Tools used as nut crackers by chimps and birds

According to the theory of punctuated equilibrium, at what rate does speciation occur? species change depending on the rate of natural selection. after periods of stasis, new species evolve relatively rapidly. species change slowly and eventually form new species. some species change quickly and others change slowly to balance the overall rate.

Which member of the following food chain will be least affected by ddt, a pesticide water pollutant, if bio-magnification is occurring? algae> zooplankton> crayfish> leopard frog> large mouth bass

What is a photon? a. part of a ribosome b. a light particle c. a carbon dioxide molecule d. part of a chloroplast b.a light particle