answer string | choices dict | id string | kind string | lang string | question string | steps list | subject string | text string | topic string |
|---|---|---|---|---|---|---|---|---|---|
(C) Antibiotic resistance; bacteria evolve drug resistance within years under selection today. | {
"A": "Dinosaur fossils",
"B": "Trilobites",
"C": "Antibiotic resistance",
"D": "Mammoth tusks"
} | bio_0501 | multiple_choice | en | Which shows evolution happening in the present day? | [
"Eliminate ancient fossils.",
"Spot ongoing selection.",
"Choose antibiotic resistance."
] | biology | Answer: (C) Resistance evolves now.
Steps:
1. Eliminate ancient fossils.
2. Spot ongoing selection.
3. Choose antibiotic resistance.
Answer: (C) | evolution |
(A) Carbon dioxide; leaves absorb CO2 from air and fix it into sugars with light energy. | {
"A": "Carbon dioxide",
"B": "Oxygen",
"C": "Nitrogen",
"D": "Hydrogen"
} | bio_0502 | multiple_choice | en | Which gas do plants absorb for photosynthesis? | [
"Eliminate released oxygen.",
"Eliminate unused gases.",
"Choose carbon dioxide."
] | biology | Answer: (A) Plants drink CO2.
Steps:
1. Eliminate released oxygen.
2. Eliminate unused gases.
3. Choose carbon dioxide.
Answer: (A) | ecology |
(D) Kidney; nephrons filter blood and shape urine, which the bladder only stores. | {
"A": "Liver",
"B": "Bladder",
"C": "Ureter",
"D": "Kidney"
} | bio_0503 | multiple_choice | en | Which organ filters blood to make urine? | [
"Eliminate storage organs.",
"Eliminate detox organs.",
"Choose kidney."
] | biology | Answer: (D) Kidneys filter urine.
Steps:
1. Eliminate storage organs.
2. Eliminate detox organs.
3. Choose kidney.
Answer: (D) | physiology |
(B) DNA; the double helix stores hereditary instructions, unlike energy and food molecules. | {
"A": "ATP",
"B": "DNA",
"C": "Glucose",
"D": "Starch"
} | bio_0504 | multiple_choice | en | Which molecule stores genetic information? | [
"Eliminate energy carriers.",
"Eliminate food sugars.",
"Choose DNA."
] | biology | Answer: (B) DNA archives heredity.
Steps:
1. Eliminate energy carriers.
2. Eliminate food sugars.
3. Choose DNA.
Answer: (B) | biochemistry |
(A) Jádro; uchovává DNA a řídí činnost celé buňky. | {
"A": "Jádro",
"B": "Membrána",
"C": "Vakuola",
"D": "Buněčná stěna"
} | bio_0505 | multiple_choice | cs | Která struktura řídí činnost buňky? | [
"Vylučte obaly a sklady.",
"Přiřaďte řízení DNA.",
"Zvolte jádro."
] | biology | Answer: (A) Buňku řídí jádro.
Steps:
1. Vylučte obaly a sklady.
2. Přiřaďte řízení DNA.
3. Zvolte jádro.
Answer: (A) | cell_biology |
(D) Two; diploid cells carry two alleles per gene, one from each parent. | {
"A": "One",
"B": "Four",
"C": "Three",
"D": "Two"
} | bio_0506 | multiple_choice | en | How many alleles of a gene does a diploid cell carry? | [
"Eliminate single copies.",
"Eliminate extra copies.",
"Choose two."
] | biology | Answer: (D) Diploids pair alleles.
Steps:
1. Eliminate single copies.
2. Eliminate extra copies.
3. Choose two.
Answer: (D) | genetics |
The fossil is about 11,460 years old; 25 percent remaining means two half-lives of 5730 years passed. | null | bio_0507 | worked_example | en | Carbon-14 has a half-life of 5730 years. A fossil holds 25 percent of its original carbon-14. Estimate its age. | [
"Note 25 percent = (1/2)^2.",
"Count 2 half-lives.",
"Multiply 2 x 5730 = 11460 years.",
"Recompute: (1/2)^2 = 0.25."
] | biology | Answer: About 11,460 years old.
