Biology 2 Exam 1

A cell that is able to give rise to every cell in the adult body is called a ____ cell. a. Determined b. Pluripotent c. Induced d. Potential e. Differentiated

b. Pluripotent

Proteins in the cytosol and/or bound to cell membrane surfaces that perceive chemical signals are called.. a. Second messengers b. Receptors c. G-proteins Desmosomes

b. Receptors

Binding of signal molecules to protein receptors that are located on the exterior surface of cell membranes is the first step in a ______ pathway. a. Signal amplification b. Signal transduction c. Signal degradation d. Signal integration

b. Signal transduction

Which one of the following statements about stickleback is true? a. The differences between marine and freshwater sticklebacks arose due to acclimatization. b. The differences between marine and freshwater sticklebacks arose due to changes in the expression of a transcription factor. c. Pitx1 expression in marine sticklebacks results in decreased body armor d. Freshwater sticklebacks have pelvic spines to stop predator birds.

b. The differences between marine and freshwater sticklebacks arose due to changes in the expression of a transcription factor.

Suppose the pair-rule genes are inactivated in Drosophila embryos. What are the likely results of the experiment? a. The embryos would develop normally b. The embryos would have missing segments c. The embryos would have impaired anterior posterior polarity d. The embryos would not develop at all

b. The embryos would have missing segments

Suppose the protein specified by Bicoid was injected into drosophila embryos, so that a high concentration was present everywhere in the embryo. What might be the result of such an experiment. a. The embryos would grow larger than normal b. The embryos would show no development of posterior regions c. The embryos would show no development of anterior regions d. The embryos would halt their development

b. The embryos would show no development of posterior regions

Suppose the protein specified by bicoid was injected into Drosophila embryos so that a high concentration was present everywhere in the embryo. What might be the result of such an experiment? a. The embryos would grow larger than normal. b. The embryos would show no development of posterior regions. c. The embryos would show no development of anterior regions. d. The embryos would halt their development.

b. The embryos would show no development of posterior regions.

What does it mean to say that a signal is transduced? a. The signal enters the cells, binds to a cytoplasmic receptor, and moves to the nucleus to alter gene expression b. The signal binds with a membrane-bound receptor and triggers a sequence of events inside of the cell, which will change cellular activity c. The signal is broken into smaller parts by a membrane-bound enzyme and these parts then enter the cell to change cellular activity d. An inhibitor prevents the signal from binding to the receptor, so that the cell can no longer respond to the signal

b. The signal binds with a membrane-bound receptor and triggers a sequence of events inside of the cell, which will change cellular activity

Acetylcholine is a neurotransmitter that binds to receptors on skeletal muscle cells. The receptor—signal complex brings about a series of events that result in contraction of skeletal muscle. Venom from black widow spiders causes an explosive release of acetylcholine. What would that do to its victims? a. The victim's muscles would be unable to contract. b. The victim's muscles would be unable to relax. c. The victim's cell receptors would no longer be able to bind regulatory hormones. d. The victim's cell receptors would be able to bind regulatory hormones but at a rate greatly exceeding normal rates.

b. The victim's muscles would be unable to relax.

During metamorphosis, a tadpole's tail is reduced in size by the process of ________. a. regeneration b. apoptosis c. meiosis d. oxidative phosphorylation e. re-differentiation

b. apoptosis

Gap genes, segment-polarity genes, and homeotic genes all ________. a. act independently of one another b. code for transcription regulatory factors c. can be activated at any time during development d. are unique to Drosophila embryos

b. code for transcription regulatory factors

Blood sugar is regulated by two pancreatic hormones—insulin and glucagon. When blood sugar rises, insulin is released; it binds to receptors and through signal transduction results in an increase in glucose uptake by cells, which effectively lowers blood glucose levels. When blood sugar decreases, glucagon is released, binds to cell receptors, and causes glucose to be released into circulation, thereby increasing blood glucose levels. Diabetes mellitus is a disorder that results from excessively high levels of blood glucose. Type II diabetics have normal to elevated levels of insulin. What, then, might be causing their elevated blood glucose levels? a. inadequate insulin production b. defective receptors c. defective second messenger d. overproduction of glucagon

