What is the difference between a closed and an open circulatory system? a. an open system has capillaries and blood vessels c. a closed system lacks capillaries b. a closed system has capillaries and blood vessels d. in a closed system blood bathes the tissues directly

Which best describes how the common cold spreads in the human body? a bacteria burst out of normal cells killing them b viruses replicate inside respiratory cells c bacteria inject dna into normal cells d viruses insert dna into bacteria

The ancestors of plants that lived in water had plenty of water for the young. angiosperms are a group of land plants that evolved a reproductive trait for living on land. this trait protect young plants by allowing them to grow only when water is present and the conditions for healthy development are right. what trait most likely young angiosperms in this way?

The main ingredient of magma is a pahoehoe. b silca c dissolved gases d obsidian