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Eyes: How They Work, Anatomy and Common Condition

 The eye is a complex sensory organ that allows us to see the world around us. The eye works by gathering light from the environment and converting it into electrical signals that can be interpreted by the brain. The basic structure of the eye includes the cornea, iris, pupil, lens, retina, and optic nerve. The cornea is the transparent outer layer of the eye that helps to focus incoming light. The iris is the colored part of the eye that regulates the amount of light that enters the eye through the pupil, which is the black circular opening in the center of the iris. The lens is a clear, flexible structure located behind the iris that helps to focus light onto the retina. The retina is a thin layer of tissue that lines the back of the eye and contains photoreceptor cells called rods and cones. These cells convert light into electrical signals that are sent to the brain via the optic nerve. The rods are responsible for the low light vision and detecting motion, while the cones are resp
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PTERIDOPHYTA

Term Pteridophyta was proposed by Hackel. The study of pteridophytes is known as pteridology. Pteridophytes are known as reptiles of the plant kingdom. They are also called as vascular cryptogams. They are vascular plants, i.e. xylem and phloem are present in it. In pteridophytes, vessels in xylem and companion cells in phloem are absent. Pteridophytes are used for medicinal purposes and as soil binders. They are also frequently grown as ornamentals. Pteridophytes are more adapted terrestrial plants as compared to bryophytes. Because vascular tissue is present in them and they have roots. Pteridophytes are not completely successful terrestrial plants because they need water for fertilization, so pteridophytes grow in cool, shady and moist places. In pteridophytes, the plant body is completely differentiated into root, stem and leaves. The primary root of pteridophytes remains alive for a short period. After some time it is replaced by adventitious roots. The stem is erect or prostrate
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BRYOPHYTA

The term Bryophyta was proposed by Robert Braun. The study of Bryophyta is known as Bryology. Father of Bryology is considered to be Hedwig but according to some scientists, it is believed that Cavers is the father of Bryology. Father of Indian Bryology is Professor Shiv Ram Kashyap. Bryophytes are the first land plant. It is believed that they originated from aquatic plants and they come on land through water because some bryophytes have characters similar to aquatic plants. They are known as amphibians of the plant kingdom because these plants can live in soil but are dependent on water for fertilization. Bryophytes are not considered as the successful land plants because vascular tissue is absent and they need water for fertilization. Due to absence of vascular tissue brayophytes can not grow very tall. The process of water conduction in bryophytes takes place with the help of parenchyma. Roots are absent in bryophytes. Stem like and leaf like structure of bryophytes are function
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DIVISION - ALGAE

Algae term was given by Linnaeus. The study of algae is called Phycology and the father of phycology is Fristch. He wrote a book Structure and reproduction of algae. The father of Indian phycology is M.O.P. Iyengar. Algae are multicellular eukaryotic organisms placed in the kingdom Plantae. They are autotrophic i.e. they manufacture their food by photosynthesis. They are found in both fresh and marine water and in many forms like filamentous, colonial. Algae are surrounded by mucilagenous sheath and below the sheath cell wall is present which is made up of cellulose and pectin but mainly made up of cellulose, galactans, mannans and mineral-like calcium carbonate. On the basis of structure, they are thalloid i.e. plant body is not differentiated into root, stem and leaves. The tissue system is also absent in algae. On the basis of nutrition, they are photoautotrophic.They have chloroplast in which photosynthetic pigments are present. classification of algae is mainly based on pigments
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KINGDOM - MYCOTA (FUNGI)

Fungi name was given by Gaspard Bauhin and the study of fungi is called mycology. Fungi show great diversity in morphology and habitat. They are cosmopolitan they found mostly in humus reach soil. but in the presence of moisture, these can grow on leather, wood, pickle, and bread. Some fungi live parasitically in plants, animals and human body. Chloroplast is absent in fungi, so fungi are heterotrophs. The fungi constitute the unique kingdom of heterotrophic organisms.Fungi obtained their own food from dead organic matter or living organisms. On the basis of  source of food fungi are of two types : Saprophytic: These fungi obtained their own food from dead organic matter such as bread, rottening fruit, vegetable, and dung. In these fungi nutrition is absorptive type. Parasitic: These obtain their own food from living organisms such as plants, animals, and humans.They obtain nutrition with the help of haustoria. Some fungi are found symbiotically associated with alga
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KINGDOM - PROTISTA

All the organisms included in Protista are unicellular (acellular) eukaryotes. Members of Protista are primarily aquatic. This kingdom forms a link with the others dealing with plants, animals, and fungi. Boundaries of this kingdom are not well defined. Living organism included in Protista are as follow : (1) Dinoflagellates (Pyrrophyta) : Dinoflagellates are mainly marine. They are found on the surface of the water. They appear yellow, green, brown, blue or red depending on the main pigment present in their cells. The pigment present in them is chlorophyll 'a', chlorophyll 'c' and xanthophylls (Dinoxanthin and Didinoxanthin). In dinoflagellates, nutrition is mainly holophytic (Plant-like nutrition/photosynthesis). They have starch as stored food. Their cell wall is divided into plates, which are made up of cellulose. Therefore the covering of dinoflagellates is seen as armoured so they are called as armoured algae . They have two flagella, one lies lon
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HISTORY OF CLASSIFICATION OF ORGANISMS

