When a cell makes a cell membrane bound growth factor that binds to receptors on neighboring cells causing them to proliferate, this is an example of
A. direct intercellular signaling.
B. contact-dependent signaling.
C. autocrine signaling.
D. paracrine signaling.
E. endocrine signaling.
Answer: B
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Sexual reproduction involves ____
a. one diploid cell fertilizing a haploid cell b. the union of two somatic cells c. the union of male and female gametes d. a single mitotic division of the parent cell to produce a daughter cell e. the union of two gametes to produce a haploid zygote
When a vesicle forms around a small, randomly chosen volume of extracellular fluid, this is termed ________
a. phagocytosis b. exocytosis c. receptor-mediated endocytosis d. bulk-phase endocytosis
A colleague has been attempting to use hydrolysis to decompose large polymers into his constituent monomers, but after each batch, he transfers the product to the scale using an iron spoon, weighs the product, and throws it away. When you ask why he does this, your colleague tells you that each time he’s weighed the reactants before hydrolysis and the products afterward and has found a slight increase in mass, indicative of a contaminant among the monomers that would render them unusable. What mistake has your colleague made?
a. He doesn’t wait for the products of the hydrolysis reaction to cool off before weighing them; hot monomers weigh more than cool monomers. b. He has been using an iron spoon to stir his solutions, which results in iron oxide contamination. c. He has forgotten that hydrolysis bonds hydrogen and hydroxyl groups to the monomers, which would increase their mass proportionally. d. Hydrolysis reactions bond monomers together; he has been inadvertently creating more massive polymers instead.
The reagent that stains the organisms demonstrated in Image C is:
a) Basic fuchsin b) Gallego solution c) Methylene blue d) Crystal violet