TNPSC BIOLOGY (ENGLISH)
WHAT IS STUDY OF LIFE?
Biology is a branch of science and it is divided into various branches like Ecology, Embroyology, physiology, External morphology, anatomy, Histology, Evolution, Genetics, etc.,
Biology literally means “the study of life”. It is such a broad field, covering the minute workings of chemical machines inside our cells, to broad scale concepts of ecosystem and global climate change. Biologists study intimate details of the human brain, the composition of our genes and even the functioning of our reproductive system.
Charles Darwin, studied adaptations and gathered a great deal of proof he later incorporated into his theory of evolution. Darwin began to catalogue his collections and ponder the seeming “fit” of organisms to their mode of existence. He eventually settled on four main points of a radical new hypothesis.
✦ Over Reproduction
✦ Natural Selection
Biology is a study of plants and animals. Biology can be divided into two main branches
✦ Botany- study of plants
✦ Zoology- study of animals
Some of the sub branches are
✦ Bacteriology- study of bacteria
✦ Virology- study of virus
✦ Phycology- study of algae
✦ Mycology- study of fungi
✦ Ethology- Study of animal behavior
✦ Ecology- Study of Environment
✦ Genetics- A science that deals with heredity
Some of the Important terms coined by,
✦ Biology- Lamarck and Treriranus
✦ Cell- Robert Hooke
✦ Protoplasm- Purkinjee
✦ Genetics- W.Bateson
✦ Vaccine- Edward Jenner
Considered as father of
✦ Aristotle- Father of biology and zoology
✦ Theoprastus- Father of botany
✦ Gregor Johann Mandel- Father of Genetics
✦ Carl Linnaeus- Father of Modern Taxonomy
✦ Living organisms show a great degree of diversity in their size.
✦ They are measured in microns and milli microns. Example: Virus, bacteria, algae, fungi and protozoan.
✦ Virus is a Latin word which means poison. Viruses are the smallest and simplest of all living organisms.
✦ The study of viruses is called Virology.
✦ The curd contains Lacto Bacillus bacteria which helps to change the milk into curd.
✦ Bacteria are unicellular and microscopic, belonging to the world microbes. The study of bacteria is called Bacteriology.
✦ Bacteria are measured in microns. 1 micron = 1/1000 millimeter.
✦ Four types of bacteria are recognized based on shape. They are
○ Cocci (Spherical shaped)
○ Bacilli (Rod shaped)
○ Spirillum (Spiral or cork screw)
○ Vibrio (Comma Shaped)
✦ On the basis of the number and arrangement of the flagella, bacteria are classified as
○Monotrichous (Single flagellum at one end)
○ Amphitrichous (Tuft of flagella arising at both ends)
○ Atrichous (without any flagella)
○ Lophotrichous (Tuft of flagella at one ends) -
○ Peritrichous (Flagella all around)
✦ Algae are a unicellular green algae. It is spherical or oval in shape.
✦ The cell wall may have a pectic sheath around it. There is a single large cup-shaped Chlamydomonas chloroplast
✦ There are narrow end of the cells which helps in locomotion.
✦ The study of algae is called phycology.
✦ The conversion of sugar solution into alcohol and liberation of carbon dioxide is known as fermentation.
✦ Wine, alcohols are prepared from the molasses by the fermentation activity of the yeast. etc.
✦ Fungi do not ‘possess chlorophyll. Hence they are incapable of photosynthesis.
✦ The study of fungi is called Mycology.
✦ Protozoans are unicellular organisms.
✦ Protozoan’s show mainly two modes of life, free living and parasitic.
✦ Free living organisms inhabit fresh and salt water. Parasitic forms lives as ectoparasites or endoparasites. They cause diseases.