1. a closed circulatory system is one in which
a. blood spreads freely throughout all of the body's issues and organs
b. blood flows though a system of blood vessels throughout the body
c. blood travels through blood vessels into cavities called sinuses
d. blood is pumped through a system of blood vessels and air sacs
2. in the open circulatory system of some mollusks, blood is found
a. in a double-loop and in sinuses
b. in alveoli and blood vessels
c. in blood vessels and sinuses
d. in gills and tracheal tubes
3. both oysters and squids are mollusk. why is an open circulatory system adequate for an oyster but not for a squid ?
a. oysters are filter feeders, but squids are carnivores
b. oysters do not move around, but squids are very active
c. oysters have higher oxygen demands than squid
d. squids live in waters with lower oxygen levels than oysters
4. why is double-loop circulation better for larger, more active animals than single-loop ?
a. pumping the blood twice actually requires less energy than pumping the blood only once
b. single loop circulatory systems make animals more susceptible to circulatory system diseases
c. with double-loop circulation, blood can flow into spaces that are outside of blood vessels
d. it is difficult for single pump to force blood through the entire system of a large animal