Introduction to the Living World

Introduction to the Living World

• Focuses on living organisms and their diversity (biodiversity) on Earth.
• Concepts are applicable in other units of study.
• "Taxonomical Aids" is removed from the NCERT and NEET syllabus.
• "What is Living" is removed from NCERT but remains in the NEET syllabus.

Ernst Mayr: A Notable Scientist

• Ernst Mayr (1904-2004) was a biologist, "Darwin of the 20th Century".
• His work focused on evolution.
• Mayr received the "Triple Crown of Biology": the International Prize for Biology, Crafoord Prize, and Balzan Prize.
• Key contribution: the biological concept of species.

Biological Concept of Species

• A species is a group of individuals that can interbreed and produce fertile offspring.
• Interbreeding between different species yields infertile offspring.
• Human male and female produce fertile offspring, indicating they're the same species.
• Male donkey and female horse produce a mule, which is sterile, showing they are different species.
• Male lion and female tiger produce a liger, which is also sterile.

Diversity in the Living World

• Contains a vast diversity of organisms in extraordinary habitats.
• Organisms display ecological relationships, including cooperation and competition.
• Cooperation involves organisms helping each other.
• Conflict involves organisms competing for resources or survival (e.g., predator-prey relations).
• Extremofiles (e.g., archebacteria) thrive in extreme conditions like deserts, ice, or very hot environments.

Characteristics vs. Defining Features of Living Organisms

• Characteristic features are found in many, but not all, living organisms.
• Defining features are present in all living organisms and absent in non-living things.

Analysis of Features

• Growth
  • Simplest definition: increase in size.
  • Can occur through increase in mass or number of individuals, also observed in non-living organisms.
  • Not a defining feature because non living organisms can grow
• Reproduction
  • Is to reproduce again
  • Not a defining feature because some living organisms are sterile.
    • May occur asexually (e.g., fungi producing spores, fragmentation in filamentous algae).
    • Not found everywhere
    • Not possible for many species & individuals
• Cellular Organization
  • Structural and functional unit of life, essential for all living beings.
  • Found in all organisms, making it a defining feature.
• Metabolism
  • All chemical reactions within an organism.
  • Includes anabolism (building up) and catabolism (breaking down).
  • Occurs due to chemical reactions.
  • The most specific one is the cytoplasmic one.
  • Body reactions such as test tube reactions happen outside the cell - but are not an animal
  • It is a defining feature because it occurs in the cell, therefore it is a defining feature.
• Consciousness
  • Found in every living organism
  • Sensing and responding to the environment.
  • Consciousness is self awareness, that occurs mostly in Octopus and Humans
  • A defining feature, as all organisms respond to their surroundings.

Growth Specifics

• Increase in mass and number of individuals are the twin characteristics of growth.
• In unicellular organisms, growth, cell division, and reproduction are inclusive events.
• Plant growth is continuous throughout their lifespan due to meristematic cells.
• Animal growth stops after a certain age.

Reproduction Specifics

• Fungi reproduce through asexual spores.
• Planaria (flatworms) exhibit regeneration.
• Bacteria and amoeba reproduce through binary fission.
• Sterile organisms like mule and worker bees do not reproduce.

Metabolism Specifics

• Anabolism: synthesis or combination which requires energy (endergonic reaction).
• Catabolism: breakdown of reactants (exergonic reaction).
• Metabolic reactions can be demonstrated in vitro (outside the body), although this is not considered a living organism.

Consciousness Specifics

• Organisms respond to various stimuli, including physical, chemical, and biological factors.
• Plants respond to environmental cues (e.g., closing stomata in response to pollutants).
• Humans use self consciousness
• The length and duration of light (photoperiod) affects reproduction in seasonal breeders.
• Self-consciousness is limited to humans and certain species, not a defining feature.
• Patients in a coma are considered brain dead because their self-consciousness is absent.

