An artificial pacemaker supplements the actions of
a. sympathetic nerves.
b. the atrioventricular node.
c. the medulla oblongata.
d. the sinoatrial node.
e. the heart muscle itself.
D
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The ultimate electron acceptor in aerobic respiration is ____
a. NAD+ b. CO2 c. ADP d. NADP+ e. O2
his4 trp1; his4 trp1; HIS4 TRP1; HIS4 TRP
A haploid yeast strain has mating type a and genotype his4 TRP1. A different haploid yeast strain has mating type ? and genotype HIS4 trp1. The two strains mate and produce diploid offspring with genotype his4 TRP1 / HIS4 trp1. The diploid cells undergo meiosis to produce a variety of tetrad types. In the following questions, the genotypes of the spores in a tetrad are shown. For each tetrad, tell what type it is: parental (PD), non-parental (NPD), or tetratype (T). A) PD B) NPD C) T D) cannot be determined
Cytokinins are water-soluble hormones produced in the root apical meristem and stimulate the growth of lateral buds. How do cytokinins reach the lateral buds?
A. by diffusion as a gas B. through the phloem C. through the xylem D. through the phloem and xylem E. through the phloem and by diffusion as a gas
In many dense forests, plants living near the ground level engage in intense competition for
A) oxygen. B) water. C) carbon dioxide. D) sunlight.