Steps:
1. Note 25 percent = (1/2)^2.
2. Count 2 half-lives.
3. Multiply 2 x 5730 = 11460 years.
4. Recompute: (1/2)^2 = 0.25. | evolution |
Tertiary consumers receive 10 kJ; each level keeps 10 percent of 10,000 kJ through three transfers. | null | bio_0508 | worked_example | en | Producers capture 10,000 kJ and each trophic level passes on 10 percent. Calculate the energy reaching tertiary consumers. | [
"Primary: 10000 x 0.1 = 1000.",
"Secondary: 1000 x 0.1 = 100.",
"Tertiary: 100 x 0.1 = 10 kJ.",
"Recompute: 10000 x 0.1^3 = 10."
] | biology | Answer: 10 kJ.
Steps:
1. Primary: 10000 x 0.1 = 1000.
2. Secondary: 1000 x 0.1 = 100.
3. Tertiary: 100 x 0.1 = 10 kJ.
4. Recompute: 10000 x 0.1^3 = 10. | ecology |
Cardiac output is 6 liters per minute; 80 mL times 75 beats gives resting heart flow. | null | bio_0509 | worked_example | en | Stroke volume is 80 mL and heart rate is 75 beats per minute. Calculate cardiac output. | [
"Multiply 80 x 75 = 6000 mL per min.",
"Convert to 6 L per min.",
"Recompute: 6 x 1000 / 75 = 80 mL."
] | biology | Answer: 6 L per min.
Steps:
1. Multiply 80 x 75 = 6000 mL per min.
2. Convert to 6 L per min.
3. Recompute: 6 x 1000 / 75 = 80 mL. | physiology |
Koncentrace je 20 g/L; 5 gramů v čtvrtlitru dá dvacetinásobek na litr. | null | bio_0510 | worked_example | cs | V 250 mL roztoku je rozpuštěno 5 g soli. Vypočítejte koncentraci v gramech na litr. | [
"Převeďte 250 mL = 0,25 L.",
"Vydělte 5 / 0,25 = 20.",
"Uveďte 20 g/L.",
"Přepočítejte: 20 x 0,25 = 5."
] | biology | Answer: 20 g/L.
Steps:
1. Převeďte 250 mL = 0,25 L.
2. Vydělte 5 / 0,25 = 20.
3. Uveďte 20 g/L.
4. Přepočítejte: 20 x 0,25 = 5. | biochemistry |
About 208 billion cells per day; 25 trillion divided by the 120-day lifespan gives daily turnover. | null | bio_0511 | worked_example | en | Red blood cells live 120 days and the body holds 25 trillion of them. Calculate daily replacement. | [
"Divide 25e12 / 120 = 2.083e11.",
"Report about 208 billion per day.",
"Recompute: 2.083e11 x 120 = 25e12."
] | biology | Answer: About 208 billion per day.
Steps:
1. Divide 25e12 / 120 = 2.083e11.
2. Report about 208 billion per day.
3. Recompute: 2.083e11 x 120 = 25e12. | cell_biology |
With incomplete dominance neither allele wins fully, so red crossed with white snapdragons yields pink offspring blending both pigments. | null | bio_0512 | concept | en | Explain incomplete dominance with the snapdragon example. | [
"Blend neither allele fully.",
"Cross red with white.",
"Yield pink middles."
] | biology | Answer: Alleles can blend to pink.
Steps:
1. Blend neither allele fully.
2. Cross red with white.
3. Yield pink middles. | genetics |
One ancestor reaching new islands diversifies fast into many niches, as finches evolved beaks for seeds, insects, and cactus from a single flock. | null | bio_0513 | concept | en | Explain adaptive radiation with Darwin's finches. | [
"Land on empty islands.",
"Split into open niches.",
"Shape beaks per diet."
] | biology | Answer: One flock became many beaks.
Steps:
1. Land on empty islands.
2. Split into open niches.
3. Shape beaks per diet. | evolution |
Primary succession colonizes bare rock from lichens upward, while secondary succession regrows disturbed land from surviving soil and seeds much faster. | null | bio_0514 | concept | en | Contrast primary and secondary succession. | [
"Start primary on bare rock.",
"Restart secondary on old soil.",
"Compare slow versus fast."
