Class 9 Science Chapter 6 MCQ

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.

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.

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. 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 sieve 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.

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.

Meristematic tissues consists of actively dividing cells and is present in the growing region of plants, e.g. tips of roots and stems. The cells of meristematic tissue are round, oval, polygonal or rectangular. They are packed closely without intercellular spaces, have him cellulose walls, dense cytoplasm and prominent nuclei. Vacuoles are almost absent in such cells because they are completely filled with sap.

Columnar epithelium consists of pillar-like cells with their nuclei towards the base. They form the lining of stomach, small intestine and colon, forming the mucous membrane. Their main function is absorption (e.g. stomach, intestine) and secretion (e.g. mucus by goblet cells). Stratified squamous epithelium, also known as pavement epithelium is covered by fibrous protein, (keratin) that covers the skin. This epithelium is waterproof and resistant to mechanical injury. Cuboidal epithelium is found in kidney tubules, thyroid vesicles and in glands.

Sclerenchyma cells are the permanent tissues present in the plants. They provide hardness and stiffness to the plant and are composed of dead cells. This tissue is present in stems around vascular bundles in the veins of leaves and in hard covering of seeds and nuts. Example, the husk of coconut is made up of sclerenchymatous tissues. The cells of sclerenchyma are long narrow and thickened due to lignin.

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.