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According to the shape and the movement, the synovial joints are of six types: 

(i) Gliding Joint: The articular surface of this joint are usually flat, permitting only back and forth and side to side movements. No rotation or twisting is possible because bones are tightly packed. e.g., joints between carpal and tarsal bones. 

(ii) Hinge joint: In this, the surface of one bone fits into the concave surface of another bone. e.g., joints in elbow, knee, ankle etc. 

(iii) Pivot joint: A pivot joint is a joint that allows movement in only one plane. In this rounded bone fits into a shallow depression of another bone. Ex. Joint between atlas and axis, radius and ulna. 

(iv) Saddle joint: It allows the movement in two planes freely. The projection of one bone fits in saddle shaped depression of another bone. e.g., the joint between the carpal and metacarpal of thumb of hand. 

(v) Ball and socket joint: This is the most freely movable joint. In this, a ball like structure on the one bone fits into socket like structure in another bone. e.g., shoulder and hip joints.

The protein present in the thin filament is Actin.

Each skeletal muscle is covered by Epimysium.

Presence of H-bonds, the plane of one base pair stacks over the other, complementarity. Presence of thymine in place of uracil. 

Detailed Answer:

Stability of Double Helical Structure of DNA 

(i) Complementarity of the two strands of DNA due to complementary nitrogenous bases which form strong hydrogen bonds with each other. Adenine forms two hydrogen bonds with thymine and cytosine form 3 hydrogen bonds with guanine. 

(ii) The base pairs are stacked with their planes one over the other in the double helical structure which provides extra stability. 

Also, DNA is less reactive due to absence of reactive -OH group at 2' carbon evolution of a process of repairs which prevents their degradation and presence of thymine instead of uracil being more stable as nitrogenous base.

Muscles are formed by Myocytes.

Glycosomes are the granules of stored glycogen.

The region between two successive Z-discs is called a Sarcomere.

The functional unit of a muscle fibre is Sarcomere.

The pigment present in the muscle fibre to store oxygen is Myoglobin.

Skeletal muscles are attached to the bones by Tendon.

The muscles attached to the bones are called Skeletal muscle.

Skeletal muscle is attached to the bone by a bundle of collagen fibres known as Tendon.

The bundle of muscle fibres is called Fascicle.

The cytoplasm of the muscle fibre is called the Sarcoplasm.

Myoglobin is a red coloured respiratory pigment of the muscle fibre.

Muscles are derived from Mesoderm.

The muscle fibres which contain a few mitochondria but possess a high concentration of glycolytic enzymes and large stores of glycogen are called glycolytic fibres. These lack myoglobin and hence these are pale. These muscle fibres are termed as white muscle fibres.

The muscle fibres that contain numerous mitochondria and have a high capacity for oxidative phosphorylation are classified as oxidative fibres. They are also called red muscle fibres.

(b) Sarcoplasm

Glycolytic fibres or white muscle fibres lack Myoglobin.

(c) Mesoderm

The skeletal system is derived from the Mesoderm.

The oxidative fibres are called as Red muscle fibres.

Functions of skeletal system

1. Support -It forms a rigid framework and supports the weight of the body against gravity. 

2. Shape – It provides and maintains the shape of the body. 

3. Protection – It protects the delicate internal organs of the body.

4. Acts as reservoir – It stores minerals such as calcium and phosphate. Fat (triglyceride) is stored in yellow bone marrow and represents a source of stored energy for the body. 

5. Locomotion – It acts as lever along with the muscles attached to it. 

6. Strength – It can withstand heavy weight and absorbs mechanical shock. 

7. Asa haemopoietic tissue – Red and white blood cells are produced in the bone marrow of the ribs, spongy bones of vertebrae and extremities of long bones.

Hinge joint e.g., elbow joint, knee joint.

A traumatic pulling of the fibres produces a tear known as Sprain

Synovial joints/Diarthroses joints are the freely movable joints.

Arthritis is an inflammatory or degenerative disease that damages the joints.

The joints are points of contact between bones.

The structural arrangements of tissues by which bones are joined together are called joints. 

There are three types of joints: 

(i) Fibrous or immovable joints: There is no movement in such joints. There is white fibrous tissue between the ends of the bones. e.g., the joints of skull, teeth etc. 

(ii) Cartilaginous or slightly movable joints: It is an articulation between bones in which motion is limited due to either fibrous tissue or cartilage. 

