BIOLOGY: The Living World

IMPORTANT POINTS:

Characteristics of Living Organisms : Growth, reproduction, metabolism, cellular organization, consciousness (ability to sense environment), self-replicating and self regulation.
• Reproduction and growth are NOT defining properties.
• Metabolism, cellular organization and consciousness are defining properties.

Biodiversity

Term used to refer to the number of varieties of plant and animals on earth.
Nomenclature: standardize the naming of living organism such that a particular organism is known by the name all over the world.
Identification: nomenclature or naming is only possible when the organism is described correctly and we known to what organism the name is attached to.
Need for classification: To organize the vast number of plants and animals into categories that could be named, remembered, studied and understood.

Rules for Nomenclature

1.Latinized names are used, written in italics
2.First word represents the genus, second word is species name.
3.Printed in italics; if handwritten then underline separately.
4.First word starts with capital letter while species name written in small letter.

ICBN: International Code of Botanical Nomenclature (for giving scientific name to plants.)

ICZN: International Code of Zoological Nomenclature (for giving scientific name to animals.)

Taxonomy: Study of principles and procedures of classification.
Binomial Nomenclature: Given by Carolus Linnaeus. Each scientific name has two components – Generic name + Specific epithet.
Systematics: It deals with classification of organisms based on their diversities and relationships among them. Term was proposed by Carolus Linnaeus who wrote ‘Systema Naturae’.

Taxonomic Hierarchy: Arrangement of various steps (categories or taxa Species → Genus → Family → Order → Class → Phylum (for animals) /Division (for plants) Kingdom→

Species

All the members that can interbreed among themselves and can produce fertile offsprings are the members of same species. This is the bio-logical concept of species proposed by Mayer.
Three Domains of Life: Proposed by Carl Woese in 1990 who also proposed the six kingdom classification for living organisms. The three Do-mains are Archaea, Eubacteria and Eukarya.

 

Herbarium

Storehouse of dried, pressed and preserved plant specimen on sheets.
Botanical Garden: Collection of living plants for reference.
Taxonomical aids: Zoological Park (Places where wild animals are kept in protected environment.)

• Keys (Used for identification of plant and animals on the basis of similarities and dissimilarities.)
• Fauna: (Index to animal species found in a particular area)
• Flora (Index to plant species found in a particular area.)
• Manuals (Provide information for identification of name of species in an area.)
• Monograph (Contain information on one taxon.)

 

Types of Plant tissues and Plant tissues

 Types of Plant tissues:

 

(1) Meristematic tissue: Meristematic tissues are group of cells, which have the ability to divide.

This tissue consists of small, cubodial densely packed cells, which keeps on dividing to form new cells.

These tissues are capable of stretching, enlarging and differentiate into other types of tissues as they mature.

Meristematic tissues give rise to permanent tissues.

 

There are three types of meristem based on the origin of meristematic cells :- Apical meristem, Lateral meristem and Intercalary meristem.

(a) Apical meristem is the region at the tip of the plant body. Thus, apical meristem helps in the increase in the height of the plant.

(b) Lateral meristem is a meristem located parallel to the sides of a stem or root, responsible for the thickening of the stem or root by the addition of secondary growth.

(c) Intercalary meristem is a meristem developing between regions of mature or permanent tissue (as at the base of the grass leaf).

 

(2) Permanent tissues:The tissues, which are derived from the Meristematic tissues, are called as permanent tissues.

They are the tissues, which have lost their ability to divide as they have attained their mature form.

Permanent tissues may be classified into three main groups:Simple,Complex and Special tissues.

(a) Simple Tissue:

Simple tissues are homogeneous and composed of structurally and functionally similar cells.

These are of three types:

(i) Parenchyma:

Parenchyma is the most common tissue which is morphologically and physiologically simple and unspecialized. These cells are found in epidermis, cortex, pericycle, pith etc. They are responsible for photosynthesis, storage of food, secretion etc.

(ii) Collenchyma:

Collenchyma are living tissues composed of more or less elongated cells and often have some chloroplast to carry on photosynthesis. It is generally situated below the epidermis.

(iii) Sclerenchyma:

Cells are long, thick-walled and lignified with tapering ends. These are fibre like in appearance and also known as sclerenchymatous fibre. These are dead cells and perform mechanical function.

(b) Complex tissue:

The complex tissues are composed of different types of cells performing diverse functions.

These  are of two types xylem and phloem:

(i) Xylem: Xylem is the one of the two types of transport tissue in vascular plants.The basic function of Xylem is transport water from roots to shoots and leaves,but it also transport some nutrients.

(ii) Phloem: It is the living tissue that transports the soluble organic compounds made during photosynthesis.

 

(c) Special tissue:

Special tissues are structurally modified and specially organized for secretary function.

These are of two types:

(i) Laticiferous tissue: These are specialized tube like structures known as laticiferous ducts found in many angiosperms.

These ducts are filled with white or yellow latex. Laticiferous ducts are of two types: Latex cells as found in madar and Latex vessels as found in rubber, papaya etc.

 

(ii) Glandular tissue: It consists of different types of glands which are formed by single cell or group of cells. These secrete resin, oil, mucilage, tannin, gums etc.

 

Tissue-Explanation and its Types

 Tissue

A group of cells that are similar in structure and work together to achieve a particular function is called tissue.

Or you can say a group of cells having common origin, similar structure and performing a definite function is called a tissue.

Organs are formed by the functional grouping together of multiple tissue.

All living organisms are made of cells.

In Unicellular organisms, a single cell performs all basic functions.

For example: Amoeba

In Amoeba, a single cell carries out movement,intake of food and respiratory gases, respiration and excretion.

But in Multi-cellular organisms there are millions of cells.Most of these are specialized to carry out a few functions. Each specialized function is taken up by a different group of cells.

Since these cells carry out only a particular function,they do it very efficiently. In human beings muscle cells contract and relax to cause movement,nerve cells carry messages, blood flows to transport oxygen,food,hormone and waste materials and so on.

In plants, vascular tissues conduct food and water from one part of the plant to other parts. So multi-cellular organisms show division of labor.

Cells specializing in one function are often group together in the body. This means that a particular function is carried out by a cluster of cells,called a tissue,is arranged and designed so as to give the highest possible efficiency of function.

Blood,phloem and muscles are all example of tissues.

Is there any difference between Plant and Animal tissue?

There are noticeable difference between plant tissues and animal tissues.

Plants are fixed they don’t move from one place to other which provides them structural strength.Most of these tissues are dead,since dead cells provide mechanical strength as easily as live ones and need less maintenance. The growth in plants are limited in certain regions.

On the other hand animals move around in search of food etc. They consume more energy as compare to plants.Most of there tissues are living. Cell growth in animals is more uniform.

Plant tissue

They are grouped into two basic types.

Meristematic tissues: Meristematic tissues are group of cells, which have the ability to divide.

This tissue consists of small, cubodial densely packed cells, which keeps on dividing to form new cells. These tissues are capable of stretching, enlarging and differentiate into other types of tissues as they mature. Meristematic tissues give rise to permanent tissues.

Permanent tissues:The tissues, which are derived from the Meristematic tissues, are called as permanent tissues.

They are the tissues, which have lost their ability to divide as they have attained their mature form.

Animal tissue

They are grouped into four basic types.

Epithelial tissue: Covers body surfaces and lines body cavities

Muscular tissues: Enables movement of structures within the body and movement of the entire person/animal

Connective tissues: Binds and Supports body parts

Nervous tissue: Enables responses to stimuli and coordinates bodily functions.