Carbon dioxide is transported in the blood in three ways: (i) dissolved in solution; (ii) buffered with water as carbonic acid; (iii) bound to proteins, particularly haemoglobin. Source: https://academic.oup.com/bjaed/article/5/6/207/331369
It is asking for one trait or characteristic that can be seen visibly and environmental traits are characteristics caused by your geographic location for example African people have more melanin in their skin because they live closer to the equator and it protects them from getting sun burnt.
It needs to reach out long to eat the leaves on the tree
