Body Movements - Class 6 Biology - Extra Questions

$$\textbf{Concept applied:}$$ Cartilage is a firm tissue but is softer and much more flexible than bone. 

$$\textbf{Explanation:}$$ Cartilage

     $$\bullet$$ Cartilage is the part of the connective tissue, where it is usually semi-rigid and flexible.

     $$\bullet$$ It covers and safeguards long bone ends in joints and nerves like a rubber pad.

     $$\bullet$$ It helps in smoothening the surface at the joints.

 

$$\textbf{Explanation:}$$ Location of cartilage

    $$\bullet$$ Cartilages are found in the upper part of the ear, the tip of the nose, trachea, and larynx, and at the tips of long bones.

 

$$\textbf{Conclusion:}$$ Cartilage is a flexible connective tissue that helps in smoothening the surface at the joints. It occurs at the joints of bones, in the nose, ear, trachea, and larynx.

 

Movement in Earthworm: -

• The body of an earthworm is made up of many rings joined end to end.
• An earthworm does not have bones. 
• It has muscles that help to extend and shorten the body. 
• During movement, the earthworm first extends the front part of the body, keeping the rear portion fixed to the ground. 
• Then it fixes the front end and releases the rear end. 
• It then shortens the body and pulls the rear end forward. This makes it move forward by a small distance. 
• Repeating such muscle expansions and contractions, the earthworm moves through the soil. 
• Also, the body secretes a slimy substance to help with the movement.

$$\textbf{Solution}$$

$$\bullet$$ The human skeletal system acts as the framework of the body which consist of individual bones and cartilages.

$$\bullet$$ Our human skeletal system is composed of 206 bones which are interconnected with each other, tendons, cartilages and ligaments.
Some of the functions of the human skeletal system are:
$$\bullet$$ It provides support structure and shape to the human body.
$$\bullet$$  It facilitates the movement of the body from one position to another.
$$\bullet$$  It acts as a protection to the internal organs that are present in human body. It prevents the internal organs from mechanical injury.
$$\bullet$$ The bones of the human skeletal system acts as the storehouse of different minerals. The most prominent mineral is calcium.
$$\bullet$$  Bones contain bone marrow inside them helps in the production of various cells like red blood cells and white blood cells.

• We can only bend or rotate our body at joints where two parts of our body seem to be joined — like elbow, shoulder, or neck.
• In our body, there are mainly few types of movable joints to help us carry out different movements and activities like:-

1. Ball and socket joint:

• In this joint, the rounded end of one bone fits into the cavity (hollow space) of another bone to permit movement in all directions. For example - Shoulder joint between the shoulder and the upper arm.

2. Pivotal Joint:

• This type of joint allows movements up and down and from side to side rather than in complete circular motion. For example - The joint between the skull and the vertebral column (where our neck joins the head).

3. Hinge joint:

• This type of joint allows only back-and-forth movements (only in one plane) similar to the hinges on a door. For example - Knee joint and elbow joint.
  

• Apart from movable joints, there are fixed joints (immovable joints) also like in between bones in our head (or skull).

• Snakes have a cylindrical, long body with scales. The body has numerous muscles and vertebrae. Snakes slither on land to move by drawing on their bellies. 
• They form loops while moving. Each loop of the snake gives it a forward push by pressing against the ground and helps the snake to move forward.

(a) Dorsal fin
(b) Caudal fin
(c) Pelvic fin
(d) Pectoral fin
Function of caudal fin-caudal fin helps in streamlined movement in water.

Snake A will move forward faster as it has more loops while slithering. The more the loops, the faster the speed of the snake. 

• The skeleton system of a bird has some modifications suitable for flying like:-

i. It is composed of hollow and light bones.
ii. Bones of hind limbs are for walking and perching. 
iii. Bones of the forelimbs are modified as wings.
iv. Shoulder bones are sturdy.
v. Breast bones in birds hold flight muscles that help them to move wings up and down. 

1. Pollination, Fertilization, Seed, Germination, Seedling.