Deck 7: Cells, Tissues and Signals

Question 1

All animal tissues are composed of differentiated cells

A) surrounded by extracellular matrix.
B) with the same structure and function.
C) joined to one another by intercellular connections.
D) that function in a coordinated way.
E) All of the answers are correct.

Answer 1

that function in a coordinated way.

Question 2

In a physiology experiment, a zoologist observes that one connective tissue (A) has much greater tolerance for repeated bending than another (B). The most likely explanation for this difference is that the

A) extracellular matrix of A contains a greater proportion of collagen fibres.
B) extracellular matrix of A contains a greater proportion of elastin fibres.
C) cells in A bind more strongly to the extracellular matrix.
D) complex polysaccharides in the extracellular matrix of A form a more flexible gel.
E) extracellular matrix of A contains a greater proportion of fibronectin.

Answer 2

extracellular matrix of A contains a greater proportion of elastin fibres.

Question 3

Glycosaminoglycans

A) are complex polysaccharides that contribute to the hydration and porosity of the extracellular matrix.
B) are composed of repeating disaccharide units with a strong positive charge that attracts water and so provides cushioning against external forces.
C) are adhesive proteins that anchor cells to fibres within the extracellular matrix.
D) are structural proteins that allow the extracellular matrix to stretch and rebound without damage.
E) combine with structural proteins to form cross-linked fibres that allow the extracellular matrix to resist tension.

Answer 3

are complex polysaccharides that contribute to the hydration and porosity of the extracellular matrix.

Question 4

Occluding junctions are found between the epithelial cells lining the lumen of the intestine of mammals. They function to

A) fasten cells together into strong sheets.
B) cross-link the cytoskeleton network of one cell to that of adjacent cells.
C) maintain the correct location of different membrane proteins on the cell surface.
D) actively transport ions from one cell to another.
E) allow chemical and electrical communication between adjacent cells.

Question 5

Desmosomes are one type of intercellular connection found between the epithelial cells lining the lumen of the intestine of mammals. They function to

A) maintain the correct location of different membrane proteins on the cell surface.
B) prevent free movement of molecules between the lumen and the interstitial space.
C) allow chemical and electrical communication between adjacent cells.
D) actively transport ions from one cell to another.
E) cross-link the cytoskeleton network of one cell to that of adjacent cells.

Question 6

Communicating junctions are protein channels that

A) allow ions to cross freely between cells.
B) actively transport ions from one cell to the next.
C) prevent free-movement of molecules in the space between adjacent cells.
D) provide pathways of high electrical resistance.
E) use integrins to span the plasma membrane and link to a similar unit in an adjacent cell.

Question 7

Hemidesmosomes are

A) adherens junctions connecting the actin cytoskeletons of two adjacent cells.
B) adherens junctions providing mechanical support through the interaction of laminin fibres.
C) occluding junctions that prevent the movement of molecules through the spaces between cells.
D) anchoring junctions that connect the actin cytoskeleton of cells to the extracellular matrix.
E) communication junctions that form open channels between adjacent cells.

Question 8

The nervous systems of lobsters include giant axons, which are connected so that electrical signals spread directly from one cell to the next without delay, and with no loss of signal strength. The intercellular connections between giant axons are

A) tight junctions.
B) gap junctions.
C) desmosomes.
D) adherens junctions.
E) cadherins.

Question 9

After observation under the microscope, an animal tissue was described as being composed of stratified, squamous epithelial cells. The tissue was a

A) multiple layer of cube-shaped cells.
B) single layer of elongated cells.
C) single layer of flattened cells.
D) multiple layer of flattened cells.
E) single layer of cube-shaped cells.

Question 10

Biochemical analysis of a particular tissue shows high levels of the protein collagen. This tissue must be

A) nervous tissue.
B) connective tissue.
C) cartilage.
D) epithelial tissue.
E) muscle tissue.

Question 11

A particular tissue is observed under the microscope and found to consist of bundles of cylindrical cells of variable length and diameter. The cells have a striated appearance and individual cells contain multiple peripheral nuclei. There is no extracellular matrix. This tissue is most likely to be

A) smooth muscle tissue.
B) cardiac muscle tissue.
C) skeletal muscle tissue.
D) fibrous connective tissue.
E) stratified epithelial tissue.

