Stem cells are . only found in humansb. cells that have undergone cell differentiationc. found only in the early embryo stages of developmentd. unspecializedcells that develop into differentiated cells

What adaptation is apparent in the bodies of the three tortoise species shown in figure 16-2

Organisms within a population must compete for resources to survive

Which phrase is the best summary of the model shown? a. the transfer of the sun's energy through trophic levels b. a series of aerobic and anaerobic reactions c. a transformation of light energy into chemical energy d. the breakdown of food molecules