When the trading of equivalent sections of DNA between homologous chromosomes occurs during crossing over, it is called: A. reciprocal exchange.
B. chromosomal exchange.
C. allele exchange.
D. similar crossing-over.

Read the following scenario to answer the following question. in some zoos, rare crosses between a male lion and a female tiger have produced hybrid offspring called "ligers." male ligers are sterile but some female ligers are fertile. in the wild, lion and tiger ranges do not naturally overlap, making such a cross unlikely. furthermore, the solitary behavior of tigers and the social organizations of lions create behavioral differences. applying the biological species concept, the sterility of ligers reveals that a. lions are probably a subspecies of tigers b. tigers and lions are the same species c. a new species called "ligers" is forming d. tigers and lions are separate species

Compare the depth of field when focusing with low power and high power. which power has the greater depth of field?

Why are scientists concerned about the depletion of the ozone levels in the stratosphere?