biology unit 1 class 9th

• Science

  The study in which observations are made, experiments are done and logical conclusions are drawn in order to understand the principles of nature
• In ancient times, all the scientific informations were included under one head i.e. 'Science'. With the passage of time scientific informations increased many folds and this enormous scientific knowledge was then classified into different branches like, biology, physics, chemistry, mathematics etc.
• According to Dr. Abdul Salam, scientific knowledge is the common heritage of mankind
• Biology


  The scientific study of life
• Major divisions of biology

  • Zoology
  • Botany
  • Microbiology
• Branches of biology


  • Morphology
  • Anatomy
  • Histology
  • Cell biology
  • Physiology
  • Embryology
  • Taxonomy
  • Genetics
  • Palaeontology
  • Environmental Biology
  • Biotechnology
  • Socio-Biology
  • Parasitology
  • Immunology
  • Entomology
  • Pharmacology
  • Molecular Biology
• Parasites


  Organisms that take food and shelter from living hosts and in return, harm them
• Major biological issues today

  • Human population growth
  • Infectious diseases
  • Addictive drugs
  • Pollution
• Relationship of biology to other sciences

  • Biophysics - study of principles of physics applicable to biological phenomena
  • Biochemistry - study of chemistry of different chemical compounds and processes occurring in living organisms
  • Biomathematics/Biometry - using mathematical techniques and tools in biological work
  • Biogeography - study of occurrence and distribution of different species of living organisms in different geographical regions
  • Bioeconomics - study of organisms from economical point of view
• Careers in biology

  • Medicine/Surgery
  • Fisheries
  • Agriculture
  • Animal Husbandry
  • Horticulture
  • Farming
  • Forestry
  • Biotechnology
• Allah hints about the origin and characteristics of living organisms at many places in the Holy Quran. Human beings have been instructed to expose the unknown aspects of life after getting the hints from the verses.
• The verse "We made everything from water" hints at the common origin of all living things in water and water makes 60-70% of the composition of protoplasm of all living things.
• The verses describe the events that occurred in the creation of human beings and Allah also hints at the method of the development of animals including human beings.
• The verse "Allah hath created every animal from water, then some of them creep up over their bellies, others walk on two legs and others on four. Allah creates what He pleases" describes the common origin and modification of organisms and also supports the modern concepts of classification.
• Contributions of Muslim scientists in biology

  • Jabir Bin Hayan - introduced experimental investigations in chemistry and wrote books on plants and animals
  • Abdul Malik Asmai - first Muslim scientist who studied animals in detail
  • Bu Ali Sina (Avicenna) - founder of medicine, wrote the canon of medicine "Al-Qanun fial-Tib"
• Levels of biological organization

  • Subatomic and Atomic level
  • Molecular Level
  • Cellular Level
  • Tissue Level
  • Organ Level
  • Organ System Level
  • Organismal Level
  • Population Level
  • Community Level
  • Ecosystem Level
  • Biosphere Level
• Bioelements


  16 elements that take part in making the body mass of a living organism
• Major bioelements


  • Oxygen
  • Carbon
  • Hydrogen
  • Nitrogen
  • Calcium
  • Phosphorus
• Biomolecules


  Stable particles formed by the combination of bioelements through ionic or covalent bonding
• Classification of biomolecules


  • Micromolecules - molecules with low molecular weight
  • Macromolecules - large molecules with high molecular weight
• Percentage composition (by mass) of bioelements in the protoplasm of living organisms

  • Oxygen 65%
  • Carbon 18%
  • Hydrogen 10%
  • Nitrogen 3%
  • Calcium 2%
  • Phosphorous 1%
  • Others 1%
• Micromolecules


  Molecules with low molecular weight e.g. glucose, water etc.
• Macromolecules


  Molecules with high molecular weight e.g. starch, proteins, lipids etc.
• Biomolecule formation


  1. Bioelements combine through ionic or covalent bonding

  2. Stable particle formed is called a molecule

  3. Molecules occurring in living organisms are called biomolecules
• An organism is formed by an enormous number of biomolecules of hundreds of different types
• Classification of Biomolecules


  • Micromolecules
  • Macromolecules
• Organelle formation


  Biomolecules assemble in a particular way to form organelles
• Cell formation


  Organelles assemble together to form cells
• Division of labour within the cell

  • Each type of organelle is specialized to perform a specific function
  • Functions of the cell are accomplished by these specialized structures
• In prokaryotes and most protists, the entire organism consists of a single cell
• In most fungi, all animals and plants, the organism consists of up to trillions of cells
• Tissue


  A group of similar cells specialized for the performance of a common function
• Each cell in a tissue carries on its own life processes and also some special processes related to the function of the tissue
• Plant tissues


  • Epidermal tissue
  • Ground tissue
• Animal tissues


  • Nervous tissue
  • Muscular tissue
• Organ formation


  1. More than one type of tissue having related functions are organized together to form an organ

  2. Different tissues of an organ perform their specific functions which collectively become the functions of that organ
• Organ system formation


  1. Different organs performing related functions are organized together to form an organ system

  2. Each organ carries out its specific function and the functions of all organs appear as the function of the organ system
• The organ system level is less definite in plants as compared to animals
• Individual formation


  1. Different organs and organ systems are organized together to form an individual (organism)

  2. In an organism, various organs and organ systems are organized in a coordinated way
• Population


  A group of organisms of the same species located at the same place, in the same time