answer string | choices dict | id string | kind string | lang string | question string | steps list | subject string | text string | topic string |
|---|---|---|---|---|---|---|---|---|---|
(C) Older; sedimentary layers pile younger on top of older, so fossils deepen in age downward unless strata are disturbed. | {
"A": "Younger",
"B": "Identical in age",
"C": "Older",
"D": "Unrelated to depth"
} | bio_0201 | multiple_choice | en | Fossils found in deeper undisturbed sedimentary rock layers are generally what relative to shallow ones? | [
"Recall superposition of sediments.",
"Eliminate younger and unrelated options.",
"Choose older."
] | biology | Answer: (C) Deeper fossils are generally older.
Steps:
1. Recall superposition of sediments.
2. Eliminate younger and unrelated options.
3. Choose older.
Answer: (C) | evolution |
(A) Tundra; long frozen winters, permafrost, and a short growing season limit vegetation to mosses, lichens, and dwarf shrubs. | {
"A": "Tundra",
"B": "Savanna",
"C": "Chaparral",
"D": "Temperate forest"
} | bio_0202 | multiple_choice | en | Which biome has permafrost, long winters, and low shrubs? | [
"Match permafrost to polar cold.",
"Eliminate grassland, scrub, and forest biomes.",
"Choose tundra."
] | biology | Answer: (A) Tundra matches permafrost and dwarf shrubs.
Steps:
1. Match permafrost to polar cold.
2. Eliminate grassland, scrub, and forest biomes.
3. Choose tundra.
Answer: (A) | ecology |
(C) Liver; hepatocytes make bile that emulsifies fats, while the gallbladder only stores and releases it. | {
"A": "Gallbladder",
"B": "Pancreas",
"C": "Liver",
"D": "Stomach"
} | bio_0203 | multiple_choice | en | Which organ produces bile for fat digestion? | [
"Separate production from storage.",
"Eliminate enzyme and acid organs.",
"Choose liver."
] | biology | Answer: (C) The liver produces bile.
Steps:
1. Separate production from storage.
2. Eliminate enzyme and acid organs.
3. Choose liver.
Answer: (C) | physiology |
(B) mRNA; messenger RNA copies a gene in the nucleus and carries the code to ribosomes for protein synthesis. | {
"A": "DNA",
"B": "mRNA",
"C": "ATP",
"D": "Amino acid"
} | bio_0204 | multiple_choice | en | Which nucleic acid carries genetic instructions out of the nucleus? | [
"Eliminate stored DNA and energy molecules.",
"Recall transcription to a mobile copy.",
"Choose mRNA."
] | biology | Answer: (B) mRNA carries the code outward.
Steps:
1. Eliminate stored DNA and energy molecules.
2. Recall transcription to a mobile copy.
3. Choose mRNA.
Answer: (B) | biochemistry |
(A) Chloroplast; obsahuje chlorofyl, který zachycuje světlo pro fotosyntézu. | {
"A": "Chloroplast",
"B": "Mitochondrie",
"C": "Ribozom",
"D": "Lyzozom"
} | bio_0205 | multiple_choice | cs | Která organela obsahuje chlorofyl a provádí fotosyntézu? | [
"Vylučte dýchací, bílkovinné a trávicí organely.",
"Přiřaďte chlorofyl chloroplastu.",
"Zvolte chloroplast."
] | biology | Answer: (A) Fotosyntézu provádí chloroplast.
Steps:
1. Vylučte dýchací, bílkovinné a trávicí organely.
2. Přiřaďte chlorofyl chloroplastu.
3. Zvolte chloroplast.
Answer: (A) | cell_biology |
(B) AA x aa; every child receives A from one parent and a from the other, so all are Aa. | {
"A": "Aa x Aa",
"B": "AA x aa",
"C": "aa x aa",
"D": "AA x AA"
} | bio_0206 | multiple_choice | en | Which cross always produces 100 percent heterozygous (Aa) offspring? | [
"Test gametes of each parental pair.",
"Eliminate pairs giving homozygotes.",
"Choose AA x aa."
] | biology | Answer: (B) AA x aa yields all Aa.
Steps:
1. Test gametes of each parental pair.
2. Eliminate pairs giving homozygotes.
3. Choose AA x aa.
Answer: (B) | genetics |
About 2 million years ago; the 4 percent difference splits equally between the two lineages diverging from their ancestor. | null | bio_0207 | worked_example | en | Two species differ at 4 percent of DNA bases. If mutations accumulate at 1 percent per million years per lineage, when did they diverge? | [
"Split 4 percent between 2 lineages = 2 percent each.",
"Divide 2 / 1 = 2 million years.",
"Recompute: 2 lineages x 2 My x 1 percent = 4 percent."
] | biology | Answer: About 2 million years ago.
Steps:
1. Split 4 percent between 2 lineages = 2 percent each.
2. Divide 2 / 1 = 2 million years.
3. Recompute: 2 lineages x 2 My x 1 percent = 4 percent. | evolution |
860 rabbits; births and immigrants add while deaths and emigrants subtract from the starting population. | null | bio_0208 | worked_example | en | A field holds 800 rabbits. In one season 120 are born, 40 die, 10 immigrate, and 30 emigrate. What is the new population size? | [
"Add gains: 800+120+10 = 930.",
"Subtract losses: 930-40-30 = 860.",
"Recompute: 860-800 = 60 net; 120+10-40-30 = 60."
] | biology | Answer: 860 rabbits.
Steps:
1. Add gains: 800+120+10 = 930.
2. Subtract losses: 930-40-30 = 860.
3. Recompute: 860-800 = 60 net; 120+10-40-30 = 60. | ecology |
About 0.02 seconds (20 milliseconds); distance divided by conduction speed gives travel time. | null | bio_0209 | worked_example | en | A nerve impulse travels 1.2 meters at 60 meters per second. How long does the trip take? | [
"Divide 1.2 / 60 = 0.02 s.",
"Convert to 20 ms.",
"Recompute: 0.02 x 60 = 1.2 m."
] | biology | Answer: About 0.02 s (20 ms).
Steps:
1. Divide 1.2 / 60 = 0.02 s.
2. Convert to 20 ms.
3. Recompute: 0.02 x 60 = 1.2 m. | physiology |
Roztok má pH 6 a je 100x kyselejší než roztok o pH 8; každá jednotka pH znamená desetinásobek koncentrace. | null | bio_0210 | worked_example | cs | Roztok má koncentraci vodíkových iontů 1e-6 mol na litr. Určete pH a kolikrát je kyselejší než roztok o pH 8. | [
"pH = -log(1e-6) = 6.",
"Rozdíl 8-6 = 2 jednotky.",
"Poměr = 10 na 2 = 100x.",
"Přepočítejte: 1e-6/1e-8 = 100."
] | biology | Answer: pH 6, 100x kyselejší.
Steps:
1. pH = -log(1e-6) = 6.
2. Rozdíl 8-6 = 2 jednotky.
3. Poměr = 10 na 2 = 100x.
4. Přepočítejte: 1e-6/1e-8 = 100. | biochemistry |
The sample holds 1.5 million cells; concentration times volume gives the count. | null | bio_0211 | worked_example | en | A culture holds 3 million cells per milliliter. How many cells are in a 0.5 mL sample? | [
"Multiply 3,000,000 x 0.5 = 1,500,000.",
"Recompute: 1,500,000 / 0.5 = 3,000,000.",
"Report 1.5 million cells."
] | biology | Answer: 1.5 million cells.
Steps:
1. Multiply 3,000,000 x 0.5 = 1,500,000.
2. Recompute: 1,500,000 / 0.5 = 3,000,000.
3. Report 1.5 million cells. | cell_biology |
Pleiotropy is one gene affecting multiple traits, as the sickle-cell allele alters hemoglobin, red cell shape, and organ function; it is the mirror image of polygenic inheritance, where many genes shape one trait. | null | bio_0212 | concept | en | What is pleiotropy? Contrast it with polygenic inheritance. | [
"Define one gene with many effects.",
"Give sickle-cell multiple symptoms.",
"Contrast with many genes for one trait."
] | biology | Answer: Pleiotropy spreads one gene across many traits.