] | biology | Answer: Rock starts slow; ruins regrow fast.
Steps:
1. Start primary on bare rock.
2. Restart secondary on old soil.
3. Compare slow versus fast. | ecology |
V tenkém střevě žluč emulguje tuky a enzymy slinivky a střevní stěny rozštěpí živiny; klky je pak vstřebají do krve a mízy. | null | bio_0515 | concept | cs | Vysvětlete trávení a vstřebávání v tenkém střevě. | [
"Emulgujte tuky žlučí.",
"Rozštěpte živiny enzymy.",
"Vstřebejte je klky."
] | biology | Answer: Tenké střevo tráví a vstřebává.
Steps:
1. Emulgujte tuky žlučí.
2. Rozštěpte živiny enzymy.
3. Vstřebejte je klky. | physiology |
DNA twists two sugar-phosphate strands into a helix joined by A-T and G-C base pairs, packing the genetic code into a stable, copyable ladder. | null | bio_0516 | concept | en | Describe the structure of the DNA double helix. | [
"Twist two backbone strands.",
"Rung them with base pairs.",
"Pack a copyable code."
] | biology | Answer: DNA is a paired spiral ladder.
Steps:
1. Twist two backbone strands.
2. Rung them with base pairs.
3. Pack a copyable code. | biochemistry |
Checkpoints at G1, G2, and M verify growth, copied DNA, and aligned chromosomes before division proceeds; broken checkpoints let cancer grow unchecked. | null | bio_0517 | concept | en | Explain cell cycle checkpoints and their link to cancer. | [
"Check growth at G1.",
"Check copies at G2.",
"Check alignment at M."
] | biology | Answer: Checkpoints gate division thrice.
Steps:
1. Check growth at G1.
2. Check copies at G2.
3. Check alignment at M. | cell_biology |
Codominant alleles both show fully, so IA and IB together produce AB blood with both antigens on each red cell. | null | bio_0518 | concept | en | Explain codominance with the AB blood group example. | [
"Express both alleles fully.",
"Build both antigens.",
"Type the blood AB."
] | biology | Answer: Codominance shows both sides.
Steps:
1. Express both alleles fully.
2. Build both antigens.
3. Type the blood AB. | genetics |
Catastrophes that shrink populations to a few survivors randomly skew gene pools, leaving cheetahs nearly identical from an ancient bottleneck. | null | bio_0519 | concept | en | Explain the bottleneck effect with the cheetah example. | [
"Crash the population.",
"Skew genes by chance.",
"Inbreed the survivors."
] | biology | Answer: Bottlenecks squeeze diversity out.
Steps:
1. Crash the population.
2. Skew genes by chance.
3. Inbreed the survivors. | evolution |
Lišejník je symbióza houby a řasy: řasa fotosyntézou živí houbu a houba jí dává vodu, ochranu a ukotvení. | null | bio_0520 | concept | cs | Vysvětlete symbiózu na příkladu lišejníku. | [
"Spojte houbu s řasou.",
"Živte houbu fotosyntézou.",
"Chraňte řasu vodou a úkrytem."
] | biology | Answer: Lišejník je houba s řasou v týmu.
Steps:
1. Spojte houbu s řasou.
2. Živte houbu fotosyntézou.
3. Chraňte řasu vodou a úkrytem. | ecology |
(A) Artery; arteries carry blood away from the heart under high pressure, while veins return it. | {
"A": "Artery",
"B": "Vein",
"C": "Capillary",
"D": "Valve"
} | bio_0521 | multiple_choice | en | Which vessel carries blood away from the heart? | [
"Eliminate return vessels.",
"Eliminate exchange vessels.",
"Choose artery."
] | biology | Answer: (A) Arteries leave the heart.
Steps:
1. Eliminate return vessels.
2. Eliminate exchange vessels.
3. Choose artery.
Answer: (A) | physiology |
(C) Carbon; its four bonds chain into the skeletons of all proteins, sugars, fats, and DNA. | {
"A": "Oxygen",
"B": "Hydrogen",
"C": "Carbon",
"D": "Nitrogen"
} | bio_0522 | multiple_choice | en | Which element forms the backbone of organic molecules? | [
"Eliminate single-bond atoms.",
"Recall four-bond chains.",
"Choose carbon."
