When two species cannot form hybrid zygotes, the mechanism that keeps the species separate is known as a(n) ________ isolating mechanism.
A. prezygotic
B. hybridization
C. differential
D. adaptive
E. postzygotic
Answer: A
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Archaeopteryx lithograpica:
A. was the first fossil directly linking birds to reptiles B. had a beak with teeth C. had a small, reptilian breastbone D. had both claws and feathers on the wings E. All of the choices provided are true
Genes are composed of DNA sequences and are condensed into larger structures called:
a. DNA. b. proteins. c. chromosomes. d. lipids. e. cell membranes.
Diploblastic organisms differ from triploblastic organisms in that diplobastic organisms are
A. larger than triploblastic organisms. B. bilaterally symmetrical. C. simpler in structure than triploblastic organisms. D. able to reproduce sexually rather than asexually.
After you swallow the first bite of your food, your stomach becomes active. Polypeptides in the ingested food stimulate the stomach to release acid and enzymes, which creates more polypeptides. This greater concentration of polypeptides stimulates the
stomach to release even more acid and enzymes, which continues until the contents of the stomach pass into the next digestive chamber. This phenomenon is best explained by A) positive feedback control. B) the relationship between structure and function. C) how evolution does not lead to a perfect animal form. D) how different tissues form an organ.