Science M.C.Q. [1 M]

The collenchyma is found in few layers below the epidermis of plant. It is generally absent in monocot stems and leaves. The cell wall is unevenly thickened.

Bichat is also known as “Father of histology”.

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.

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.

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.

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.

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

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.

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.

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

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.

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

Husk of a coconut is made up of sclerenchymatous fibres.

Permanent tissues formed by meristematic tissues take up a specific role and lose the ability to divide further.

Phloem is a complex tissue in the plant which conducts water from leaves to the other parts of the plant.

Active divisions take place in the cells of cambium. Cambium is a meristematic tissue.

Nasal and genital tracts are lined by pseudostratified epithelium.

The matrix of bone is made up of proteins and is heavily coated with salts of calcium and phosphorous. These minerals make the bone very tough.

The parenchyma is present in soft parts of the plant such as cortex, pith, palisade and some parts of the flower. It is considered as a fundamental or ground tissue.

Cardiac muscle fibre contains intercalated discs.

Glands develop from epithelial tissue. They may be unicellular or multicellular.

Simple squamous epithelial cells are extremely thin and flat and form a delicate lining. Squamous epithelial tissue forms the inner lining of a blood vessel.

Squamous epithelium is also called pavement epithelium as it is made up of single thin layer of flattened cells.

The meristematic cells are full of cytoplasm and have a big nucleus.

The cells of connective tissue are embedded in a matrix. The matrix may be jelly like, fluid, dense or rigid. It is produced by fibroblasts.

Smooth muscles are found in alimentary canal and blood vessels. The movement of food in the alimentary canal or the contraction and relaxation of blood vessels are involuntary movement.

Areolar connective tissue is found between the skin and muscles, around blood vessels and nerves and in the bone marrow. It fills the space inside the organs, supports internal organs and helps in repair of tissues.

Phloem is made up of four types of elements:
Sieve tubes, companion cells, phloem fibres and the phloem parenchyma.

Skin epithelial cells are arranged in many layers to prevent wear and tear. Since they are arranged in a pattern of layers, the epithelium is called stratified squamous epithelium.

Simple tissues are made up of only one type of cells. There are three types of simple tissue occur in plants: Parenchyma, collenchyma and sclerenchyma.

Collenchyma tissue are found below epidermis in leaves and stem.

Cardiac muscle fibres are branched, striated and involuntary. These muscles are exclusively present in the heart.

Cardiac muscle fibres are branched, striated and uninucleate. These muscles are involuntary. These muscles are exclusively present in the heart and show rhythmic contraction and relaxation throughout life.

Meristematic tissue consists of cells which are not differentiated and which are cabable of cell division. It is found on those regions of the plant which grows.

Platelets are not true cells in the blood.

The meristem which occurs at the growing tips of roots and shoots and increases the length of the stem and root is called apical meristem.