Starting with 500 calories of energy at the Primary productivity level in the energy pyramid, tell how much numerically will be available to the primary, secondary, and
tertiary - consumers.

What must happen before meiosis can begin? a. four gametes must be produced b. the four tetrads must be pulled apart c. dna doubles and produces sister chromatids d. the cell membrane pinches together

How many species of living things are alive on earth today? more than 1,000,000 none of these answers are correct 100-500 1,000 –500,000 o 500,000 -1,000,000

In general, characteristics that an organism survive and reproduce become more common in a population over time. what mechanism of evolution cause this change?