What primary method does the cell employ to ensure gene expression only occurs when necessary? Limited amounts of specific DNA
Phosphorylation cascade with multiple steps
Receptors that only fit specific hormones
Unique transcription factors made of carbohydrates

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

How does the carbon cycle involve an exchange of carbon

Abiology teacher asks students to give examples of genetic variations that support the idea that changes in a population’s environment affect genetic variation. which is the least supportive example? a.changes in genetics in human populationsb.antibiotic resistance in bacteria populationsc.pesticide resistance in garden insectsd.changes in the color of the peppered moth population in england