Class 9 Science Chapter 6 MCQ

The conducting tissues in plants conduct different shapes and have different structures. The primary conducting tissues of plants are xylem and phloem. Xylem conducts water from roots to the other parts of the plant, whereas phloem transports food and other material from the leaves to other parts of plants.

Xylem vessels are very long tube-like structures formed by a row of cells placed end to end. The transverse walls between these cells are partially or completely dissolve to from continuous water channels. Parenchyma serves as the packing tissue in plants therefore they do not have intercellular spaces. Collenchymatous tissues are mechanical tissues in the plants and are characterized by the deposition of cellulose at the corners of the cell, which leads to localised thickening of the cell wall. Apical and intercalary meristem bring primary growth (increase in height) and secondary growth (increase in diameter) respectively and are classified under meristematic tissues. Meristematic tissues are dividing units of the plants and contain dense cytoplasm and large nucleus with few or no vacuoles at all. Phloem fibres are thick walled, elongated, spindle shaped dead cells which possess narrow lumen. They provide mechanical support to the tissue. Phloem parenchyma are thin walled living cells of parenchyma. They have two functions, storage and lateral food conduction.

Companion cells are present along the sieve tube are connected to them via plasmodesmata. These cells are metabolically active and sieve tube elements are dependent on these cells. They do not lose nuclear nucleus at maturity. RBC vessels and sieve tube cells lose their nucleus at maturity.

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.

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.

Tendons are cord-like, strong, inelastic, structures that join skeletal muscles to bones. A tendon is a white fibrous tissue which has great strength but limited flexibility. It consists of parallel bundles of collagen fibres, between which are present, rows of fibroblasts (called tendinocytes).

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.

Skeletal muscles are striped, voluntary muscles, due to presence of alternate dark and light bands. They are called voluntary as they work according to our will. While doing work and running skeletal muscles contract and pull the tendon (which connects muscles to bones) to move the bone. Note: Smooth muscles are involuntary, i.e., they do not work according to our will, therefore option [A] and [B] cannot be the answer. Ligament connects bone to bone but it is the tendon which connect muscles to bones.

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

The cell walls of sclerenchyma are greatly thickened of lignin. Sclerenchyma cells are dead cells and they are devoid of protoplasm. The cells of sclerenchyma are closely packed without intercellular spaces.