Steps:
1. Define one gene with many effects.
2. Give sickle-cell multiple symptoms.
3. Contrast with many genes for one trait. | genetics |
Sexual selection favors traits that win mates rather than survive better, such as peacock tails that attract peahens despite hindering escape; female choice and male contests drive these ornaments to extremes. | null | bio_0213 | concept | en | Explain sexual selection with an example. | [
"Define mating success as the selective pressure.",
"Describe female choice of peacock tails.",
"Note survival costs of ornaments."
] | biology | Answer: Mating preferences shape costly ornaments like peacock tails.
Steps:
1. Define mating success as the selective pressure.
2. Describe female choice of peacock tails.
3. Note survival costs of ornaments. | evolution |
Fragmentation carves habitats into small patches with long edges, where altered light, wind, and predators penetrate; interior species decline while edge-tolerant and invasive species spread. | null | bio_0214 | concept | en | Explain edge effects and how habitat fragmentation harms biodiversity. | [
"Define exposed patch borders.",
"Trace microclimate and predator intrusion.",
"Link shrinking interiors to extinctions."
] | biology | Answer: Fragment edges invade interiors and shrink refuges.
Steps:
1. Define exposed patch borders.
2. Trace microclimate and predator intrusion.
3. Link shrinking interiors to extinctions. | ecology |
Žaludek mísí potravu s kyselinou chlorovodíkovou, která ničí mikroby a aktivuje pepsin štěpící bílkoviny; vzniklý chymus pak po dávkách odchází do dvanáctníku. | null | bio_0215 | concept | cs | Vysvětlete trávení v žaludku. | [
"Popište kyselinu a její úlohu.",
"Vysvětlete aktivaci pepsinu.",
"Sledujte vznik a odchod chymu."
] | biology | Answer: Kyselina a pepsin mění potravu v chymus.
Steps:
1. Popište kyselinu a její úlohu.
2. Vysvětlete aktivaci pepsinu.
3. Sledujte vznik a odchod chymu. | physiology |
In feedback inhibition the end product of a pathway binds an early enzyme and slows it, preventing wasteful overproduction; when levels fall, inhibition lifts and synthesis resumes. | null | bio_0216 | concept | en | Explain feedback inhibition in metabolic pathways. | [
"Trace product buildup to early enzyme.",
"Describe allosteric slowing.",
"Show release when product is used."
] | biology | Answer: End products brake their own synthesis.
Steps:
1. Trace product buildup to early enzyme.
2. Describe allosteric slowing.
3. Show release when product is used. | biochemistry |
Chloroplasts have an envelope around a stroma with stacks of thylakoids; light reactions on thylakoid membranes make ATP and NADPH, which the Calvin cycle in the stroma uses to fix CO2 into sugar. | null | bio_0217 | concept | en | Describe chloroplast structure and where each photosynthetic stage occurs. | [
"Outline envelope, stroma, and thylakoids.",
"Place light reactions on thylakoids.",
"Place the Calvin cycle in stroma."
] | biology | Answer: Thylakoids catch light; stroma fixes carbon.
Steps:
1. Outline envelope, stroma, and thylakoids.
2. Place light reactions on thylakoids.
3. Place the Calvin cycle in stroma. | cell_biology |
Transcription starts when RNA polymerase binds the promoter, elongates by adding RNA nucleotides along the template, and ends at a terminator, producing pre-mRNA that is capped, spliced, and tailed before export. | null | bio_0218 | concept | en | Describe the stages of transcription in eukaryotes. | [
"Start at the promoter.",
"Elongate along the template.",
"Terminate and process the transcript."
] | biology | Answer: Polymerase starts, copies, stops, and the RNA is processed.
Steps:
1. Start at the promoter.
2. Elongate along the template.
3. Terminate and process the transcript. | genetics |
Multicellularity likely evolved when single cells stayed together in colonies, then divided labor between feeding, moving, and reproducing cells, with adhesion and signaling genes making specialization heritable. | null | bio_0219 | concept | en | Explain one hypothesis for the evolution of multicellularity. | [
"Start with sticky colonial cells.",
"Divide labor among cell types.",
"Fix specialization with signaling genes."
] | biology | Answer: Colonies divided labor until cells specialized.
Steps:
1. Start with sticky colonial cells.
2. Divide labor among cell types.
3. Fix specialization with signaling genes. | evolution |
Biodiverzita zahrnuje rozmanitost genů, druhů a ekosystémů; zajišťuje opylování, úrodnost, čistou vodu i odolnost vůči škůdcům a změnám, proto je její úbytek hrozbou. | null | bio_0220 | concept | cs | Vysvětlete, co je biodiverzita a proč je důležitá. | [
"Rozlište tři úrovně rozmanitosti.",
"Uveďte ekosystémové služby.",
"Varujte před důsledky úbytku."
] | biology | Answer: Rozmanitost genů, druhů a ekosystémů živí stabilitu.
Steps:
1. Rozlište tři úrovně rozmanitosti.
2. Uveďte ekosystémové služby.
3. Varujte před důsledky úbytku. | ecology |
(D) Dendrite; branched dendrites receive signals and funnel them toward the cell body and axon hillock. | {
"A": "Axon",
"B": "Myelin sheath",
"C": "Synaptic knob",
"D": "Dendrite"
} | bio_0221 | multiple_choice | en | Which part of a neuron carries impulses toward the cell body? | [
"Eliminate sending, insulating, and output parts.",
"Recall branched receivers.",
"Choose dendrite."
] | biology | Answer: (D) Dendrites carry signals inward.
Steps:
1. Eliminate sending, insulating, and output parts.
2. Recall branched receivers.
3. Choose dendrite.
Answer: (D) | physiology |
(B) Inner mitochondrial membrane; electron carriers on the cristae pump protons that drive ATP synthase. | {
"A": "Stroma",
"B": "Inner mitochondrial membrane",
"C": "Cytosol",
"D": "Nucleus"
} | bio_0222 | multiple_choice | en | Where is ATP made during oxidative phosphorylation? | [
"Eliminate chloroplast, cytoplasm, and nuclear sites.",
"Recall cristae electron transport.",
"Choose inner mitochondrial membrane."
] | biology | Answer: (B) ATP forms on mitochondrial cristae.
Steps:
1. Eliminate chloroplast, cytoplasm, and nuclear sites.
2. Recall cristae electron transport.
3. Choose inner mitochondrial membrane.
Answer: (B) | biochemistry |
(D) Mature red blood cells; they eject their nucleus to pack more hemoglobin for oxygen transport. | {
"A": "Neurons",
"B": "White blood cells",
"C": "Muscle fibers",
"D": "Mature red blood cells"
} | bio_0223 | multiple_choice | en | Which human cells lack a nucleus when mature? | [
"Eliminate nucleated nerve, immune, and muscle cells.",
"Recall red cells eject nuclei.",
"Choose mature red blood cells."
] | biology | Answer: (D) Mature red blood cells lack nuclei.
Steps:
1. Eliminate nucleated nerve, immune, and muscle cells.
2. Recall red cells eject nuclei.
3. Choose mature red blood cells.
Answer: (D) | cell_biology |
(A) 23; meiosis halves the diploid set of 46 so each gamete carries one chromosome of each pair. | {
"A": "23",
"B": "46",
"C": "92",
"D": "44"
} | bio_0224 | multiple_choice | en | How many chromosomes are in a normal human gamete? | [
"Recall diploid cells hold 46.",
"Halve the set for gametes.",
"Choose 23."
] | biology | Answer: (A) Human gametes carry 23 chromosomes.
Steps:
1. Recall diploid cells hold 46.
2. Halve the set for gametes.
3. Choose 23.
Answer: (A) | genetics |
(D) Zachovalý zbytek organismu; fosilie vznikají mineralizací kostí, otisků či stop v usazeninách. | {
"A": "Živý organismus",
"B": "Chemická sloučenina",
"C": "Druh horniny",
"D": "Zachovalý zbytek organismu"
} | bio_0225 | multiple_choice | cs | Co je to fosilie? | [
"Vylučte živé a neživé nesprávné možnosti.",
"Přiřaďte zbytky organismů.",
"Zvolte zachovalý zbytek."
] | biology | Answer: (D) Fosilie je zachovalý zbytek organismu.
Steps:
1. Vylučte živé a neživé nesprávné možnosti.
2. Přiřaďte zbytky organismů.
3. Zvolte zachovalý zbytek.
Answer: (D) | evolution |
(C) Deforestation; clearing forests removes habitats outright and fragments what remains, driving the most species losses. | {
"A": "Recycling",
"B": "Protecting parks",
"C": "Deforestation",
"D": "Monitoring wildlife"
} | bio_0226 | multiple_choice | en | Which human activity most directly causes habitat loss? | [
"Eliminate protective and neutral actions.",
"Recall forest clearing destroys homes.",
"Choose deforestation."
