Which of the following has the greatest population density?
a.125,000 organisms in 2.5mi^2
b. 13,000 organisms in 1.0mi^2
c. 150,000 organisms in 4.0mi^2
d. 100,000 organisms in 0.5mi^2

Where do homologous chromosomes exchange genetic material through crossing over?               a.  chlorophyll    b.  centrosomes    c.  centromeres    d.  chiasma

Which of the following would be a body response when stepping outside without a coat on a snowy day? a. senaceous glands. secrete more senum b. more liquid is transported by the body to the skin fir insulation c. blood vessels in the skin narrow and contract d. blood vessels in the skin expand

9. the history of life on earth is recorded in