Every year, a new influenza vaccine is developed. what is the most likely reason that doctors do not use the same vaccine each year? a. the vaccine turns into a new virus that causes a recurrence of the same influenza each year. b. the virus which causes influenza adapts each year to the last vaccine in order to survive and reproduce. c. any vaccine can only last for a year before it dies. d. a new, different virus that causes influenza enters the food chain through plants about once every year, infecting humans.

Christie's doctor recommends that she eat 40 grams of protein a day. she's already consumed 50% of her protein recommendation for the day. how many servings of the given snack should christie have to meet her daily protein recommendation?

Biomass can be used to generate electricity. biomass relies heavily on agricultural crops. plants release carbon dioxide and water in combustion. plants use photosynthesis to originally generate the energy that is needed. the chemical energy of these plants all started with what energy source?

Examine the two squirrel populations in the accompanying figure. the populations are separated by a geographic barrier. if after a long period of time the two species are no longer separated, what evidence is needed to determine if speciation has occurred? the figure shows two populations of squirrels separated by a geographic barrier. examine the two squirrel populations in the accompanying figure. the populations are separated by a geographic barrier. if after a long period of time the two species are no longer separated, what evidence is needed to determine if speciation has occurred? the figure shows two populations of squirrels separated by a geographic barrier. polyploidy is creating new species. the two populations are not interbreeding freely. hybrid offspring of the two populations begin to appear. one species will increase into a population size twice as large as the other species.