] | biology | Answer: (C) Deforestation destroys habitats directly.
Steps:
1. Eliminate protective and neutral actions.
2. Recall forest clearing destroys homes.
3. Choose deforestation.
Answer: (C) | ecology |
About 1.8 liters of urine per day; filtering 180 liters and reclaiming 99 percent leaves 1 percent excreted. | null | bio_0227 | worked_example | en | Kidneys filter 180 liters of fluid per day and reabsorb 99 percent. How much urine is produced daily? | [
"Excreted fraction = 1 - 0.99 = 0.01.",
"Multiply 180 x 0.01 = 1.8 L.",
"Recompute: 1.8/180 = 0.01 = 1 percent."
] | biology | Answer: About 1.8 L of urine per day.
Steps:
1. Excreted fraction = 1 - 0.99 = 0.01.
2. Multiply 180 x 0.01 = 1.8 L.
3. Recompute: 1.8/180 = 0.01 = 1 percent. | physiology |
190 kcal in total; protein yields 4 and fat 9 kcal per gram. | null | bio_0228 | worked_example | en | A snack has 25 g of protein and 10 g of fat. Using 4 kcal per gram of protein and 9 per gram of fat, calculate its energy content. | [
"Protein: 25 x 4 = 100 kcal.",
"Fat: 10 x 9 = 90 kcal.",
"Total: 100 + 90 = 190 kcal.",
"Recompute: 190 - 90 = 100; 100/25 = 4."
] | biology | Answer: 190 kcal total.
Steps:
1. Protein: 25 x 4 = 100 kcal.
2. Fat: 10 x 9 = 90 kcal.
3. Total: 100 + 90 = 190 kcal.
4. Recompute: 190 - 90 = 100; 100/25 = 4. | biochemistry |
Surface area is about 1256.6 square micrometers and volume about 4188.8 cubic micrometers, a ratio of 0.3 per micrometer. | null | bio_0229 | worked_example | en | A spherical cell has radius 10 micrometers. Calculate its surface area, volume, and surface-to-volume ratio. | [
"SA = 4 x pi x 100 = 1256.6.",
"V = 4/3 x pi x 1000 = 4188.8.",
"Ratio = 1256.6/4188.8 = 0.3.",
"Recompute: 0.3 x 4188.8 = 1256.6."
] | biology | Answer: SA 1256.6, V 4188.8, ratio 0.3.
Steps:
1. SA = 4 x pi x 100 = 1256.6.
2. V = 4/3 x pi x 1000 = 4188.8.
3. Ratio = 1256.6/4188.8 = 0.3.
4. Recompute: 0.3 x 4188.8 = 1256.6. | cell_biology |
Všichni potomci, tedy 100 procent, mají genotyp AaBb; každý rodič dává jen jeden typ gamet. | null | bio_0230 | worked_example | cs | Při křížení AAbb x aaBB vypočítejte očekávaný podíl potomků s genotypem AaBb. | [
"Gamety rodičů: Ab a aB.",
"Všechna spojení dávají AaBb.",
"Podíl = 4/4 = 1, tedy 100 procent.",
"Přepočítejte: žádný jiný genotyp nevzniká."
] | biology | Answer: 100 procent AaBb.
Steps:
1. Gamety rodičů: Ab a aB.
2. Všechna spojení dávají AaBb.
3. Podíl = 4/4 = 1, tedy 100 procent.
4. Přepočítejte: žádný jiný genotyp nevzniká. | genetics |
420 heterozygous individuals are expected; the 2pq frequency of 0.42 scales to the population of 1000. | null | bio_0231 | worked_example | en | In Hardy-Weinberg equilibrium with dominant allele frequency p = 0.7, how many heterozygotes are expected in 1000 diploid individuals? | [
"q = 1 - 0.7 = 0.3.",
"2pq = 2 x 0.7 x 0.3 = 0.42.",
"Multiply 0.42 x 1000 = 420.",
"Recompute: 420/1000 = 0.42; 0.42/2/0.7 = 0.3 = q."
] | biology | Answer: 420 heterozygotes.
Steps:
1. q = 1 - 0.7 = 0.3.
2. 2pq = 2 x 0.7 x 0.3 = 0.42.
3. Multiply 0.42 x 1000 = 420.
4. Recompute: 420/1000 = 0.42; 0.42/2/0.7 = 0.3 = q. | evolution |
Decomposers break dead matter into mineral nutrients that plants reuse; without bacteria and fungi, carbon, nitrogen, and phosphorus would lock up in corpses and litter. | null | bio_0232 | concept | en | Explain the role of decomposers in nutrient cycling. | [
"Digest dead matter externally.",
"Release minerals to soil.",
"Feed producers to restart cycles."
] | biology | Answer: Decomposers unlock nutrients from the dead for the living.
Steps:
1. Digest dead matter externally.
2. Release minerals to soil.
3. Feed producers to restart cycles. | ecology |
Intense exercise outruns oxygen supply, so muscles ferment pyruvate to lactate and burn energy stores; the resulting oxygen debt is repaid after rest by oxidizing lactate and restoring ATP and creatine phosphate. | null | bio_0233 | concept | en | Explain muscle fatigue and oxygen debt after intense exercise. | [
"Outrun oxygen with hard effort.",
"Ferment to lactate for quick ATP.",
"Repay the debt by oxidizing lactate at rest."
] | biology | Answer: Muscles borrow anaerobic energy and repay it with oxygen.
Steps:
1. Outrun oxygen with hard effort.
2. Ferment to lactate for quick ATP.
3. Repay the debt by oxidizing lactate at rest. | physiology |
Water's polarity and hydrogen bonds make it dissolve ions and polar molecules, transport nutrients, stabilize temperature with high heat capacity, and drive hydrophobic folding of proteins and membranes. | null | bio_0234 | concept | en | Explain why water is an excellent solvent and name two biological roles that follow. | [
"Link polarity to dissolving power.",
"Explain transport and temperature stability.",
"Add hydrophobic effects on structure."
] | biology | Answer: Polarity dissolves, transports, and stabilizes life.
Steps:
1. Link polarity to dissolving power.
2. Explain transport and temperature stability.
3. Add hydrophobic effects on structure. | biochemistry |
Mikrotubuly z tubulinu vedou transport a dělí chromozomy, aktinová mikrofilamenta hýbou buňkou a intermediární filamenta zpevňují; společně drží tvar a organizují vnitřek buňky. | null | bio_0235 | concept | cs | Popište cytoskelet a funkce jeho tří složek. | [
"Přiřaďte mikrotubulům transport a dělení.",
"Přiřaďte mikrofilamentům pohyb.",
"Přiřaďte intermediárním filamentům pevnost."
] | biology | Answer: Cytoskelet transportuje, hýbe a zpevňuje buňku.
Steps:
1. Přiřaďte mikrotubulům transport a dělení.
2. Přiřaďte mikrofilamentům pohyb.
3. Přiřaďte intermediárním filamentům pevnost. | cell_biology |
Ribosomes read mRNA codons and match each to a tRNA anticodon carrying its amino acid, joining the chain with peptide bonds until a stop codon releases the finished protein. | null | bio_0236 | concept | en | Explain how ribosomes build proteins from mRNA during translation. | [
"Start at AUG with initiator tRNA.",
"Elongate by codon-anticodon matching.",
"Stop and release at a stop codon."
] | biology | Answer: Ribosomes match codons to tRNAs and link amino acids.
Steps:
1. Start at AUG with initiator tRNA.
2. Elongate by codon-anticodon matching.
3. Stop and release at a stop codon. | genetics |
Whole-genome duplication instantly creates tetraploids that cannot breed with diploid parents, forming a new species in one step; many crop plants such as wheat arose this way. | null | bio_0237 | concept | en | Explain how polyploidy can cause instant speciation in plants. | [
"Double the chromosome set.",
"Block breeding with diploids.",
"Establish fertile tetraploid populations."
] | biology | Answer: Doubled genomes isolate new plant species at once.
