It is also possible to move substances across membranes against their concentration gradient (from areas of low concentration to areas of high concentration). ... If the energy of ATP is directly used to pump molecules against their concentration gradient, the transport is called primary active transport.
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Answer:
1. The animal can't see what happening behind its head.
2. Head can be moved upto 180 degree angle in most of the animals including humans. But it is not true in case of birds.
Explanation:
