photosynthesisWhere does the Calvin cycle take place?

*a. stroma of the chloroplast

b. thylakoid membrane

c. cytoplasm surrounding the chloroplast

d. chlorophyll molecule

e. outer membrane of the chloroplast

In a plant cell, where are the ATP synthetase complexes located?

a. A. stroma of the chloroplast

b. B. thylakoid membrane

c. C. outer membrane of the chloroplast

d. D. inner membrane of the mitochondria

*e. choices B and D are both correct

What key component is necessary for photosystems to harvest light?

a. vesicles

b. NADP reductase

*c. pigment molecules

d. ATP synthase

e. Calvin cycle

Which of the following are products of the light reactions of photosynthesis that are utilized in the Calvin cycle?

a. CO2 and glucose

b. H2O and O2

c. ADP, Pi, and NADP+

d. electrons and H+

*e. ATP and NADPH

Which of the following are true about photorespiration?

a. A. It is an apparently wasteful side reaction of ribulose bisphosphate carboxylase (Rubisco).

b. B. It is a useful supplement to cellular respiration.

c. C. It is minimized in C4 plants due to specialized photosynthetic pathways and leaf architecture.

d. All of the above.

*e. Choices A and C are both correct.

Photosystem II strips electrons from chlorophyll and delivers them to the chloroplast electron transport (cytochrome) chain.  Where do the replacement electrons come from?

a. splitting O2     b. photosystem I *c. splitting H2O d. splitting CO2 e. NADPH

Where is the chlorophyll located in a plant? a. Cristae b. Plasma membrane of the cell c. Outer membrane of the chloroplast *d. Thylakoid membrane e. Stroma

The dry biomass of three treatments at the end of the experiment is shown above.Most of the biomass that accumulates in the presence of light and water comes from:

a. Water during photosynthesis. b. The building of carbohydrates during respiration. c. The release of CO2 during respiration. *d. The incorporation of CO2 into carbohydrates during the Calvin cycle.

Cell signalingReceptors are

*a. proteins that change conformation upon interaction with a stimulus b. genes that change expression in response to a stimulus c. phosphorylation cascades  that control cellular responses d. specialized organelles that perceive environmental signals e. all of the above

The process by which information from a cell’s environment is perceived and relayed to control a cellular response is known as

*a. signal transduction b. chemotaxis c. meiosis d. translation e. impulsive respondus

Cell communication a. requires cytoplasmic connections. b. only occurs over short distances. c. controls mitotaxis. d. involves the exchange of genes. *e. coordinates developmental processes in multicellular organisms.

Your textbook defines three categories of cell surface receptors that respond to extracellular signals.  They are:

a. Ligand-gated ion channels, steroid receptors, G-protein coupled receptors *b. Enzyme-linked receptors, G-protein coupled receptors, ligand-gated ion channels c. Steroid receptors, enzyme-linked receptors, G-protein couple receptors d. Ligand-gated channels, exocrine receptors, G-protein couple receptors e. Exocrine receptors, enzyme-linked receptors, ligand-gated ion channels

What is the likely mechanism by which a G-protein coupled receptor might transduce and amplify a signal intracellularly?

a. By upregulating the expression of a transporter. *b. By promoting the production of a second messenger. c. By degrading a repressor.

What is the likely mechanism by which an enzyme-linked receptor might transduce and amplify a signal intracellularly?

*a. By activating a protein kinase cascade. b. By degrading a repressor. c. By upregulating the expression of a transporter. 

What benefits do hormone signaling provide for a multicellular organism? a. Long distance cellular communication. b. Amplification of weak signals. c. Coordination of bodily functions d. Protection from pathogen attack. e. None of the above *f. All of the above  

From the graph above showing the amount of ligand bound to the receptor at different ligand concentrations, what do you estimate to be the Kd for ligand/receptor interaction as shown?

a. About 1 pM

*b. About 5 pM

c. About 15 pM

d. About 30 pM

e. About 60 pM

If you did another experiment with the same ligand, only this time you add a fixed amount of a weak competitive inhibitor of the ligand along with the ligand, which of the following would be true? Note: You are still measuring the amount of ligand bound while increasing the ligand concentration.

a. The Kd will decrease.

b. The maximum binding will decrease.

*c. The Kd will increase. 

With reference to the above diagram from your textbook. The G-protein is activated….(finish the sentence)

a. when the β/γ dimer associates with the α subunit.

b. when ATP concentrations are high enough to activate adenylyl cyclase.

