Why might knowledge of the gene and protein sequences of a species be useful in classifying that species? (2 points)
O It would keep the species from being interbred with any other species that might appear physically similar to
it.
• It would make it possible to compare that species to other species at a level deeper than outward appearance.
• It would allow more accurate naming of the species by basing names on genes rather than appearance.
It would prove that all the members of a given species were genetically identical to each other.

Match the following terms describing electrical events with the correct phases of the cardiac cycle. the ventricular muscle cells depolarize at the start of this phase. during this phase, na+ entry through the funny channels causes the pacemaker potential of sa nodal cells to gradually become less negative until it reaches threshold. the ventricular muscle cells repolarize right before this phase. the cytosolic concentration of calcium in the contractile cells of the ventricle is highest during this phase. a. isovolumetric relaxation b. ventricular ejection c. isovolumetric contraction d. ventricular filling

Explain what a zygote is. use the terms egg cell, sperm cell, and fertilization in your explanation.

2. which of the following statements does not accurately describe stem cells? a. embryonic stem cells make up the inner cell mass of a blastocyst. b. with more research, stem cells may be used to repair or replace damaged cells. c. the use of stem cells is without any objections since it can be used in therapies to humans. d. adult stem cells are multipotent and can differentiate into many types of cells.