b. defective receptors

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. most cells lack the Y chromosome required d. only target cells possess the cytosolic enzymes that transduce the testosterone e. only in target cells is testosterone able to initiate the phosphorylation cascade leading to activated transcription factor

b. intracellular receptors are present only in target cells

What is the different between a neuron and a muscle cell in the same organism? a. the cell genome b. the transcription factors expressed c. genes d. their DNA

b. the transcription factors expressed

1. Which of the following represents the correct sequence of steps of a signal transduction pathway in order from beginning to end? 1. final target causes response 2. a ligand binds to the cell surface receptor 3. the receptor activates a protein at the membrane 4. second messenger molecules are released a. 1,2,3,4 b. 2,4,3,1 c. 2,3,4,1 d. 2,4,1,3

c. 2,3,4,1

All of the following proteins may be found in the extracellular matrix of animal cells EXCEPT ________. a. Collagen b. Fibronectin c. Actin d. All of the above

c. Actin

Steroid hormones are lipid soluble, which means that they... a. Act by signal transduction across the cell membrane b. Bind to proteins in order to cross the cell membrane c. Are able to pass through the cell membrane and initiate a response inside the cell d. Act quickly and have short-lived effects

c. Are able to pass through the cell membrane and initiate a response inside the cell

Different body cells can respond differently to the same lipid-insoluble hormones because____. a. Different target cells have different DNA b. Each cell converts that hormone to a different metabolite c. Different target cells express different genes, so the proteins involved in signal transduction pathways differ among cell types d. The circulatory system regulates responses to hormones by routing the hormones to specific targets

c. Different target cells express different genes, so the proteins involved in signal transduction pathways differ among cell types

Short-term signaling in cells might involve: a. Changes in the activation or deactivation of particular target protein that already exists in the cell b. Changes in the translation or destruction of mRNA that already exists in the cell c. Changes in which of the genes are being expressed in the cell d. Both A and B

d. Both A and B

During development of the zebrafish, a cell from the developing epidermis was transplanted into the developing circulatory system. The cell continued to develop as an epidermal cell, meaning that it was ____. a. Pluripotent b. A stem cells c. Differentiated d. Determined

d. Determined

At puberty, an adolescent female body changes in both structure and function of several organ systems, primarily under the influence of changing concentrations of estrogens and other steroid hormones. How can one hormone, such as estrogen, mediate so many effects? a. Estrogen is produced in very large concentration by nearly every tissue of the body. b. Each cell responds in the same way when steroids bind to the cell surface. c. Estrogen is kept away from the surface of any cells not able to bind it at the surface. d. Estrogen binds to specific receptors inside many kinds of cells, each with different responses. e. Cells metabolize steroids in different ways, producing by-products that stimulate tRNA production.

d. Estrogen binds to specific receptors inside many kinds of cells, each with different responses.

Cell to cell communications that allow direct communication by allowing the passage of ions and small molecules between cells are called ________ in animals and ________ in plants. a. Adhesions.... Tight junctions b. Desmosomes... plasmodesmata c. Tight junctions... desmosomes d. Gap junctions... plasmodesmata

d. Gap junctions... plasmodesmata

Suppose you found several Drosophila mutants that possessed additional legs growing out of their head segments. The probable mutation would be found in ________. a. Segment-polarity genes b. Gap genes c. Pair-rule genes d. Homeotic genes

d. Homeotic genes

Suppose you found several drosophila mutants that possessed additional legs growing out of their head segments. The probable mutation would be found in ____. a. Segment-polarity genes b. Gap genes c. Pair-rule genes d. Homeotic genes

d. Homeotic genes

There are several types of receptors that allow cells to communicate. Which of the following is true regarding these cell receptors? a. Binding of a ligand to receptor tyrosine kinases causes a direct change in ion distribution across a membrane. b. Ligand-gated ion receptors are receptors for a group of signaling molecules called growth factors. c. G protein-coupled receptors (GPCRs) are the least diverse type of cell receptor. d. Intracellular receptors can be found in the cytoplasm or nucleus.

d. Intracellular receptors can be found in the cytoplasm or nucleus.

