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

the water is warmed up by the sun and then it evaporates into the atmosphere. the sunlight warms the water by its heat. water is then cooled down and condensation takes place. the water then finally returns back to the earth by the process of precipitation in the form of rain or ice.

explanation:

interphase

the period of cell growth when the cell synthesizes new molecules and organelles. the cell is not dividing and it constitutes the majority of the time spent in the cell cycle

prophase

changes occur in the nucleus and cytoplasm. the chromatin condenses to form structures (sister chromatids) visible with a light microscope and the mitotic spindle begins to form, but the nucleus is still in tact

prometaphase

the nuclear envelope fragments and the spindle microtubules attach to the kinetochores of the sister chromatids

metaphase

all the cell's duplicated chromosomes are lined up at an imaginary plane equidistant between the poles of the mitotic spindle

anaphase

begins when sister chromatids separate from each other and ending when a complete set of daughter chromosomes arrives at each of the two poles of the cell

telophase

the daughter nuclei form at the two poles of a cell

cytokinesis

the division of a cytoplasm to form two separate daughter cells. usually occurs during telophase during mitosis. this and mitosis make up to mitotic (m) phase of the cell cycle