Why are gills, a heart, and a closed circulatory system a much more efficient way of getting oxygen to all the cells than that of insects?

Due to fast transportation of oxygen, waste material and nutrients.

Explanation:

Gills, a heart, and a closed circulatory system are more efficient ways to provide oxygen to all cells than that of open circulatory system of insects because in the closed circulatory system blood transfers is faster than open circulatory system, thus oxygen, nutrients, and wastes transport is also very fast so we can say that closed circulatory system is more efficient than open circulatory system.

an organism's phenotype is the  form of a trait  that it  displays. for  flowercolor, a pea  plant  can  display  a phenotype of purple or white flowers. an organism's  genotype  is the alleles of a gene it contains. based on his data, mendel concluded that a phenotype can be  determined  by more than one  genotype.

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