotransmitter B. altering basilar membrane stiffness to shift response by receptor cells C. passing through ion channels and altering membrane potentials D. binding to membrane-bound receptor proteins of sensory neurons E. binding to rhodopsin, leading to a change in cGMP levels

In the human ear, how do different hair cells respond to different frequencies of sound? A. Hair cells are "sandwiched" between membranes. B. Because the basilar membrane varies in stiffness, it vibrates in certain places in response to certain frequencies. C. Receptor proteins in the stereocilia of each hair cell are different; each protein responds to a certain range of frequencies. D. Waves of pressure move through the fluid in the cochlea.

Which of the following comparisons of rods and cones is false? A. Both rods and cones use retinal and opsins to detect light. B. Most human eyes have one type of rod and three types of cones. C. Rods are more sensitive to dim light than cones are. D. Nocturnal animals have fewer rods than diurnal animals

Within an organism, what makes one cell type different from another? A. Each cell type expresses different genes B. Each cell type inherits different genes C. Each cell type discards different genes D. Each gene codes different proteins in different cells.

What makes each insect body segment different from another? A. Each inherits different genes B. Each expresses different genes C. Each discards different genes D. Each gene codes different proteins in different segments.

What would you expect to be the phenotype of a larva in which the bicoid gene was expressed in both the anterior and posterior region of the oocyte? A. The larva would look normal B. The larva would not form, development would be arrested prior to larva formation C. The larva would have anterior structures at both ends D. The larva would lack anterior structures

In Drosophila oocytes, concentrations of a gene product called nanos are high near the posterior and decline toward the head. nanos might be an example of a: A. Segment identity gene B. Homeotic gene C. Gap gene D. Pair rule gene E. Morphogen

What group of proteins plays a key role in controlling the program of developmental changes ? A. Motor proteins B. Transporter proteins C. Transcription factors D. Cyclin dependent kinases E. Restriction endonucleases

How do neurons establish differential concentrations of ions inside and outside the cell? A. transpiration B. active transport C. facilitated diffusion D. simple diffusion E. osmosis

The inside of a resting neuron is negatively charged. Where is the [K+] higher? A. Inside the cell B. Outside the cell C. [K+] is irrelevant

The major signaling cell of the nervous system is the 1. Axon 2. Neuron 3. Dendrite 4. Glia 5. Myelin

Which of the following contribute to the resting potential of a neuron? A. Bulk flow B. Voltage-gated Cl- channels C. Ungated ion specific "leak" channels D. Anions in the cytoplasm E. Na+/K+ pump F. Ligand-gated Na+ channels A. B and C B. A, B, E C. C, D, E D. D, E, F E. A, D, E F. B, E, F