Characteristics and Formation of Living Things: A Comprehensive Guide
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.