:
Body structure : 2Marks
Movement : 1 Mark
Snakes are vertebrates with a vertebral column. Its body is supported by a skeleton made up of vertebrae which run continuously from head to tail. As they do not have any limbs, snakes do not have appendicular skeleton. They have a long back bone and many interconnected muscles that help them to slither. They have muscles connecting the backbone, ribs and skin.
Snakes move in grass, sand and water. Though the snakes do not have arms or legs, they can climb trees. Theymove in a loop-like, zig-zag manner. They cannot move in a straight line. They have difficulty in moving on very smooth surfaces.

:
Animal movements: 1 Mark each
Snakes :
Snakes have a backbone and many interconnected muscles that help them to slither. They have muscles connecting the backbone, ribs and skin. Snakes move in a loop-like, zig-zag manner. They cannot move in a straight line, and have difficulty in moving on very smooth surfaces.
Cockroaches :
Cockroach is an arthropod with six jointed legs. These legs aid in walking, and two pairs of wings are used to fly. A cockroach moves its legs with the help of muscles near the limbs. It uses its breast muscles to move its wings and fly.
Snails :
Snail moves with the help of a single muscular foot. The under surface of the foot is lubricated with mucus which helps the snail to move easily. The rhythmic contractions and relaxations of the foot brings about a moving action in the body. The entire body except the foot lies inside the shell.
Earthworms:
Earthworms move with help of tiny, stiff hair-like projections called bristles. Every segment of the earthworm's body possesses "setae" which help in their movement. They move forward by repeated contractions and relaxations of their muscles in the skin. A slimy substance secreted by the earthworm helps in its movement.
Fish:
Fish possess a streamlined body which helps them to swim in water. They swim with the help of their fins and their tails. The tail flaps from side to side to propel in the right direction. Some fish, however, move by bending their bodies from one side to another in quick succession. This produces a thrust that helps it move forward.

:
Atissueis a group of cells thattogether perform a particular function.

:
Types of joints: 1 Mark each
1. Fixed or immovable jointsare the joints which do not allow the bones to move but they offer protection for the structure in which they are present. Examples are the sutures between the bones of the cranium, ribs in the breastbone and bones of the hip girdle.
2. Slightly movable jointsprovide support to the structure in which they are present. They also help the structure to move slightly.An example is the joint in the lower jaw which is slightly movable.
3. Freely movable jointsare the joints which help in the movement of the part in which they are present. There are four freely movable joints present in our body - ball and socket joint, Pivot joint, hinge joint and the gliding joint.

Answer: Option C. -> pivot joint
:
C
A joint is a junction where two or more bones meet. They aid in movement.
Joints are of various types:
$\bullet$ The joint that connect our neck to head is called a pivot joint. It allows movement of neck in the forward and backward direction, as well as sideways movement.
$\bullet$ Hinge jointallows back and forth movement. It is found in ankles, elbows and kneejoints.
$\bullet$ Ball and socket joints form when a bone ending with a ball like structure fits into the socket of adjacent bone. The bone with a ball can move nearly in all directions. These joints are present in hip and shoulder.
$\bullet$ Fixed joints don't permit any movement and are extremely strong. They are present between various bones of the skull.

Answer: Option A. -> fixed joints
:
A
Joints which do not allow any movement of bones are called fibrous or fixed joints. These joints bind the bones closely and tightly.On the other hand, the ball and socket joint, hinge joint and pivot joint allow partial or free movement of bones.Fixed joints are present between various bones of the skull.

Answer: Option C. -> hinge
:
C
In human body, elbows have back and forth movement (similar to opening and closing of a door). Hinge joints are the type of joints that allow this type of movement. These joints are present in knees and ankles as well.

Answer: Option B. -> False
:
B
Earthworms do not have bones. They have muscles which help them extend and shorten their body by alternatecontraction and relaxation.Earthworms also haveorgans called setae which help in locomotion.

Answer: Option C. -> Three
:
C
Cockroaches have three pairs of legs. Body of cockroach has three regions - head, thorax and abdomen. Each one of these segments has a pair of legs.

Answer: Option B. -> No
:
B
The snake's body curves into many loops and each loop gives a push, so that it canmovevery fast but not in a straight line.