Why is a respiratory pigment like haemoglobin necessary in large-bodied animals?
Question
Why is a respiratory pigment like haemoglobin necessary in large-bodied animals?
Because diffusion pressure alone cannot deliver enough oxygen to all body parts
Because they do not have lungs
Because they lack blood vessels
Because oxygen is toxic without it
Answer
Because diffusion pressure alone cannot deliver enough oxygen to all body parts
Detailed Explanation
When body size is large, diffusion alone cannot supply enough oxygen throughout the body, so haemoglobin actively transports it to oxygen-deficient tissues.