Which statement best describes a keystone species? A. It has little genetic variation
B. It has an extremely high population
C. It remains unaffected by all environmental changes
D. It has a strong influence on the ecosystem
E. It's the first species to populate a new ecosystem

Which scientific design has both practical limitations and limitations due to scale? studying the effect of bleach on the growth of mold spores exposing cultures of duckweed to different intensities of light observing the replication of dna molecules with a hand lens using colored marbles to model a cross between two colors of rabbits