Suppose there was a mutation in the segment-polarity genes of Drosophila, what do you suppose might be the outcome? a. Several segments of the embryo will be missing b. Every other segment of the embryo will be missing c. Legs will appear in the place of antennae d. Specific body structures like antennae will appear in a different part of their usual segment

d. Specific body structures like antennae will appear in a different part of their usual segment

A cell with membrane-bound proteins that selectively bind a specific hormone is called that hormone's ________. a. Secretory cell b. Plasma cell c. Endocrine cell d. Target cell e. Regulatory cell

d. Target cell

If you know that the Hox gene AbdB is expressed in the most posterior part of the abdomen in a Drosophila embryo which conclusion about a homologous gene in humans would most likely be correct? a. There is no homologous gene in humans because the evolutionary distance between humans and flies is so great b. The homologous gene in humans is expressed only in adults, not in human embryos c. The homologous gene is expressed in the head of human embryos d. The homologous gene is expressed near the rump of the human embryo

d. The homologous gene is expressed near the rump of the human embryo

Gap genes, segment-polarity genes, and homeotic genes (e.g., Hox genes) all _____. a. act independently of one another b. can be activated at any time during development c. are unique to Drosophila embryos d. code for regulatory transcription factors

d. code for regulatory transcription factors

Which of the following developmental processes would you not be able to observe under a microscope? a. Growth b. Differentiation c. Determination d. None of the above

d. none of the above

A benefit of the many steps after activation of a G protein is that they allow for a. Activation or inhibition of many enzymes within the cell b. Amplification of the signal c. Distribution of the signal throughout the inside of the cell d. Variation of the response from cell to cell e. All of the above

e. All of the above

In all of the previous experiments Dorothy used smooth muscle cells surrounding blood vessels. When she uses smooth muscle cells surrounding the stomach and the intestines, she observes that epinephrine causes those smooth muscle cells to relax. Why might the different types of smooth muscle cells show a different response to the same signal? a. The different smooth muscle cells express different receptors for epinephrine b. The different smooth muscle cells express similar receptors for epinephrine, but include different enzymes in the signal transduction pathway c. The different smooth muscle cells have different genes d. None of the above e. Both A and B

e. Both A and B

Which developmental processes can be induced by cell-cell communication? a. differentiation b. cell proliferation c. cell migration d. programmed cell death e. all of the above

e. all of the above

In signal transduction, phosphatases ________. a. move the phosphate group of the transduction pathway to the next molecule of a series b. prevent a protein kinase from being reused when there is another extracellular signal c. amplify the transduction signal so it affects multiple transducers d. amplify the second messengers such as cAMP e. inactivate protein kinases and turn off the signal transduction

e. inactivate protein kinases and turn off the signal transduction

Shh is also known to be involved in cranio-facial development. Humans with Shh mutations often have holoprosencephaly, a syndrome characterized by cranio-facial deformities, sometimes as severe as having only one centrally-located eye. Mouse models of holoprosencephaly also exist. In studying one such mouse model, scientists find that there is a normal amount and distribution of Shh protein in the cranio-facial region of embryonic mice, However, they discover that there is reduced phosphorylation of some key proteins required for normal development. Based on this information, name one component of a signaling pathway that is mutated. (signal, second messengers, kinases, phosphates, receptor, or target gene), and indicate where in the cell (plasma membranes, cytoplasm or nucleus) the receptor for Shh is located.

A receptor is located in the cytoplasm since the Shh protein is lipid soluble which makes the SHH receptor be cell surface.

A mouse has a mutation that results in severely reduced expression of Shh by the ZPA. What do you predict will happen to the number and type of digits? Why?

If there is a lower concentration of Shh it would produce a lower gradient digit such as digit 2.

