Class 9 Science Chapter 6 MCQ

The gymnosperms are characterized by the presence of tracheids as their major conducting tissues. These are elongated dead cells with hard lignified walls. They conduct water and do not have open ends like the vessels.

If the tip of sugarcane plant is removed the apical meristem is also removed as it is situated in the apices of growing roots and stem. Intercalary meristem are located at the base of leaves or nodes and leads to the increase in the length of an organ such as leaves and internodes.

The matrix of cartilage has delicate network of collagen fibres and chondrocytes (living cells). These are present in fluid-filled spaces called lacunae. Chondrocytes multiply by mitosis and help in internal growth of cartilage. A mast cell is a resident granulocyte of several types of tissues. It contains granules rich in histamine and heparin. They play a key role in allergy and are involved in wound healing and defence against pathogens. Basophils are granulocytes of white blood cells (WBCs) and are involves in functions of body defence by engulfing bacteria and other foreign substances. Osteocytes are the bone cells.

Areolar tissue is a loose and cellular connective tissue. Its matrix consists of two kinds of fibres, i.e., the white collagen fibres (which changes into boiling in water) and the yellows elastic fibres or elastin. Several other kinds of irregular cells, (example, fibroblasts), which can engulf bacteria and prevent infection (example, macrophages) are also present in the matrix. It is the simplest and most widely distributed connective tissue. It joins skin to muscles, fills spaces inside organs and is found around muscles, blood vessels and nerves. It acts as supporting and packing tissue between organs lying in the body cavity. Matrix of the tissue is important in diffusion of oxygen and nutrients from small blood vessels. It helps in repairing of tissues and to combat foreign toxins. Dislocation of joints occurs when there is an abnormal separation in joint, which are held together by ligament. Therefore, ligament break and may result in dislocation of bone. Areolar tissues join skin to muscles, fills spaces inside organs and is found around muscles, blood vessels and nerves. Hence are not concerned with bones. Tendon break may cause inflammation and occurs due to factors including age, body weight, nutrition, sports etc. 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. Adipose tissue consists of oval and round cells filled with fat globules, scattered in the matrix. This tissue is found below the skin, between internal organs and in the yellow bone marrow. It stores fat and acts as an insulator. Cuboidal epithelium help in absorption, excretion and secretion, whereas bones and cartilage are specialized connective tissue and they provide support to the internal organs.

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.

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.

Girth of the stem increases due to lateral meristematic tissues. They are found beneath the bark (called cork cambium) and in vascular bundles of dicot roots and stems (called vascular cambium) as thin layers. This increase in the diameter and girth of the plant is called secondary growth. The apical meristem is situated at the growing tip of stems, root and also at the apices of leaf. They bring about elongation i.e., increase in height (primary growth) of the plant. Intercalary meristem are located at base of leaf and internode and produces an increase in the length of an organ.

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].