Bird skeletons are very delicate, and therefore, difficult to be preserved. The bones of the birds are soft. The small animals are very prone to physicochemical as well as biological decay. This is why the fossil record of bird is incomplete and well-preserved fossils of birds are rare to find, except at a few unusual sites.
Answer:
Photosynthesis and chemosynthesis are both processes by which organisms produce food; photosynthesis is powered by sunlight while chemosynthesis runs on chemical energy.
Explanation:
hope it helps
The answer for 21 I think is false

Work done = 100J
Distance = 5 meters
Force = ?

Force = 100/5 = 20N
Therefore, the force needed is 20 Newtons