In previous decades there are many scientists came who gave different - different classification of organisms. Some of them are discussed here. (1) Aristotle :  Aristotle was the father of biology and father of zoology. He was the Greek political philosophers. He classified plants on the basis of morphological character (growth habit) in three groups : Trees Shrubs Herbs (2) Theophrastus (371 - 287 B.C.) :  He is known as father of ancient plant taxonomy and father of botany. He was also the Greek political philosophers. Theophrastus wrote book on plants named Historia plantarum . He also proposed the term Annual, Biennial and Perennial. He gave the artificial classification of plants. He classified plant kingdom in to four groups on the basis of growth habit : Trees Shrubs Under shrubs Herbs (3) Carolus Linnaeus (1707 - 1778) :  His real name was Carl Von Linne . On the basis of work in Latin language, he changed his name to Carolus Linnaeus. He w
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PLANT TAXONOMY

Taxonomy consist of two words "Taxis" means arrangement and "nomos" means law and together we will called it law of arrangement or classification. The word taxonomy was proposed by A.P.de. Candolle in his book "Theories elementaire de la botanique" (Theory of elementary botany). Taxonomy includes study of following points : Identification : A process by which an organism is recognised  from the other already known organisms and is assigned to a particular taxonomic group is called identification. Nomenclature : Naming of organisms according to international scientific rules is called nomenclature. Classification : A process by which any organism is grouped into convenient categories on the basis of some easily observable characters. In modern taxonomical studies, taxonomists use external and internal structure structure, along with the structure of cell, development process and ecological information of organisms. The number of species tha
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HUMAN EVOLUTION

When we start to talk about the human evolution, the first line which appear in our mind is hat the human is evolve from monkey or monkey is our ancestor, you also hear about this from most of the people that monkey is our ancestor but this is not true. Monkey and human was originated from common ancestors, so monkey are similar to human but when we talk about similarities the apes were more closer to human than monkey because apes and humans share there ancestors for very recent times. Some evidences for common origin of human and apes : Banding pattern of chromosome no. 3 and 6 of human and chimpanzee is 100% similar. Number of chromosomes are approx same in human (46) and apes (48). DNA content and DNA matching is same in both. This similarity is more than 99% with chimpanzee, 94% with Gibbon, 88% with Rhesus monkey. The skull of baby chimpanzee is more like adult human skull than adult chimpanzee skull. Composition of Hb is same in both. Only one amino acid is differen
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NEODARWINISM / Modern synthetic theory of organic evolution

Neo-Darwinism is a modified form of Darwinism along with recent researches of Weismann, De Vries, Stebbins, Dobzhansky, Sewall Wright, Mayr etc . According to this theory following factors are responsible for formation of new species : Rapid multiplication Limited food and space Struggle for existence Genetic variations Natural Selection Isolation : Isolation is a segregation of populations by some barriers which prevent interbreeding. The reproductive isolation between the populations due to certain barriers leads to the formation of new species. NATURAL SELECTION Natural selection is a process in which heritable variations enabling better survival are enabled to reproduce and leave greater number of progeny. A critical analysis makes us believe that variation results in changed frequency of genes and alleles in future generation. Coupled to enhance reproductive success, natural selection makes it look like different population and lead to new species formation.
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DARWINISM (Theory of Natural Selection)

Charles Robert Darwin was born on 12th Feb. 1809 in England. He was an English naturalist, geologist and biologist . Darwin travelled by H.M.S. Beagle ship, from 27 Dec. 1831 to 02 Oct. 1836 through South America, South Africa, Australia and Galapagos Islands. Later on he wrote a book "On the origin of species by means of Natural Selection" (1859) . In this book he gave his theory of Natural selection. Basic concepts of Darwinism : Branching Descent and Natural selection are the two key concepts of Darwinian Theory of evolution and his theory is based on certain observations which are factual. (1) Over production : All organisms have the capability to produce enormous number of offspring or organisms (multiply in geometric ratio). Hence, theoretically population size will grow exponentially if everybody reproduced maximally but the fact is that population sizes in reality are limited. (2) Struggle for existence : Natural resources are limited and
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LAMARCKISM (Theory of organic evolution)

Organic evolution is the changes in flora and fauna during the course of time. But when we see in our surrounding we didn't observe any changes because these changes are very small so we can't determine it but changes is taking pace in every moment of time and in previous post we see the evidences in favour of organic evolution and today we going to discuss about the theories of organic evolution. There were many theories given by various scientists for organic evolution, some of them we discuss here today.   LAMARKISM / Theories of inheritance of acquired  characters:- Jean Basptiste de Lamarck (1744 - 1829) was a French naturalist who proposed the first logical theory of evolution in his book Philosophie Zoologique (1809) Basic concepts of Lamarckism:- Internal vital forces : Due to the presence of some internal vital forces all organisms have the tendency to increase in size of their organs or entire body Effect of environment and new needs :  Environ
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Evidences of Organic Evolution

Hello everyone, In previous posts we talk about the journey of evolution from non-cellular life to prokaryotes and after that eukaryotes and also we would see the various theories which try to explain this journey, and also the evidences of the theory which explain this journey in best way, which was Modern theory given by Oparin and Haldane.Now this part end i.e., how the first life originated on earth now we will discuss evolution of life forms on earth i.e., the changes in flora and fauna that have occurred over millions of years on earth. When we think about evolution the first question arise in our mind is, What is Evolution?  The word evolution means to unfold or unroll or to reveal hidden potentialities. Evolution simply means an orderly change from one condition to another. The term evolution was introduced by Herbert Spencer and It can be best explained by Darwin's Concept of "Descent with modification" which we will discuss in our Upcoming posts.
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