Q. Give reasons for the following.
A)The backbone is not made of a single long bone.
B) Snakes move in a zigzag manner.
C) Our body has different types of moveable joints.
Answers
Answer:
A). Backbone is made up of different types of vertebrae. Backbone support our head and trunk. It also forms framework of the trunk and provide musculature for back. Each vertebrae has different sizes and shapes which help us. For example , lumbar vertebrae have large size as they had to carry almost half weight of our weight . Thoracic vertebrae helps for attachment of ribs. This wouldn't be possible with just one single long bone. Thus, backbone is not made of a single long bone.
B) Snakes move on a zigzag manner due to alternatively tightening and relaxing a set of muscles along each side of its body.
C) . Different types of moveable joints have different functions. This joint allow as to make movement in certain direction. Like ball and socket (shoulder joint) joint will help us to thrown ball while playing cricket. Also, saddle joint help us to write. So, Our body has different types of moveable joints because it helps us to perform different functions or task.