Biology: Characteristics of Life

Definition of Life

• Life is the condition or quality of being alive, distinguished from inanimate matter or death.
• It is characterized by the ability to grow, reproduce, respond to stimuli, metabolize, and maintain homeostasis.

Characteristics of Life

• Organization: Living organisms are composed of cells, which are the basic structural and functional units of life.
• Metabolism: Living organisms carry out chemical reactions to maintain homeostasis and sustain life.
• Homeostasis: Living organisms maintain a stable internal environment despite changes in the external environment.
• Growth and Development: Living organisms increase in size and complexity through growth and development.
• Reproduction: Living organisms produce offspring to ensure the continuation of their species.
• Response to Stimuli: Living organisms respond to changes in their environment, such as light, temperature, and touch.
• Evolution: Living organisms adapt to their environment through the process of evolution.

Types of Life

• Prokaryotes: Single-celled organisms lacking a true nucleus, such as bacteria and archaea.
• Eukaryotes: Organisms with cells that have a true nucleus, including plants, animals, fungi, and protists.
• Autotrophs: Organisms that produce their own food through photosynthesis or chemosynthesis.
• Heterotrophs: Organisms that obtain energy by consuming other organisms or organic matter.

Origin of Life

• Primordial Soup Hypothesis: The theory that life arose from a mixture of organic compounds in the early Earth's oceans.
• RNA World Hypothesis: The theory that life began with RNA molecules that could replicate and evolve.

Stages of Life

• Birth: The process by which a new individual is produced.
• Growth: The process of increasing in size and complexity.
• Development: The process of maturation and differentiation of cells, tissues, and organs.
• Reproduction: The process of producing offspring.
• Aging: The process of deterioration and decline in physical and biological functions.
• Death: The permanent cessation of all biological functions.

Definition of Life

• Life is characterized by the ability to grow, reproduce, respond to stimuli, metabolize, and maintain homeostasis.
• It is the condition or quality of being alive, distinguished from inanimate matter or death.

Characteristics of Life

• Organization is the characteristic of living organisms being composed of cells, which are the basic structural and functional units of life.
• Metabolism involves living organisms carrying out chemical reactions to maintain homeostasis and sustain life.
• Homeostasis is the ability of living organisms to maintain a stable internal environment despite changes in the external environment.
• Growth and development involve living organisms increasing in size and complexity through growth and development.
• Reproduction involves living organisms producing offspring to ensure the continuation of their species.
• Response to stimuli involves living organisms responding to changes in their environment, such as light, temperature, and touch.
• Evolution is the process by which living organisms adapt to their environment through evolution.

Types of Life

• Prokaryotes are single-celled organisms lacking a true nucleus, such as bacteria and archaea.
• Eukaryotes are organisms with cells that have a true nucleus, including plants, animals, fungi, and protists.
• Autotrophs are organisms that produce their own food through photosynthesis or chemosynthesis.
• Heterotrophs are organisms that obtain energy by consuming other organisms or organic matter.

Origin of Life

• The Primordial Soup Hypothesis suggests that life arose from a mixture of organic compounds in the early Earth's oceans.
• The RNA World Hypothesis suggests that life began with RNA molecules that could replicate and evolve.

Stages of Life

• Birth is the process by which a new individual is produced.
• Growth is the process of increasing in size and complexity.
• Development is the process of maturation and differentiation of cells, tissues, and organs.
• Reproduction is the process of producing offspring.
• Aging is the process of deterioration and decline in physical and biological functions.
• Death is the permanent cessation of all biological functions.

Ecosystems

Definition

• A community of living and non-living things that interact with each other in a specific environment.
• Includes plants, animals, microorganisms, soil, water, air, and sunlight.

Components

Biotic Factors

• Living components, such as:
  • Producers (plants, algae, phytoplankton)
  • Consumers (herbivores, carnivores, omnivores)
  • Decomposers (bacteria, fungi)

Abiotic Factors

• Non-living components, such as:
  • Light
  • Temperature
  • Water
  • Soil
  • Air
  • Nutrients

Types of Ecosystems

Terrestrial Ecosystems

• Land-based ecosystems, such as:
  • Forests
  • Grasslands
  • Deserts

Freshwater Ecosystems

• Freshwater-based ecosystems, such as:
  • Rivers
  • Lakes
  • Wetlands

Marine Ecosystems

• Saltwater-based ecosystems, such as:
  • Coral reefs
  • Estuaries
  • Open ocean

Energy Flow

• Energy sources: sunlight, chemical energy from inorganic compounds
• Energy flow: producers convert energy into organic compounds, which are then consumed by consumers
• Trophic levels: levels of energy consumption, with producers at the base and apex predators at the top

Interactions

Symbiotic Relationships

• Close and often long-term relationships between different species, such as:
  • Mutualism (both species benefit)
  • Commensalism (one species benefits, the other is not affected)
  • Parasitism (one species benefits, the other is harmed)

Predation

• A predator-prey relationship, where one species captures and consumes the other

Ecosystem Services

Provisioning Services

• Providing essential resources, such as:
  • Food
  • Water
  • Medicine

Regulating Services

• Regulating ecosystem processes, such as:
  • Climate regulation
  • Water purification
  • Soil formation

Cultural Services

• Providing cultural and spiritual benefits, such as:
  • Recreation
  • Tourism
  • Spiritual enrichment