Class 9 Science Chapter 6 MCQ

When a nail is inserted in the trunk of a tree at a height of 1 m from the ground, even after 3 years the nail remains the same level. It does not move upward as the apical meristem responsible for growth (length) is present in the apices only and lateral meristem responsible of increase in girth will lead to no change in length.

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.

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.

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.

Voluntary muscles are the muscles, which are under our complete control for e.g., the working and movement of limbs. On the other hand, involuntary muscles are controlled by hypothalamus i.e., they are regulated rhythmically, e.g., alimentary canal, iris of the eye and bronchi of lungs. Note: Alimentary canal, iris of the eye and bronchi of lungs, the movements of the above organs are not under our will.

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.

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. Note: Tendons joint skeletal muscles to bone and ligaments join bones to bones.

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].

Lymph is a colorless fluid that is filtered out of the blood capillaries and white blood cells are found in abundance.