Science Olympiad Practice Set

Pulmonary: right ventricle → lungs → left atrium (picks up O2). Systemic: left ventricle → body → right atrium (delivers O2).

Difference between the pulmonary and systemic circuits?

The hormone CCK, released when fatty food enters the duodenum.

What triggers the gallbladder to release bile?

Point-source outbreak.

An epidemic curve with one sharp peak, clustered around a single incubation period, suggests what kind of outbreak?

Vector transmission.

Mosquitoes spreading malaria is an example of what transmission type?

Food recall.

Best control measure for a foodborne Salmonella outbreak?

Time between exposure to a pathogen and the onset of symptoms.

What is the incubation period?

Epidemic = spread over a region larger than expected; pandemic = spread across multiple countries/continents.

Difference between an epidemic and a pandemic?

Multiple peaks, spaced roughly by the incubation period, as the disease spreads person-to-person.

What does a propagated outbreak's epidemic curve look like?

Hand hygiene and isolation.

Control measure for disease spread by direct/respiratory contact?

Chlorination.

Control measure for a waterborne pathogen like cholera?

The first identified/documented case in an outbreak investigation.

What is the index case?

Prophase, Metaphase, Anaphase, Telophase.

Correct order of mitosis phases?

Nonsense mutation.

A mutation that creates a premature stop codon is called?

An mRNA strand.

Transcription produces what?

1/4.

In a cross of Aa × Aa (A dominant), what fraction of offspring show the recessive phenotype?

Multiple codons can code for the same amino acid, so some mutations don't change the protein at all.

Why is the genetic code called "redundant"?

Holds sister chromatids together; it's where spindle fibers attach to pull chromatids apart in anaphase.

What does a centromere do?

Both heterozygous carriers (Aa × Aa).

Two unaffected parents have a child with a recessive trait — what are the parents' genotypes?

Homozygous = two identical alleles (AA or aa); heterozygous = two different alleles (Aa).

Homozygous vs. heterozygous?

Missense changes the amino acid coded for; silent changes the codon but not the amino acid.

Missense vs. silent mutation?

Acidic.

A water sample with pH 4 is acidic or basic?

Eutrophication.

Excess nutrient runoff feeding algal blooms, followed by oxygen depletion, is called?

Decreases.

As water temperature increases, dissolved oxygen solubility does what?

Point source pollution.

Pollution traceable to one identifiable source, like a factory pipe, is called?

Around 2 mg/L or below (stress typically starts around 4-5 mg/L).

Roughly what dissolved oxygen level causes fish kills?

Reduces light penetration, can clog fish gills, raises water temperature.

Effects of high turbidity on an aquatic ecosystem?

Agricultural or urban runoff — diffuse and hard to trace to one source.

Example of nonpoint source pollution?

Depletes it, as decomposers consume oxygen breaking down dead algae.

What does eutrophication ultimately do to dissolved oxygen?

At night.

CAM plants open their stomata mainly when?

Thylakoid membranes.

Where do the light-dependent reactions of photosynthesis occur?

Fruit.

After fertilization, the ovary develops into the?

Non-vascular → seedless vascular → gymnosperms → angiosperms.

Correct order of plant evolution?

Any two of: thick waxy cuticle, reduced leaf surface area/spines, sunken stomata, CAM photosynthesis, water-storage tissue.

Name two xerophyte adaptations.

To take in CO2 while minimizing water loss from daytime heat.

Why do CAM plants open stomata at night instead of during the day?

Xylem moves water/minerals one-way, upward, through dead cells; phloem moves sugars both directions through living cells.

Key difference between xylem and phloem?

E.g., 1 cotyledon vs. 2; parallel leaf veins vs. net veins; fibrous roots vs. taproot.

Two differences between monocots and dicots?

Anther produces pollen; stigma receives pollen.

What does the anther produce, and what does the stigma do?

-40° (-40°C = -40°F).

At what temperature do Celsius and Fahrenheit read the same number?

Exothermic = negative (releases heat); endothermic = positive (absorbs heat).

Sign of ΔH for exothermic vs. endothermic reactions?

Negative — more ordered state.

Sign of entropy change when a gas condenses into a liquid?

Positive — more disorder.

Sign of entropy change when a reaction increases the number of moles of gas?

Energy can't be created or destroyed, only converted between forms.

