Practice Questions Chapter 16 and 20

Which of the following is not an example of a connective tissue? Select one: a. bone b. the layer of photoreceptors in the eye c. the jellylike interior of an eye d. cartilage

b. the layer of photoreceptors in the eye

Which of the following statements about collagen is false? Select one: a. Collagen synthase organizes the mature collagen molecules into ordered collagen fibrils. b. Collagen is synthesized as procollagen and secreted to the outside of the cell in a secretory vesicle. c. The terminal procollagen domains are cleaved by a protease in the extracellular space. d. Cells can break down a collagen matrix using matrix proteases.

a. Collagen synthase organizes the mature collagen molecules into ordered collagen fibrils.

Which of the following statements about collagen is false? Select one: a. Collagen synthase organizes the mature collagen molecules into ordered collagen fibrils. b. Collagen is synthesized as procollagen and secreted to the outside of the cell in a secretory vesicle. c. The terminal procollagen domains are cleaved by a protease in the extracellular space. d. Cells can break down a collagen matrix using matrix proteases.

a. Collagen synthase organizes the mature collagen molecules into ordered collagen fibrils.

Which of the following statements is true? Select one: a. Extracellular signal molecules that are hydrophilic must bind to a cell-surface receptor so as to signal a target cell to change its behavior. b. To function, all extracellular signal molecules must be transported by their receptor across the plasma membrane into the cytosol. c. A cell-surface receptor capable of binding only one type of signal molecule can mediate only one kind of cell response. d. Any foreign substance that binds to a receptor for a normal signal molecule will always induce the same response that is produced by that signal molecule on the same cell type.

a. Extracellular signal molecules that are hydrophilic must bind to a cell-surface receptor so as to signal a target cell to change its behavior

Which of the following statements about molecular switches is false? Select one: a. Phosphatases remove the phosphate from GTP on GTP-binding proteins, turning them off. b. Protein kinases transfer the terminal phosphate from ATP onto a protein. c. Serine/threonine kinases are the most common types of protein kinase. d. A GTP-binding protein exchanges its bound GDP for GTP to become activated.

a. Phosphatases remove the phosphate from GTP on GTP-binding proteins, turning them off

Which type of junction involves a connection to the actin cytoskeleton? Select one: a. adherens junctions b. desmosomes c. tight junctions d. gap junctions

a. adherens junctions

Induced pluripotent stem (iPS) cells ______________________. Select one: a. are created by the expression of a set of key genes in cells derived from adult tissues so that these cells can differentiate into a variety of cell types. b. require a supply of donor egg cells, such as embryonic stem cells. c. can differentiate into a greater variety of adult tissues than embryonic stem cells. d. are created by nuclear transplantation.

a. are created by the expression of a set of key genes in cells derived from adult tissues so that these cells can differentiate into a variety of cell types.

When a terminally differentiated cell in an adult body dies, it can typically be replaced in the body by a stock of ________. Select one: a. proliferating precursor cells. b. cells more apically located than the terminally differentiated cells. c. Wnt proteins. d. induced pluripotent cells.

a. proliferating precursor cells.

Which of the following statements about the cytoskeleton is false? Select one: a. The cytoskeleton is made up of three types of protein filaments. b. Covalent bonds between protein monomers hold together cytoskeletal filaments. c. The cytoskeleton controls the location of organelles in eukaryotic cells. d. The cytoskeleton of a cell can change in response to the environment.

b. Covalent bonds between protein monomers hold together cytoskeletal filaments.

Which of the following statements about gap junctions is false? Select one: a. Gap junctions are made of connexons. b. Molecules up to 1000 daltons in molecular mass can move across gap junctions. c. Because gap junctions do not allow ions to pass through, they are not used for electrically coupling cells. d. Gap junctions can close in response to extracellular signals.

c. Because gap junctions do not allow ions to pass through, they are not used for electrically coupling cells

Which of the following situations would lead to relaxation of the smooth muscle cells in the absence of acetylcholine? Select one: a. a smooth muscle cell that has a defect in guanylyl cyclase such that it cannot bind NO b. a muscle cell that has a defect in guanylyl cyclase such that it constitutively converts GTP to cyclic GMP c. a muscle cell that has cyclic GMP phosphodiesterase constitutively active d. a drug that blocks an enzyme involved in the metabolic pathway from arginine to NO

b. a muscle cell that has a defect in guanylyl cyclase such that it constitutively converts GTP to cyclic GMP

A pluripotent cell _________. Select one: a. can only be produced in the laboratory. b. can give rise to all the tissues and cell types in the body. c. can only give rise to stem cells. d. is considered to be terminally differentiated.

b. can give rise to all the tissues and cell types in the body.

