A student conducted an investigation to study gravitropism. The
control group was planted normally, while the experimental group was
planted upside down. After seven days, the control group looked
normal. The experimental group after 7 days the roots started to grow
toward the direction of gravity.
Which statement best explains why the experimental group started to
grow toward the ground?

Which of the following factors would not contribute to allopatric speciation? a) a population becomes geographically isolated from the parent population. b) the separated population is small, and genetic drift occurs. c) the isolated population is exposed to different selection pressures than the ancestral population. d) different mutations begin to distinguish the gene pools of the separated populations. e) gene flow between the two populations is extensive.