Biology for Non-STEM Majors Unit 1 Review: Introduction to Biology

Key Concepts and Terminology

• Biology studies life at various levels from molecules to ecosystems includes subdisciplines like genetics, ecology, and evolutionary biology
• Cells are the fundamental units of life consisting of cytoplasm enclosed within a membrane and containing DNA and organelles
  • Two main types of cells: prokaryotic (bacteria and archaea) and eukaryotic (animals, plants, fungi, and protists)
• DNA (deoxyribonucleic acid) stores genetic information used in the development, functioning, and reproduction of all known living organisms
  • DNA is a double helix structure composed of four nucleotide bases: adenine (A), thymine (T), guanine (G), and cytosine (C)
• Genes are segments of DNA that code for specific proteins and determine an organism's traits
• Evolution is the change in heritable characteristics of biological populations over successive generations driven by natural selection, genetic drift, mutation, and gene flow
• Biodiversity encompasses the variety of life at all levels from genes to ecosystems includes species diversity, genetic diversity, and ecosystem diversity
• Ecosystems are communities of living organisms interacting with each other and their physical environment involve energy flow and nutrient cycling

The Scientific Method in Biology

• The scientific method is a systematic approach to acquiring knowledge about the natural world through observation, hypothesis testing, and experimentation
  1. Make an observation or ask a question
  2. Formulate a hypothesis (testable prediction)
  3. Design and conduct an experiment to test the hypothesis
  4. Analyze data and draw conclusions
  5. Communicate results and revise hypothesis if necessary
• Controlled experiments involve manipulating one variable (independent variable) while keeping all other variables constant (controlled variables) and measuring the effect on the dependent variable
• Reproducibility is crucial in science ensures that results can be verified by other researchers following the same methods
• Peer review is the evaluation of scientific work by experts in the same field helps maintain high standards and ensures the validity of published research
• Scientific theories (evolution, cell theory) are well-supported explanations based on multiple lines of evidence, while hypotheses are testable predictions that can be supported or refuted through experimentation

Characteristics of Living Things

• Living things share several common characteristics that distinguish them from non-living matter
  • Cellular organization: composed of one or more cells, the basic units of life
  • Metabolism: carry out chemical reactions to maintain life, including energy transformation and waste elimination
  • Homeostasis: regulate internal conditions to maintain a stable environment
  • Growth and development: increase in size and complexity over time
  • Reproduction: produce offspring, either sexually or asexually
  • Response to stimuli: detect and react to changes in the environment
  • Adaptation and evolution: populations change over time in response to environmental pressures
• Viruses are not considered living organisms because they lack cellular structure, metabolism, and the ability to reproduce independently

Cell Structure and Function

• Cells are the basic structural and functional units of life
  • Prokaryotic cells (bacteria, archaea) lack a nucleus and membrane-bound organelles
  • Eukaryotic cells (animals, plants, fungi, protists) have a nucleus and membrane-bound organelles
• The cell membrane is a selectively permeable barrier that controls the movement of substances in and out of the cell
• The nucleus contains the cell's genetic material (DNA) and directs cellular activities
• Ribosomes are the sites of protein synthesis
• Mitochondria are the powerhouses of the cell, generating ATP through cellular respiration
• Chloroplasts are organelles in plant cells that carry out photosynthesis, converting light energy into chemical energy
• The endoplasmic reticulum (ER) is a network of membranes involved in protein and lipid synthesis and transport
• The Golgi apparatus modifies, packages, and distributes proteins and lipids
• Lysosomes contain digestive enzymes that break down cellular waste and foreign particles
• The cytoskeleton provides structure and support to the cell and is involved in cell movement and division

