The heart is a muscular organ that pumps blood. blood that contains waste materials is brought to the heart by blood vessels. this blood enters the and then moves down. the presence of the prevents the backflow of blood inside the heart

Which would best keep the oxygen cycle stable? a. cutting down jungles to create farmland b. eliminating parks in large cities c. dumping toxic chemicals into the ocean d. reducing the amount of deforestation d. reducing the amount of deforestation

Study the diagram of a cell. which structure is found only in plant cells and functions in the process of photosynthesis? w x y z

Ascientist discovers a new body between the orbit of neptune and the kuiper belt. the object is round and travels in an orbit around neptune with other space objects. the scientist claims that she has found a new dwarf planet. where is the scientist’s error? the object is an asteroid, not a dwarf planet.the object is a moon, not a dwarf planet.the object is not a dwarf planet because it travels with other objects.the object is not a dwarf planet because it is round.