*c. by the dissociation of the β/γ dimer from the αsubunit.

d. by the exchange of ATP for GTP.

e. All of the above

f. None of the above

 

With reference to the above diagram from your textbook.  Epinephrine acts …. (finish the sentence)

a. bythe GPCR transducing the signal across the plasma membrane.

b. by promoting the dissociation of the G-protein β/γ dimer from the α subunit.

c. by producing a second messenger (cyclic adenosine monophosphate).

*d. All of the above.

e. None of the above.

In response to unidirectional light… (Finish the sentence) a. a plant seedling will bend away from the light. b. the hormone auxin will accumulate on the side facing the light. *c. the side facing the light will grow more slowly than the side away from the light. d. the hormone auxin will slow growth on the side of the seedling to which the hormone accumulates. e. All of the above. 

 Indoleacetic acid (IAAH) is an example of an auxin, a plant hormone.  Its chemical structure is depicted in the figure above.  Many plant cells also express an auxin influx carrier protein (pink in the figure).  Why is this carrier protein expressed?

a. IAAH cannot cross the membrane without a carrier protein.

*b. Depending upon the pH, IAAH may not be able to cross the membrane.

c. The carrier protein transports the auxin across the plant cell wall.

d. All of the above.

The localized expression patterns of auxin efflux carrier proteins influence the direction of auxin transport.  These expression patterns are dynamic and change in response to environmental signals.  Would the PIN protein expression pattern in cell

A or cell B represent the condition when auxin transport towards the roots needs to be increased?

*a. Cell A

b. Cell B

 The figure above illustrates the activation and inactivation of a G protein-coupled receptor.  If a nonhydrolyzable form of GTP, a form that does not loose the terminal phosphate group to form GDP, was added to cells, which of the following would be true?

a. The ligand would not bind to the receptor.

b. The αβγ subunits of the G protein would not dissociate.

*c. Once activated, signaling through the receptor would continue for a longer time than normal.

d. None of the above

e. All of the above

The figure above illustrates signaling through the EGF receptor.  Which of the following would represent a gain-of-function situation for the EGF receptor?

a. A mutation in the EGF receptor that binds ligand, but does not allow the receptor to dimerize.

b. Deletion of the gene encoding Erk

c. Increased cell division due to the inactivation of a tumor suppressor

*d. Deletion of the ligand binding domain of the EGF receptor so that it becomes ligand independent

e. None of the above

f. All of the above

The figure above illustrates signaling through the EGF receptor.  Which of the following would represent a loss-of-function situation for the EGF receptor?

a. A constitutively active from of the Ras protein.

b. Deletion of the ligand binding domain of the EGF receptor so that it becomes ligand independent

*c. A mutation of the EGF receptor so that it can no longer be phosphorylated.

d. All of the above

e. None of the above

 

 

You want to test the hypothesis that EGF receptor activation is sufficient for stimulate cell division in cultured epithelial cells.  Which of the following would potentially test your hypothesis?

a. A. Forcing expression of the Her2 protein in the cultured cells. The Her2 form of the EGF receptor is constitutively active.

b. B. Add epidermal growth factor to the cell culture medium.

c. C. Add GDP to the cell culture medium

d. All of the above

*e. A and B above

 

You want to test the hypothesis that Ca2+ release is necessary to form activated calmodulin.  Which of the following is the best test your hypothesis?

a. Add a Ca2+ionophore to the cell culture medium. Ca2+ionophores form Ca2+ permeable channels in cell membranes.

b. Inhibit the activity of G protein-coupled receptors

*c. Deplete the cells of Ca2+ and then activate phospholipase C leading to IP3 release.

Which is NOT a hormone found in animals: a. Amine b. peptide *c. auxin d. steroid

Which is true about hypothalamus and pituitary: a. Hypothalamus makes neurohormones b. The neurohormones travel to anterior pituitary c. Anterior pituitary can synthesize different hormones to regulate various processes *d. All of the above

20. If Iodine (I) is missing in the diet, what will happen to the thyroid gland:

*a. increase in size b. decrease in size c. remain the same d. none of the above

In pancreas, two hormones, Insulin and Glucagon, function antagonistically to regulate blood glucose level. Insulin functions to:

a. Increase blood glucose level *b. Decrease blood glucose level c. Does not change blood glucose leveld)None of the above

In pancreas, two hormones, Insulin and Glucagon, function antagonistically to regulate blood glucose level. Glucagon functions to:

