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.

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.

Each nerve cell or neuron is composed of three parts. i)Cyton or cell body: It contains central nucleus and cytoplasm with characteristic deeply stained particles called “Nissl’s granules” (i.e. clumps of ribosome). ii) Dendron: These are short processes arising from cyton and further branching into dendrities. ii)Axon : It is a single long cylindrical process of uniform diameter which forms fine branches terminally. The dendrites receives impulses and the axon takes impulses away from the cell the body. 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.

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.

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.

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.

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].

Here, all these statements are correct. Hence, your answer will be option [D].