10th Class Biology: Properties of Life

Properties of Life

• Organisms are composed of cells that create structured, functional units.
• Energy processing involves metabolism, where organisms need energy (ATP) for cellular function, utilizing light or chemical sources.
• Homeostasis helps regulate internal environments, ensuring stable conditions like temperature.
• Growth refers to the increase in size and cell numbers, with organisms developing through various changes.
• Organisms respond to stimuli in their environments, adapting to physical or chemical changes.
• Reproduction, either asexual (identical offspring) or sexual (genetically diverse offspring), continues life's lineage.
• Evolution enables species to adapt over generations in response to environmental changes.

Cells as Basic Units of Life

• Cells are the fundamental unit of structure and function, capable of performing life activities.
• All cells have membranes, DNA, cytoplasm, ribosomes, and can utilize environmental resources.
• Prokaryotic cells lack a nucleus and membrane-bound organelles, are mostly unicellular, and are smaller than eukaryotic cells.
• Eukaryotic cells have DNA contained in a nucleus and are characterized by membrane-bound organelles; can be unicellular or multicellular.

DNA and Genetic Information

• DNA serves as the blueprint for life, ensuring transmission of genetic information through generations.
• Comprised of two strands forming a double helix, DNA consists of nucleotides (A, T, C, G) encoding genes for protein synthesis.
• Gene expression involves transcribing DNA into RNA, which is then translated into proteins that perform specific functions.
• The genetic code is universal across organisms, indicating a common ancestry among all life forms.

Biological Organization

• Reductionism analyzes complex systems by breaking them down into simpler components for study.
• Systems biology focuses on interactions among biological parts to understand emergent properties.
• Levels of biological organization range from biosphere, ecosystems, communities, populations, and organisms down to cells and molecules.
• Each level of organization contributes to understanding life processes, from global ecosystems to cellular functions.

Biological Classification

• Life can be classified based on evolutionary lineage starting from domains, including Eukarya (with kingdoms such as Animalia, Plantae, Fungi), Archaea, and Bacteria.
• Classification helps categorize organisms by shared characteristics and evolutionary relationships.

Ecosystem Dynamics

• Life's energy and matter exchange is vital, characterized by nutrient cycling and one-way energy flow.
• Producers (e.g. plants) create their own food, while consumers (e.g. animals) rely on producers, and decomposers (e.g. bacteria, fungi) recycle organic matter.
• Photosynthesis in plants converts sunlight into chemical energy (food), which sustains consumers within the ecosystem.

Genetic Equilibrium and Evolution

• Genetic equilibrium indicates a stable allele frequency in a population, suggesting no evolutionary changes.
• The Hardy-Weinberg principle outlines conditions for maintaining equilibrium: no mutations, random mating, no selection, large population size, and no gene flow.
• The equations (p + q = 1 for allele frequencies, p² + 2pq + q² = 1 for genotype frequencies) predict genetic variations in populations, indicating evolution when observed frequencies diverge from expected values.

Explore the fundamental properties of life and the characteristics that define living organisms in this quiz. From cell structure to metabolism and reproduction, test your understanding of how organisms interact with their environments and evolve over time.