Inter-relatedness

• Living phenomena are due to underlying interactions between cells, tissues, and organs.
• Lower-level interactions create higher-level emergent properties.
• Living organisms are self-replicating, evolving, self-regulating, and responsive.
• There is relation in similarities in the world
• All living organisms are connected by DNA and share similarities.

Diversity and Taxonomy

• Exploration reveals new organisms.
• 1.7 to 1.8 million species have been identified.
• Each organism must be named which provides a standard name to avoid confusion.
• Biological names or scientific names are important.
• Scientific names are important for living organisms
• ICBN (International Code for Botanical Nomenclature) and ICZN (International Code of Zoological Nomenclature) are agencies for scientific naming.
• Carl Linnaeus standardized binomial nomenclature (two-part naming system).

Binomial Nomenclature Rules

• Two components: generic name (genus) and specific epithet (species).
• The genus name starts with a capital letter, and the species name starts with a lowercase letter.
• Both names are derived from Latin and are often italicized when typed or underlined separately.
• Author's abbreviated name is written at the end in Roman script.
• Examples include Homo sapiens and Periplaneta; Linnaeus changed his name to fit this standard.

Taxonomic Categories

• 1.7-1.8 million animals are classified properly
• Grouping into categories is needed for taxonomy.
• Taxa: Scientific name for categories.
• Taxonomy: Process of classifying organisms into different taxa.
• A name should have categories name called Taxa

Taxonomy and Systematics

• Conventional taxonomy relies on characterization, identification, classification, and nomenclature.
• Process of Taxanomy is to get the characteristics, identification, classification, and then the specific nomenclature
• Modern taxonomy includes anatomy, morphology, cell structure, developmental processes, and ecological information.
• Systematics includes evolutionary relationships (phylogeny) in addition to taxonomy.
• Systematics: Systematic arrangment/ group study
• Earliest classifications were based on the use of organisms (transport, food, clothing, shelter).

Taxonomic Hierarchy

• Begins with species and ends with kingdom.
• Hierarchy is an arrangement.
• Taxanamic Hiearchy = Texca + Arrangement

Taxonomic Rank/ Levels

• Species: lowest ranking with shared fundamental similarities.
• Genus: A group of similar species.
• Family: group of similar genus.
• As you increase from species - similar traits descrease

Taxonomic Hierarchy Mnemonics

• Keep - Kingdom
• Podiem - Phylom/ Division
• Clean - Class
• Or - Order
• Fam - Family
• Gets - Genus
• Sick - Species

Taxonomic Hierarchy Details

• Species: smallest category with fundamental similarities that can interbreed fertiley.
• Genus: A group of similar species.
• Family: group of similar genus.
• While placing plants, they consider both vegetative factors, and reproductorary factor.
• As you increase the rank in taxonomy, you look for some agreement to see "if it makes it it in"
• Then you get broader & have more variety.
• Example : As you go form species-Kingdom - number of common traits decrease.
• When you increase the texca on taxonomy, you think what you would agree more so rather than have it
• There are only 7 categories, there is a bit of things going on and it is a complicated place to be

Species Chart

• S - Species
• G - Genus
• F - Family
• O - Order
• C - Class
• P - Phylom
• K - Kindom

Example 1 - Man

• S - Sepeins - Species
• G- Homo - Genus
• F - Hominidae - Family
• O - Primata - Order
• C - Mammalia - Class
• P - Chordata - Phylom
• K - Animal - Kindom

Example 2 - House Fly

• S - Domestic
• G- Mosca
• F - Muscidae
• O - Diptera
• C - Inscecta - Class
• P - Athropoda - Phylom
• K - Animal - Kindom

Example 3 - Mango

• k - Plant
• P - Angiosperm
• D - Dicots -
• o - Spindoles
• F - Acardiac
• G/S - Minifora Indica

Example 4 - Wheat

• k - Plant
• P - Angiosperm
• D - Monocots -
• o - Pois
• F - Poaec
• G/S - Triucum estivum