Science Answer the questions.[Bio-2M]

Types of white blood cells (WBCs) are:

• Eosinophils.
• Basophils.
• Neutrophils.
• Monocytes.
• Lymphocytes.

1. Apical meristem: It brings about the elongation of the root and stem.

2. Lateral meristem: It causes the organ (stem or root) to increase in diameter and girth.

Sclerenchyma cells are dead cells and they are devoid of protoplasm. The cells walls of sclerenchyma are greatly thickened by lignin. The cells of sclerenchyma are closely packed without intercellular spaces.

They are located at the base of leaves or internodes, e.g., stems of grasses and other monocots. Such tissues also occur below the nodes. It produces an increase in the length of an organ such as leaves and internodes.

The cells of squamous epithelium tissue are extremely thin and flat and form a delicate lining. It is found in the alveoli of lungs and blood vessels and protects the underlying parts from germs, harmful chemicals and injury.

When blood circulates in the body, it passes through all the organs and thus connects different tissues and organs of the body. Hence it is considered to be a connective tissue.

1. Plants are stationary or fixed as they don’t move while animlas move around in search of food, mates and shelter.
2. The growth in plants is limited to certain regions, while this is not so in animals.

Cartilage contains chondrin and bone contains ossein respectively.

1. Glandular epithelium is present in sweat gland.
2. Germinal epithelium is present in testis.

Simple squamous epithelial cells are extremely thin and flat which allows diffusion of substances through it.

Lymph is a colorless or slightly yellowish fluid which is called the middleman between tissues cells and blood.

Adipose tissue forms blubber of whale and hump of camel.

The cell wall of cork is coated with suberin, a waxy substance which which makes these impermeable to water and gases.

White blood cells are protect our body from various germs that infact our body, hence they are known as soldiers of the body.

Bone and cartilage cells reside in small spaces within the matrix that are called lacunae.

Bone marrow is responsible for the production of blood cells in the body. If bone marrow is destroyed, the formation of white blood cells, red blood corpuscles and platelets will stop.

Apical meristems are the growing parts of the roots and stems and are present at the tips of roots, branches, leaves and shoots. If the apical meristems are damanged or cut, the growth of that part of the plant will stop.

Blood platelets are responsible for clotting of blood. If blood platelets are removed from the blood, clotting will not happen after injury and bleeding will continue. This might lead to the death of the injured person.

Amoeba is a single cell unicellular organism. It performs all vital life activities like respiration, intake of food, exchange of respiratory gases, excretion, reproduction.

In multicellur organisms, each kind of cell is structured to perform all vital life activities and one specific function as a component of tissues.

The cell wall is generally unevenly thickened in collenchymas. The walls are rich in hemicellulose.

The number of blood platelets is 2,50,000-300,000 per cubic mm.

Myelin (medullary) sheath is a fatty covering that surrounds axon of nerve fibres. It insulates the nerve fibre (axon) and prevents leakage of ions.

Muscular tissue is responsible for movement in our body. The cells of this tissue contain special proteins called contractile proteins, which contract and relax to cause movement.

Importance of tissues:

1. Formations of tissues have brought about a division of labour in multicellular organisms.
2. Tissues become organised to form organs and organs organise into organ system.

It is responsible for growth in grith of stem or root.

It has finger-like projections called cilia on the outer suface of columnar epithelial. These cilia can move, and their movement pushes the mucus forward to clear it.

Skeletal connective tissue forms the endoskeleton of the body. It includes bones and cartilage.

Functions of skeletal connective tissue:

1. It provides support to the body.
2. Protects the vital organs of the body like brain, ear, heart, lungs etc.
3. It anchors the muscles and provide movement to animal body.

Serum is blood plasma of blood from which fibrinogen is removed.

Division of labour is adaptation of different parts of an organism to carry out different functions. Hence, there are several kinds of tissues, each with specific properties to carry out specific function in the body.

The normal RBC range for men is 4.7 to 6.1 million cells per microliter. The normal RBC range for women is 4.2 to 5.4 million cells per microliter.

Myelin (medullary) sheath is a fatty covering that surrounds axon of nerve fibres. It insulates the nerve fibre (axon) and prevents leakage of ions.

In human, it ranges from 5000 to 11000 leucocytes/ mm³ blood.

Tendon is a fibrous (dense) connective tissue which connects a muscle with a bone.

The sclerenchyma fibers are of great economical importance since they constitute the source material for many fabrics, hemp, flex, jute.

The process of taking up a permanent shape, size and a function is called differentiation.

A neuron consists of a cell body or cyton with a nucleus and cytoplasm, from which long thin hair-like parts arise.

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.

Tracheary elements are the elements of xylem. Their function is to carry water and mineral salts in upward direction from the roots to different part of shoots.

Group of cells that are similar in structure and perform same function is called a tissue.

Tissue provide structural strength, mechanical strength and show division of labour.

Skeletal and cardiac muscles are two types of striated muscle fibres.

Functions of Phloem:

Phloem transports photosynthetically prepared food materials from the leaves to the storage organs and later from storage organs to the growing regions of the plant body.

Functions of Xylem:

1. The main function of xylem is to carry water and mineral salts upward from the root to different parts of shoots.
2. Since walls of tracheids, vessels and sclerenchyma of xylem are lignified, they give mechanical strength to the plant body.

Simple permanent tissues: These tissues are composed of cells which are structurally and functionally similar.

There are three types of simple permanent tissues:

1. Parenchyma: Parenchyma cells are living and posses the power of division. The cell wall is thin and encloses a dense cytoplasm which contains a small nucleus and surrounds a large central vacuole.

2. Collenchyma: Its tissues consists of living cells. It is characterized by the deposition of extra cellulose at the corners of the cells. In collenchymas, intercellular spaces are generally absent. Collenchyma cells are elongated in shape. They often contain a few chloroplasts.

3. Sclerenchyma: Sclerenchyma cells are dead cells and they are devoid of protoplasm. The cells walls of Sclerenchyma are greatly thickened of lignin. The cells of Sclerenchyma are closely packed without intercellular spaces.

The nerve fiber which is surrounded by a myelin sheath is called medullated nerve fiber. In this nerve fiber, conduction of nerve impulse is faster.

Xylem vessels and tracheids are two elements of xylem tissue which help in the transportation of water.

Two characteristics of nerve cells are:

1. They are highly specialised unit cells.
2. Neurons have the ability to receive stimuli from within or outside the body and to conduct (send) impulses (signals) to different parts of the body.

Functions of microvilli:

1. They increase the absorptive surface of the intestinal cell (enterocyte).
2. They increase the surface area available for reactions.

Root hair is formed by the extension of epidermal cell in roots of a plant.