Mice express a homologous regulatory gene to eyeless, Pax6m that encodes a transcription factor required for normal eye development in mice. If the mouse Pax6 gene is expressed in regions of the fly body besides the head, the ectopic eye tissue develops. The black arrows in the figure below indicate the ectopic tissue. Explain why the fly eyes, not mouse eyes, appear on the fly body where Pax6 is expressed.

The regulatory sequence between mice and flies are homologous which means they are very similar.

Certain mutations result in eyeless being expressed inappropriately in more posterior segments in the fruit fly. This results in the formation of little bumps of red eye tissue in those regions. Are these mutations in the promoter regulatory sequences or the coding region of the eyeless gene?

They are in the regulatory sequence because you still have eyes as normal in the same spot a usual.

Where would you expect to find tight junctions? a. Between the epithelial cells that make up an animal's skin b. Between the primary and secondary wall of a plant cell c. Between the smooth endoplasmic reticulum and the rough endoplasmic reticulum d. Between the extracellular layer and the plasma membrane of prokaryotic cells

a. Between the epithelial cells that make up an animal's skin

During Drosophila development, there is a regulatory cascade of gene activation. The proper sequence for this cascade is _____. a. Bicoid, gap genes, pair-rule genes, and segment polarity genes b. Bicoid, pair-rule genes, gap genes, and segment polarity genes c. Bicoid, segment-polarity genes, gap genes, and pair-rule genes

a. Bicoid, gap genes, pair-rule genes, and segment polarity genes

Muscle cells differ from nerve cells mainly because they ____. a. Express different genes b. Contain different genes c. Use different genetic codes d. Have unique ribosomes e. Have different chromosomes

a. Express different genes

Muscle cells differ from nerve cells mainly because they ________. a. Express different genes b. Contain different genes c. Use different genetic codes d. Have unique ribosomes e. Have different chromosomes

a. Express different genes

A G-protein receptor with GTP bound to it ________. a. Is in its active site b. Signals a protein to maintain its shape and conformation c. Will use cGMP as a second messenger d. Directly affects gene expression

a. Is in its active site

A G-protein with GTP bound to it____. a. Is in its active state b. Signals a protein to maintain its shape and conformation c. Will always use cGMP as a second messenger d. Directly affects gene expression

a. Is in its active state

Which of the following plays a major role in determining the anterior-posterior axis of the developing sea urchin? a. Morphogens from maternal genes b. Gap genes c. Pair rule genes

a. Morphogens from maternal genes

1. Which of the following statements regarding cell signaling is true? a. Paracrine signaling allows neighboring cells to communicate over relatively short distances. b. In endocrine signaling, signals are released from a cell and bind to receptors on its own cell membrane. c. Synaptic signaling is a type of autocrine signaling. d. Direct signaling is a type of signaling found only in plant cells.

a. Paracrine signaling allows neighboring cells to communicate over relatively short distances.

The duplication of homeotic genes has been significant in the evolution of animals because it____. a. Permitted the evolution of novel body forms b. Caused the extinction of major groups c. Reduced morphological diversity into simpler forms of life d. Allowed animals to survive on significantly fewer calories e. Eliminated the need for body segments in higher organisms

a. Permitted the evolution of novel body forms

What is a major difference between the extracellular matrix (ECM) of a plant cell and the ECM of an animal cell? a. Plant ECM is composed primarily of proteins, whereas animal ECM is mainly carbohydrates. b. Plant ECM is primarily carbohydrate in nature, whereas animal ECM is mainly proteins. c. Plant and animal ECMs are quite similar in structure and function.

a. Plant ECM is composed primarily of proteins, whereas animal ECM is mainly carbohydrates.

