Introduction to Biology

• Biology is the scientific study of life, examining structure, function, growth, origin, evolution, and distribution of living organisms.
• Biology encompasses fields from molecular biology to ecology.

Characteristics of Life

• Living organisms share key traits: organization, metabolism, homeostasis, growth, reproduction, response to stimuli, and adaptation.
• Organization is specific and complex arrangement of structures, from cells to tissues.
• Metabolism is the sum of chemical reactions within an organism, covering energy acquisition and use.
• Homeostasis maintains a stable internal environment.
• Growth involves increase in size/cell number.
• Reproduction generates new individuals.
• Response to stimuli involves reacting to environmental changes.
• Adaptation is the evolutionary process of becoming better suited to an environment.

Levels of Biological Organization

• Biological organization spans from atoms to the biosphere.
• The levels include: atoms, molecules, cells, tissues, organs, organ systems, organisms, populations, communities, ecosystems, and the biosphere.
• The cell is the basic unit of life.
• Tissues are groups of similar cells with specific functions.
• Organs are structures of different tissues working together.
• Organ systems are multiple organs coordinating bodily functions.
• Organisms are individual living entities.
• Populations are organisms of the same species in the same area.
• Communities include all populations in an area.
• Ecosystems encompass the community and its non-living environment.
• The biosphere is the sum of all ecosystems on Earth.

Cell Structure and Function

• Cells are fundamental units of life, with two types: prokaryotic and eukaryotic.
• Prokaryotic cells lack a nucleus and membrane-bound organelles and include bacteria and archaea.
• Eukaryotic cells have a nucleus and membrane-bound organelles encompassing protists, fungi, plants, and animals.
• Eukaryotic cell structures include: the nucleus (containing DNA), mitochondria (energy production), endoplasmic reticulum (protein and lipid synthesis), Golgi apparatus (processing and packaging), lysosomes (waste breakdown), and ribosomes (protein synthesis).
• Plant cells feature chloroplasts (photosynthesis) and cell walls (structural support).

Genetics and Heredity

• Genetics studies heredity and variation in organisms.
• DNA (deoxyribonucleic acid) carries genetic information.
• Genes are specific DNA sequences encoding proteins/RNA molecules.
• Chromosomes made of DNA & proteins contain genes.
• Heredity passes traits from parents to offspring through genes.
• Genetic variation arises through mutation, gene flow, and sexual reproduction.

Evolution and Natural Selection

• Evolution is change in heritable traits of biological populations across generations.
• Natural selection is the main evolution mechanism, where advantageous trait holders are more likely to survive/reproduce.
• Adaptation results from natural selection acting on genetic variation.
• Evidence for evolution includes the fossil record, comparative anatomy, embryology, and molecular biology.

Biological Diversity

• Biological diversity (biodiversity) is the variety of life, including genes, species, and ecosystems.
• Taxonomy classifies and names organisms.
• The Linnaean system includes: domain, kingdom, phylum, class, order, family, genus, and species.
• The three domains of life are Bacteria, Archaea, and Eukarya.
• Ecosystem diversity involves the variety of habitats, communities, and ecological processes in the biosphere.

Ecology and Ecosystems

• Ecology studies interactions between organisms and their environment.
• Ecosystems consist of biotic (living) and abiotic (non-living) components.
• Energy flows through ecosystems via food chains and webs.
• Producers (autotrophs) convert sunlight to chemical energy via photosynthesis.
• Consumers (heterotrophs) obtain energy by feeding on other organisms.
• Decomposers break down dead matter, recycling nutrients.
• Nutrient cycles (carbon, nitrogen, water) are vital for ecosystem function.

Plant Biology

• Plants are multicellular, eukaryotic organisms in the kingdom Plantae.
• They perform photosynthesis using chloroplasts to convert sunlight, carbon dioxide, and water into glucose and oxygen.
• Plant structures include roots (water and nutrient absorption), stems (support and transport), and leaves (photosynthesis).
• Plant reproduction can be sexual (pollination and fertilization) or asexual (vegetative propagation).
• Plant adaptations include specialized structures for water conservation, defense, and seed dispersal.

Animal Biology

• Animals are multicellular, eukaryotic organisms in the kingdom Animalia.
• They are heterotrophic and obtain nutrients by consuming other organisms.
• Animal body plans vary widely, reflecting adaptation to environments.
• Animal organ systems include digestive, circulatory, respiratory, excretory, nervous, endocrine, and reproductive systems.
• Animal behavior is influenced by genetics and environment.
• Animal reproduction is primarily sexual, involving fertilization of an egg by sperm.

Microbiology

• Microbiology is the study of microorganisms, including bacteria, archaea, viruses, fungi, and protists.
• Microorganisms play roles in nutrient cycling, decomposition, and disease.
• Bacteria and archaea are prokaryotic organisms with metabolic capabilities.
• Viruses are non-cellular entities requiring a host cell to replicate.
• Fungi are eukaryotic organisms that play roles in decomposition and nutrient cycling.
• Protists are diverse eukaryotic microorganisms, including algae and protozoa.

Human Biology

• Human biology studies the human body, its structure, function, and health.
• The human body is composed of cells, tissues, organs, and organ systems.
• Key organ systems include skeletal, muscular, nervous, endocrine, cardiovascular, respiratory, digestive, urinary, immune, and reproductive systems.
• Human health is influenced by genetics, lifestyle, and environment.
• Diseases can be caused by pathogens, genetic mutations, or environmental factors.
• Medical advances have improved human health and longevity.

Biotechnology

• Biotechnology uses biological systems and organisms to develop technologies and products.
• Genetic engineering manipulates genes to produce desired traits.
• Biotechnology's applications include medicine, agriculture, and environmental science.
• Examples include pharmaceutical production, genetically modified crops, and bioremediation technologies.
• Ethical considerations are important in biotechnology, including issues of safety, privacy, and environmental impact.