Dictyostelium discoideum is an unusual organism, one that straddles the boundary between the unicellular and the multicellular. Its feeding phase consists of individual amoeba-like cells that move independently, feeding on bacteria by phagocytosis. When the food runs out, cells begin to aggregate into a multicelled structure that migrates toward light. The cells differentiate into a base, stalk, and spores; only the spores survive to colonize a new habitat. Dictyostelium discoideum is which of the following?
a. An autotroph
b. A heterotroph and autotroph
c. A heterotroph
d. A detritovore
e. A heterotroph and detritovore
Answer: c. A heterotroph
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Which of the following statements about basidiomycetes and ascomycetes is incorrect?
A. Basidiomycetes have a short heterokaryotic stage, whereas ascomycetes have a long heterokaryotic stage. B. Basidiomycetes produce spores in clubshaped cells, whereas ascomycetes produce spores in elongated, saclike cells. C. Basidiomycetes plug their septal pores following damage in a different way from ascomycetes. D. Basidiomycetes produce four spores from each basidium, whereas ascomycetes produce eight spores from each ascus. E. Basidiomycete fruiting bodies are composed entirely of dikaryotic hyphae, whereas ascomycete fruiting bodies are composed of a combination of haploid and dikaryotic hyphae.
The antimicrobial aspect(s) of the skin is/are
A. dryness. B. saltiness. C. acidity. D. toxicity. E. All of the choices are correct.
Stored energy resulting form the interactions between particles or objects
What will be an ideal response?
Which of the following human genetic disorders is caused by a dominant allele?
a. hemophilia b. sickle cell anemia c. cystic fibrosis d. Huntington's disease