Which of these is NOT a factor that may lead to different conclusions from two different studies investigating the same thing (eg., the relationship, if any, between caffeinated coffee and memory)?

A. using a control group
B. different sample sizes
C. different amounts of caffeine
D. different ways of evaluating memory (eg., long-term vs. short-term memory)
E. different types of participants (eg., participants of different ages or professions)

Suggest why placing wheels under a heavy box reduces the neccessary force required to push it along at a constant speed.

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.

Identify the structures ! 20 points