Correct option - They have a crystalline structure.
Answer:
Frog - The frog has three respiratory surfaces on its body that it uses to exchange gas with the surroundings: the skin, in the lungs and on the lining of the mouth. ... A frog may also breathe much like a human, by taking air in through their nostrils and down into their lungs.
Tadpole - Tadpoles open their mouths as they swim and take in water. As the mouth closes, muscles transfer the water to the gills. These consist of thin membranes called lamellae, which take oxygen from the water where it enters the blood stream through the process of diffusion.
Elevated carbon dioxide levels may mitigate losses of biodiversity from nitrogen pollution. ... Rising levels of carbon dioxide may overheat the planet and cause other environmental problems, but fears that rising carbon dioxide levels could directly reduce plant biodiversity can be allayed, according to a new study.
Answer:
Humans take natural resources for things such as manufacturing oil, building, making plastics, etc. For example, harvesting trees to cut and make planks of depletes the Earth of a necessary resource for filtering oxygen.