One characteristic of life and living systems is that they are able to adapt. In general, cells interact with other cells and their environment through the action of their ________. a. Plasma membrane and extracellular matrix b. Microtubular tracks c. Hormones d. Intracellular electrical currents

a. Plasma membrane and extracellular matrix

Ligands are signaling molecules that bind to receptors. Which of the following statements is true of ligands? a. The binding of a ligand to a receptor molecule causes the receptor to change shape b. All ligands are proteins c. Each ligand is only able to bind to one specific receptor. d. Ligands can bind to cell-surface receptors, but they cannot enter the cell.

a. The binding of a ligand to a receptor molecule causes the receptor to change shape

Gene expression in developing organisms is regulated on several different levels. In many developing animals, regulation of gene expression is influenced by the action of Hox gene. Which of the following regulatory elements is produced by many hox genes? a. Transcriptional factors b. Cell-surface molecules for cella cell interactions c. Signals from maternal cytoplasm, such as Bicoid d. mRNA processing factors

a. Transcriptional factors

You are working with salamander embryos in the early gastrula stage and you transplant cells destined to become neural tissue to a region that would normally form epidermis. As the embryo develops further, you find that the transplanted cells from epidermis instead of neural tissue. You repeat the experiment on a late- stage gastrula and find that as the embryo develops further, the transplanted cells form neural tissue. From these results, you can conclude that the cells being transplanted ______. a. Were determined to form neural tissue prior to the early gastrula stage b. Underwent morphogenesis between the early and late gastrula stages c. Became determined to become neural tissue between the early and late gastrula stages d. Differentiated into neural tissue between the early and late gastrula stages

a. Were determined to form neural tissue prior to the early gastrula stage

Since steroid hormones, such as estrogen and testosterone, are lipid soluble, they _____. a. bind to receptors inside the cell b. have very short-lived effects c. do not bind to receptors

a. bind to receptors inside the cell

In combination, the products of gap genes, pair-rule genes, and segmentation polarity genes _____. a. define the segmented body plan of the embryo b. reorganize the larval body into an adult body c. set up the dorsal-to-ventral axis of the larval body d. direct cell movements during differentiation

a. define the segmented body plan of the embryo

The activation of receptor tyrosine kinases is characterized by ________. a. dimerization and phosphorylation b. dimerization and IP3 binding c. a phosphorylation cascades d. GTP hydrolysis e. channel protein shape change

a. dimerization and phosphorylation

The duplication of homeotic (Hogenes has been significant in the evolution of animals because it ________. a. permitted the evolution of novel forms b. caused the extinction of major groups c. reduced morphological diversity into simpler forms of life d. allowed animals to survive on significantly fewer calories

a. permitted the evolution of novel forms

Insulin is a peptide hormone produced by the pancreas. Even though it circulates throughout the bloodstream, it affects only certain cells and tissue. This data would suggest that _____. a. target specificity is determined at the level of a receptor molecule on the surface of the cell b. target specificity is determined at the level of DNA c. insulin degrades before reaching all cells/tissues d. insulin is not transported to every part of the body

a. target specificity is determined at the level of a receptor molecule on the surface of the cell

Cell differentiation always involves ________. a. the production of tissue-specific proteins, such as muscle actin b. the movement of cells c. the transcription of the myoD gene d. the selective loss of certain genes from the genome e. the cell's sensitivity to environmental cues, such as light or heat

a. the production of tissue-specific proteins, such as muscle actin

Gene expression in developing organisms is regulated on several different levels. In many developing animals regulation of gene expression is influenced by the action of Hox genes. Which of the following regulatory elements is produced by many Hox genes? a. transcriptional factors b. cell-surface molecules for cell—cell interactions c. signals from maternal cytoplasm, such as Bicoid d. mRNA processing factors

a. transcriptional factors

Put the steps of the process of G-protein mediated signal transduction in the order they occur: 1. A conformational change in the signal-receptor complex activates an enzyme 2. Protein Kinases are activated 3. A signal molecule binds to a receptor 4. Target proteins are phosphorylated 5. Second messenger molecules are released a. 3,1,2,4,5 b. 3,1,5,2,4 c. 1,2,5,3,4

