Answer:
When winter arrives availability of food and water decreases so birds travel to warmer places to escape the cold also to survive over there
Explanation:
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B. CO2 levels in the atmosphere could increase and contribute to global warming problems.
Answer:
A balance between Osteoblasts and osteoclasts maintain bone tissue.
Explanation:
Osteoblasts are bone making cells, osteoclasts resorb or break down bone, and osteocytes are mature bone cells.
