Diversity

Diversity of Living Things:

• Genetic Diversity:

  • Refers to the variation in the genetic makeup among individuals within a population or species.

  • Helps populations adapt to environmental changes, reduces the risk of disease, and increases survival chances.

• Species Diversity:

  • Describes the number of different species and their relative abundance within an ecosystem.

  • An indicator of ecosystem health and stability.

• Structural Diversity:

  • Refers to the physical characteristics of an ecosystem (e.g., variety in plant size, types of habitats, or ecosystem layers).

  • It can influence how organisms interact and use resources.

• Protists:

  • A diverse group of eukaryotic organisms, which can be unicellular or multicellular.

  • Can be autotrophic (like algae) or heterotrophic (like protozoa).

• Bacteria:

  • Unicellular, prokaryotic organisms.

  • Can be found in almost all environments, and are classified into two major groups: Archaebacteria and Eubacteria.

• Fungi:

  • A kingdom of eukaryotic organisms, including molds, mushrooms, and yeasts.

  • They absorb nutrients from organic material, and often act as decomposers.

• Binomial Nomenclature:

  • A formal system of naming species using two terms: the first is the genus (capitalized) and the second is the species (lowercase), e.g., Homo sapiens.

• Morphology:

  • The study of the form and structure of organisms.

  • Includes shape, size, structure, and appearance, often used to classify organisms.

2. Levels of Classification (DKPCOFGS):

• The hierarchical system used to classify living organisms:

  • Domain > Kingdom > Phylum > Class > Order > Family > Genus > Species

  • Domain is the broadest category; Species is the most specific.

Example for Humans:

• Domain: Eukarya

• Kingdom: Animalia

• Phylum: Chordata

• Class: Mammalia

• Order: Primates

• Family: Hominidae

• Genus: Homo

• Species: Homo sapiens

3. Prokaryotes vs. Eukaryotes – Organelles, Genetic Material, Metabolism:

Prokaryotes:

• Organelles: Lack membrane-bound organelles (e.g., no nucleus, mitochondria).

• Genetic Material: DNA is in a single, circular chromosome located in the nucleoid region.

• Metabolism: Can perform aerobic or anaerobic respiration. Some bacteria can even fix nitrogen.

• Examples: Bacteria and Archaea.

Eukaryotes:

• Organelles: Have membrane-bound organelles (nucleus, mitochondria, etc.).

• Genetic Material: DNA is linear and housed inside a membrane-bound nucleus.

• Metabolism: Primarily aerobic respiration, but some eukaryotes (e.g., yeast) can undergo anaerobic respiration.

• Examples: Animals, plants, fungi, and protists.

Key Difference: Prokaryotes are simpler, smaller cells, while eukaryotes are larger and more complex.

4. Kingdom Specifics – Reproduction, Habitat, Physical Structure, Metabolism:

Fungi:

• Reproduction: Both sexual (via spores) and asexual (via budding or conidia).

• Habitat: Typically found in moist, decomposing organic matter, but also in symbiotic relationships (e.g., mycorrhizae with plants).

• Structure: Multicellular (except yeasts); cell walls made of chitin.

• Metabolism: Heterotrophic, decomposers, or symbiotic (e.g., lichens).

Protists:

• Reproduction: Asexual (binary fission) or sexual (gametes).

• Habitat: Mostly aquatic environments, can also be found in symbiosis with other organisms.

• Structure: Can be unicellular or multicellular.

• Metabolism: Can be autotrophic (photosynthetic) or heterotrophic (consume organic matter).

Bacteria:

• Reproduction: Asexual via binary fission.

• Habitat: Found everywhere – in soil, water, and inside other organisms.

• Structure: Unicellular, no membrane-bound organelles.

• Metabolism: Can be autotrophic (e.g., some bacteria perform photosynthesis) or heterotrophic.

Plants:

• Reproduction: Primarily sexual via seeds or spores, some asexual reproduction (e.g., runners, budding).

• Habitat: Mostly terrestrial, but some aquatic.

• Structure: Multicellular; cell walls made of cellulose.

• Metabolism: Autotrophic (photosynthesis).

5. Evolution of Prokaryotes to Eukaryotes & Evolution of Plants:

Evolution of Prokaryotes to Eukaryotes:

• Endosymbiotic Theory: Suggests that eukaryotic cells evolved from a symbiotic relationship between a primitive eukaryote and engulfed prokaryotes (e.g., mitochondria and chloroplasts were once free-living bacteria).

• Prokaryotic cells (simpler) gave rise to more complex eukaryotic cells (larger, with organelles).

Evolution of Plants:

• From Green Algae to Land Plants:

  • Plants evolved from aquatic green algae, adapting to land through the development of structures like roots, stems, and leaves.

  • The evolution of vascular tissue (xylem and phloem) enabled the transport of water and nutrients.

  • The development of seeds and flowers allowed for greater reproductive success on land.

6. Making a Dichotomous Key:

• A dichotomous key is a tool used to identify organisms based on a series of binary choices (yes/no or either/or) at each step.

Steps to make a dichotomous key:

• Step 1: Choose observable characteristics (e.g., presence of leaves, type of leaf structure, etc.).

• Step 2: Divide organisms based on these characteristics.

• Example:

  • Does the organism have leaves?

  • Yes → Step 2

  • No → It's a fungus

  • Are the leaves needle-like?

  • Yes → Pine tree

  • No → Maple tree

7. Viruses – Structure, Reproduction, Uses:

Structure:

• Viruses are made up of a protein coat (capsid) that encloses genetic material (DNA or RNA).

• Some viruses have an envelope made from the host cell’s membrane.

Reproduction:

• Viruses cannot reproduce on their own. They must infect a host cell and hijack the cell’s machinery to replicate.

• The viral genome directs the host to make new viral proteins and assemble new virus particles.

Uses:

• Gene therapy: Viruses can be engineered to deliver genes into human cells to treat genetic disorders.

• Biotechnology: Viruses are used in research and industrial applications (e.g., vaccines, recombinant DNA technology).

8. Why Biodiversity is Important to Ecosystems:

• Ecosystem Stability: Biodiversity helps ecosystems respond to environmental changes and recover from disturbances (e.g., fires, storms).
  
  

• Ecosystem Services:
  
  

  • Pollination (by insects, birds, etc.) is crucial for plant reproduction.

  • Water purification by plants and microorganisms.

  • Soil fertility maintained by decomposers.

• Human Benefits:
  
  

  • Biodiversity provides essential resources such as food, medicine, and materials.

  • A wide variety of species ensures resilience against diseases and pests.

• Adaptation and Evolution: Greater biodiversity allows species to adapt to new conditions, increasing the chances of survival.