When a signal needs to be sent to most cells throughout a multicellular organism, the signal most suited for this is a ___________. Select one: a. neurotransmitter. b. hormone. c. dissolved gas. d. scaffold.

b. hormone

A major distinction between the connective tissues in an animal and other main tissue types such as epithelium, nervous tissue, or muscle is _______________. Select one: a. the ability of connective-tissue cells such as fibroblasts to change shape. b. the amount of extracellular matrix in connective tissues. c. the ability of connective tissues to withstand mechanical stresses. d. the numerous connections that connective-tissue cells make with each other.

b. the amount of extracellular matrix in connective tissues.

Which of the following statements is false? Select one: a. Proteoglycans can act as filters to regulate which molecules pass through the extracellular medium. b. The negative charge associated with proteoglycans attracts cations, which cause water to be sucked into the extracellular matrix. c. Proteoglycans are a major component of compact connective tissues but are relatively unimportant in watery tissues such as the jellylike substance in the interior of the eye. d. Glycosaminoglycans are components of proteoglycan.

c. Proteoglycans are a major component of compact connective tissues but are relatively unimportant in watery tissues such as the jellylike substance in the interior of the eye.

The lab you work in has discovered a previously unidentified extracellular signal molecule called QGF, a 75,000-dalton protein. You add purified QGF to different types of cells to determine its effect on these cells. When you add QGF to heart muscle cells, you observe an increase in cell contraction. When you add it to fibroblasts, they undergo cell division. When you add it to nerve cells, they die. When you add it to glial cells, you do not see any effect on cell division or survival. Given these observations, which of the following statements is most likely to be true? Select one: a. Because it acts on so many diverse cell types, QGF probably diffuses across the plasma membrane into the cytoplasm of these cells. b. Glial cells do not have a receptor for QGF. c. QGF activates different intracellular signaling pathways in heart muscle cells, fibroblasts, and nerve cells to produce the different responses observed. d. Heart muscle cells, fibroblasts, and nerve cells must all have the same receptor for QGF.

c. QGF activates different intracellular signaling pathways in heart muscle cells, fibroblasts, and nerve cells to produce the different responses observed.

Which of the following statements about plant cell walls is true? Select one: a. The molecular components of the cell wall are the same in all plant tissues. b. Because plant cell walls are rigid, they are not deposited until the cell has stopped growing. c. The microtubule cytoskeleton directs the orientation in which cellulose is deposited in the cell wall. d. The cellulose found in cell walls is produced as a precursor molecule in the cell and delivered to the extracellular space by exocytosis.

c. The microtubule cytoskeleton directs the orientation in which cellulose is deposited in the cell wall.

Tight junctions ______________________. Select one: a. allow small, water-soluble molecules to pass from cell to cell. b. interact with the intermediate filaments inside the cell. c. are formed from claudins and occludins. d. are found in cells in connective tissues.

c. are formed from claudins and occludins.

During nervous-system development in Drosophila, the membrane-bound protein Delta acts as an inhibitory signal to prevent neighboring cells from developing into neuronal cells. Delta is involved in ______________ signaling. Select one: a. endocrine b. parcrine c. neuronal d. contact-dependent

d. Contact-dependent

Which of the following statements is false? Select one: a. Nucleotides and amino acids can act as extracellular signal molecules. b. Some signal molecules can bind directly to intracellular proteins that bind DNA and regulate gene transcription. c. Some signal molecules are transmembrane proteins. d. Dissolved gases such as nitric oxide (NO) can act as signal molecules, but because they cannot interact with proteins they must act by affecting membrane lipids.

d. Dissolved gases such as nitric oxide (NO) can act as signal molecules, but because they cannot interact with proteins they must act by affecting membrane lipids

How do reproductive cloning and therapeutic cloning differ? Select one: a. The DNA in the nucleus of cells produced for therapeutic cloning is genetically identical to the donor genome, whereas in cells produced for reproductive cloning it is not. b. Reproductive cloning requires a supply of fertilized donor egg cells, whereas therapeutic cloning requires unfertilized egg cells. c. Therapeutic cloning requires nuclear transplantation, whereas reproductive cloning does not. d. Embryos are placed into foster mothers during reproductive cloning but not during therapeutic cloning.

d. Embryos are placed into foster mothers during reproductive cloning but not during therapeutic cloning

Which of the following statements about cellulose is false? Select one: a. Cellulose synthase enzyme complexes are integral membrane proteins. b. An array of microtubules guides the cellulose synthase complex as it moves in the membrane. c. The sugar monomers necessary for the synthesis of a cellulose polymer are transported across the plasma membrane. d. Microtubules are directly attached to the outside surface of the plasma membrane to form tracks that help orient the cellulose polymers.

d. Microtubules are directly attached to the outside surface of the plasma membrane to form tracks that help orient the cellulose polymers

The artificial introduction of three key ______________ into an adult cell can convert the adult cell into a cell with the properties of ES cells. Select one: a. chromosomes b. viruses c. hormones d. transcription factors

d. transcription factors