(iii) Synovial or freely movable joints: It is a freely movable joint characterized by the presence of a fluid filled synovial cavity between the articulating surfaces of the two bone.

(i) There is a membrane present called synovial membrane. 

(ii) This membrane is composed of secretory epithelial cells which secrete a thick sticky fluid, of the consistency of the white of an egg called synovial fluid. 

(iii) It acts as a lubricant to the joint, provides nutrient materials for the structures within the joint cavity and helps to maintain the stability of the joint. 

(iv) Bone ends are covered by articular cartilages. 

(v) Ligaments join the bones and tendons connect the bones with muscles. 

(vi) Little sacs of synovial fluid or bursae are found in some joints.

The reduction in the force of contraction of a muscle after prolonged stimulation is called muscle fatigue. 

(i) A muscle is able to contract for a short time in the absence of oxygen. But it gets fatigue sooner because the metabolic products of glycolysis mainly lactic acid accumulate, in the absence of oxygen. 

(ii) The accumulation of lactic acid leads to muscle fatigue.

Correct Answer is : (b) Tetany

Muscle fatigue is the inability of a muscle to contract after repeated muscle contractions. This is due to lack of ATP and accumulation of lactic acid by anaerobic breakdown of glucose.

1. Mehrgarh 

2. Sindhu 

3. Trade 

4. Rigveda 

5. Hothar

Myasthenia gravis: An autoimmune disorder affecting the action of acetylcholine at neuromuscular junction leadihg to fatigue, weakening and paralysis of skeletal muscles. Acetylcholine receptors on the sarcolemma are blocked by antibodies leading to weakness of muscles. When the disease progresses, it can make chewing, swallowing, talking and even breathing difficult.

c). Burzaham.

1. A reference to grama appears in Rigveda 

2. Rajan was the Head of the tribes 

3. Puru clan & Bharatha clan were important 

4. Non-Aryan tribes Dasyu and Paani conflicted with Aryans 

5. Sabha & Samithi helped to king 

6. A soliders was called as ‘Yodha’ 

7. Inrasions and conflicts used to take

1. These are the reflective discoursed of philosophy 

2. The evidence of the intellectual maturity of Indians during the Vedas period

After the death of an individual, the membrane of muscle cells become more permeable to calcium ions. This happens due to partial contraction of skeletal muscles. The contracted muscles are unable to relax. This condition is known as rigor mortis.

Vertebral column is also called the back bone. It consists of 33 serially arranged vertebrae which are interconnected by cartilage known as intervertebral disc. The vertebral column extends from the base of the skull to the pelvis and forms the main frame work of the trunk. The vertebral column has five major regions.

They are, the cervical, thoracic, lumbar, sacrum (5 sacral vertebrae found in the infant which are fused to form one bone in the adult) and coccyx (4 coccygeal vertebrae found in the infant which are fused to form one bone in the adult).

Each vertebra has a central hollow portion, the neural canal, through which the spinal cord passes. The first vertebra is called as the atlas and the second vertebra is called as the axis. Atlas is articulated with the occipital condyles. The vertebral column protects the spinal cord, supports the head and serves as the point of attachment for the ribs and musculature of the back. 

There are 12 pairs of ribs. Each rib is a thin flat bone connected dorsally to the vertebral column and ventrally to the sternum. It has two articulation surfaces on its dorsal end, hence called bicephalic.

The first seven pairs of ribs are called ‘true ribs or vertebro-stemal ribs. Dorsally they are attached to the thoracic vertebrae and ventrally connected to the sternum with the help of hyaline cartilages.

The 8th, 9th and 10th pairs of ribs do not articulate directly with the sternum but joined with the cartilaginous (hyaline cartilage) part of the seventh rib. These are called ‘false ribs’ or vertebrochondral ribs.

The last 11th and 12th pairs of ribs are not connected ventrally. Therefore, they are called as ‘floating ribs’ or vertebral ribs. Thoracic vertebrae, ribs and sternum together form the ribcage. Rib cage protects the lungs, heart, liver and also plays a role in breathing.

Thoracic vertebrae ribs and sternum together constitute the ribcage.

The first vertebra is called as the Atlas.

Exercise protects us from heart attack.

The second vertebra is called as the Axis.

Sternum is the flat bone on the mid ventral line of the thorax.

The cranium protects the Brain.