Steps:
1. Double the chromosome set.
2. Block breeding with diploids.
3. Establish fertile tetraploid populations. | evolution |
Large near islands hold more species than small far ones because immigration rises with closeness and extinction falls with area, balancing at a richness set by both forces. | null | bio_0238 | concept | en | State the basics of island biogeography theory. | [
"Link nearness to immigration.",
"Link area to persistence.",
"Balance the two into richness."
] | biology | Answer: Near big islands gather and keep more species.
Steps:
1. Link nearness to immigration.
2. Link area to persistence.
3. Balance the two into richness. | ecology |
In systole ventricles contract and pump blood through open semilunar valves while AV valves shut with a lub, then in diastole chambers refill as semilunar valves close with a dub. | null | bio_0239 | concept | en | Describe the cardiac cycle: systole, diastole, and valve sounds. | [
"Contract ventricles in systole.",
"Close AV valves with a lub.",
"Refill in diastole with a dub."
] | biology | Answer: Ventricles pump in systole and refill in diastole.
Steps:
1. Contract ventricles in systole.
2. Close AV valves with a lub.
3. Refill in diastole with a dub. | physiology |
Bílkoviny jsou polypeptidy z aminokyselin; slouží jako enzymy, protilátky, přenašeče typu hemoglobin, stavební kolagen i hormony jako inzulín. | null | bio_0240 | concept | cs | Vysvětlete stavbu a funkce bílkovin s příklady. | [
"Definujte polypeptidy z aminokyselin.",
"Uveďte enzymy a protilátky.",
"Přidejte hemoglobin, kolagen a inzulín."
] | biology | Answer: Bílkoviny katalyzují, brání, přenášejí i staví.
Steps:
1. Definujte polypeptidy z aminokyselin.
2. Uveďte enzymy a protilátky.
3. Přidejte hemoglobin, kolagen a inzulín. | biochemistry |
(C) Nucleolus; it transcribes ribosomal RNA and assembles ribosome subunits for export to the cytoplasm. | {
"A": "Lysosome",
"B": "Peroxisome",
"C": "Nucleolus",
"D": "Golgi apparatus"
} | bio_0241 | multiple_choice | en | Which structure produces ribosomal RNA and assembles ribosome subunits? | [
"Eliminate digestive and shipping organelles.",
"Recall the dense nuclear region.",
"Choose nucleolus."
] | biology | Answer: (C) The nucleolus builds ribosome parts.
Steps:
1. Eliminate digestive and shipping organelles.
2. Recall the dense nuclear region.
3. Choose nucleolus.
Answer: (C) | cell_biology |
(A) Klinefelter syndrome; an extra X chromosome in males causes reduced fertility and tall stature. | {
"A": "Klinefelter syndrome",
"B": "Turner syndrome",
"C": "Down syndrome",
"D": "Hemophilia"
} | bio_0242 | multiple_choice | en | A human with XXY sex chromosomes has which condition? | [
"Eliminate single-X and trisomy-21 options.",
"Eliminate the clotting disorder.",
"Choose Klinefelter syndrome."
] | biology | Answer: (A) XXY is Klinefelter syndrome.
Steps:
1. Eliminate single-X and trisomy-21 options.
2. Eliminate the clotting disorder.
3. Choose Klinefelter syndrome.
Answer: (A) | genetics |
(D) Analogous; wings of insects and birds perform the same function but evolved independently from different structures. | {
"A": "Homologous",
"B": "Vestigial",
"C": "Fossil",
"D": "Analogous"
} | bio_0243 | multiple_choice | en | Which term describes traits that are similar because of convergent evolution rather than common ancestry? | [
"Eliminate shared-ancestry and remnant terms.",
"Eliminate preserved remains.",
"Choose analogous."
] | biology | Answer: (D) Such traits are analogous.
Steps:
1. Eliminate shared-ancestry and remnant terms.
2. Eliminate preserved remains.
3. Choose analogous.
Answer: (D) | evolution |
(B) Grasshopper; it eats plants directly, placing it on the second trophic level. | {
"A": "Hawk",
"B": "Grasshopper",
"C": "Snake",
"D": "Mushroom"
} | bio_0244 | multiple_choice | en | Which organism is a primary consumer? | [
"Eliminate predators and decomposers.",
"Identify the plant eater.",
"Choose grasshopper."
] | biology | Answer: (B) The grasshopper eats producers.
Steps:
1. Eliminate predators and decomposers.
2. Identify the plant eater.
3. Choose grasshopper.
Answer: (B) | ecology |
(C) Ledviny; filtrují krev, zpětně vstřebávají potřebné látky a tvoří moč. | {
"A": "Játra",
"B": "Srdce",
"C": "Ledviny",
"D": "Plíce"
} | bio_0245 | multiple_choice | cs | Který orgán čistí krev a tvoří moč? | [
"Vylučte pumpu, detoxikaci a dýchání.",
"Přiřaďte filtraci ledvinám.",
"Zvolte ledviny."
] | biology | Answer: (C) Krev čistí ledviny.
Steps:
1. Vylučte pumpu, detoxikaci a dýchání.
2. Přiřaďte filtraci ledvinám.
3. Zvolte ledviny.
Answer: (C) | physiology |
(A) Nucleic acids; DNA stores hereditary instructions and RNA carries them out during protein synthesis. | {
"A": "Nucleic acids",
"B": "Lipids",
"C": "Carbohydrates",
"D": "Proteins"
} | bio_0246 | multiple_choice | en | Which class of macromolecules stores genetic information? | [
"Eliminate energy and structural classes.",
"Recall DNA and RNA roles.",
"Choose nucleic acids."
] | biology | Answer: (A) Nucleic acids store genetic information.
Steps:
1. Eliminate energy and structural classes.
2. Recall DNA and RNA roles.
3. Choose nucleic acids.
Answer: (A) | biochemistry |
About 10 cells are in prophase; the half-hour phase occupies 1/48 of the 24-hour cycle. | null | bio_0247 | worked_example | en | A cell cycle lasts 24 hours and prophase lasts 30 minutes. In a sample of 480 unsynchronized cells, how many are expected to be in prophase? | [
"Fraction = 0.5/24 = 1/48.",
"Multiply 480 x 1/48 = 10.",
"Recompute: 10/480 = 1/48 and 1/48 x 24 = 0.5 h."
] | biology | Answer: About 10 cells in prophase.
Steps:
1. Fraction = 0.5/24 = 1/48.
2. Multiply 480 x 1/48 = 10.
3. Recompute: 10/480 = 1/48 and 1/48 x 24 = 0.5 h. | cell_biology |
100 percent of daughters are phenotypically normal; each receives a normal X from her father that masks any recessive allele from her mother. | null | bio_0248 | worked_example | en | For an X-linked recessive trait, a carrier woman (XNXn) and a normal man (XNY) have daughters. What proportion of daughters is phenotypically normal? | [
"Father gives XN to all daughters.",
"Daughters are XNXN or XNXn.",
"Both genotypes show the normal trait.",
"Proportion normal = 4/4 = 100 percent."
] | biology | Answer: 100 percent of daughters are normal.
Steps:
1. Father gives XN to all daughters.
2. Daughters are XNXN or XNXn.
3. Both genotypes show the normal trait.
4. Proportion normal = 4/4 = 100 percent. | genetics |
36 white-flowered and 168 carrier plants are expected; q squared of 0.09 gives q of 0.3 and a 2pq class of 0.42. | null | bio_0249 | worked_example | en | In 400 diploid pea plants, 9 percent have white flowers (homozygous recessive). Assuming Hardy-Weinberg equilibrium, how many white and how many heterozygous carriers are expected? | [
"q squared = 0.09, so q = 0.3.",
"p = 1 - 0.3 = 0.7.",
"White = 0.09 x 400 = 36.",
"Carriers = 2 x 0.7 x 0.3 x 400 = 168.",
"Recompute: 196+168+36=400."
] | biology | Answer: 36 white, 168 carriers.
Steps:
1. q squared = 0.09, so q = 0.3.
2. p = 1 - 0.3 = 0.7.
3. White = 0.09 x 400 = 36.
4. Carriers = 2 x 0.7 x 0.3 x 400 = 168.
5. Recompute: 196+168+36=400. | evolution |
Odhad je 200 jedinců; podíl označených ve vzorku odpovídá podílu v populaci. | null | bio_0250 | worked_example | cs | Při sčítání bylo označeno 60 zajíců. Při dalším odlovu 50 kusů bylo 15 označených. Odhadněte velikost populace. | [
"Zapište N = M x C / R.",
"Dosaďte 60 x 50 / 15.",
"Vypočítejte 3000 / 15 = 200.",
"Přepočítejte: 200 x 15 / 50 = 60."
