Nitrogen-fixing bacteria convert atmospheric nitrogen (N2 gas) into ammonium (NH4). Why is this conversion important for life on Earth?
A) Ammonium is an important cleaning agent.
B) Nitrogen gas is toxic.
C) Ammonium is a very important plant nutrient.
D) Nitrogen gas leads to global warming.
C
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The adhesion step in extravasation is most likely to be mediated by:
A. integrin proteins. B. cell wall proteins. C. collagen. D. keratin.
The exposure of plants to low temperatures in order to stimulate flowering is called
a. cryptotropism. b. thigmotropism. c. vernalization. d. florigen. e. cryotropism.
The iron-response element (IRE) is a(n)
A) insulator element that binds IRE-binding protein in the absence of iron. B) transcriptional promoter that directly binds iron to prevent transcription of nearby genes. C) long noncoding RNA that binds iron and regulates transcription of multiple genes. D) sequence in the 5? untranslated region of mRNA that forms a hairpin loop, preventing translation of the mRNA by binding to IRE-binding protein in the absence of iron. E) example of a prokaryotic riboswitch that causes early termination of transcription in the presence of iron.
Sexual reproduction in zygomycetes differs from sexual reproduction in basidiomycetes in one key way. Which of the following is true of zygomycetes, but not true of basidiomycetes?
A. Haploid nuclei fuse in the process of karyogamy to form a diploid nucleus B. Mushrooms are formed of secondary (dikaryotic) mycelium C. Gametangia of opposite mating types undergo plasmogamy D. Meiosis to produce haploid spores is delayed, resulting in a discrete diploid state