] | biology | Answer: (C) Carbon frames life.
Steps:
1. Eliminate single-bond atoms.
2. Recall four-bond chains.
3. Choose carbon.
Answer: (C) | biochemistry |
(B) Ribosome; ribosomes read mRNA and assemble amino acids into proteins. | {
"A": "Mitochondrion",
"B": "Ribosome",
"C": "Lysosome",
"D": "Vacuole"
} | bio_0523 | multiple_choice | en | Which organelle builds proteins? | [
"Eliminate digesters.",
"Eliminate storage sacs.",
"Choose ribosome."
] | biology | Answer: (B) Ribosomes build proteins.
Steps:
1. Eliminate digesters.
2. Eliminate storage sacs.
3. Choose ribosome.
Answer: (B) | cell_biology |
(D) Heterozygous; carrying two different alleles makes the genotype heterozygous. | {
"A": "Homozygous",
"B": "Purebred",
"C": "Dominant",
"D": "Heterozygous"
} | bio_0524 | multiple_choice | en | Which term means carrying two different alleles? | [
"Eliminate identical pairs.",
"Eliminate single-trait labels.",
"Choose heterozygous."
] | biology | Answer: (D) Mixed alleles are heterozygous.
Steps:
1. Eliminate identical pairs.
2. Eliminate single-trait labels.
3. Choose heterozygous.
Answer: (D) | genetics |
(B) Archaeopteryx; spojuje dinosauří znaky s peřím a křídly ptáků. | {
"A": "Trilobit",
"B": "Archaeopteryx",
"C": "Mamut",
"D": "Amonit"
} | bio_0525 | multiple_choice | cs | Která fosilie dokládá vývoj ptáků z dinosaurů? | [
"Vylučte nepříbuzné skupiny.",
"Spojte peří s dinosauří kostrou.",
"Zvolte archaeopteryxe."
] | biology | Answer: (B) Ptáky s dinosaury spojuje archaeopteryx.
Steps:
1. Vylučte nepříbuzné skupiny.
2. Spojte peří s dinosauří kostrou.
3. Zvolte archaeopteryxe.
Answer: (B) | evolution |
(C) Tundra; the frozen treeless biome circles the poles with permafrost and dwarf plants. | {
"A": "Taiga",
"B": "Rainforest",
"C": "Tundra",
"D": "Grassland"
} | bio_0526 | multiple_choice | en | Which biome is frozen and treeless? | [
"Eliminate forested biomes.",
"Eliminate warm biomes.",
"Choose tundra."
] | biology | Answer: (C) Tundra freezes treeless.
Steps:
1. Eliminate forested biomes.
2. Eliminate warm biomes.
3. Choose tundra.
Answer: (C) | ecology |
About 99.2 percent is reabsorbed; only 1.5 of 180 liters leaves as urine. | null | bio_0527 | worked_example | en | Kidneys filter 180 liters daily but excrete only 1.5 liters of urine. Calculate the percent of filtrate reabsorbed. | [
"Subtract 180 - 1.5 = 178.5 L.",
"Divide 178.5 / 180 = 0.9917.",
"Convert to about 99.2 percent.",
"Recompute: 180 x 0.9917 = 178.5."
] | biology | Answer: About 99.2 percent reabsorbed.
Steps:
1. Subtract 180 - 1.5 = 178.5 L.
2. Divide 178.5 / 180 = 0.9917.
3. Convert to about 99.2 percent.
4. Recompute: 180 x 0.9917 = 178.5. | physiology |
One hundred times more H+ ions; a 2-unit pH gap means 10 squared acidity. | null | bio_0528 | worked_example | en | Solution A has pH 3 and solution B has pH 5. How many times more H+ ions does A contain? | [
"Subtract 5 - 3 = 2 units.",
"Raise 10^2 = 100.",
"Recompute: log10(100) = 2."
] | biology | Answer: 100 times more H+.