*a. Increase blood glucose level b. Decrease blood glucose level c. Does not change blood glucose level d. None of the above

Under stress conditions, hypothalamus produce Cortcotropin-releasing hormone (CRH) and pituitary produces Adrenocorticotropic hormone (ACTH). Which is NOT true:

a. CRH in hypothalamus controls the production of ACTH in pituitary *b. ACTH in pituitary controls the production CRH in hypothalamus c. ACTH in pituitary can stimulate adrenal gland to produce stress hormone such as glucocorticoid d. glucocorticoid regulates many stress responses

In pituitary giants, growth hormone levels are: a. Decreased *b. Increased c. Not changed d. None of the above

Cell specializationMulticellularity/specializationWhich of the following is an example of extracellular matrix

a. Collagen b. Fibronectin c. Chitin *d. All of the above e. None of the above 

Which of the following is a function of the extracellular matrix (ECM)? a. Strengthening cell-cell and tissue-tissue contacts b. Providing support. Tissues such as bone are largely ECM. c. Mediating cell signaling *d. All of the above e. None of the above

Which of the following is true of the plant cell wall? a. It forms a barrier making plant cells resistant to osmotic lysis. b. A major component is cellulose. c. A major component is glucose. d. It is composed of a primary and a secondary cell wall, each with distinctive properties. *e. All of the above f. None of the above

Which of the following is true of the plant cell wall? a. It strengthens cell-cell and tissue-tissue contacts. b. A major component is cellulose. c. A major component is glucose. *d. All of the above e. None of the above

Which of the following is true about collagen? a. It is a triple helix made up of identical subunits. b. It is a triple helix made up of different types of subunits. c. There are at least 27 different collagen proteins in humans. d. Differential gene expression helps regulate which collagens are expressed in specific tissues and locations in the body. *e. All of the above f. None of the above

Given the information in the table above, which of the following is a reasonable conclusion?

a. All collagens have similar physical characteristics.

b. Collagens only form long fibers.

c. Collagens are not found throughout the body.

*d. Collagens are found in the extracellular matrix of cells.

26.

Given the information in the table above, which of the following is a reasonable conclusion?

a. All collagens have similar physical characteristics.

*b. Collagens form fibers that can be rigid, flexible, elastic, or form meshworks.

c. Collagens are not found throughout the body.

d. Collagen fibers are found within cells.

Why would it be important to have epithelial layers lining compartments such as the intestine?

a. For cellular communication via gap junctions *b. To strictly control what substances cross the barrier c. To create a smooth surface d. To secrete ECM molecules onto the surface e. A  and C

Which of the following statements about the extracellular matrix is most correct?

a. It is composed of living cells.

b. It is a site of electron transport. c. It is composed of lipopolysaccharides. d. It is a static, rigid structure. *e. Its components are produced and secreted by the cell.

 Tight junctions -

a. connect the cytoplasm of one cell to another. b. are composed of pectin. c. connect cells to the extracellular matrix. *d. form seals that prevent solutes from diffusing in between cells. e. pair chromosomes during meiosis.

All but which of the following are involved in physically holding cells together?

a. Extracellular matrix b. anchoring junctions *c. paracrine ligands d. middle lamella e. cell adhesion molecules

Which of the following processes are important for normal development? a. cell division b. cell migration c. cell differentiation d. programmed cell death e. A,B,C *f. all of the above

The kidneys are able to regulate salt concentration in the blood because a. the endoplasmic reticulum performs dialysis b. osmosis concentrates salt in kidney cells *c. sodium transporters pump Na+ ions across the epithelium separating capillary blood from renal ducts d. electron transport produces a negative charge that attracts Na+ ions e. Na+ is selectively filtered through the extracellular matrix

Cellulose is *a. found in the plant extracellular matrix b. a component of the cytoskeleton c. associated with DNA to form chromosomes d. produced in chloroplasts e. a type of proteoglycan

The figure above from your textbook shows some of the features of collagen synthesis and assembly. Which of the following is a true statement?

a. Collagen fibers consist of a bundle of collagen fibrils made up of a single collagen molecule.

b. Collagen is initially synthesized as a procollagen that is then assembled into large multimeric macromolecules in the cell.

*c. Procollagen assembles into collagen fibrils after removal of the extension sequences.

d. Procollagen synthesis does not require a signal sequence.

36.

