Question

Water and air are very different environments for gas exchange. How did living on land create a challenge (something that makes it more difficult) for animals to perform gas exchange? How did living on land benefit (something that makes it easier) gas exchange for animals?

Answer 1

Yes, water and air is different. So let's have a look on the two possibilities given above:--

1. How is this challenge for land animals:-- as we know that in water environment the fishes they just use gills and flowing water having O2 diffuse in capillaries of gills. But in land the the O2 concentration is upto 21% and animals they have got to be dependent on pressure (air pressure) that is the lungs and outside. And proper removal of CO2 and O2 gas from body. As we know that on land:---

Primary factor for gases:-- atmospheric pressure

And atmospheric pressure changes with altitude of land surface like mountains animals etc.

So respiration must be maintained in different pressure to meet the need of body.

This pressure is not the limiting factor for aqueous fauna because water in ocean is at the same height.

Now second possibily:--

What makes its easier?:-

As we know that gas has little concentration in water as compared to air why air is just the gases mixture and you heard about( like dissolve like) in chemistry.

But here Hemoglobin is there to capture gas from environment and others.

Main tool that we have is Lungs more efficient and evolve type than gills and maintain pressure for gas exchanges.