Steps:
1. Subtract 5 - 3 = 2 units.
2. Raise 10^2 = 100.
3. Recompute: log10(100) = 2. | biochemistry |
640 cells after 2 hours; six doublings multiply the 10 founders sixty-four-fold. | null | bio_0529 | worked_example | en | Bacteria double every 20 minutes. Starting from 10 cells, how many are present after 2 hours? | [
"Convert 2 hours = 120 minutes.",
"Count doublings: 120/20 = 6.",
"Compute 10 x 2^6 = 10 x 64 = 640.",
"Recompute: 640/10 = 64 = 2^6."
] | biology | Answer: 640 cells.
Steps:
1. Convert 2 hours = 120 minutes.
2. Count doublings: 120/20 = 6.
3. Compute 10 x 2^6 = 10 x 64 = 640.
4. Recompute: 640/10 = 64 = 2^6. | cell_biology |
Pravděpodobnost genotypu bb je 1/4, tedy 25 procent; čtverec Bb x Bb dá jednu ze čtyř kombinací. | null | bio_0530 | worked_example | cs | Při křížení Bb x Bb vypočítejte pravděpodobnost potomka s genotypem bb. | [
"Sestavte čtverec: BB, Bb, Bb, bb.",
"Spočítejte bb: 1 ze 4.",
"Převeďte na 1/4 = 25 procent.",
"Přepočítejte: 1/4 + 1/2 + 1/4 = 1."
] | biology | Answer: 1/4, tedy 25 procent.
Steps:
1. Sestavte čtverec: BB, Bb, Bb, bb.
2. Spočítejte bb: 1 ze 4.
3. Převeďte na 1/4 = 25 procent.
4. Přepočítejte: 1/4 + 1/2 + 1/4 = 1. | genetics |
q equals 0.6, p equals 0.4, and carriers equal 48 percent; the square root of 0.36 gives q. | null | bio_0531 | worked_example | en | In a mouse population, 36 percent show a recessive trait. Assuming Hardy-Weinberg equilibrium, calculate q, p, and the carrier frequency. | [
"q = sqrt(0.36) = 0.6.",
"p = 1 - 0.6 = 0.4.",
"2pq = 2 x 0.4 x 0.6 = 0.48.",
"Recompute: 0.16+0.36+0.48=1.0."
] | biology | Answer: q=0.6, p=0.4, carriers=48%.
Steps:
1. q = sqrt(0.36) = 0.6.
2. p = 1 - 0.6 = 0.4.
3. 2pq = 2 x 0.4 x 0.6 = 0.48.
4. Recompute: 0.16+0.36+0.48=1.0. | evolution |
Keystone species hold food webs together out of proportion to their numbers, as sea otters eating urchins protect the kelp forests sheltering hundreds of species. | null | bio_0532 | concept | en | Explain keystone species with the sea otter example. | [
"Define outsized impact.",
"Eat urchins with otters.",
"Shelter kelp forests."
] | biology | Answer: Otters guard kelp by eating urchins.
Steps:
1. Define outsized impact.
2. Eat urchins with otters.
3. Shelter kelp forests. | ecology |
Sound vibrates the eardrum and ossicles, waves ripple cochlear fluid, and hair cells convert the motion into nerve signals the brain reads as sound. | null | bio_0533 | concept | en | Explain how the ear converts sound into nerve signals. | [
"Vibrate drum and bones.",
"Ripple cochlear fluid.",
"Fire hair-cell nerves."
] | biology | Answer: Ears turn waves into signals.
Steps:
1. Vibrate drum and bones.
2. Ripple cochlear fluid.
3. Fire hair-cell nerves. | physiology |
Competitive inhibitors block the active site directly and yield to more substrate, while noncompetitive ones bind elsewhere and warp the enzyme regardless of substrate. | null | bio_0534 | concept | en | Contrast competitive and noncompetitive enzyme inhibition. | [
"Block the site directly.",
"Warp the enzyme elsewhere.",
"Compare substrate rescue."
] | biology | Answer: Blockers sit in or bend from afar.
