Class 9 Science Chapter 6 MCQ

The nature of matrix differs according to their functions for e.g., cartilage has calcium salts as it provides support to bones whereas muscles passes contractile proteins for their function of movement. Adipose tissue consists of oval and round cells filled with fat globules, scattered in the matrix. This tissues are found below the skin, between internal organs and in the yellow bone marrow. It stores fat and acts as an insulator. Cuboidal epithelium helps in absorption, excretion and secretion whereas bones and cartilage are specialised connective tissues and they provide support to the internal organs.

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.

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.

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.

Epidermis is present as outermost layer of plant body such as leaves, flowers, stem and root. It is covered with cuticle (a waterproof a layer of a waxy substance cutin). The main function of epidermis is to protect the plant from desiccation and infection. In fact, cuticle of epidermis helps to reduce water loss by evaporation from the plant surface and also helps in preventing the entry of pathogen (bacteria, fungi etc.) The aerial surface of many plant bear cutinized hair (trichomes) to reduce transpiration.

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.

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.

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.