BIO Exam 1 (Study Guide)

Five characteristics of life

Organization, energy use, homeostasis, growth and reproduction, evolution

Definition of biological organization

Living things are structured in hierarchical levels from atoms to biosphere

Life’s organizational hierarchy (most inclusive → least inclusive)

Biosphere → ecosystem → community → population → organism → organ system → organ → tissue → cell → organelle → molecule → atom

Three domains of life

Bacteria, Archaea, Eukarya

Key feature of Bacteria

Prokaryotic cells with peptidoglycan cell walls

Key feature of Archaea

Prokaryotic cells often living in extreme environments with unique membranes

Key features of Eukarya

Eukaryotic cells including animals, plants, fungi, and protists

Taxonomic hierarchy

Domain → Kingdom → Phylum → Class → Order → Family → Genus → Species

Grammar rule for genus and species

Genus capitalized, species lowercase; both italicized or underlined

Definition of node on a phylogenetic tree

A common ancestor shared by descendant lineages

Definition of falsifiable hypothesis

A statement that can be tested and potentially proven false

Difference between hypothesis and theory

Hypothesis is narrow and testable; theory is broad and well-supported

Independent variable

What you change

Dependent variable

What you measure

Standardized variable

Factor kept constant

Control group

Baseline group used for comparison (placebo)

Placebo effect

A measurable response caused by expectation rather than treatment

Single blind vs. double blind

Single: participant unaware; double: participant and researcher unaware

Correlation vs. causation

Correlation shows association; causation shows one factor produces another

Anecdotal evidence

Personal stories or isolated examples; unreliable for scientific conclusions

Controlled experiment

Study where variables are manipulated to test a hypothesis

Observational study

Study where variables are observed without manipulation

Why sample size matters

Larger samples reduce chance variation and increase reliability

Why science is a continuous process

New evidence refines or revises existing knowledge

Limitation of scientific inquiry

Science cannot test supernatural, moral, or non-falsifiable claims

Definition of pseudoscience

Claims presented as scientific but lacking evidence or testability

Definition of scientific myth

Widely believed idea not supported by scientific evidence

Step order of the scientific method

Observation → question → hypothesis → prediction → experiment → results → conclusion

Purpose of peer review

Ensures research quality, accuracy, and credibility before publication

Why chemistry is essential for understanding biology

Living organisms are made of atoms and molecules, and biological processes are chemical reactions

Three subatomic particles of an atom

Protons, neutrons, electrons

Location of protons and neutrons

In the nucleus

Location of electrons

In electron shells around the nucleus

Six elements making up most living mass

NCHOPS (nitrogen, carbon, hydrogen, oxygen, phosphorus, sulfur)

Definition of atomic number

Number of protons in an atom

Definition of atomic mass

Number of protons plus neutrons

Definition of isotope

Atoms of the same element with different numbers of neutrons

Definition of ion

Atom with a charge due to loss or gain of electrons

Difference between chemical and nuclear reactions

Chemical reactions involve electrons; nuclear reactions change the nucleus

Definition of electronegativity

An atom’s ability to attract electrons in a bond

Nonpolar covalent bond

Equal sharing of electrons

Polar covalent bond

Unequal sharing of electrons creating partial charges

Ionic bond

Electron transfer resulting in charged ions

Hydrogen bond

Weak attraction between a hydrogen and an electronegative atom (O,N,F)

Cohesion

Water molecules sticking to each other

Adhesion

Water molecules sticking to other surfaces

Hydrophilic substances

Polar or charged substances that dissolve in water

Hydrophobic substances

Nonpolar substances that do not dissolve in water

Definition of pH

Measure of hydrogen ion concentration

Role of buffers

Stabilize pH by accepting or releasing H+

Why carbon is the basis of life

Forms four bonds and create diverse stable structures

Functional group:hydroxyl

-OH group found in alcohols

Functional group: carboxyl

-COOH group found in organic acids

Functional group: amino

-NH2 group found in amino acids

Monosaccharide

Single sugar molecule

Polysaccharide

Long chain of sugars

Saturated fatty acid

No double bonds; solid at room temperature

Unsaturated fatty acid

Has double bonds; liquid at room temperature

Phospholipid behavior in water

Forms bilayers due to hydrophilic heads and hydrophobic tails

Peptide bond

Bond formed between amino acids by dehydration synthesis

Primary protein structure

Sequence of amino acids

Secondary protein structure

Alpha helices and beta sheets

Tertiary protein structure

Three-dimensional folding of a polypeptide

Quaternary protein structure

Multiple polypeptides forming one functional protein

Nucleotide components

Sugar, phosphate, nitrogenous base

Purines

Adenine and guanine (two rings)

Pyrimidines

Cytosine, thymine, uracil (one ring)

DNA vs. RNA

DNA: deoxyribose, double-stranded; RNA: ribose, single-stranded

Strongest base pair

G-C due to three hydrogen bonds

Central Dogma of Biology

DNA → RNA → Protein

Three principles of cell theory

All organisms are made of cells; the cell is the basic unit of life; all cells come from pre-existing cells

Why cells are small

Surface area grows slower than volume, limiting nutrient exchange and waste removal

Four components found in all cells

Plasma membrane, cytoplasm, DNA, ribosomes

Light microscope function

Views living cells at moderate magnification

TEM function

Shows internal cells structures at very high magnification

SEM function

Shows 3D surface structures at high magnification

Prokaryotes vs. eukaryotes

Prokaryotes lack nucleus and organelles; eukaryotes have both

Plant vs animal cells

Plant cells have cell wall, chloroplasts, large vacuole; animal cells do not

Function of the plasma membrane

Controls movement of substances and maintains homeostasis

Why membranes are semipermeable

Only certain molecules pass freely; others require transport proteins

Four major membrane components

Phospholipid, proteins, cholesterol, carbohydrates

Phospholipid bilayer structure

Hydrophilic heads face water; hydrophobic tails face inward

Function of mitochondria

Produce ATP through cellular respiration

Function of chloroplasts

Carry out photosynthesis in plant cells

Function of the Golgi apparatus

Modifies, sorts, and packages proteins and lipids

Function of lysosomes

Digest waste and damaged cell components

Evidence for endosymbiosis

Mitochondria and chloroplasts have their own DNA, double membranes, and divide independently

Three cytoskeleton components

Microfilaments, intermediate filaments, microtubules

Microfilament function

Cell movement and shape

Intermediate filament function

Structural support and stability

Microtube function

Vesicle transport and cell division

Plant cell communication

Plasmodesmata allow cytoplasm to flow between cells

Animal cell communication

Gap junctions allow ions and small molecules to pass between cells

Tight junction function

Seal cells together to prevent leakage

Desmosome function

Anchor cells together for mechanical strength

Gap junction function

Enable direct communication between animal cells

Central dogma cellular locations

DNA → RNA in nucleus; RNA → protein at ribosomes/Er

Consequence of mitochondrial malfunction

Low ATP production leading to cell dysfunction or death

Consequence of lysosome malfunction

What buildup causing cellular damage