] | biology | Answer: N=200 zajíců.
Steps:
1. Zapište N = M x C / R.
2. Dosaďte 60 x 50 / 15.
3. Vypočítejte 3000 / 15 = 200.
4. Přepočítejte: 200 x 15 / 50 = 60. | ecology |
About 1.4 liters of water; a 2 percent loss of a 70 kg body is 1.4 kg, roughly 1.4 L. | null | bio_0251 | worked_example | en | A 70 kg athlete loses 2 percent of body mass as sweat. Estimate the water loss in liters. | [
"Multiply 70 x 0.02 = 1.4 kg.",
"Treat 1 kg of water as 1 L.",
"Recompute: 1.4/70 = 0.02 = 2 percent."
] | biology | Answer: About 1.4 L lost.
Steps:
1. Multiply 70 x 0.02 = 1.4 kg.
2. Treat 1 kg of water as 1 L.
3. Recompute: 1.4/70 = 0.02 = 2 percent. | physiology |
Cofactors are inorganic helpers such as zinc or iron ions, while coenzymes are organic helpers such as NAD+ or vitamin-derived FAD; both assist enzymes by carrying electrons, atoms, or stabilizing active sites. | null | bio_0252 | concept | en | Distinguish enzyme cofactors from coenzymes with examples. | [
"Define inorganic metal-ion helpers.",
"Define organic vitamin-derived helpers.",
"Give zinc versus NAD+ roles."
] | biology | Answer: Cofactors are inorganic ions; coenzymes are organic carriers.
Steps:
1. Define inorganic metal-ion helpers.
2. Define organic vitamin-derived helpers.
3. Give zinc versus NAD+ roles. | biochemistry |
The sodium-potassium pump uses one ATP to expel 3 sodium ions and import 2 potassium ions, building gradients that power nerve impulses, nutrient uptake, and cell volume control. | null | bio_0253 | concept | en | Explain how the sodium-potassium pump works and why it matters. | [
"Count 3 Na out and 2 K in per ATP.",
"Build concentration gradients.",
"Power nerves and transport with them."
] | biology | Answer: The pump trades 3 Na out for 2 K in per ATP.
Steps:
1. Count 3 Na out and 2 K in per ATP.
2. Build concentration gradients.
3. Power nerves and transport with them. | cell_biology |
A test cross mates an individual showing a dominant trait with a homozygous recessive; any recessive offspring prove the parent is heterozygous, while all-dominant offspring suggest homozygosity. | null | bio_0254 | concept | en | What is a test cross and how does it reveal an unknown genotype? | [
"Cross unknown with aa.",
"Interpret recessive offspring as proof of Aa.",
"Interpret all dominant as likely AA."
] | biology | Answer: Crossing to aa exposes hidden recessives.
Steps:
1. Cross unknown with aa.
2. Interpret recessive offspring as proof of Aa.
3. Interpret all dominant as likely AA. | genetics |
Fosilie ukazují postupné změny znaků v čase a přechodné formy jako Archaeopteryx mezi plazy a ptáky či Tiktaalik mezi rybami a čtvernožci; jejich řazení ve vrstvách odpovídá příbuzenským stromům. | null | bio_0255 | concept | cs | Vysvětlete, jak fosilie dokládají evoluci. | [
"Popište změny ve vrstvách.",
"Uveďte přechodné formy.",
"Propojte s příbuzenskými stromy."
] | biology | Answer: Fosilie a přechodné formy mapují vývoj života.
Steps:
1. Popište změny ve vrstvách.
2. Uveďte přechodné formy.
3. Propojte s příbuzenskými stromy. | evolution |
Parasites live on or in hosts and drain resources, as tapeworms absorb digested food, ticks drink blood, and mistletoe taps tree sap; hosts evolve defenses while parasites evolve stealth, fueling coevolution. | null | bio_0256 | concept | en | Explain parasitism with examples and its coevolutionary effects. | [
"Define plus-minus living together.",
"Give tapeworm, tick, and mistletoe.",
"Trace defense and stealth arms races."
] | biology | Answer: Parasites drain hosts and drive defense arms races.
Steps:
1. Define plus-minus living together.
2. Give tapeworm, tick, and mistletoe.
3. Trace defense and stealth arms races. | ecology |
Damaged vessels expose collagen that activates platelets, which plug the gap and trigger a cascade converting fibrinogen to fibrin threads; the fibrin mesh traps cells into a clot that seals the wound. | null | bio_0257 | concept | en | Describe the basic steps of blood clotting. | [
"Expose collagen at the wound.",
"Activate platelets into a plug.",
"Build a fibrin mesh clot."
] | biology | Answer: Platelets plug and fibrin nets seal wounds.
Steps:
1. Expose collagen at the wound.
2. Activate platelets into a plug.
3. Build a fibrin mesh clot. | physiology |
Cellular respiration oxidizes glucose by C6H12O6 + 6 O2 to 6 CO2 + 6 H2O; glycolysis in the cytosol splits glucose, the Krebs cycle in the matrix releases CO2, and the electron chain on cristae makes most ATP. | null | bio_0258 | concept | en | Write the respiration equation and locate its three stages. | [
"Balance glucose with oxygen.",
"Place glycolysis in cytosol.",
"Place Krebs in matrix and chain on cristae."
] | biology | Answer: Cytosol splits, matrix burns, cristae pay ATP.
Steps:
1. Balance glucose with oxygen.
2. Place glycolysis in cytosol.
3. Place Krebs in matrix and chain on cristae. | biochemistry |
Apoptosis is programmed cell suicide in which enzymes dismantle the cell neatly for recycling; it sculpts fingers from webbed buds, removes infected cells, and fails in cancer when damaged cells refuse to die. | null | bio_0259 | concept | en | What is apoptosis and why does it matter? | [
"Define orderly self-dismantling.",
"Give finger sculpting and defense.",
"Link failure to cancer."
] | biology | Answer: Apoptosis neatly removes unneeded or damaged cells.
Steps:
1. Define orderly self-dismantling.
2. Give finger sculpting and defense.
3. Link failure to cancer. | cell_biology |
Pohlaví určuje otec: matka dává vždy chromozom X, otec X nebo Y; kombinace XX vede k dívce a XY díky genu SRY k chlapci. | null | bio_0260 | concept | cs | Vysvětlete dědičnost pohlaví u člověka. | [
"Popište gamety matky a otce.",
"Přiřaďte XX dívce a XY chlapci.",
"Uveďte úlohu genu SRY."
] | biology | Answer: Otec rozhoduje: XX dívka, XY chlapec.
Steps:
1. Popište gamety matky a otce.
2. Přiřaďte XX dívce a XY chlapci.
3. Uveďte úlohu genu SRY. | genetics |
(D) Embryology; early embryos of fish, chickens, and humans share gill slits and tails that reveal common descent. | {
"A": "Fossils",
"B": "DNA sequencing",
"C": "Biogeography",
"D": "Embryology"
} | bio_0261 | multiple_choice | en | Which field compares embryos of different species as evidence for evolution? | [
"Eliminate rocks, molecules, and geography.",
"Recall shared gill slits and tails.",
"Choose embryology."
] | biology | Answer: (D) Embryology compares developing forms.
Steps:
1. Eliminate rocks, molecules, and geography.
2. Recall shared gill slits and tails.
3. Choose embryology.
Answer: (D) | evolution |
(B) Ecosystem; it joins a community of interacting species with the water, soil, light, and climate around them. | {
"A": "Population",
"B": "Ecosystem",
"C": "Community",
"D": "Species"
} | bio_0262 | multiple_choice | en | Which term describes all living things plus their physical environment in an area? | [
"Eliminate single-species and living-only terms.",
"Recall abiotic plus biotic union.",
"Choose ecosystem."
] | biology | Answer: (B) An ecosystem joins life and environment.
Steps:
1. Eliminate single-species and living-only terms.
2. Recall abiotic plus biotic union.
3. Choose ecosystem.
Answer: (B) | ecology |
(A) Pulmonary artery; it is the rare artery carrying oxygen-poor blood, from the right ventricle to the lungs. | {
"A": "Pulmonary artery",
"B": "Pulmonary vein",
"C": "Aorta",
"D": "Coronary vein"
} | bio_0263 | multiple_choice | en | Which vessel carries oxygen-poor blood from the heart to the lungs? | [
"Eliminate oxygen-rich carriers to the body.",
"Eliminate return veins from lungs and heart.",
"Choose pulmonary artery."
