BIOL-100 Exam 1 Review: Foundations of Life, Scientific Method, and Ecology

The Science of Life

The Scientific Method

The scientific method is a systematic approach used by scientists to investigate natural phenomena, develop hypotheses, and draw conclusions based on empirical evidence. It ensures that scientific inquiry is objective and reproducible.

• Observation: Gathering information using the senses, leading to questions about natural phenomena.

• Question: Formulating a question based on observations.

• Hypothesis: Proposing a tentative explanation for the observed phenomenon.

• Experiment: Designing and conducting tests to investigate the hypothesis.

• Results: Collecting and comparing data between control and experimental groups.

• Conclusion: Inferring and deducing conclusions from the data; conclusions may lead to further questions and experiments.

Infer vs. Deduce

Understanding how to draw conclusions from data is essential in scientific reasoning.

• Infer: Deriving a conclusion based on facts and evidence. Example: Seeing smoke and inferring there is a fire.

• Deduce: Applying general principles to specific situations using deductive reasoning. Example: All dogs have ears; golden retrievers are dogs, therefore they have ears.

Opinions vs. Facts

Distinguishing between opinions and facts is crucial for scientific literacy.

• Fact: Objectively true information based on evidence. Example: Smoking can cause health ailments.

• Opinion: Personal judgment or belief, not necessarily verifiable. Example: Pitbulls are the most dangerous dogs alive.

Evaluating Media Articles

Critical evaluation of scientific claims in media requires understanding the source and reliability of information.

• Peer Review: Work evaluated by impartial experts is considered the gold standard.

• Reliable Information: Up-to-date, reputable, unbiased, and drawn from known sources.

CRAAP Test

The CRAAP test is a tool for evaluating the credibility of information sources.

• Currency: Timeliness of information.

• Relevance: Importance for your needs.

• Authority: Source credibility.

• Accuracy: Truthfulness and correctness.

• Purpose: Reason for the information.

Designing Controlled Experiments

Controlled experiments are designed to test hypotheses by manipulating one variable at a time while keeping others constant.

• Independent Variable (IV): The variable that is changed.

• Dependent Variable (DV): The response measured.

• Control Group: Establishes a baseline for comparison.

• Negative Control: No change expected.

• Positive Control: Change expected.

Data Visualization

Tables and graphs are used to efficiently present and interpret experimental data.

• Line Graphs: Display continuous changes.

• Bar Graphs: Compare categories.

• Pie Charts: Show percentages summing to 100%.

Characteristics and Organization of Life

The Seven Characteristics of Life

All living things share seven fundamental characteristics:

• Reproduction: Producing offspring.

• Growth and Development: Inheriting genes for growth.

• Energy Use: Taking in and converting energy.

• Cells: Fundamental unit of life.

• Order: Highly ordered structures.

• Response to Environment: Reacting to changes.

• Evolution: Adaptation over generations.

Levels of Organization in Life

Biological organization ranges from atoms to the biosphere, each level representing increasing complexity.

• Biosphere: All life and environments on Earth.

• Ecosystem: Living organisms and nonliving components in an area.

• Community: Interacting populations in an ecosystem.

• Population: Individuals of one species in an area.

• Organism: Individual living being.

• Organ System: Group of organs performing vital functions.

• Organ: Multiple tissues performing a task.

• Tissue: Similar cells working together.

• Cell: Fundamental unit of life.

• Organelle: Cell component with specific function.

• Molecule: Group of atoms bonded together.

• Atom: Smallest unit of an element.

Distinguishing Science from Pseudoscience

Pseudoscience vs. Valid Science

Pseudoscience is falsely presented as scientific, often relying on anecdotal evidence and unprovable claims. Valid science is based on empirical evidence and reproducible results.

• Examples of Pseudoscience: Fortune telling, phrenology.

Primary and Secondary Sources

Understanding the difference between primary and secondary sources is essential for evaluating scientific information.

• Primary Source: Original research, peer-reviewed articles.

• Secondary Source: Reviews, summaries, commentary.

Origin and Diversity of Life

Biogenesis Model of the Origin of Life

The biogenesis model explains how life originated from non-living matter through natural processes.

• Primordial Environment: Basic elements and water.

• Energy Source: Volcanic activity, lightning, UV radiation.

• Chemical Building Blocks: Simple organic molecules.

• Formation of Monomers and Polymers: Simple molecules form complex ones.

• Assembly of Protobionts: Aggregates with some properties of life.

• Emergence of Self-Replication: RNA molecules capable of replication.

• Development of Metabolism: Evolution of metabolic pathways.

• Cellular Organization: Formation of cellular structures.

• Diversification and Evolution: Natural selection and genetic variation drive diversity.

Archaea vs. Bacteria

Archaea and Bacteria are two domains of prokaryotic life, sharing similarities but also key differences.

• Prokaryotes: Single, simple cells lacking membrane-bound organelles.

• Differences: Cell wall composition, genetic machinery, environmental adaptations.

• Similarities: Unicellular, lack nucleus, reproduce by binary fission.

Helpful vs. Harmful Bacteria

Bacteria can be beneficial or pathogenic, impacting human health and the environment.

• Harmful Bacteria: Pathogens causing diseases (e.g., MRSA, bubonic plague, anthrax, Lyme disease, salmonella).

• Helpful Bacteria: Nitrogen-fixing, decomposers, sewage treatment, probiotics, bioremediation.