The figure above from your textbook shows some of the features of collagen synthesis and assembly. Which of the following is a true statement?

a. Collagen fibers consist of a bundle of collagen fibrils made up of a single collagen molecule.

b. Collagen is initially synthesized as a procollagen. Procollagen is then assembled into large multimeric macromolecules in the cell.

c. Procollagen spontaneously assembles into collagen fibrils.

*d. Procollagen synthesis requires a signal sequence.

The figure above from your textbook shows some of the features of collagen synthesis and assembly. Which of the following is a true statement?

a. Collagen fibers consist of a bundle of collagen fibrils made up of a single collagen molecule.

*b. Collagen is initially synthesized as a procollagen that is then exported from the cell.

c. Procollagen spontaneously assembles into collagen fibrils.

d. Procollagensynthesis does not require a signal sequence.

What is the purpose of cell-cell junctions

a. To keep the extracellular matrix from breaking

*b. To link cells together in various ways

c. To facilitate the movement of cells

d. To make sure that cells will obtain food

39.

Which types of cell-cell junctions allow form a seal between intestinal epithelial cells?

*a. Tight junctions

b. Anchoring junctions

c. Gap junctions

Which types of cell-cell junctions allow for the passing of small molecules between cells?

a. Tight junctions

b. Anchoring junctions

*c. Gap junctions

Which types of cell-cell junctions have close assocations with the cytoskeleton?

a. Tight junctions

*b. Anchoring junctions

c. Gap junctions

The figure above is from your textbook. It shows an electron micrograph of two intestinal epithelial cells from an experiment where lanthanum, an electron dense element, was injected into the bloodstream of a mouse. What outcome would you predict if the mouse was fed lanthanum rather than injected with it?

a. The lanthanum would be observed on both sides of the tight junction.

*b. The lanthanum would be observed on the apical side of the tight junction.

c. The lanthanum would be observed on the basal side of the tight junction.

d. The lanthanum would not be seen as it would be degraded in the digestive tract.

Which of the following statements about epithelial cells is true? a. Epithelia are only found on the outer surfaces of organisms. b. Epithelia are a single cell layer thick. *c. Epithelia are tightly adherent cells. d. All of the above e. None of the above

Most multicellular organisms have which of the following? a. An outer cell layer that separates the organism from the environment. b. Cell-cell communication

c. A transport system that allows fluids to move within the organism. *d. All of the above e. None of the above

What is a function of the extracellular matrix? a. To support the organism b. To help arrange cells in space c. To help cells sense and respond to environmental changes *d. All of the above e. None of the above 

Pattern formation involves which of the following? a. Axis information provided by the mother b. Cell-cell communication c. Gradients of morphogens d. The influence of gravity *e. All of the above f. None of the above

Pattern formation involves which of the following? a. The expression of homeotic genes b. Differential gene expression c. Communication of anterior-posterior and dorsal-ventral axis information d. The influence of gravity *e. All of the above f. None of the above

Which of the following statements is true? a. A finger muscle cell and a finger skincell express similar pattern formation genes, but the muscle expresses mesoderm genes and the skin cell expresses endoderm genes. b. An arm neuron and a leg skin cell express different pattern formation genes, but both expressed common endoderm genes before diverging into neuronal and epidermal lineages. *c. Morphogens function in a concentration-dependent manner. d. Once cells occupy a specific region in the embryo, they differentiate only based on their history or lineage.

Which of the following statements illustrate the principle of differential gene regulation?

a. Neurons have a different mRNA profile than muscle cells. b. Only a subset of cells will respond to the presence of a hormone. c. Many cells express the same set of actin proteins, but at different levels. *d. All of the above

e. None of the above

In extracellular cellular matrix (ECM), Elastin protein: a. provides tensile strength *b. provides elasticity c. provides both strength and elasticity d. none of the above

In extracellular cellular matrix (ECM), collagen protein: *a. provides tensile strength b. provides elasticity c. provides both strength and elasticity d. none of the above

What is the major component in plant cell wall: a. Collagen b. Elastin *c. Cellulose d. Chlorophyll

In animal cells, the cell junctions can be: a. Anchoring junctions b. Tight junctions c. Gap junctions *d. All of the above

In anchoring junctions, there are two kinds of cell adhesion molecules (CAMs), cadherin and integrin. The function of integrin is:

a. to create cell-to-cell junctions *b. to create connections between cells and ECM (extracellular matrix) c. to mediate both cell-to-cell and cell-to-ECM interactions d. None of the above