Question 12

Neurons are highly specialised cells that are assisted in normal functioning by

A) glial cells.
B) dendritic cells.
C) myelin cells.
D) companion cells.
E) the extracellular matrix.

Question 13

Secondary plant cell walls are strengthened by

A) the polyphenolic compound lignin.
B) the arrangement of cellulose microfibrils.
C) cement-like polysaccharides called pectins.
D) the arrangement of groups of rigid plasmodesmata.
E) the acetylglucosamine polymer chitin.

Question 14

Plasmodesmata

A) are fine channels across the cell wall that link the plasma membranes and cytosols of adjacent plant cells.
B) connect and support the cell walls of adjacent plant cells through networks of cytoskeletal elements.
C) are integrin protein links similar to tight junctions in animal cells, which maintain the correct location of different membrane proteins.
D) are transmembrane protein channels that connect adjacent plant cells and allow ions to cross freely between them.
E) link cell walls to form tight barriers that prevent the free movement of molecules through the interstitial spaces between plant cells.

Question 15

Unlike animal organs, the organs of vascular plants are

A) surrounded by an epidermis of closely packed cells covered by a water-insoluble cuticle.
B) each composed of a single tissue system.
C) composed of the same number of tissues but with different arrangements.
D) composed of variable numbers and arrangements of tissues.
E) not composed of tissues.

Question 16

The three major tissue systems of vascular plants are

A) dermal, ground and meristem.
B) meristem, xylem and phloem.
C) dermal, vascular and ground.
D) meristem, ground and vascular.
E) dermal, phloem, xylem.

Question 17

Cells in the apical meristems of the roots of vascular plants divide by mitosis to produce

A) vascular tissue.
B) dermal tissue.
C) ground tissue.
D) vascular tissue and dermal tissue.
E) vascular tissue, dermal tissue and ground tissue.

Question 18

Which tissue system of vascular plants is analogous to epithelial tissue in animals?

A) Ground tissue.
B) Dermal tissue.
C) Vascular tissue.
D) Cuticle.
E) None of the tissue systems of vascular plants is analogous to epithelial tissue.

Question 19

Cells of the yeast Saccharomyces cerevisiae use chemical signalling to identify individuals of the opposite mating type and initiate the mating process. Each cell secretes a mating factor that binds to receptor proteins on the other cell. You would expect successful mating to occur between cells with

A) identical mating factors and receptor proteins.
B) identical mating factors and complementary receptor proteins.
C) complementary mating factors and identical receptor proteins.
D) complementary mating factors and receptor proteins.
E) complementary mating factors and cAMP receptors.

Question 20

Lipid-soluble ligand-receptor complexes trigger a cellular response by

A) changing the permeability of the plasma membrane.
B) activating an enzyme.
C) adhering to the surface of the plasma membrane.
D) altering the expression of a gene.
E) binding a G-protein and inducing the production of cAMP.

Question 21

Cell adhesion molecules

A) are ligands, located on the surface of cells or bound to the extracellular matrix.
B) bind to a specific sequence in DNA to induce gene expression.
C) are membrane-bound signal molecules on the surface of a cell.
D) are produced by a cell in response to a direct interaction between membrane-bound receptors and surface ligands on other cells or the extracellular matrix.
E) bind to ligands on the surfaces of other cells or components of the extracellular matrix.

Question 22

Mechanoreceptors respond to physical stimuli including

A) stretch and motion.
B) touch and membrane depolarisation.
C) gravity and magnetic fields.
D) sound and light.
E) mechanical distortion and electrical fields.

Question 23

A type of sensory organ found in many invertebrates consists of a spherical, fluid filled chamber that contains grains of sand or other dense granules. The cells lining the chamber are mechanoreceptors with sensitive cilia that project into the lumen. The granules settle at the low point within the chamber, deforming the cilia underneath and stimulating the cells directly below them. In this sensory organ, the cells lining the chamber are mechanoreceptors specialised for detecting

A) pressure.
B) vibration.
C) stretch.
D) mechanical distortion.
E) touch.

Question 24

A type of sensory organ found in many invertebrates consists of a spherical, fluid filled chamber that contains grains of sand or other dense granules. The cells lining the chamber are mechanoreceptors with sensitive cilia that project into the lumen. The granules settle at the low point within the chamber, deforming the cilia underneath and stimulating the cells directly below them. In this sensory organ, the responses of multiple mechanoreceptors are combined to enable the detection of

A) movement.
B) pressure.
C) gravity.
D) temperature.
E) sound.

