How are red blood cells able to move through narrow vessels to carry oxygen throughout a multicellular organism?
A. They are small because they lack a nucleus.
B. They are long and thin with a tail like end
C. They are small because their organelles are smaller than those of other cells.
D. They are flexible because they lack a plasma membrane.
A. They are small because they lack a nucleus.
The correct answer is C. They are small because their organelles are smaller than those of other cells.
Red blood cells, also known as erythrocytes, are small in size and lack a nucleus, allowing for more space to carry oxygen. Their small size is mainly due to their organelles being smaller than those of other cells. This small size enables them to pass through narrow vessels, such as capillaries, which have a smaller diameter than the red blood cells themselves. The lack of a nucleus also contributes to their flexibility, allowing them to easily change shape and deform as they squeeze through narrow spaces.