Chapter 1 — The Study of Life (Vocabulary Flashcards)

Chapter 1 focus: The Study of Life — Miss Nikki summarizes the most challenging concepts for students.

Characteristics of life (from the book):

• Living things are organized
• They require materials and energy
• They can reproduce
• They can respond to stimuli
• They can maintain homeostasis (are homeostatic)
• They have the capacity to adapt

Levels of biological organization (visual from the textbook):

• Biosphere is the most inclusive level (umbrella for all life on Earth)
• As you go up, each level includes everything below it (nested hierarchy)
• Smallest level: atom
• Cells are above atoms; a key criterion for a thing to be a cell is that it contains molecules and is composed of atoms (with more criteria to be discussed later)
• Tissue (e.g., nervous tissue) is shown as an example of a higher level
• Organs, organ systems, tissues, cells, molecules, atoms are successive levels
• Organ system criterion: to be an organ system, it must contain organs, tissues, cells, molecules, and atoms
• Example question framing: which level is more inclusive; biosphere vs atom? (biosphere is more inclusive, atom is least inclusive)

What is required to be living? Materials and energy (passage from sun to food chain):

• Plants are producers: they convert sunlight into glucose (food) and release oxygen
• Glucose can be used by consumers (e.g., animals) to obtain energy for life processes
• Consumers ingest plants or other animals; example: carrot or potato
• Decomposers (fungi and some bacteria) break down dead matter (carcasses) into their components and recycle them into soil

Reproduction and development:

• Females produce eggs; males produce sperm; fertilization forms a zygote
• A single cell zygote grows into a fetus, then a born individual, and develops into an adult
• Adults can reproduce, continuing the cycle
• Image from McGraw-Hill illustrates the progression from fertilized egg to fetus to birth to mature adult

Response to stimuli (example of reflex-like behavior):

• Stepping on a piece of glass triggers an automatic response: lift the foot off the glass immediately, without conscious deliberation
• This demonstrates an organism’s ability to respond to a stimulus

Homeostasis (stability around a set point):

• Example: body temperature fluctuates (e.g., normal around 98.6°F), but the body works to return to the center line
• If overheated (in the sun, working hard), sweating helps cool the body as sweat evaporates, reducing temperature
• Mechanism: temperature receptors in skin send signals to the brain, which triggers sweating to restore temperature toward homeostasis

Adaptation and the role of natural selection:

• Adaptation: organisms have traits that fit their environment; some individuals within a species may have traits that allow them to survive better
• Natural selection: individuals with advantageous traits have greater reproductive success, increasing the frequency of those traits in the population over generations
• Example mindset: blue eyes — a trait that could be more common in certain populations due to historical selective pressures (e.g., mate choice, climate adaptations, etc.); long-distance travel or stamina-related traits could confer advantages in specific environments
• The result is evolution: changes in trait frequencies within a population over time

Evolution: basics and structure (defining the theory):

• Evolution is explained via a framework of domains and kingdoms
• Domains: Bacteria, Archaea, Eukarya
• Under Eukarya, four kingdoms: Protists, Plants, Fungi, Animals
• Branching diagram (phylogeny) shows adaptation events that split lineages over millions of years
• Shared basic similarities across domains: cell membranes, DNA, and DNA bases (nucleotides) A, T, C, G
• In this view, fungi and animals are more closely related to each other than either is to protists
• Protists are a broad, catch-all category for many aquatic organisms with nuclei that are not plants, fungi, or animals
• Time scale: lines represent millions of years of divergence
• The slide emphasizes that evolution, natural selection, and adaptation form a coherent theory supported by evidence; theories are well-substantiated explanations that can be revised with new data
• Common misconception addressed: “it’s only a theory” — theories are based on extensive testing and evidence; they can be updated but remain the best explanations given current data

Classification and taxonomy (categories and inclusivity):

• Domain is the broadest category; kingdoms are subcategories under Eukarya
• Mnemonics exist to help memorize the order of taxa (e.g., Dancing Karaoke Players Can Order Free Grape Soda); choose a mnemonic or method that works for you
• Mnemonic choice is personal; Google-able mnemonics exist for different disciplines

The process of science (how biology is studied):

• Core sequence: Observation → Hypothesis → Prediction → Experiment → Data → Accept or reject hypothesis
• Hypothesis: a testable statement about why something happens
• Prediction: a specific forecast that follows from the hypothesis
• Experiment: tests the prediction under controlled conditions
• Data: evidence collected from experiments
• Acceptance or rejection of hypothesis is based on evidence
• Practical example: observing that a car won't start
• Hypothesis 1: the battery is dead
• Test: replace with a new battery and try starting the car
• If it starts: accept the battery is dead as the cause
• If it still won't start: reject the battery hypothesis and test another possibility (e.g., the alternator)
• The process of science is iterative; multiple hypotheses and experiments are used to reach well-supported conclusions

Experimental design and key terms:

• Control group: no treatment (baseline)
• Placebo group: sometimes used as a non-treatment group in experiments
• Experimental group(s): receive the treatment being tested
• Independent variable (experimental variable): the factor being deliberately changed or tested
• Dependent variable (response variable): the outcome that is measured and observed; depends on the independent variable
• Example: testing two fertilizers (A and B) to see which yields better plant growth
• Independent variable: type of fertilizer (A or B)
• Dependent variable: plant growth (height)
• Control: plants growing without fertilizer
• You could have multiple experimental groups to compare different fertilizers or concentrations

Data and graphing (lab practice):

• The y-axis of graphs represents the dependent (response) variable
• The x-axis represents the independent (experimental) variable
• Example graph scenario: blood cholesterol levels over time under a drug treatment
• X-axis: drug treatment (independent variable)
• Y-axis: cholesterol levels (dependent variable) over time
• Graphs visually show how the dependent variable changes in response to the independent variable

Summary and practical study tips (from the instructor):

• Read the learning objectives and answer them to build your own study guide
• Exam questions may integrate multiple objectives, not just a single objective from the chapter
• Don’t hesitate to email questions for clarification

Additional notes and emphasis points discussed:

• The sun-to-glucose diagram illustrates producers converting solar energy into chemical energy and releasing oxygen
• The food chain shows energy transfer from producers to consumers to decomposers
• The concept of homeostasis includes a centerline or set point and mechanisms (like sweating) to return to that point
• Adaptation includes internal (physiological) and external (environmental) adjustments that improve fitness in a given environment
• Evolution is supported by evidence across domains and kingdoms, including shared DNA chemistry (A, T, C, G) and basic cellular features
• Protists are a catch-all aquatic group within Eukarya that do not fit neatly into plants, fungi, or animals
• The discussion stresses that the science process is ongoing and subject to revision with new data, but current understanding represents the best interpretation of available evidence

Key terms to remember (quick reference):

• A, T, C, G — DNA nucleotides
• 98.6^\circ ext{F} — typical human body temperature (Fahrenheit)
• Independent variable, dependent (response) variable
• Control group, experimental group, placebo
• Domain: Bacteria, Archaea, Eukarya; Kingdoms under Eukarya: Protists, Plants, Fungi, Animals
• Natural selection, adaptation, evolution
• Homeostasis, stimulus, response
• Levels of biological organization: atom → molecule → cell → tissue → organ → organ system → organism → population → community → ecosystem → biosphere