In lab, you are shown a freshly cut woody stem. Covering the stem are several cell layers, including cork, living parenchyma, and the cork cambium. These layers replace the function of a single epidermis layer that would be found in immature stems and nonwoody stems that don't have secondary growth. This collection of cell layers is the
A. endoderm.
B. periderm.
C. mesoderm.
D. pachyderm.
E. ectoderm.
B. periderm.
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The main reason that cellular aerobic respiration needs to occur step by step instead of a single, big reaction is
A. cells don't have enough mitochondria to catalyze the larger, single reaction. B. too much energy would be released as heat and destroy the cell. C. cells don't store enough oxygen to absorb all the energy in one release. D. cells produce the enzymes needed for cellular respiration very slowly. E. glucose breaks down slowly, carbon by carbon, inside a cell.
Researchers often want to isolate a certain type of RNA. For some RNA species, this can be accomplished via affinity chromatography, using beads coated with chains of poly-deoxythymidine (poly-dT). The desired RNA will stick to the beads while unwanted RNAs will flow through the column. The retained RNA can then be eluted. What RNA species can be purified using this method?
A. bacterial mRNA B. eukaryotic mRNA C. eukaryotic rRNA D. bacterial rRNA
Pyruvate is the end product of ____.
A. glycolysis B. acetyl-CoA formation C. fermentation D. aerobic respiration E. the citric acid cycle
Glyptodons are fossil forms that resemble ____.
A. ostriches B. armadillos C. kangaroos D. turtles E. sloths