] | biology | Answer: (A) The pulmonary artery feeds the lungs.
Steps:
1. Eliminate oxygen-rich carriers to the body.
2. Eliminate return veins from lungs and heart.
3. Choose pulmonary artery.
Answer: (A) | physiology |
(C) Lactic acid fermentation; it regenerates NAD+ from pyruvate so glycolysis keeps making ATP without oxygen. | {
"A": "Krebs cycle",
"B": "Electron transport",
"C": "Lactic acid fermentation",
"D": "Photosynthesis"
} | bio_0264 | multiple_choice | en | Which process makes ATP without oxygen in working muscle? | [
"Eliminate oxygen-requiring pathways.",
"Eliminate plant energy capture.",
"Choose lactic acid fermentation."
] | biology | Answer: (C) Fermentation pays ATP without oxygen.
Steps:
1. Eliminate oxygen-requiring pathways.
2. Eliminate plant energy capture.
3. Choose lactic acid fermentation.
Answer: (C) | biochemistry |
(B) Anafáze; mikrotubuly vřeténka táhnou sesterské chromatidy k opačným pólům. | {
"A": "Profáze",
"B": "Anafáze",
"C": "Metafáze",
"D": "Telofáze"
} | bio_0265 | multiple_choice | cs | Ve které fázi mitózy se sesterské chromatidy rozcházejí k pólům? | [
"Vylučte sbalování, řazení a obnovu jader.",
"Přiřaďte rozchod chromatid.",
"Zvolte anafázi."
] | biology | Answer: (B) Chromatidy se rozcházejí v anafázi.
Steps:
1. Vylučte sbalování, řazení a obnovu jader.
2. Přiřaďte rozchod chromatid.
3. Zvolte anafázi.
Answer: (B) | cell_biology |
(D) Gametes; sperm and eggs carry 23 chromosomes each after meiosis halves the diploid set. | {
"A": "Skin cells",
"B": "Neurons",
"C": "Muscle cells",
"D": "Gametes"
} | bio_0266 | multiple_choice | en | Which human cells are haploid? | [
"Eliminate diploid body cells.",
"Recall meiosis halves gametes.",
"Choose gametes."
] | biology | Answer: (D) Gametes are haploid.
Steps:
1. Eliminate diploid body cells.
2. Recall meiosis halves gametes.
3. Choose gametes.
Answer: (D) | genetics |
About 2 million years ago; the 6 percent difference splits into 3 percent per lineage at 1.5 percent per million years. | null | bio_0267 | worked_example | en | Two rodents differ at 6 percent of DNA bases. If mutations accumulate at 1.5 percent per million years per lineage, when did they diverge? | [
"Split 6 percent between 2 lineages = 3 percent each.",
"Divide 3 / 1.5 = 2 million years.",
"Recompute: 2 x 2 x 1.5 = 6 percent."
] | biology | Answer: About 2 million years ago.
Steps:
1. Split 6 percent between 2 lineages = 3 percent each.
2. Divide 3 / 1.5 = 2 million years.
3. Recompute: 2 x 2 x 1.5 = 6 percent. | evolution |
Growth rate is 8 percent per year and next year's population is about 540; net gain of 40 on 500 gives the rate. | null | bio_0268 | worked_example | en | A deer herd of 500 gains 60 births and loses 20 deaths in a year. Calculate the per-capita growth rate and next year's size. | [
"Net gain = 60 - 20 = 40.",
"Rate = 40/500 = 0.08 = 8 percent.",
"Next year = 500 + 40 = 540.",
"Recompute: 540 - 500 = 40; 40/500 = 0.08."
] | biology | Answer: 8 percent growth, about 540 deer.
Steps:
1. Net gain = 60 - 20 = 40.
2. Rate = 40/500 = 0.08 = 8 percent.
3. Next year = 500 + 40 = 540.
4. Recompute: 540 - 500 = 40; 40/500 = 0.08. | ecology |
Stroke volume is 70 mL and ejection fraction is about 58.3 percent; the ventricle ejects over half its filled volume each beat. | null | bio_0269 | worked_example | en | A ventricle holds 120 mL at end-diastole and 50 mL at end-systole. Calculate stroke volume and ejection fraction. | [
"SV = 120 - 50 = 70 mL.",
"EF = 70/120 = 0.5833 = 58.3 percent.",
"Recompute: 0.5833 x 120 = 70; 70 + 50 = 120."
] | biology | Answer: SV 70 mL, EF about 58.3 percent.
Steps:
1. SV = 120 - 50 = 70 mL.
2. EF = 70/120 = 0.5833 = 58.3 percent.
3. Recompute: 0.5833 x 120 = 70; 70 + 50 = 120. | physiology |
Svačina má 165 kcal; sacharidy dávají 4 a tuky 9 kcal na gram. | null | bio_0270 | worked_example | cs | Svačina obsahuje 30 g sacharidů a 5 g tuku. Při 4 kcal na gram sacharidů a 9 kcal na gram tuku vypočítejte energii. | [
"Sacharidy: 30 x 4 = 120 kcal.",
"Tuky: 5 x 9 = 45 kcal.",
"Celkem: 120 + 45 = 165 kcal.",
"Přepočítejte: 165 - 45 = 120; 120/30 = 4."
] | biology | Answer: 165 kcal celkem.
Steps:
1. Sacharidy: 30 x 4 = 120 kcal.
2. Tuky: 5 x 9 = 45 kcal.
3. Celkem: 120 + 45 = 165 kcal.
4. Přepočítejte: 165 - 45 = 120; 120/30 = 4. | biochemistry |
Net water movement is inward and cells may burst (hemolysis); the dilute external solution is hypotonic to the cells. | null | bio_0271 | worked_example | en | Red blood cells are isotonic in 0.9 percent NaCl. Predict net water movement when placed in 0.2 percent NaCl and the likely outcome. | [
"Compare 0.2 percent to isotonic 0.9 percent.",
"Identify external solution as hypotonic.",
"Predict water enters by osmosis.",
"Conclude cells swell and may lyse."
] | biology | Answer: Water enters and cells may burst.
Steps:
1. Compare 0.2 percent to isotonic 0.9 percent.
2. Identify external solution as hypotonic.
3. Predict water enters by osmosis.
4. Conclude cells swell and may lyse. | cell_biology |
Pedigrees reveal autosomal dominant traits in every generation, autosomal recessive traits skipping generations, and X-linked recessive traits striking mainly males through carrier mothers. | null | bio_0272 | concept | en | Explain how pedigree analysis distinguishes inheritance patterns. | [
"Spot dominant traits in all generations.",
"Spot recessive traits skipping generations.",
"Spot X-linked traits in males via mothers."
] | biology | Answer: Pedigree shapes reveal dominant, recessive, or X-linked paths.
Steps:
1. Spot dominant traits in all generations.
2. Spot recessive traits skipping generations.
3. Spot X-linked traits in males via mothers. | genetics |
Gene flow moves alleles between populations through migration and mating, homogenizing differences and spreading useful variants, though strong flow can swamp local adaptation. | null | bio_0273 | concept | en | Explain gene flow and its evolutionary effects. | [
"Define migration plus mating.",
"Show homogenizing of allele frequencies.",
"Note spread of adaptations and swamping."
] | biology | Answer: Migrants blend gene pools and spread alleles.
Steps:
1. Define migration plus mating.
2. Show homogenizing of allele frequencies.
3. Note spread of adaptations and swamping. | evolution |
Pyramids of numbers and biomass usually narrow upward but can invert, while energy pyramids never invert because each level loses about 90 percent of energy as heat. | null | bio_0274 | concept | en | Compare ecological pyramids of numbers, biomass, and energy. | [
"Stack counts that can invert.",
"Stack mass that can invert.",
"Stack energy that always narrows."
] | biology | Answer: Counts and mass may invert; energy never does.
Steps:
1. Stack counts that can invert.
2. Stack mass that can invert.
3. Stack energy that always narrows. | ecology |
Malý oběh vede krev ze srdce do plic a zpět pro okysličení, velký oběh rozvádí okysličenou krev do těla a vrací odkysličenou; oba okruhy se střídají při každém srdečním cyklu. | null | bio_0275 | concept | cs | Vysvětlete malý a velký krevní oběh. | [
"Sledujte malý okruh do plic.",
"Sledujte velký okruh do těla.",
"Propojte oba přes srdce."