Unicellular Protists vs. Prokaryotes

Protists are eukaryotic, often unicellular, and more complex than prokaryotes.

• Protists: Eukaryotic, nucleus, membrane-bound organelles, diverse reproduction.

• Prokaryotes: No nucleus, simple structure, cell wall, reproduce by binary fission.

• Similarities: Found in diverse environments, various locomotion methods.

Colony of Cells vs. Multicellular Organism

A colony consists of independent cells, while a multicellular organism has specialized, interdependent cells.

• Colony: Cells can survive independently.

• Multicellular Organism: Cells are specialized and interdependent.

Benefits of Multicellularity

Multicellular organisms benefit from cell specialization, division of labor, larger size, complexity, longer lifespan, improved defense, and adaptability.

Biodiversity and Classification

Fungi

Fungi are eukaryotes that recycle nutrients, produce antibiotics, and can be parasitic or beneficial (e.g., yeast, lichen, edible mushrooms).

Algae vs. Plants

Algae are aquatic and evolved adaptations to live on land, eventually giving rise to plants.

Animal Characteristics

Animals are multicellular, heterotrophic, possess nervous and reproductive systems, muscles, are diploid, and undergo developmental stages.

Ecology and Ecosystems

Ecology & Ecosystem

Ecology is the study of interactions between organisms and their environment. An ecosystem includes all living and nonliving components in a given area.

Biotic and Abiotic Factors

Ecosystems consist of biotic (living) and abiotic (nonliving) factors. Abiotic factors include energy, nutrients, wind, temperature, water, and fire.

Biogeochemical Cycling

Biogeochemical cycles track elements as they move through biotic and abiotic components of ecosystems, both locally and globally.

The Carbon Cycle

Carbon moves between the atmosphere, organisms, and the environment through photosynthesis, respiration, and human activities like burning fossil fuels.

Greenhouse Gases and Climate Change

Greenhouse gases trap heat in Earth's atmosphere, contributing to the greenhouse effect and global climate change. Carbon dioxide is the most common greenhouse gas emitted by humans.

Impact of Greenhouse Gas Emissions

Increased emissions change Earth's climate and oceans, causing desert expansion, melting ice, wildfires, and coral bleaching.

Climate Change vs. Climate Variability

Climate change refers to long-term shifts, while climate variability involves short-term fluctuations.

Importance of Reducing Greenhouse Gas Emissions

Reducing emissions is vital to prevent global warming, environmental damage, health risks, and economic consequences.

Chemistry of Life

Chemical Bonds in Water

Water molecules are held together by polar covalent bonds and hydrogen bonds, giving water its unique properties.

Properties of Water

Water is a universal solvent, regulates temperature, exhibits cohesion and adhesion, and supports life.

Frozen Water Molecules

Ice is less dense than liquid water due to hydrogen bonds, allowing it to float.

The pH Scale

pH measures acidity; acids have pH < 7, bases have pH > 7, and neutral solutions have pH = 7.

Acids, Bases, and Buffers

Acids donate protons, bases accept protons, and buffers stabilize pH by resisting changes.

Water and Nutrient Cycles

Water and nutrients cycle through ecosystems via precipitation, evaporation, and biological processes.

Impact of CO2 on Ocean pH

Rising CO2 levels cause ocean acidification, harming marine life and coral reefs.

Ecology: Population and Energy

Population Growth Models

Exponential growth occurs with unlimited resources, while logistic growth is limited by carrying capacity.

Species Interactions and Food Chains

Species interactions can be helpful, harmful, or neutral. Food chains trace energy flow through trophic levels.

Species Diversity and Keystone Species

Species diversity includes richness and abundance. Keystone species maintain ecosystem balance.

Biodiversity

Biodiversity encompasses genetic, species, and ecosystem diversity. Loss is caused by habitat destruction, overharvesting, invasive species, pollution, and climate change.

Trophic Levels and Energy Transfer

Energy flows from producers to consumers and decomposers, with only about 10% transferred between levels.

Biodiversity Hotspots

Hotspots are areas with high concentrations of endangered and endemic species.

Energy and Life

Ecological Footprints and Carrying Capacity

Ecological footprint measures resource use; higher footprints reduce carrying capacity.

Potential vs. Kinetic Energy

Potential energy is stored; kinetic energy is motion. Chemical energy is most important in biological systems.

Energy Release and Conservation

Energy is released by breaking chemical bonds and is conserved by conversion between forms.

Entropy

Entropy is the measure of disorder in a system.

Biofuels vs. Fossil Fuels

Biofuels are made from modern biomass; fossil fuels from ancient biomass. Both derive energy from photosynthesis.

Photosynthesis and Cellular Respiration

Photosynthesis converts solar energy to chemical energy; cellular respiration releases energy from sugars.

Chloroplasts and Chlorophyll

Photosynthesis occurs in chloroplasts, using chlorophyll to absorb light.

Stages of Photosynthesis

Light reactions capture energy; Calvin cycle produces sugars.

Conservation Biology and Restoration Ecology

Conservation biology aims to sustain biodiversity; restoration ecology repairs degraded areas.

Methods in Conservation Biology

• Protecting biodiversity

• Species recovery

• Reducing isolation

• Bioremediation

• Sustainable development

Reducing Carbon Footprint and Sustainable Development

Adopting sustainable practices and energy sources is key to reducing CO2 emissions and living sustainably.