Biology Laboratory Techniques, Water Quality, and Molecular Biology

Comprehensive vocabulary flashcards covering laboratory measurements, pipetting techniques, experimental design, water quality assessment parameters, and DNA barcoding procedures.

Accuracy

How close a measurement is to its true value.

Precision

The ability to repeatedly measure a value and get the same results.

Density

The ratio of mass to volume, calculated as $\text{mass (g)} / \text{volume (mL)}$.

P20

A micropipette designed for volumes ranging from $2\,\mu\text{L}$ to $20\,\mu\text{L}$ that uses the same tip size as the P200.

P200

A micropipette designed for volumes ranging from $20\,\mu\text{L}$ to $200\,\mu\text{L}$.

P1000

A micropipette designed for volumes ranging from $100\,\mu\text{L}$ to $1000\,\mu\text{L}$ ($1\,\text{mL}$) that uses a larger tip than the P20 and P200.

First Stop (Pipetting)

The initial resistance point reached when pushing down the plunger, ensuring only the desired volume of liquid is drawn up.

Second Stop (Blowout Stop)

The final stopping point on a pipette plunger pushed only when releasing liquid to dispense all remaining liquid inside the tip.

Percent Error

A measure of accuracy calculated as $[\frac{\text{theoretical amount} - \text{measured amount}}{\text{theoretical amount}}] \times 100\%$.

Buffer

An aqueous solution containing a specific mixture of salts, buffering agents, detergents, or cofactors used to resist changes in $H^+$ (or $H_3O^+$) concentrations.

Stock Solution

A concentrated solution with a known concentration that is commonly diluted for experimental procedures.

Dilution Factor (DF)

The ratio determining dilution extent, expressed as $C_1/C_2$ or $V_2/V_1$ (the greater number divided by the smaller number, or total volume over transfer volume).

LabQuest 3

A technological handheld device to which probes can be attached to collect and display data such as temperature, pH, and absorbance.

Blank (Spectrophotometry)

A calibration sample containing everything except the absorbing compound of interest, used to zero the absorbance on a spectrophotometer.

Discovery Science

A scientific methodology that uses large amounts of data or surveys of natural systems to discover patterns and correlations without modifying the environment.

Hypothesis-Driven Science

A scientific method in which a cause-and-effect relationship is determined by establishing observations, hypotheses, predictions, and experiments.

Independent Variable

The specific parameter that is deliberately altered or manipulated by the researcher.

Dependent Variable

The parameter that responds to changes in the independent variable and is measured during an experiment.

Control Variable

Extraneous factors held constant across all experimental treatments because they could otherwise influence the dependent variable.

Control Group

The experimental baseline group from which the independent variable is omitted, keeping all control variables identical to the experimental group.

Experimental Group

The test group in an experiment in which the independent variable is altered or added.

Mean

The mathematical average of a data set, which can be heavily skewed by outliers, especially in small sample sizes.

Median

The middle value in an ordered data set, preferred over the mean when data sets contain extreme outliers.

Mode

The value that appears most frequently in a given data set.

Point Source Pollution

Contamination that enters the environment from an identifiable, easily determinable location.

Non-Point Source Pollution

Diffuse pollution that is harder to pinpoint to a single specific origin, such as agricultural runoff and precipitation.

Lotic

Refers to running or flowing freshwater systems, such as rivers and streams.

Lentic

Refers to standing or stationary freshwater bodies, such as lakes and ponds.

Water Quality Index (WQI)

A composite environmental metric determined from nine weighted water test parameters, where higher values signify better overall water quality.

Thermal Pollution

Artificially induced water temperature variations caused by industrial runoff, removal of riparian shade trees, or climate change.

Thermal Stratification

The seasonal temperature and density layering of lake water that drives biannual nutrient cycling during spring and fall turnovers.

Dissolved Oxygen (DO)

The quantity of gaseous oxygen dissolved in water, measured as percent saturation, serving as the most heavily weighted ($17\%$) indicator in WQI.

Biochemical Oxygen Demand (BOD)

The amount of dissolved oxygen required by aerobic microorganisms to decompose organic material present in water ($\text{mg/L}$).

Total Solids

A measure of all suspended, colloidal, and dissolved solid matter (such as salts, silt, and plankton) in a water sample ($\text{mg/L}$).

Turbidity

A measure of the cloudiness or lack of clarity in water caused by suspended particles, quantified in Nephelometric Turbidity Units (NTU).

Methemoglobinemia

Also known as blue baby syndrome; a potentially fatal condition caused by ingesting water with nitrate concentrations exceeding $10\,\text{mg/L}$.

Eutrophication

The ecological aging process triggered by excess nitrate and phosphate input, leading to algal blooms, reduced clarity, and dead biomass accumulation.

Fecal Coliform Test

A presumptive microbiological assay used to detect sewage contamination by incubating samples at $44.5^\circ\text{C}$ to measure $CO_2$ produced from lactose fermentation by E. coli.

Conserved Region of DNA

A specific nucleotide sequence exhibiting minimal or no evolutionary sequence variation among individuals within a species.

DNA Barcoding

A molecular taxonomic method that employs short, standardized DNA sequences to identify organisms at the species level.

COI Gene

The mitochondrial cytochrome c oxidase subunit I gene utilized as the standard barcode sequence for animal species identification.

rbcL

A chloroplast gene encoding the large subunit of RuBisCO used as the standard DNA barcode for plant identification.

16S rRNA

The gene encoding prokaryotic ribosomal RNA used as the DNA barcode for bacteria, yielding an approximately $1500\,\text{bp}$ PCR fragment.

Polymerase Chain Reaction (PCR)

An in vitro enzymatic technique used to exponentially amplify specific target DNA fragments over repeated thermal cycles.

Denaturation (PCR)

The initial PCR step carried out at $95^\circ\text{C}$ that breaks hydrogen bonds between nucleotide base pairs to yield single-stranded DNA templates.

Annealing (PCR)

The second PCR step occurring at $50^\circ\text{C}$ where oligonucleotide primers bind specifically to complementary conserved flanking sequences.

Synthesis (PCR)

The elongation phase of PCR performed at $72^\circ\text{C}$ where thermostable Taq polymerase synthesizes a complementary DNA strand in the $5'$ to $3'$ direction.

Gel Electrophoresis

A laboratory procedure used to separate, visualize, and size DNA fragments based on their charge-driven migration through an agarose matrix toward the positive anode.

DNA Ladder

A molecular weight standard containing DNA fragments of known base-pair lengths used to determine the sizes of experimental PCR products.

Ethidium Bromide

A fluorescent intercalating agent and weak carcinogen incorporated into agarose gels to facilitate ultraviolet light visualization of DNA bands.