Which statement is true? comets are most like planets. comets have elliptical orbits. comets are like the sun in their composition. comets do not have orbits.

Veins have a much lower blood pressure than arteries. which of these prevents backflow of blood in veins? a. pressure applied by the heart b. one–way valves in veins c. thin muscular walls of veins

10. in which phase will crossing-over occur? a. mitosis b. metaphase ii c. prophase i d. meiosis ii

9. technology can bring both good and bad things. building a vertical farm can increase food supplies in cities (good), but it may cause unemployment in rural areas (bad). give another example of both the good and bad sides of a technological advancement (5 noints)