b. 3,1,5,2,4

In plants cells, the plasmodesmata _____. a. Prevents dehydration of adjacent cells b. Allows adjacent cells to adhere to one another c. adjacent cells

b. Allows adjacent cells to adhere to one another

When we compare animal development to plant development, we find that ____. a. Plant cells, but not animal cells, migrate during morphogenesis b. Animal cells, but not plant cells, migrate during morphogenesis c. Plant and animal cells migrate extensively during morphogenesis d. Neither plant nor animal cells migrate during morphogenesis

b. Animal cells, but not plant cells, migrate during morphogenesis

Gap genes, segment polarity genes, and homeotic genes all _____ a. Act independently of one another b. Code for regulatory transcription factors c. Can be activated at any time during development d. Are unique to drosophila

b. Code for regulatory transcription factors

Cortisol is a lipid-soluble, steroid hormone that is released by the human body during stressful conditions. It causes changes in activity in many different types of cells throughout the body including glycogen breakdown in the liver cells, salt and water balance in the kidney cells. And reducing the action of the immune cells. How can one hormone such as cortisol, cause any effects? a. Cortisol is produced in very small concentrations by nearly every tissue of the body b. Cortisol binds to specific receptors inside many kinds of cells; and because of different types of proteins in those cells, cortisol causes different cellular responses. c. Ells respond differently to cortisol depending on whether the signal receptor is located in the cell's plasma membrane or in the cytoplasm d. Lipid soluble, steroid hormones are repelled at the surface of cells

b. Cortisol binds to specific receptors inside many kinds of cells; and because of different types of proteins in those cells, cortisol causes different cellular responses.

In combination, the products of gap genes, pair-rule genes, and segmentation polarity genes ____. a. Initiate the organization of the larval body into an adult body b. Define the segmented body plan of the embryo c. Set up the dorsal-to-ventral axis of the larval body d. Direct cell movements during differentiation

b. Define the segmented body plan of the embryo

1. Which statement about development is true? a. Cell death does not play a role in morphogenesis b. Differential gene expression plays an important role in determining cell fate c. Throughout development, especially in animals, the range of possible cell fates becomes progressively less restricted d. The developmental potential of early embryonic cells is narrower than the potential of cells from more advanced embryos

b. Differential gene expression plays an important role in determining cell fate

Kinase enzymes in signal transduction pathways are often involved in... a. Binding to g-proteins b. Phosphorylation of proteins c. Synthesis of cyclic AMP d. Conversion of GTP to GDP

b. Phosphorylation of proteins

Heroin is a drug that stimulates the opioid receptors in brain cells. Many heroin addicts have consistently increased the amount of heroin that they take in order to feel the effects over time. If addicts go to rehab and stop using heroin for a number of months, they are more likely to overdoes if they relapse. This is because affects typically use the same amount of heroin after rehab as they did before rehab. Why does using the same amount of heroin lead to an overdose? a. Upregulation of heroin, follow by allergic response b. Downregulation of heroin, followed by allergic response c. Downregulation of opioid receptors during ongoing use of heroin pre-rehab, followed by upregulation of receptors during and post- rehab

c. Downregulation of opioid receptors during ongoing use of heroin pre-rehab, followed by upregulation of receptors during and post- rehab

Meristematic cells in plants are most similar to which kind of cells in animals? a. Somite cells b. Ectodermal cells c. Embryonic stem cells d. Mesodermal cells

c. Embryonic stem cells

Which sequence represents the correct cascade of gene action in determining the pattern of segmentation in Drosophila? a. Segment polarity, pair rule, gap b. Gap, segment polarity, pair rule c. Gap, pair rule, segment polarity d. Hox, pair rule, segment polarity, e. Segment polarity, pair rule, maternal effect

c. Gap, pair rule, segment polarity

Chicken embryos express both Hoxc6 and Hoxc8 in regions where ribs form, but only Hoxc6 is expressed in regions where forelimbs form. The fossilized jawbone of an extinct species of animak was found, and enough DNA was extracted to discover that it had both Hoxc8 and Hoxc6 genes. Which of the following is true about the development of limbs in this species? a. It definitely has forelimbs b. It definitely does not have forelimbs c. Limb development cannot be predicted without knowing the expression pattern of the two genes d. Can't tell because chicken genes tell us nothing about species

c. Limb development cannot be predicted without knowing the expression pattern of the two genes