Question 25

When the vertebrate retina is exposed to light

A) production of the photopigment rhodopsin in photoreceptors is increased.
B) the rate of neurotransmitter released from photoreceptors is decreased.
C) the plasma membranes of photoreceptors become depolarised.
D) the photoreceptor rhodopsin changes shape and binds the cyclic nucleotide cGMP.
E) cilia protruding from photoreceptors are distorted.

Question 26

Mammals have cold-sensitive nerve cells, which respond to decreasing temperature and warm-sensitive nerve cells, which respond to increasing temperature. Detection of an increase in temperature leads to

A) a decrease in the frequency of nerve impulses from warm-sensitive receptors and an increase from cold-sensitive receptors.
B) a decrease in the frequency of nerve impulses from cold-sensitive receptors and no change in the frequency of nerve impulses from warm-sensitive receptors.
C) an increase in the frequency of nerve impulses from warm-sensitive receptors and a decrease from cold-sensitive receptors.
D) an increase in the frequency of nerve impulses from warm-sensitive receptors and no change in the frequency of nerve impulses from cold-sensitive receptors.
E) a large increase in the frequency of nerve impulses from warm-sensitive receptors and the breakdown and recycling of cold-sensitive receptors.

Question 27

To assist them to locate food, the bills of platypus have a class of sensory receptor previously thought to have occurred only in fish. This receptor is sensitive to

A) the earth's magnetic field.
B) mechanical stimulation from the water movement of prey.
C) the body heat of prey.
D) electrical signals generated when prey move.
E) pheromones released by prey.

Question 28

Which of the following responses is mediated by intermediate proteins and second messengers?

A) An electrical signal is generated when a mechanoreceptor is distorted by water movement.
B) The rate of synthesis of a particular protein is increased when a hormone/receptor complex binds to a specific region of DNA.
C) Ion channels on the plasma membrane of a photoreceptor are closed after the absorption of a photon of light.
D) Water soluble ligands interact with receptors to open an ion channel and cause membrane depolarisation.
E) All of the answers are correct.

Question 29

Adenyl cyclase is a (n)

A) cell surface receptor.
B) G-protein.
C) membrane-bound enzyme.
D) second messenger.
E) inactive form of cyclic AMP.

Question 30

In mammals, the hormone epinephrine activates an intracellular signalling pathway that leads to the breakdown of glycogen in the liver. The binding of epinephrine to a G-protein linked receptor on the surface of liver cells activates a succession of relay molecules including the adenyl cyclase, cAMP and protein kinase A, The final protein to be activated is the enzyme glycogen phosphorylase, which catalyses the breakdown of glycogen to glucose-1-phosphate. In this signalling pathway, the second messenger is

A) the G-protein.
B) active protein kinase A.
C) adenyl cyclase.
D) cAMP.
E) glycogen phosphorylase.

Question 31

In mammals, the hormone epinephrine activates an intracellular signalling pathway that leads to the breakdown of glycogen in the liver. The binding of epinephrine to a G-protein linked receptor on the surface of liver cells activates a succession of relay molecules including the adenyl cyclase, cAMP and protein kinase A, the final protein to be activated is the enzyme glycogen phosphorylase, which catalyses the breakdown of glycogen to glucose-1-phosphate. In this signalling pathway, an increase in the concentration of cAMP would lead to an increase in the concentration of

A) adenyl cyclase.
B) inactive protein kinase A.
C) active protein kinase A.
D) the G-protein.
E) glycogen phosphorylase.

Question 32

If a signalling molecule (ligand) triggers an effect (protein phosphorylation) via a second messenger system, which will produce the greatest change in the magnitude of the effect in a target cell?

A) Adding one molecule of ligand to the cytoplasm of the cell.
B) Adding one molecule of ligand to the extracellular fluid surrounding the cell.
C) Adding one molecule of the second messenger to the cytoplasm of the cell.
D) Adding ATP to the cytoplasm of the cell.
E) Adding one molecule of activated protein kinase to the cytoplasm of the cell.

Question 33

Connective tissues are composed of

A) cells.
B) collagen fibres.
C) elastin fibres.
D) fluid matrix.
E) All of these substances may be present in connective tissue.