Steps:
1. Block the site directly.
2. Warp the enzyme elsewhere.
3. Compare substrate rescue. | biochemistry |
Mitochondrie spalují glukózu s kyslíkem na oxid uhličitý, vodu a ATP; vnitřní membrána s kristami hostí dýchací řetězec. | null | bio_0535 | concept | cs | Popište mitochondrie a průběh buněčného dýchání. | [
"Popište stavbu s kristami.",
"Spalte glukózu na ATP.",
"Uveďte dýchací řetězec."
] | biology | Answer: Mitochondrie dýchají glukózu na ATP.
Steps:
1. Popište stavbu s kristami.
2. Spalte glukózu na ATP.
3. Uveďte dýchací řetězec. | cell_biology |
In small populations chance alone shifts allele frequencies each generation, randomly fixing or losing variants no matter their survival value. | null | bio_0536 | concept | en | Explain genetic drift in small populations. | [
"Shrink the gene pool.",
"Sample alleles by luck.",
"Fix or lose variants."
] | biology | Answer: Small pools drift by luck.
Steps:
1. Shrink the gene pool.
2. Sample alleles by luck.
3. Fix or lose variants. | genetics |
Human arms, bat wings, and whale flippers share the same bone pattern from a common ancestor, reshaped by selection for grasping, flying, and swimming. | null | bio_0537 | concept | en | Explain homologous structures with the forelimb example. | [
"Share one bone pattern.",
"Inherit from one ancestor.",
"Reshape per lifestyle."
] | biology | Answer: One forelimb, many callings.
Steps:
1. Share one bone pattern.
2. Inherit from one ancestor.
3. Reshape per lifestyle. | evolution |
Fertilizer runoff feeds algal blooms that block light and, when decaying, drain oxygen into dead zones where fish suffocate. | null | bio_0538 | concept | en | Explain eutrophication and how dead zones form. | [
"Feed blooms with runoff.",
"Block light with algae.",
"Drain oxygen by decay."
] | biology | Answer: Fertilizer blooms choke waters dead.
Steps:
1. Feed blooms with runoff.
2. Block light with algae.
3. Drain oxygen by decay. | ecology |
Damaged vessels summon platelets that plug the leak, then a fibrin cascade weaves a mesh trapping blood cells into a clot that seals the wound. | null | bio_0539 | concept | en | Describe how blood clots after injury. | [
"Plug leaks with platelets.",
"Weave fibrin mesh.",
"Seal wounds with clots."
] | biology | Answer: Platelets plug, fibrin seals.
Steps:
1. Plug leaks with platelets.
2. Weave fibrin mesh.
3. Seal wounds with clots. | physiology |
Sacharidy jsou cukry a škroby ze sacharidových jednotek: monosacharidy (glukóza), disacharidy (sacharóza) a polysacharidy (škrob, celulóza). | null | bio_0540 | concept | cs | Vysvětlete, co jsou sacharidy a jak se dělí. | [
"Definujte sacharidové jednotky.",
"Rozlište mono-, di- a polysacharidy.",
"Uveďte příklady."
] | biology | Answer: Sacharidy se dělí podle délky řetězce.
Steps:
1. Definujte sacharidové jednotky.
2. Rozlište mono-, di- a polysacharidy.
3. Uveďte příklady. | biochemistry |
(A) Nucleolus; the dense knot inside the nucleus transcribes ribosomal RNA and assembles ribosome parts. | {
"A": "Nucleolus",
"B": "Lysosome",
"C": "Vacuole",
"D": "Centriole"
} | bio_0541 | multiple_choice | en | Which structure builds ribosomes? | [
"Eliminate digesters.",
"Eliminate storage sacs.",
"Choose nucleolus."
] | biology | Answer: (A) The nucleolus makes ribosomes.
Steps:
1. Eliminate digesters.
2. Eliminate storage sacs.
3. Choose nucleolus.
Answer: (A) | cell_biology |
(D) Mendel; his pea-plant crosses revealed the laws of inheritance. | {
"A": "Darwin",
"B": "Pasteur",
"C": "Lamarck",
"D": "Mendel"
} | bio_0542 | multiple_choice | en | Who is called the father of genetics? | [
"Eliminate evolution author.",
"Eliminate germ and acquired-trait pioneers.",
"Choose Mendel."
