Why is maple sap collected in the spring instead of the fall?

Sarah and john are having a discussion on genetic diversity. sarah believes that it happen over a long period of time. john it happens immediately. who is correct? a. sarah is correct because genetic diversity occurs over a long period of time. b. john is correct because genetic diversity occurs immediately. c. both are correct because genetic variation can occur or long period of time. d. neither are correct because genetic diversity occurs over any period of time

Under which of the following circumstances would natural selection not operate on an organism

Based on their relative positions in the periodic table, which two elements would have the same number of valence electrons?