Chapter 11: Cell-Cell Interactions Flashcards
Which of the following statements about the extracellular matrix in organisms is true?
A) The extracellular matrix is found only in multicellular organisms.
B) The extracellular matrix is always a cell wall.
C) The extracellular matrix is a fibre composite that provides strength.
D) The extracellular matrix consists solely of proteins.
C) The extracellular matrix is a fibre composite that provides strength.
What causes turgor pressure in plant cells?
A) sliding of cellulose fibrils in the matrix past one another
B) absorption of water by pectins
C) osmosis of water out of the plant cell due to the higher concentration of solutes outside the cell
D) osmosis of water into the plant cell due to the higher concentration of solutes inside the cell
D) osmosis of water into the plant cell due to the higher concentration of solutes inside the cell
Which of the following would you expect to be true of plant species that don’t produce lignin?
A) These plants do not perform photosynthesis.
B) These plant cells do not produce turgor pressure.
C) These plants lack cell walls.
D) These plants do not produce wood.
D) These plants do not produce wood.
Integrins have binding sites for _____.
A) actin and fibronectin
B) collagen and fibronectin
C) fibronectin and lignin
D) actin and collagen
A) actin and fibronectin
Which of the following cell types is likely to contain tight junctions?
A) red blood cells that travel singly through the circulatory system
B) cells lining the stomach, which prevent nutrients from leaking out
C) muscle cells in which the intermediate filaments of the cytoskeleton are bound to each other
D) cells of water-transporting tissue in plant stems
B) cells lining the stomach, which prevent nutrients from leaking out
Sponges are among the most ancient groups of animals. They have only a few cell types and relatively simple bodies. If the cells of adult sponges from differently pigmented species A, B, and C were dissociated and then mixed together in a culture dish, what would happen?
A) Adult sponges with a mixture of different pigmented cells will re-form.
B) The dissociated sponge cells will produce antibodies against the foreign sponge cells.
C) The cells will remain dissociated.
D) Adult sponges will re-form into species A, B, and C.
D) Adult sponges will re-form into species A, B, and C.
Which of the following statements about cell–cell attachments is true?
A) Tight junctions are static structures that seal adjacent plasma membranes.
B) Tight junctions contain adhesion proteins called cadherins that bind only to other cadherins of the same type.
C) Desmosomes link the cytoskeletons of adjacent cells.
D) The middle lamella consists mainly of gelatinous collagens that hold adjacent plant cells together.
C) Desmosomes link the cytoskeletons of adjacent cells.
Which of the following are most easily shared by adjacent plant or animal cells?
A) ions
B) proteins
C) mitochondria
D) DNA
A) ions
Which of the following statements about signal receptors is true?
A) The ability of a receptor to respond to a signal is unchanging.
B) Receptors cannot be blocked.
C) Receptors change conformation upon signal binding.
D) Each type of receptor is found in all cell types, and more than one type of receptor occurs in a single cell.
C) Receptors change conformation upon signal binding.
Predict which receptor type may contain a DNA-binding domain, allowing it to bind DNA and direct changes to gene expression when activated.
A) steroid hormone receptor
B) receptor tyrosine kinase
C) G-protein-coupled receptor
D) None of the listed responses is correct.
A) steroid hormone receptor
Predict what would happen if a mutant G protein was unable to exchange GDP for GTP.
A) The proteins downstream from the G protein would not become phosphorylated.
B) The receptor could not become phosphorylated after hormone binding.
C) The proteins downstream from the G protein would never be produced and would not be present in the cell.
D) Receptors could no longer bind their hormone.
A) The proteins downstream from the G protein would not become phosphorylated.
Which of the following statements about G proteins is true?
A) They are activated when they are bound to GDP.
B) They become phosphorylated after hormone binding.
C) When activated, they activate enzymes that catalyze the production of second messengers.
D) When activated, they catalyze the phosphorylation of other proteins.
C) When activated, they activate enzymes that catalyze the production of second messengers.
Which of the following is an example of signal deactivation?
A) Calcium is released from the smooth endoplasmic reticulum.
B) GTP bound to G protein becomes hydrolyzed to GDP.
C) cAMP is produced from an enzyme activated by a G protein.
D) A kinase catalyzes the phosphorylation of a downstream protein kinase.
B) GTP bound to G protein becomes hydrolyzed to GDP.
What is the correct order for the four steps in signal transduction?
A) processing, reception, response, and deactivation
B) reception, processing, response, and deactivation
C) reception, response, processing, and deactivation
D) response, processing, reception, and deactivation
B) reception, processing, response, and deactivation
Signal receptors for hydrophilic and lipid-soluble hormones are similar in which of the following ways?
A) Both receptor types are lipid molecules.
B) Both receptor types are located in the plasma membrane.
C) Both receptor types are located in the cytoplasm.
D) Both receptor types change shape upon hormone binding.
D) Both receptor types change shape upon hormone binding.
