Body Movements Test - 13

The birds can fly because their bodies are well suited for flying. Their bones are hollow and light. The bones of the hind limbs are typical for walking and perching. The bony parts of the forelimbs are modified as wings. The shoulder bones are strong. The breastbones are modified to hold muscles of flight which are used to move the wings up and down.
Hence, the correct option is D. 

The earthworm, actually, eats its way
through the soil. Its body then throws
away the undigested part of the material
that it eats. This activity of an earthworm
makes the soil more useful for plants. 
Hence the correct option is A.

• The joint where our neck joins the head is called a pivotal joint.
• It allows us to bend our head forward and backwards and turn the head to our right or left.

Thus, Option B is correct.

A joint is a point where two bones make contact and regulate movements in the body. There are different types of joints in our body to help us carry out different movements. For example: Hinge joint, Ball and socket joints and pivotal joint. 

• The skeleton of the fish is covered with strong muscles. 
• During swimming, muscles make the front part of the body curve to one side and the tail part swings towards the opposite side. The fish forms a curve. 
• Then, quickly, the body and tail curve to the other side. 
• This makes a jerk and pushes the body forward. A series of such jerks make the fish swim ahead. This is helped by the fins of the tail. 

Hence the correct option is C.

The human skeleton comprises the skull, the back bone, ribs and the breast bone, shoulder and hipbones, and the bones of hands and legs. The statement is true. Thus, Option A is correct.

$$\textbf{Concept applied:}$$ Cartilage is a type of flexible tissue found in many parts of the body providing support and flexibility.

$$\textbf{Correct option:}$$ Option A

$$\textbf{Explanation for correct option:}$$

Option A

$$\bullet$$ The ear has the presence of cartilage on its upper portion (also known as pinna). 

$$\bullet$$ This cartilage maintains the shape of the ear and also allows its flexibility.

$$\bullet$$ It supports the external ear and allows the ear bones to develop.

$$\textbf{Explanation for incorrect options:}$$

Option B: The hands of the body are made up of bones and muscles. There is the presence of cartilage at the joints to avoid friction during movement.

Option C: The legs of the body are made up of long bones with associated muscles. The joints of these long bones have the presence of cartilage which acts as a cushion.

Option D: The shoulder part is made up of shoulder bones that form the pectoral girdle.

$$\textbf{Conclusion:}$$ The upper portion of the ear (pinna) is made completely of cartilage.

The joints where no movement of bones is possible are called fixed joint. The joints in the skull bone and jaw bones are examples of fixed or immovable joints. Thus, Option C is correct.

In ball and socket joints, the rounded end of one bone fits into the cavity (hollow space) of the other bone. Thus, Option A is correct.

Bones and cartilage form the skeleton of the human body. It gives the frame and shape to the body and helps in movement. It protects the inner organs. Thus, Option D is correct.