Week 1-2 (Generated)

• Classification is the process of arranging organisms into groups using similar characteristics. It is based on key characters/features used in groupings.

  
• Taxonomy


  The practice of categorizing and naming of species. It is a major part of systematics that includes description, identification, nomenclature, and classification. It derived from the Greek word "taxis" meaning arrangement or division, and "nomos" means method

  
• Taxonomic hierarchy


  • Domain
  • Kingdom
  • Phylum
  • Class
  • Order
  • Family
  • Genus
  • Species
• Binomial nomenclature


  Carolus Linnaeus offered the first comprehensive, consistent and much simpler method of naming the organisms. It is composed of two terms, where, the first term indicates the genus and the second term indicates the species of the organism. Each and every organism would have one scientific name which would be used by everyone to identify an organism.

  
• There are two international codes which are agreed upon by all the biologists over the entire world in giving name of the living organism. They are: International Code of Botanical Nomenclature (ICBN) – Deals with the biological nomenclature for plants, and International Code of Zoological Nomenclature (ICZN) – Deals with the biological nomenclature of animals.
• Systematics


  The study of the diversity of organisms in evolutionary history and relationships among organisms.

  
• Phylogeny


  The study of evolutionary history and relationships among organisms. The evidences from the wide variety of sources including the paleontology, embryology, morphology, anatomy and molecular biology can be used to establish phylogeny.
• Plants, animals, and other organism have the ability to reproduce. Reproduction is a biological process in which different organisms have the ability to produce another of their kind.
• Types of asexual reproduction

  • Budding
  • Fragmentation
  • Binary fission
  • Vegetative reproduction
  • Spore formation
• Sexual reproduction


  Involves the union of gametes (i.e., the sperm and the egg cell) inside or outside the body of an organism. The sperm and the egg fuse to create a fertilized egg known as the zygote, which will eventually become the embryo.
• Plants use their physical characteristics to attract pollinators. Some plants have bright-colored flowers to attract insects, and thus enabling the transfer of pollen from one flower to another.
• Some animals also use color display to attract a mate. The peacock shows a magnificent color display of its feathers during courtship to attract the female peafowl, the peahen.
• One distinguishing characteristic of animals is sexual selection, wherein some male species compete with other males to copulate with females. This form of natural selection allows successful transfer of genes from one generation to the next.
• Another difference between plants and animals is their method of fertilization. Sexual reproduction in most animals requires physical interaction with each other in close proximity, while plants need a vector, such as an insect or a bird.
• At the unicellular stages of their development, plant cells are positionally fixed, which means that they are not capable of movement, whereas animal cells are motile or capable of movement.
• During the growth stages, the body plan of plants is highly regulated by the environment because plants cannot choose or change their growing locations, whereas the body plan of animals is clearly determined by its genes.
• Plant and animal life cycles are also different from one another. Most plants undergo alternation of generations, where they have sexual and asexual life cycles, whereas the animal life cycle has only one continuous multicellular stage (after fertilization).
• The processes in the formation of gametes are also different between plants and animals. During meiosis, plants produce spores first before forming the gametes, whereas in animals, the gametes are directly formed.
• Another developmental difference between plants and animals is shown in their morphogenesis, or change in shape. Plants develop by going through a longer period of morphogenesis than animals. Plants just grow and develop continuously until they die, whereas animals develop into a distinct and complete body shape (usually during adulthood). Plants grow by increasing their cell size, whereas animals grow by increasing the number of their cells.
• Nutrition is the process of providing or obtaining food necessary for health, survival, and growth of an organism.
• Modes of nutrition


  • Autotrophic
  • Heterotrophic
• Autotrophic


  Organisms that can manufacture their own nutrients by synthesizing inorganic materials. Depending on the energy source, autotrophs are of two types: photoautotrophic and chemoautotrophic.
• Photoautotrophic


  Organisms that directly use the energy from the sun and other inorganic substances such as carbon dioxide and water to form organic food. Examples are plants and some forms of bacteria and protists.
• Chemoautotrophic


  Organisms that use chemicals to create simpler organic substances important for their survival. Most bacteria and members of the group Archaea that live in extreme environments such as volcanoes and deep-sea vents are classified in this group.
• Types of heterotrophic nutrition

  • Saprophytic or saprotrophic
  • Parasitic
  • Holozoic
• Saprophytic or saprotrophic


  Organisms that obtain their nutrients from dead organic matter. They secrete digestive juices to the surroundings, which will be later absorbed through their body surface. Includes fungi and bacteria.
• Parasitic


  An organism takes food from another organism. The organism that takes food is called a parasite, and the organism from where the food is taken is called the host. The parasite can be either outside (ectoparasite) or inside (endoparasite) the host.
• Types of holozoic nutrition

  • Herbivorous
  • Carnivorous
  • Omnivorous
• Herbivorous


  Organisms that take in only plants as source of their energy. Examples are sheep, rabbits, and cows.
• Carnivorous


  Organisms that eat other animals. Examples are lions, tigers, and sharks.
• Omnivorous


  Organisms that take both plants and animals. Examples are pigs, hens, and bears.