Characteristics and Formation of Living Things: A Comprehensive Guide

Posted on Oct 29, 2024 in Biology

Characteristics of Living Things

  • Complexity: Composed of numerous molecules.
  • Cells: Unicellular and multicellular organisms.
  • Life Functions:
    • Nutrition: Obtaining matter and energy.
    • Relation: Interaction with the environment.
    • Reproduction: Producing offspring.

Formation of Living Things

Formed by chemical compounds similar to bioelements (e.g., carbon, hydrogen, oxygen, nitrogen) called biomolecules.

Types of Biomolecules

  • Inorganic: Water and minerals (carbonates, phosphates).
  • Organic: All contain carbon.
    • Carbohydrates: Source of energy (e.g., sugars).
    • Lipids: Provide twice the energy of carbohydrates (e.g., fats, waxes).
    • Proteins: Form the structure of living things (e.g., fibers).
    • Nucleic Acids: DNA and RNA.

Metabolism

Chemical reactions occurring within cells.

  • Anabolism: Builds organic molecules and consumes energy.
  • Catabolism: Destroys organic molecules and releases energy.

Nutrition

Incorporation of matter and energy to satisfy needs.

Autotrophs

Incorporate inorganic matter (e.g., plants, algae).

Photosynthesis: Carbon dioxide + water + light → organic matter + oxygen.

Photosynthesis is crucial because it produces organic matter for the ecosystem and oxygen.

Heterotrophs

Cannot transform inorganic matter into organic; feed on living organisms (e.g., animals, fungi, protozoa).

Four phases of heterotrophic nutrition:

  • Ingestion: Introduction of food.
  • Digestion: Breakdown of molecules.
  • Absorption: Obtaining energy or structural elements.
  • Excretion: Expulsion of waste.

Cellular Respiration

Process by which cells destroy organic matter to obtain energy.

Oxidation: Organic matter + oxygen → carbon dioxide + water + energy.

Relation and Survival

Living things react to environmental changes (stimuli) with responses (physiological and movement).

Types of Responses

  • Single-celled organisms (e.g., protozoa, bacteria): Tactism (positive or negative).
  • Plants: Tropism (phototropism, geotropism, hydrotropism), Nastic movements.
  • Animals: Nervous system, hormonal system.

Types of Cellular Movements

  • Amoeboid
  • Cilia
  • Flagellum

Reproduction

Production of new organisms.

  • Asexual: Involves a single individual (e.g., spores, tubers, cuttings).
  • Sexual: Involves two individuals with germ cells (haploid) formed by meiosis. Fertilization creates a diploid zygote.

Ecosystems

A small part of nature formed by living things and their environment (e.g., forest, lake, park, river).

Ecosystem Components

  • Biotic (living organisms): Biocenosis.
  • Abiotic (physical environment): Biotope.

Ecosystem Classification

  • Aquatic (water)
  • Terrestrial (air)

Biotic Factors

Relationships between living things in an ecosystem.

  • Intraspecific: Between individuals of the same species (competition, collaboration).
  • Interspecific: Between individuals of different species (competition, parasitism, predation, commensalism, mutualism, symbiosis).

Food Webs and Trophic Levels

  • Producers: Autotrophs (e.g., plants, algae).
  • Primary Consumers: Herbivores.
  • Secondary Consumers: Carnivores.
  • Tertiary Consumers: Top predators.
  • Decomposers: Fungi and bacteria.

Embryonic Development

  • Oviparous: Lay eggs.
  • Viviparous: Do not lay eggs.
  • Ovoviviparous: Eggs hatch inside the body.

Abiotic Factors

Physicochemical factors influencing an ecosystem (e.g., moisture, temperature, light).

Aquatic and Terrestrial Ecosystems

Diverse ecosystems based on water or land environments.