] | biology | Answer: Malý okruh okysličuje, velký zásobuje tělo.
Steps:
1. Sledujte malý okruh do plic.
2. Sledujte velký okruh do těla.
3. Propojte oba přes srdce. | physiology |
Vitamins are organic micronutrients such as C and D that assist enzymes and regulation, while minerals are inorganic elements such as iron and calcium that build structures and carry signals. | null | bio_0276 | concept | en | Contrast vitamins and minerals as micronutrients. | [
"Define organic helpers from diet.",
"Define inorganic elements needed.",
"Give vitamin C versus iron roles."
] | biology | Answer: Vitamins are organic helpers; minerals are inorganic essentials.
Steps:
1. Define organic helpers from diet.
2. Define inorganic elements needed.
3. Give vitamin C versus iron roles. | biochemistry |
Animal cells pinch apart with a cleavage furrow of actin, while plant cells build a cell plate of vesicles across the equator that becomes the new wall and membranes. | null | bio_0277 | concept | en | Contrast cytokinesis in animal and plant cells. | [
"Pinch animal cells with actin.",
"Build plant cell plates from vesicles.",
"Link the wall to the different solution."
] | biology | Answer: Animals pinch; plants build a wall plate.
Steps:
1. Pinch animal cells with actin.
2. Build plant cell plates from vesicles.
3. Link the wall to the different solution. | cell_biology |
Female mammals silence one X chromosome per cell into a dense Barr body, equalizing X-gene dosage with males; random choice makes females mosaics, visible in tortoiseshell cat patches. | null | bio_0278 | concept | en | Explain Barr bodies and X-inactivation in females. | [
"Silence one X into a Barr body.",
"Equalize dosage with males.",
"Show mosaic tortoiseshell coats."
] | biology | Answer: Females silence one X per cell into Barr bodies.
Steps:
1. Silence one X into a Barr body.
2. Equalize dosage with males.
3. Show mosaic tortoiseshell coats. | genetics |
Mass extinctions wipe out dominant groups and empty niches, letting survivors radiate; after dinosaurs fell 66 million years ago, mammals diversified into bats, whales, and primates. | null | bio_0279 | concept | en | Explain how mass extinctions lead to adaptive radiations, with an example. | [
"Empty niches by catastrophe.",
"Release survivors from competition.",
"Radiate mammals after dinosaurs."
] | biology | Answer: Extinctions empty stages for new radiations.
Steps:
1. Empty niches by catastrophe.
2. Release survivors from competition.
3. Radiate mammals after dinosaurs. | evolution |
Nika je role druhu včetně potravy, stanoviště a času aktivity; generalisté využívají širokou nabídku, zatímco specialisté úzkou, a proto hůře snášejí změny. | null | bio_0280 | concept | cs | Vysvětlete, co je ekologická nika, a rozdíl mezi generalisty a specialisty. | [
"Definujte roli druhu.",
"Popište širokou niku generalistů.",
"Popište úzkou niku specialistů."
] | biology | Answer: Nika je role druhu; generalisté jsou pružní, specialisté zranitelní.
Steps:
1. Definujte roli druhu.
2. Popište širokou niku generalistů.
3. Popište úzkou niku specialistů. | ecology |
(A) LH; a surge of luteinizing hormone ruptures the follicle and releases the egg mid-cycle. | {
"A": "LH",
"B": "Insulin",
"C": "Melatonin",
"D": "Calcitonin"
} | bio_0281 | multiple_choice | en | Which hormone surge triggers ovulation? | [
"Eliminate metabolic, sleep, and calcium hormones.",
"Recall pituitary control of the cycle.",
"Choose LH."
] | biology | Answer: (A) An LH surge triggers ovulation.
Steps:
1. Eliminate metabolic, sleep, and calcium hormones.
2. Recall pituitary control of the cycle.
3. Choose LH.
Answer: (A) | physiology |
(C) Creatine phosphate; it donates a phosphate to ADP within seconds during sprints until glycolysis and respiration take over. | {
"A": "Glycogen",
"B": "Glucose",
"C": "Creatine phosphate",
"D": "Fatty acid"
} | bio_0282 | multiple_choice | en | Which molecule directly regenerates ATP within seconds during sprinting? | [
"Eliminate slow fuel stores.",
"Recall instant phosphate donation.",
"Choose creatine phosphate."
] | biology | Answer: (C) Creatine phosphate reloads ATP instantly.
Steps:
1. Eliminate slow fuel stores.
2. Recall instant phosphate donation.
3. Choose creatine phosphate.
Answer: (C) | biochemistry |
(B) Tight junction; fused membrane proteins seal the gaps so substances must pass through cells, not between them. | {
"A": "Gap junction",
"B": "Tight junction",
"C": "Plasmodesma",
"D": "Desmosome"
} | bio_0283 | multiple_choice | en | Which cell junction prevents leakage between epithelial cells? | [
"Eliminate channels and plant bridges.",
"Eliminate anchoring-only junctions.",
"Choose tight junction."
] | biology | Answer: (B) Tight junctions seal epithelia.
Steps:
1. Eliminate channels and plant bridges.
2. Eliminate anchoring-only junctions.
3. Choose tight junction.
Answer: (B) | cell_biology |
(D) 92; after S phase each of the 46 chromosomes holds 2 sister chromatids. | {
"A": "23",
"B": "46",
"C": "69",
"D": "92"
} | bio_0284 | multiple_choice | en | How many chromatids are in a human cell in G2 phase? | [
"Recall 46 chromosomes after S.",
"Double for sister chromatids.",
"Choose 92."
] | biology | Answer: (D) G2 cells hold 92 chromatids.
Steps:
1. Recall 46 chromosomes after S.
2. Double for sister chromatids.
3. Choose 92.
Answer: (D) | genetics |
(A) Genetický drift; náhodné kolísání nejsilněji působí v malých populacích. | {
"A": "Genetický drift",
"B": "Přírodní výběr",
"C": "Pohlavní výběr",
"D": "Umělý výběr"
} | bio_0285 | multiple_choice | cs | Který proces náhodně mění frekvence alel v malých populacích? | [
"Vylučte směrované formy výběru.",
"Přiřaďte náhodu driftu.",
"Zvolte genetický drift."
] | biology | Answer: (A) Náhodné změny působí genetický drift.
Steps:
1. Vylučte směrované formy výběru.
2. Přiřaďte náhodu driftu.
3. Zvolte genetický drift.
Answer: (A) | evolution |
(C) Secondary succession; soil and seeds survive the fire, so grasses, shrubs, and trees recolonize in sequence. | {
"A": "Primary succession",
"B": "No succession occurs",
"C": "Secondary succession",
"D": "Extinction"
} | bio_0286 | multiple_choice | en | Which succession follows a forest fire that leaves soil intact? | [
"Eliminate bare-substrate starts.",
"Eliminate no-change options.",
"Choose secondary succession."
] | biology | Answer: (C) Burned forests regrow by secondary succession.
Steps:
1. Eliminate bare-substrate starts.
2. Eliminate no-change options.
3. Choose secondary succession.
Answer: (C) | ecology |
BMI is about 26.2, in the overweight range; weight divided by height squared gives the index. | null | bio_0287 | worked_example | en | A person weighs 85 kg and is 1.80 m tall. Calculate body mass index (BMI). | [
"Square height: 1.80 x 1.80 = 3.24.",
"Divide 85 / 3.24 = 26.23.",
"Recompute: 26.23 x 3.24 = 85.0 within rounding.",
"Report about 26.2."
] | biology | Answer: BMI about 26.2.
Steps:
1. Square height: 1.80 x 1.80 = 3.24.
2. Divide 85 / 3.24 = 26.23.
3. Recompute: 26.23 x 3.24 = 85.0 within rounding.
4. Report about 26.2. | physiology |
12.5 mL of stock is needed; dilution conserves moles of solute. | null | bio_0288 | worked_example | en | Using C1V1 equals C2V2, what volume of 2 M stock is needed to prepare 250 mL of 0.1 M solution? | [
"Write V1 = C2V2 / C1.",
"Substitute 0.1 x 250 / 2.",
"Compute 25 / 2 = 12.5 mL.",
"Recompute: 2 x 12.5 = 25 and 0.1 x 250 = 25."
