Question

A very small organism does not need a circulatory system because:
O A it has a large surface area to volume ratio
B it has a small surface area to volume ratio
OC the surface area and volume are equal
OD the surface area is greater than the volume
RIF


Answer 1

Answer:

the answer is b

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Answer 2

Answer:

(A) A very small organism does not need a circulatory system because it has a large surface area to volume ratio.

Explanation:

• The respiratory system's functionality is proportional to the size of the organism.
• Diffusion increases as animal size increases, however the surface area to volume ratio decreases.
• The simplest animals, such as sponges (Porifera) and rotifers (Rotifera), do not require a circulatory system since diffusion allows for adequate water, nutrient, and waste exchange, as well as the interchange of dissolved gases.  
• Diffusion is a passive, slow mode of transfer.
• The rate of oxygen intake must match the rate of diffusion across the membrane for it to be a viable method of oxygen delivery to the cell.
• It would not be able to give oxygen to the inside of the cell quickly enough if the cell is exceedingly large or thick.
• As a result, relying on diffusion for respiration is limited to microscopic animals or those with extremely flattened bodies, such as many flatworms (Platyhelminthes).