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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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.
The ultimate electron acceptor in aerobic respiration is ____
a. NAD+ b. CO2 c. ADP d. NADP+ e. O2