In anchoring junctions, there are two kinds of cell adhesion molecules, cadherin and integrin. The function of cadherin is:

*a. to create cell-to-cell junctions b. to create connections between cells and ECM (extracellular matrix) c. to mediate both cell-to-cell and cell-to-ECM interactions d. None of the above

Gap junctions function to: a. Connect cells to the extracellular matrix

*b. Permit the passage of molecules from the cytoplasm of one cell to another c. Form tight seals that prevent extracellular fluids from leaking between cells d. None of the above

Tight junctions function to: a. Connect cells to the extracellular matrix b. Permit the passage of molecules from the cytoplasm of one cell to another *c. Form tight seals that prevent extracellular fluids from leaking between cells d. None of the above

During limb formation, which is NOT true: a. Cell division promotes the growth of the limb b. Cell migration causes cells to reach to their correct location c. Cell differentiation produces specialized cells d. Apoptosis eliminates cells in between the fingers *e. Cells undergo meiosis

Pattern formation during development can be determined/influenced by: a. Morphogens b. Cell contacts c. Cell signaling *d. All of the above

Which is not true about Bicoid: a. is a morphogen that regulates Drosophila embryo polarity b. the gene is transcribed in nurse cells and transported into anterior end of Oocyte c. is a transcription factor *d. Mutation of its genes leads to embryos with two heads

Drosophila embryos have 15 segments, the identity of which is determined by:

a. Bicoid b. Gap genes c. Pair-rule genes d. Segment-identify genes *e. A transcriptional hierarchy of Bicoid/Gap genes/Pair-rule genes/Segment identity genes

The segment identity gene, Bithorax, determines that two wings form in the 2nd thoracic segment, in the bithoraxt mutant, there are:

a. 2 wings at 2nd thoracic segment b. 2 wings at 3rd thoracic segment *c. 2 wings at 2nd thoracic segment and 2 wings at 3rd thoracic segment d. None of the above

If the homeotic gene Antennapedia is ectopically expressed in embryonic segment that gives rise to antenna, the fly will have:

*a. legs form in the place for antenna b. legs everywhere c. legs in abdomen d. None of the above

Above is a model for flower patterning in Arabidopsis. If you mutate C function gene (AG), what the four wholes will be:

a. Sepal-Petal-Stamen-Carpel

b. Sepal-Sepal-Petal-Petal

c. Sepal-Petal-Sepal-Petal

*d. Sepal-Petal-Petal-Sepal

The figure shown above represents the chromosome locations and expression patterns of homeotic genes (Hox or Hom genes) in Drosophila and mice. Which of the following statements is consistent with the information shown?

a. Mice have more Hox genes than Drosophila.

b. The anterior to posterior expression patterns of Hox gene expression is conserved.

c. The Abdominal B genes were likely duplicated multiple times over the course of evolution.

*d. All of the above

e. None of the above

The figure shown above illustrates the expression domains of homeotic genes (Hox genes) in chickens and mice. Which of the following statements is consistent with the information shown?

a. Chickens and mice express similar sets of Hox genes in the same anterior to posterior order.

b. The different body morphologies between mice and chickens is due in part to changing the domains of the expression of Hox genes.

c. The locations of forelimbs and hindlimbsis governed by conserved mechanisms in vertebrates.

*d. All of the above

e. None of the above

The figure shown above illustrates the expression domains of homeotic genes in Arabidopsis. What would the pattern of structures be (Whorl 1 to Whorl 4) for a loss-of-function mutant in B?

a. Sepals, Petals, Stamens, Carpels

b. Sepals, Sepals, Stamens, Stamens

*c. Sepals, Sepals, Carpels, Carpels

d. Carpels, Stamens, Stamens, Carpels

The figure shown above illustrates the expression domains of homeotic genes in Arabidopsis. What would the pattern of structures be (Whorl 1 to Whorl 4) for a loss-of-function mutant in C? C limits the domain of expression of A.

