Skeletal system.
Without a proper skeleton, we would not have enough rigidity to properly move. We'd be an awkward pile of skin, muscle & bodily fluids.
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The sky is transparent not blue, it only appears to be blue because of the ocean. but in the night it appears to be dark grey. the sky being blue is considered as an optical illusion.
Answer:
fast, intensive reproductive investment
Explanation:
Channel proteins, also known as transport proteins, allow the passage of molecules in and out of the plasma membrane.
The stomach lining contains glands that produce stomach acid and enzyme.