Question 34

A scientist is designing a new drug that will mimic a particular signal molecule and reduce its activity. It is therefore necessary to produce a molecule that will

A) bind specifically to the receptor molecule, induce a change in shape of the molecule which will ultimately prevent a cellular response.
B) bind specifically to adenylyl cyclase to activate protein kinase A and stimulate the cellular response.
C) bind to the membrane bilayer and cause membrane depolarisation to prevent the response.
D) bind to the membrane receptor and open a ligand-gated channel.
E) bind to phospholipase C and activate the G-protein to prevent a cellular response.

Question 35

Which of the following statements about G proteins is INCORRECT?

A) G-proteins link the receptor protein to the signalling pathway of a specific ligand.
B) G-proteins produce second messengers to activate adenylyl cyclase to amplify the signal.
C) G-protein-linked receptors have seven transmembrane domains and act through G-proteins to alter the activity of an ion channel.
D) Intracellular processing of signals may involve G-proteins, leading to a release of Ca²⁺ ions in the cell.
E) G-protein-linked receptors have seven transmembrane domains and act through G-proteins to alter the activity of an intracellular enzyme.

Question 36

A PhD student has been given a tissue sample that looks like gut epithelium. How might the student go about gathering further evidence to support this experimentally?

A) Test the DNA of the tissue for molecular markers that correspond to epithelium
B) Measure the cytoplasmic content of the tissue, the concentration of which proportional to the tissue volume is indicative of cell type
C) Determine if the tissue is absorptive and secretes enzymes
D) Extract total protein and run on a 2-D gel matrix
E) All options listed here are correct

Question 37

What is the name given to epithelial tissue that forms the lining of some internal structures, such as blood vessels?

A) Endothelia
B) Apothelia
C) Exothelia
D) Ectothelia
E) Enterothelia

Question 38

In plant cells, where would you find the middle lamella?

A) Surrounding the endodermis
B) All options listed here are incorrect
C) Secreted in the rhizosphere
D) As a protective layer around developing fruits and seeds
E) As a thick layer laid down either side of thin cell wall sheets of adjacent cells

Question 39

Gene expression is one response that can result from the binding of a ligand to a cell receptor. How might the reception of such a signal travel from the receptor to produce such a cellular response?

A) By direct interaction of the cell receptor with the target DNA
B) The receptor produces a transcript that travels to the nucles
C) It is not known how signals travel from receptors to induce gene expression
D) Via a cascade of molecular events
E) Via electron excitation transfer

Question 40

Which of the following statements about cell responses to signals is INCORRECT?

A) Cells most commonly respond to signals secreted by other cells.
B) Autocrine signalling occurs only in cells responding to environmental stresses or pathogens.
C) Cells can respond to their own secreted signal molecules.
D) Paracrine and autocrine signals are both commonly responded to in equal proportions.
E) Cells most commonly respond to paracrine signalling.

Question 41

The mechanism by which animals sense magnetic fields is

A) unknown.
B) magnetite.
C) Fe-oxide.
D) Fe₃O₄.
E) light responsive cryptochromes.

Question 42

Some chemical signal molecules are excluded from entering the cell whereas others are able to enter. Based on your knowledge of the structure of cell membranes, which of the following signal molecules would be able to pass through the cell membrane?

A) Water-soluble chemical signals
B) Esterified chemical signals
C) Phenolic-based chemical signals
D) Carbonylic chemical signals
E) Lipid-soluble chemical signals

Question 43

Why is nitrous oxide (NO) an exception among other water-soluble chemical signals?

A) Its receptor is not located in the cytoplasm.
B) NO is not an exception to other water-soluble chemical signals and has the same chemical properties in relation to membrane permeability.
C) It lacks a receptor protein.
D) It is present in the cell in a monoxide state, rather than as a dioxide.
E) It is able to pass through the cell membrane.

Question 44

Which statement in relation to the binding of insulin to an insulin receptor is CORRECT?

A) It causes dimerization of the insulin receptor and autophosphorylation.
B) It leads to the synthesis of the polysaccharide glycogen synthase.
C) It results in the eventual enzymatic degradation of glycogen.
D) It causes cross linking of carbohydrates.
E) It inactivates the insulin response proteins.