Class 9 Science Chapter 6 MCQ

Cellulose is a basic of the cell wall present in plants. The cell wall of almost all the organisms are made up of cellulose whereas lipids along with some proteins forms the basic building blocks of plasma membrane. Plasma membrane is semi-permeable and it is not impervious to water. Lignin is a complex polymer which acts as a cement and hardens the cell wall. It provides flexibility, great tensile and compressional strength to the cell wall and makes the cell wall impermeable. It is present in sclerenchyma cells and not in cork cells. The walls of cork cells are heavily thickened with an organic substance, suberin. Suberin makes these cells impervious to water and gases.

Parenchyma cells from the bulk of the plant body. These cells are living and their possess the power of division. The cells are rounded, or isodiametric i.e. equally expanded on all sides. The cells are oval, ground, polygonal or elongated in shape with a thin cell wall. It encloses a dense cytoplasm, which contains small nucleus and surrounds large central vacuole.

Cuticle are protective, hydrophobic waxy covering produced by epidermal cells of leaves, young shoots and other aerial parts. It minimizes the water loss through transpiration (with the help of stomata) and also reduces pathogen entry. Lignin hardens the cell wall and provides flexibility, tensile and compressional strength to the cell wall. Suberin is present in cork cell and makes the cell impervious to water.

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.

Cartilage is specialised connective tissue, which is compact and less vascular. The cartilage cells (chondroblasts) are widely spaced and the matrix is reinforced by fibres. Cartilage occurs at the joints of bones, in the nose, ear, trachea and larynx. It helps in smootheing the surface at the joints. It lends support and provide flexibility to 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).

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.

Explanation: 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.

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].