Class 9 Science Chapter 6 MCQ

The nature of matrix differs according to their functions for e.g., cartilage has calcium salts as it provides support to bones whereas muscles passes contractile proteins for their function of movement. Adipose tissue consists of oval and round cells filled with fat globules, scattered in the matrix. This tissues are found below the skin, between internal organs and in the yellow bone marrow. It stores fat and acts as an insulator. Cuboidal epithelium helps in absorption, excretion and secretion whereas bones and cartilage are specialised connective tissues and they provide support to the internal organs.

Chlorenchyma consists of living cells and are characterized by the presence of cellulose. Chlorenchyma is a mechanical tissue in young dicotyledonous stems and provides mechanical support and elasticity. It provides great tensile strength with flexibility to those organs in which it is found. It allows easy bending in various plants of a plant mainly young growing stream without breaking them.

Cardiac muscles show characteristics of both smooth and straight and muscles. These muscles are striated, cylindrical, branched and involuntary in nature. In addition to the light and dark bands, these muscles should densely stained cross bands called intercalated dises. These act as impulse is boosters. Cardiac muscles contract and relax rapidly, rhythmically and tirelessly throughout a lifetime, from early embryonic stage until death. Voluntary muscles are under our control and act accordingly to our need e.g., skeletal muscles. Smooth muscles also known as striated, visceral or involuntary muscles are found in walls of hollow tubular organs like alimentary canal, ducts of glands, urogenital ducts and blood vessels except heart. They show slow contractions but remain contracted for a long period of time.

Each nerve cell or neuron is composed of three parts. i)Cyton or cell body: It contains central nucleus and cytoplasm with characteristic deeply stained particles called “Nissl’s granules” (i.e. clumps of ribosome). ii) Dendron: These are short processes arising from cyton and further branching into dendrities. ii)Axon : It is a single long cylindrical process of uniform diameter which forms fine branches terminally. The dendrites receives impulses and the axon takes impulses away from the cell the body. Tendon are the connective tissue, which join skeletal muscles to bones, hence nervous tissue is absent is them. Nervous tissue is specialized to transmit messages within our body. It contains highly specialized unit cells called nerve cells or neurons. They have the ability to receive stimuli from within or out-side the body and to conduct (send) impulses (signals) to different parts of the body. Brain, spinal cord are all associated with the regulation of body activity and are composed of nervous tissue.

Contractile proteins are found in muscles, as they are associated with the movement of body or limbs. The contraction and relaxation of contractile proteins, present in muscles bring about movement of limbs, internal organs etc. The bones are the major supporting tissues which form the endoskeleton of a vertebrate body. Blood is a fluid connective tissues responsible for transport of oxygen, nutrients, hormones etc. and for producing antitoxins and antibodies etc. Cartilage provides support and flexibility to the body parts and smoothens surface at joints. Note: Bones, blood and cartilage all are different types of connective tissues and are not responsible for movement of any of the body parts.

Bone cells are embedded in a hard matrix, which is strengthened by fibres, and hardened by calcium and phosphorus salts. The matrix is deposited in the form of concentric layers of lamellae formed around a central Haversian canal.

Smooth muscles are found in the walls of hollow visceral organs. They do not work according to our will. They are involved in peristaltic movement of gastro-intestinal tract and male genital tract. Cardiac muscles are present in the heart. They contract and relax rapidly, rhythmically and tirelessly. They help to pump the blood to various parts of the body. The working of both smooth and cardiac muscles is involuntary while skeletal or straited in muscles are moving to our will and are voluntary in action.

Tracheids and vessels are xylem elements and are concerned with the transport of water. They are long tube-like structures with partially or completely dissolved walls to from water pipes (in vessels) and pits in cell wall (in tracheids) for conducting water. Sieve tubes are slender tube-like structure with their end walls perforated by numerous pores and are called seive plates. They are phloem elements and are main food conducting elements. Companion cells possess numerous mitochondria and ribosomes and are supporting units of sieve tubes. Note: Companion cells are associated with sieve tubes and connected to them by numerous plasmodesmata. They help in maintaining pressure gradient in sieve tubes. They are not perforated.

Here, all these statements are correct. Hence, your answer will be option [D].

Here, all these statements are correct. Hence, your answer will be option [D].