*a. Sepals, Petals, Petals, Sepals

b. Sepals, Sepals, Stamens, Stamens

c. Sepals, Sepals, Carpels, Carpels

d. Carpels, Stamens, Stamens, Carpels

The figure shown above illustrates the expression domains of homeotic genes in Arabidopsis. What would the pattern of structures be (Whorl 1 to Whorl 4) for a loss-of-function mutant in A? A limits the domain of expression of C.

a. Sepals, Petals, Stamens, Carpels

b. Sepals, Sepals, Stamens, Stamens

c. Sepals, Sepals, Carpels, Carpels

*d. Carpels, Stamens, Stamens, Carpels

A mouse lacking both copies of MyoD does not show a phenotype. It forms muscle. Based on this experiment, what could you conclude about the function of MyoD?

a. MyoD is sufficient for muscle cell differentiation under these conditions. b. MyoD is NOT sufficient for muscle cell differentiation under these conditions. c. MyoD is necessary for muscle cell differentiation under these conditions. *d. MyoD is NOT necessary for muscle cell differentiation under these conditions.

What has happened in the mutant larva (b), a loss of function situation, to result in the phenotype shown?

a. a DNA mutation caused bicoid to be over-expressed, causing both ends to become posterior

*b. a DNA mutation caused bicoid to not be expressed, causing both ends to become posterior

c. the normal larva was transformed into one with two spiracles

d. All of the above

e. None of the above

Shoot lateral meristems are……(Finish the sentence) a. totipotent stem cells *b. pluripotent stem cells c. bipotent stem cells d. determined cells e. All of the above f. None of the above 

Root meristems are……(Finish the sentence) a. totipotent stem cells *b. pluripotent stem cells c. bipotent stem cells d. determined cells e. All of the above f. None of the above

Shoot apical meristems are……(Finish the sentence) a. totipotent stem cells *b. pluripotent stem cells c. bipotent stem cells d. determined cells e. All of the above

f. None of the above

A loss-of-function mutation in a Drosophila melanogaster gene called dorsal causes a pattern defect in the fly embryo. Mutant embryos are completely dorsalized; that is, dorsal structures form where there should be ventral structures. What does this tell us about the normal function of the dorsal+ gene?

a. That it is required for producing dorsal structures. b. That it is not required for producing dorsal structures. *c. That it is required for making ventral structures. d. That it is not required for making ventral structures. e. None of the above.

A molecule that during development provides positional information via a concentration gradient is known as a

a. transcription factor b. exon c. endocrine signal d. plastochron *e. morphogen

 Zebrafish is used as a model organism to study development because

a. their embryos are almost identical to humans b. they live longer than other fish c. they have synchronous cell division cycles d. they reproduce apomictically

*e. they have rapid generation times

In plant development, the following is NOT true of shoot apical meristems

*a. they only occur in embryos b. they involve pattern formation, morphogens, transcriptional hierarchies, progressive restriction of cell fate c. they occur at the tips of shoots and roots d. they are a self-renewing cell population (like animal stem cells) e. Continually produce organs, tissues, ect. 

Which of the following is NOT true of homeotic genes that control the identity of flower organs?

a. Mutants show changes in organ identity b. They encode transcription factors c. They function in a transcriptional hierarchy d. They function combinatorially *e. All these statements are true.

In plant development, what makes flower organs (petals, stamens, etc.) different from each other?

a. Each inherits different genes *b. Each expresses different genes c. Each discards different genes d. Each gene codes different proteins in different organs e. Each organ inherits different morphogens. 

Which of the following DOES NOT contribute to the differentiation of stem cell daughters?

a. transcriptional hierarchy b. cell signaling c. progressive restriction of cell fate *d. altered genetic content e. altered gene expression

Loss-of-function mutations in a gene called Pax6 cause mammal or fish embryos to not form eyes. What is the normal function of the Pax6gene?

*a. It is required for eye formation b. It blocks eye formation c. It is a morphogen d. It signals formation of an R8 cell. e. The function cannot be determined from the information given.

Expression of segment identity genes in Drosophila embryogenesis is determined by

*a. A transcriptional hierarchy b. Stem cells c. The dorsal-ventral axis d. Mutants e. Ommatidial signaling

In bone marrow, there are hematopoetic stem cells (cells that generate blood) and other cells called stromal cells. Stromal cells express a protein called ”kit”. Injecting mice bone marrow with anti-kit antibodies causes inactivation of the kit protein and results in a dramatic decrease in the number of hematopoetic stem cells. The most likely function for the kit protein is

a. a ribosome b. an ion channel c. a membrane receptor *d. a secreted signaling ligand e. a cell adhesion molecule

The Hox gene complex is a cluster of genes that a. Controls parasympathetic neural signaling b. Controls alternation of generations in plants c. Encode a signal transduction pathway that promotes oogenesis *d. Controls anterior-posterior body segment identities in vertebrates and insects e. Controls stem cell proliferation and differentiation