] | biology | Answer: 12.5 mL of 2 M stock.
Steps:
1. Write V1 = C2V2 / C1.
2. Substitute 0.1 x 250 / 2.
3. Compute 25 / 2 = 12.5 mL.
4. Recompute: 2 x 12.5 = 25 and 0.1 x 250 = 25. | biochemistry |
800 cells after 6 hours; four doublings multiply the 50 founders sixteen-fold. | null | bio_0289 | worked_example | en | Yeast doubles every 90 minutes. Starting from 50 cells, how many are present after 6 hours of exponential growth? | [
"Convert 6 hours = 360 minutes.",
"Count doublings: 360/90 = 4.",
"Compute 50 x 2^4 = 50 x 16 = 800.",
"Recompute: 800/50 = 16 = 2^4."
] | biology | Answer: 800 cells.
Steps:
1. Convert 6 hours = 360 minutes.
2. Count doublings: 360/90 = 4.
3. Compute 50 x 2^4 = 50 x 16 = 800.
4. Recompute: 800/50 = 16 = 2^4. | cell_biology |
Podíl heterozygotů Aa je 1/2, tedy 50 procent; dvě ze čtyř políček čtverce nesou Aa. | null | bio_0290 | worked_example | cs | Při křížení Aa x Aa s úplnou dominancí vypočítejte očekávaný podíl heterozygotních potomků (Aa). | [
"Sestavte čtverec: AA, Aa, Aa, aa.",
"Spočítejte 2 ze 4 jako Aa.",
"Podíl = 2/4 = 1/2.",
"Přepočítejte: 1/2 = 50 procent."
] | biology | Answer: 1/2, tedy 50 procent Aa.
Steps:
1. Sestavte čtverec: AA, Aa, Aa, aa.
2. Spočítejte 2 ze 4 jako Aa.
3. Podíl = 2/4 = 1/2.
4. Přepočítejte: 1/2 = 50 procent. | genetics |
Allele frequency falls from 0.5 to about 0.333 in one generation; selection removes all aa while Aa shelters a copies. | null | bio_0291 | worked_example | en | A recessive allele has frequency q = 0.5 and all homozygous recessive individuals fail to reproduce (selection coefficient 1). What is q after one generation? | [
"Surviving genotypes are AA and Aa only.",
"Use q next = q/(1+q) for full selection.",
"Compute 0.5/1.5 = 0.3333.",
"Recompute: p=0.5, Aa = 2x0.5x0.5=0.5 of zygotes; a copies = 0.25 of 0.75 surviving alleles = 0.333."
] | biology | Answer: q falls to about 0.333.
Steps:
1. Surviving genotypes are AA and Aa only.
2. Use q next = q/(1+q) for full selection.
3. Compute 0.5/1.5 = 0.3333.
4. Recompute: p=0.5, Aa = 2x0.5x0.5=0.5 of zygotes; a copies = 0.25 of 0.75 surviving alleles = 0.333. | evolution |
In Batesian mimicry a harmless species copies a dangerous one, as hoverflies mimic wasps, while in Mullerian mimicry several harmful species share one warning pattern, as alike-stinging bees and wasps do. | null | bio_0292 | concept | en | Distinguish Batesian from Mullerian mimicry with examples. | [
"Define harmless copying harmful.",
"Define shared warnings among harmful.",
"Give hoverfly versus bee patterns."
] | biology | Answer: Batesian fakes danger; Mullerian shares real warnings.
Steps:
1. Define harmless copying harmful.
2. Define shared warnings among harmful.
3. Give hoverfly versus bee patterns. | ecology |
After about 120 days the spleen and liver trap worn red cells, macrophages digest hemoglobin into bilirubin for bile and recycle iron to new red cells in bone marrow. | null | bio_0293 | concept | en | Explain how old red blood cells are recycled. | [
"Trap aged cells in spleen and liver.",
"Split hemoglobin into bilirubin and iron.",
"Reuse iron in marrow for new cells."
] | biology | Answer: Spleen and liver turn old red cells into new ones.
Steps:
1. Trap aged cells in spleen and liver.
2. Split hemoglobin into bilirubin and iron.
3. Reuse iron in marrow for new cells. | physiology |
Steroids share a four-ring carbon skeleton; cholesterol stiffens membranes and serves as the raw material for sex hormones, vitamin D, and bile salts. | null | bio_0294 | concept | en | Describe steroid structure and three biological roles. | [
"Define the fused four-ring frame.",
"Place cholesterol in membranes.",
"Derive hormones, vitamin D, and bile."
] | biology | Answer: Four-ring steroids tune membranes and signal.
Steps:
1. Define the fused four-ring frame.
2. Place cholesterol in membranes.
3. Derive hormones, vitamin D, and bile. | biochemistry |
Lyzozom je váček s trávicími enzymy, které rozkládají pohlcené částice, opotřebované organely i celé buňky při vývoji; proto se mu říká trávicí ústrojí buňky. | null | bio_0295 | concept | cs | Popište lyzozom a jeho funkci v buňce. | [
"Popište váček s kyselými hydrolázami.",
"Vysvětlete trávení částic a organel.",
"Uveďte roli při vývoji tkání."
] | biology | Answer: Lyzozom tráví a recykluje obsah buňky.
Steps:
1. Popište váček s kyselými hydrolázami.
2. Vysvětlete trávení částic a organel.
3. Uveďte roli při vývoji tkání. | cell_biology |
Gel electrophoresis pulls negatively charged DNA through a gel toward the positive pole, so short fragments run far and long ones lag, separating bands by size for comparison. | null | bio_0296 | concept | en | Explain how gel electrophoresis separates DNA fragments. | [
"Load charged DNA into gel wells.",
"Pull fragments toward positive pole.",
"Read small-far, large-near band patterns."
] | biology | Answer: Gels sort DNA by size through electric pull.
Steps:
1. Load charged DNA into gel wells.
2. Pull fragments toward positive pole.
3. Read small-far, large-near band patterns. | genetics |
The Red Queen hypothesis holds that species must evolve constantly just to hold their ground against ever-adapting parasites, predators, and competitors, like running to stay in place. | null | bio_0297 | concept | en | What is the Red Queen hypothesis in evolution? | [
"Name ever-adapting enemies.",
"Require constant counter-adaptation.",
"Link to sex and immune diversity."
] | biology | Answer: Species must run evolutionarily to stand still.
Steps:
1. Name ever-adapting enemies.
2. Require constant counter-adaptation.
3. Link to sex and immune diversity. | evolution |
Phosphate weathers from rocks into soil and water, is taken up by producers, passed to consumers, and returned by decomposers, with no significant atmospheric gas phase unlike nitrogen and carbon. | null | bio_0298 | concept | en | Describe the phosphorus cycle and how it differs from carbon and nitrogen cycles. | [
"Weather phosphate from rock.",
"Cycle through food and decay.",
"Note the missing air phase."
] | biology | Answer: Phosphorus cycles rock to life without an air leg.
Steps:
1. Weather phosphate from rock.
2. Cycle through food and decay.
3. Note the missing air leg. | ecology |
A tap stretches receptors that fire sensory neurons to the spinal cord, where interneurons relay to motor neurons that contract the thigh muscle, jerking the leg before the brain weighs in. | null | bio_0299 | concept | en | Describe the reflex arc using the knee-jerk response. | [
"Stretch receptors in the tendon.",
"Signal through cord interneurons.",
"Contract muscle before brain input."
] | biology | Answer: Reflexes loop through the cord for instant action.
Steps:
1. Stretch receptors in the tendon.
2. Signal through cord interneurons.
3. Contract muscle before brain input. | physiology |
Dýchací řetězec na kristách předává elektrony z NADH a FADH2 na kyslík, pumpuje protony do mezimembránového prostoru a jejich zpětný tok přes ATP syntázu vyrábí ATP chemiosmózou. | null | bio_0300 | concept | cs | Vysvětlete dýchací řetězec a tvorbu ATP chemiosmózou. | [
"Sledujte elektrony na kyslík.",
"Popište pumpování protonů.",
"Vysvětlete ATP syntázu a chemiosmózu."
] | biology | Answer: Elektrony pumpují protony, jejich tok točí ATP syntázu.
Steps:
1. Sledujte elektrony na kyslík.
2. Popište pumpování protonů.
3. Vysvětlete ATP syntázu a chemiosmózu. | biochemistry |
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