The loss of webbing between the digits of chick feet during development is an example of: a. Cell proliferation b. Cell-cell interactions c. Programmed cell death

c. Programmed cell death

Most signal transduction pathways have essential components called ______ that increase the intensity and duration of the perceived signal. a. Amplifiers b. Receptors c. Second messengers d. G-protein

c. Second messengers

Acetylcholine is a neurotransmitter that binds to receptors on skeletal muscle cells. The receptor's signal complex brings about a series of events that result in contraction of skeletal muscle. Botulinum toxin prevents the release of acetylcholine from nearby, secretory cells. What would botulism do to its victims? a. The victim's cell receptors would no longer be capable of binding acetylcholine b. The victims cell receptors would be able to bind acetylcholine but at a rate far greater than normal c. The victim's muscles would be unable to contract d. The victim's muscles would be unable to relax

c. The victim's muscles would be unable to contract

What do the cell walls of plants and the extracellular matrix of animal cells have in common? a. They are largely composed of phospholipids and glycoproteins. b. Their proteins are made by free cytoplasmic ribosomes. c. They form rigid structures that provide structural support for cells but limit their expansion. d. They limit the passage of small molecules. e. They have functional connections with the cytoskeleton inside the cell.

c. They form rigid structures that provide structural support for cells but limit their expansion.

Different body cells can respond differently to the same peptide hormones because ________. a. different target cells have different sets of genes b. each cell converts that hormone to a different metabolite c. a target cell's response is determined by the components of its signal transduction pathways d. the circulatory system regulates responses to hormones by routing the hormones to specific targets e. the hormone is chemically altered in different ways as it travels through the circulatory system

c. a target cell's response is determined by the components of its signal transduction pathways

Protein Kinase is an enzyme that _____. a. functions as a second messenger molecule b. serves as a receptor for various signal molecules c. activates or inactivates other proteins by adding a phosphate group to them d. produces second messenger molecules

c. activates or inactivates other proteins by adding a phosphate group to them

Phosphorylation cascades involving a series of protein kinases are useful for cellular signal transduction because they ________. a. are species specific b. always lead to the same cellular response c. amplify the original signal many times d. counter the harmful effects of phosphatases e. use a small and fixed number of molecules

c. amplify the original signal many times

What is mutated in PITX1 in freshwater sticklebacks? a. coding region b. mRNA c. regulatory sequences within the promoter d. exons

c. regulatory sequences within the promoter

The receptors for steroid hormones are located inside the cell instead of on the membrane surface like most other signal receptors. This is NOT a problem for steroids because ________. a. the receptors can be readily stimulated to exit and relocate on the membrane surface b. steroids do not directly affect cells but instead alter the chemistry of blood plasma c. steroid hormones are lipid soluble d. so they can readily diffuse through the lipid bilayer of the cell membrane e. steroids must first bond to a steroid activator, forming a complex that then binds to the cell surface

c. steroid hormones are lipid soluble

Some intercellular signals require transduction. Which one of the following signals requires cellular transduction to initiate a cellular response? a. A tertiary messenger produced by the enzyme adenylate cyclase b. A signal that binds to a receptor in the cytoplasm c. A signal that binds to a receptor in the membrane of the nucleus d. A lipid-insoluble signal

d. A lipid-insoluble signal

Pemphigus vulgaris is an autoimmune disorder in humans in which antibodies are produced against proteins that make up the desmosomes. The blistering of the skin and mucous membranes characteristic of this disorder is probably a result of ____. a. Decrease in flexibility of the cell membrane b. An inadequate number of G-protein receptors c. An inadequate production of cytoskeletal proteins d. A loss in cell-cell adhesion

d. A loss in cell-cell adhesion