State the First Law of Thermodynamics.

The total entropy of an isolated system never decreases over time.

State the Second Law of Thermodynamics.

Sublimation = solid directly to gas; deposition = gas directly to solid.

Sublimation vs. deposition?

q = heat transferred, m = mass, c = specific heat capacity, ΔT = change in temperature.

In q = mcΔT, what does each variable stand for?

Primary (sequence), secondary (helices/sheets), tertiary (3D shape of one chain), quaternary (multiple subunits).

Name the four levels of protein structure.

Backbone C=O and N-H groups, four residues apart.

In an alpha helix, hydrogen bonds form between which groups?

Cysteine, via its thiol (-SH) group.

Which amino acid forms disulfide bonds, and via what group?

An imidazole ring (basic).

What distinctive side chain does histidine have?

Uses a guide RNA to direct the Cas9 enzyme to cut DNA at a specific sequence, enabling gene editing.

What does CRISPR-Cas9 do?

Disabling or removing a gene's function, often to study what it normally does.

What is a gene knockout?

It loses secondary/tertiary/quaternary structure, but the primary sequence stays intact.

What happens to a protein during denaturation?

Separating DNA or protein fragments by size using an electric field through a gel.

What is gel electrophoresis used for?

Identifying compounds by measuring the mass-to-charge ratio of ionized fragments.

What is mass spectrometry used for?

Measuring light absorption/transmission at specific wavelengths to identify or quantify a substance.

What is spectrophotometry used for?

Cuticle (outermost), cortex (middle), medulla (innermost).

Name the three hair layers, outermost first.

Protein; blue turns purple/violet if positive.

Biuret test — what does it detect, and the color change?

Iodine detects starch (blue-black); Benedict's detects reducing sugars (blue turns green/orange/brick-red).

Iodine test and Benedict's test — what do they detect?

Lipids/fats; turns red if positive.

Sudan III test — what does it detect, and color change?

Loop, whorl, arch.

Name the three fingerprint pattern classes.

Latent = invisible, needs development; patent = already visible; plastic = a 3D impression in a soft material.

Latent vs. patent vs. plastic prints?

The documented, unbroken record of who handled evidence, from collection through court.

What is chain of custody?

The reactant that runs out first, capping how much product can form.

What's the limiting reactant?

(actual yield ÷ theoretical yield) × 100%.

Formula for percent yield?

(P₁V₁)/T₁ = (P₂V₂)/T₂ — temperature must be in Kelvin.

The combined gas law, and one requirement for using it?

Rate doubles.

If a reaction is first-order in a reactant and you double that concentration, what happens to the rate?

Rate quadruples.

If a reaction is second-order in a reactant and you double that concentration, what happens to the rate?

It's constant, independent of starting concentration.

What's distinctive about first-order half-life?

If a system at equilibrium is disturbed, it shifts to counteract the disturbance.

State Le Châtelier's principle.

Equivalence point = moles of acid and base are stoichiometrically equal; endpoint = where the indicator visibly changes color.

Equivalence point vs. endpoint in a titration?

Spectator ions.

What does a net ionic equation leave out?

It increases (the species loses electrons — "OIL RIG").

In a redox reaction, what happens to the oxidation number of the species that's oxidized?

Series: R_total = R₁ + R₂ + ...; Parallel: 1/R_total = 1/R₁ + 1/R₂ + ...

Total resistance formula for resistors in series vs. parallel?

Current is the same throughout; voltage divides.

What's constant in a series circuit, and what divides?

Voltage is the same across every branch; current divides.

What's constant in a parallel circuit, and what divides?

V = IR.

State Ohm's law.

P = IV = I²R = V²/R.

Give the three power formulas.

Acts as an open circuit — no current flows through it.

How does a fully charged capacitor behave in a DC steady-state circuit?

τ = RC; the time for the capacitor to charge/discharge to about 63% of its total change.

What is the RC time constant, and what does it represent?

Allows current to flow in only one direction.

What does a diode do?

Current entering a junction equals current leaving it.

Kirchhoff's Current Law (junction rule)?

Sum of voltage changes around any closed loop equals zero.

Kirchhoff's Voltage Law (loop rule)?

Ammeters in series (measure current through); voltmeters in parallel (measure voltage across).

How are ammeters and voltmeters wired into a circuit?