If horizontal gene transfer was predominant in early evolution, what effect does this have on building the tree of life?
a. Horizontal gene transfer places viruses firmly at the beginning of the tree of life.
b. Horizontal gene transfer blurs the concept of species making it difficult to delineate ancestral species.
c. Horizontal gene transfer resulted in chloroplasts that confuse the plant lineage.
d. Horizontal gene transfer means that life-forms do not share a history of common descent.
B
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Natural killer cells like Tc cells use ________ and granzymes to kill their targets without prior exposure or contact with the foreign cells
A) coagulants B) M protein C) perforin D) interferon gamma
A drug, colchicine, can be added to cells in culture and it stops the polymerization of microtubules. What effect would this have on mitosis?
A. It would slow or block mitosis by interfering with the spindle apparatus function. B. It would speed up mitosis by increasing the rate of DNA replication. C. It would speed up mitosis by increasing the elongation rate of the dividing cell. D. It would slow or block mitosis by preventing DNA replication.
If a diploid cell with 40 chromosomes undergoes meiosis, each daughter nuclei will have ____ chromosomes
a. 10 b. 20 c. 40 d. 60 e. 80
Which vertebrate body system is most closely associated functionally with respiration?
a. urinary b. digestive c. endocrine d. circulatory e. integumentary