Biology Characteristics of Life

Characteristics of Life

• Living organisms exhibit eight key characteristics: Order, Response to Stimuli, Reproduction, Heredity, Growth and Development, Energy Processing, Evolution and Adaptation, Homeostasis.
• Order refers to organized structures, such as unicellular prokaryotes (e.g., bacteria) and multicellular eukaryotes (e.g., whales).
• Response to Stimuli involves reactions to environmental factors, classified as external or internal stimuli.
• Reproduction encompasses the creation of offspring through asexual (one parent, identical offspring) or sexual (two parents, unique offspring) means.
• Heredity is the transmission of genetic material (DNA) from parents to offspring.
• Growth and Development signify that all living things grow and age.
• Energy Processing refers to the use of energy, primarily sourced from ATP produced in mitochondria.
• Homeostasis is the ability to maintain stable internal conditions in response to external changes.
• Evolution and Adaptation allow living beings to change to survive in varying environments.

Responses to Stimuli

• Phototropism refers to the plant's response to light.
• Gravitropism indicates how organisms respond to gravity.
• Regeneration is the process through which organisms heal and regrow lost parts.
• Metamorphosis describes significant physical changes in an organism.
• The axolotl exemplifies adaptation with its ability to regenerate limbs, gills, and lungs quickly.

Population Dynamics

• A population consists of organisms of the same species, influenced by birth, immigration (increase), death, and emigration (decrease).
• Population Dynamics studies the changes in population size, composition, and distribution over time.
• Key components include size (total number of individuals), density (population relative to space), growth (change in size over time), and distribution (spatial arrangement).
• The world population reached 8 billion in 2022, with India predicted to surpass China in population by 2024.
• Population density highlights extremes with Monaco (25,927) and Macao (22,508) having the highest, while lower densities occur in places like CAR.

Limiting Factors and Carrying Capacity

• Limiting factors restrict population growth and are categorized as density-independent (abiotic factors like natural disasters) or density-dependent (biotic factors like competition).
• Carrying Capacity (K) is the maximum number of individuals an environment can sustain, influenced by resources and ecological factors.
• Exponential growth occurs rapidly under abundant resources, while logistic growth decelerates as resources become limited.

Reproductive Strategies

• Reproductive patterns vary; R-strategies (e.g., oysters) focus on high offspring numbers with shorter lifespans, while K-strategies (e.g., chimpanzees) emphasize fewer offspring with longer lifespans.

Biodiversity

• Biodiversity encompasses the variety of life, including genetic, species, and ecosystem diversity.
• Genetic diversity allows populations to adapt to changing environments.
• Species richness refers to the total number of species in an ecosystem, while species abundance measures the relative population of each species.
• Endemic species are native to specific regions (e.g., Philippine Eagle), whereas invasive species can cause harm to native populations (e.g., Midas Cichlid).

Water Properties

• Water covers 70% of the Earth's surface and is critical for processes like digestion, circulation, and thermoregulation.
• Molecularly composed of two hydrogen and one oxygen atom (H2O), it exhibits properties such as high surface tension, heat capacity, and cohesion/adhesion.

Biomolecules

• Four main types of macromolecules are carbohydrates, proteins, lipids, and nucleic acids.
• Carbohydrates are primary energy sources, with monomers called monosaccharides (e.g., glucose).
• Lipids, which include fats and oils, provide long-term energy storage and are hydrophobic.
• Proteins are composed of amino acids, playing roles in structure, function, and regulation within organisms.
• Nucleic acids (DNA and RNA) are responsible for genetic information and directing cellular activities.

Explore the essential characteristics that define life in this quiz. From order and response to stimuli, to reproduction and homeostasis, discover how these traits help classify living organisms. Perfect for students studying biology and life sciences.