Science M.C.Q. [1 M]

(A)

Cardiac muscles show rhythmic contraction and relaxation.

Epithelial tissue that is only one cell thick is called the simple epithelium.
Simple squamous, simple cuboidal, simple columnar and simple pseudostratified are four types of simple epithelium.
Epithelium that is two or more cells thick is called the stratified epithelium.

It is composed of a single layer of tall and slender cells. Their nuclei are located at the base. Free surface may have microvilli. It is generaly found in the lining of stomach and intestine and help in secretion and absorption.

Xylem consists of tracheids, vessels, xylem parenchyma and xylem fibres. The cells have thick walls, and many of them are dead cells.

Ligament is a dense connective tissue which connects a bone with bone.

A group of cells that are similar in structure and / or work together to achieve a particular function forms a tissue.

It is because of conducing tissues that plants are able to take up water from soil. Thus, plants could be able to survive in terrestrial environment where availability of water can be a major issue.

Under the microscope, striated muscles show alternate light and dark bands or striations when stained appropriately. As a result, they are also called striated muscles.

Voluntary muscles are those muscles that our under our will i.e. those muscles that can be controlled. Limbs are made of voluntary muscles; their actions are under our control. Alimentary canal, iris of eye and bronchi of lungs are involuntary and they are regulated on their own in a specific pattern.

Collenchyma: It is a simple permanent living mechanical tissue.

• It is found in the hypodermal regions of dicot stem, leaf and fruit walls.
• Cell wall is unevenly thickened with cellulose and pectin.
• Provides mechanical support to growing parts of plants such as young stem, petiole of leaf.

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

Phleom is composed of four types of elements i.e., sieve tubes, campanion cells, phloem parenchyma and phloem fibers or best fibers. All type of cells are living except best fibers.

The cells of the sclerencyma are dead. They are long, elongated, narrow, thick walled and lignified.

Generally, some group of cells have same function and structure and also are derived from same origin.These group of cells are called tissue.

Kidney is composed of different kinds of epithelial tissues.

Movement of organs in other options is not controlled by individual volition. Hence, voluntary muscles are not found in them.

Each neuron has a single long part, called th axon and many short, branched parts called dendrites.

The conducting tissues in plants conduct different saps 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.

Epithelial tissue cells are tightly packed and form a continuous sheet. They have only a small amount of cementing material between them and almost no intercellular spaces.

Other meristems in options facilities growth in length, while lateral meristem cause the organ to increase in diameter and growth which happens in the case of girth.

Mast cells are cells that secrete histamine and heparin during allergic response and are specialized components of the areolar tissue.

The tissues formed by meristematic tissues take up a specific role and lose the ability to divide further. As a result, they form a permanent tissue. This process of taking up a permanent shape, size, and a function is called differentiation. Cells of meristematic tissue differentiate to form different types of permanent tissue.

An epithelium is a tissue composed of one or more layer of cells covering the external surface and internal body organs.

Walls of collenchymas are irregularly thickened due to the deposition of pectin.

Connective tissues are most abundant and widely distributed in the body of complex animals.

The cork cells are dead and lack inter cellular spaces. Its cells, whose walls are impregnated with suberin, are arranged in radial rows and fit closely together except where the cork is interrupted by lenticles.

As epidermis is formed of cutin, suberin gives rise to cork cells which makes them impervious to gas and water. No other given option is formed from suberin.

Ligament is a dense connective tissue which connects a bone with bone.

A dipose tissue is fat storing connective tissue which is found mainly beneath the skin. Blubber of whale and hump of camel are adipose tissue which store fat.

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 movements of limbs, internal organs, etc. The bones are the major supporting tissue which form the endoskeleton of a vertebrate body. Blood is a fluid connective tissue 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.

Tendon is a form of dense connective tissue which connects a muscle with a bone.

Phloem fibres are the dead element of phloem. Phloem tissue consists of conducting cells, generally called sieve elements, parenchyma cells, including both specialized companion cells or albuminous cells and unspecialized cells and supportive cells, such as fibres and sclereids.

Husk of a coconut is made up of sclerenchymatous fibres.

Adipose tissue stores fat and since fat is a bad conductor it acts as an insulator and prevents loss of heat from the body. Therefore, a fatty person is less affected by cold.

This is the reason our heart keeps on pumping the blood throughout the life. Other types of muscles work as and when required because they do not need to work continuously.

Sclerenchyma is entirely composed of dead cells. Tissues mentioned in others options are composed of living cells only.