DNA and Genetics Basics

• DNA (deoxyribonucleic acid) is the hereditary material in living organisms
  • DNA is a double helix structure composed of two complementary strands held together by hydrogen bonds between base pairs
  • The four nucleotide bases are adenine (A), thymine (T), guanine (G), and cytosine (C); A pairs with T, and G pairs with C
• Genes are segments of DNA that code for specific proteins and determine an organism's traits
  • The genetic code is the set of rules that translates the sequence of nucleotides in DNA into amino acids, which make up proteins
• Chromosomes are structures in the nucleus that contain tightly coiled DNA molecules
  • Humans have 23 pairs of chromosomes (46 total), with one set inherited from each parent
• Meiosis is a type of cell division that produces gametes (eggs and sperm) with half the number of chromosomes as the parent cell
• Mitosis is a type of cell division that produces two genetically identical daughter cells with the same number of chromosomes as the parent cell
• Mutations are changes in the DNA sequence that can lead to variations in traits
  • Mutations can be caused by errors in DNA replication, exposure to mutagens (UV radiation, chemicals), or viral infections

Evolution and Biodiversity

• Evolution is the change in heritable characteristics of biological populations over successive generations
  • Natural selection is the primary mechanism of evolution, where organisms with advantageous traits are more likely to survive and reproduce
  • Genetic drift is random changes in allele frequencies, particularly in small populations
  • Mutations introduce new genetic variations into populations
  • Gene flow is the transfer of alleles between populations through migration or interbreeding
• Evidence for evolution comes from various sources
  • Fossil record shows gradual changes in organisms over time
  • Comparative anatomy reveals homologous structures (shared ancestry) and analogous structures (similar function)
  • Embryology shows similarities in early developmental stages among related species
  • Molecular biology demonstrates the shared genetic code and similarities in DNA sequences among organisms
• Biodiversity refers to the variety of life at all levels, from genes to ecosystems
  • Species diversity is the number and relative abundance of different species in an area
  • Genetic diversity is the variation in genes within a species or population
  • Ecosystem diversity is the variety of habitats, communities, and ecological processes in an area
• Biodiversity is important for ecosystem stability, resource availability, and potential medical and agricultural applications

Ecosystems and Environmental Interactions

• Ecosystems are communities of living organisms interacting with each other and their physical environment
  • Biotic factors are the living components of an ecosystem (plants, animals, microorganisms)
  • Abiotic factors are the non-living components (temperature, water, sunlight, soil)
• Energy flows through ecosystems in trophic levels
  • Primary producers (plants, algae) convert sunlight into chemical energy through photosynthesis
  • Consumers (herbivores, carnivores, omnivores) obtain energy by eating other organisms
  • Decomposers (bacteria, fungi) break down dead organisms and recycle nutrients back into the ecosystem
• Nutrient cycling involves the movement of essential elements (carbon, nitrogen, phosphorus) through biotic and abiotic components of an ecosystem
• Ecological relationships among organisms include
  • Competition: organisms compete for limited resources
  • Predation: one organism (predator) hunts and consumes another (prey)
  • Symbiosis: close and long-term interactions between different species
    • Mutualism: both species benefit (flowers and pollinators)
    • Commensalism: one species benefits while the other is unaffected (barnacles on whales)
    • Parasitism: one species (parasite) benefits at the expense of the other (host)
• Human activities (habitat destruction, pollution, climate change) can have significant impacts on ecosystems and biodiversity

Practical Applications in Everyday Life

• Understanding biology helps us make informed decisions about personal and public health
  • Knowledge of nutrition, disease prevention, and treatment options
  • Development of new medicines, vaccines, and medical technologies
• Biotechnology applies biological processes to develop products and services
  • Genetic engineering modifies DNA to produce desired traits (pest-resistant crops, insulin-producing bacteria)
  • Bioremediation uses microorganisms to clean up environmental pollutants
• Agriculture and food production rely on biological principles
  • Selective breeding and genetic modification improve crop yields and resistance to pests and diseases
  • Understanding soil ecology and nutrient cycling helps maintain soil health and fertility
• Conservation biology aims to protect and restore biodiversity and ecosystems
  • Identifying and managing threatened and endangered species
  • Designing protected areas and wildlife corridors
  • Promoting sustainable resource use and reducing human impacts on the environment
• Forensic science uses biological techniques to aid in criminal investigations
  • DNA profiling identifies individuals based on unique genetic markers
  • Entomology (study of insects) helps estimate time of death in murder cases
• Bioinspired design looks to nature for solutions to engineering challenges
  • Mimicking shark skin texture to create more efficient swimsuits and aircraft surfaces
  • Studying leaf structure to develop better solar panels and water-collection systems