] | biology | Answer: (D) Mendel fathered genetics.
Steps:
1. Eliminate evolution author.
2. Eliminate germ and acquired-trait pioneers.
3. Choose Mendel.
Answer: (D) | genetics |
(B) The best-adapted leave the most offspring; fitness means reproductive success, not strength or speed. | {
"A": "The strongest individuals survive",
"B": "The best-adapted leave the most offspring",
"C": "The largest win every fight",
"D": "The fastest always escape"
} | bio_0543 | multiple_choice | en | What does survival of the fittest mean? | [
"Eliminate strength myths.",
"Define fitness as reproduction.",
"Choose best-adapted breeders."
] | biology | Answer: (B) Fitness means offspring.
Steps:
1. Eliminate strength myths.
2. Define fitness as reproduction.
3. Choose best-adapted breeders.
Answer: (B) | evolution |
(D) Lion and zebra; the lion hunts and eats the zebra, a true predator-prey pair. | {
"A": "Moss and rock",
"B": "Bee and flower",
"C": "Remora and shark",
"D": "Lion and zebra"
} | bio_0544 | multiple_choice | en | Which pair shows a predator-prey relationship? | [
"Eliminate partnerships.",
"Spot the hunter and hunted.",
"Choose lion and zebra."
] | biology | Answer: (D) Lions prey on zebras.
Steps:
1. Eliminate partnerships.
2. Spot the hunter and hunted.
3. Choose lion and zebra.
Answer: (D) | ecology |
(A) Bránice; její stahy nasávají vzduch do plic při každém nádechu. | {
"A": "Bránice",
"B": "Biceps",
"C": "Srdeční sval",
"D": "Žvýkací sval"
} | bio_0545 | multiple_choice | cs | Který sval je hlavním dýchacím svalem? | [
"Vylučte končetiny a čelisti.",
"Přiřaďte nádech bránici.",
"Zvolte bránici."
] | biology | Answer: (A) Dýchání pohání bránice.
Steps:
1. Vylučte končetiny a čelisti.
2. Přiřaďte nádech bránici.
3. Zvolte bránici.
Answer: (A) | physiology |
(B) Ribose; RNA builds its backbone from ribose, while DNA uses deoxyribose. | {
"A": "Deoxyribose",
"B": "Ribose",
"C": "Glucose",
"D": "Sucrose"
} | bio_0546 | multiple_choice | en | Which sugar is found in RNA? | [
"Eliminate DNA sugar.",
"Eliminate food sugars.",
"Choose ribose."
] | biology | Answer: (B) RNA runs on ribose.
Steps:
1. Eliminate DNA sugar.
2. Eliminate food sugars.
3. Choose ribose.
Answer: (B) | biochemistry |
50 cells fit in one centimeter; 10,000 micrometers divided by 200 gives the count. | null | bio_0547 | worked_example | en | An onion cell is 200 µm long. How many fit end to end in 1 cm? | [
"Convert 1 cm = 10000 µm.",
"Divide 10000 / 200 = 50.",
"Recompute: 50 x 200 = 10000."
] | biology | Answer: 50 cells.
Steps:
1. Convert 1 cm = 10000 µm.
2. Divide 10000 / 200 = 50.
3. Recompute: 50 x 200 = 10000. | cell_biology |
The probability is 1/4, i.e. 25 percent; the Cc x Cc square yields one cc in four. | null | bio_0548 | worked_example | en | For the cross Cc x Cc, calculate the probability of cc offspring. | [
"List square: CC, Cc, Cc, cc.",
"Count cc: 1 of 4.",
"Convert to 1/4 = 25 percent.",
"Recompute: 1/4+1/2+1/4=1."
] | biology | Answer: 1/4, i.e. 25 percent.
Steps:
1. List square: CC, Cc, Cc, cc.
2. Count cc: 1 of 4.
3. Convert to 1/4 = 25 percent.
4. Recompute: 1/4+1/2+1/4=1. | genetics |
About 3.75 billion years old; 12.5 percent remaining means three half-lives of 1.25 billion years passed. | null | bio_0549 | worked_example | en | Potassium-40 has a half-life of 1.25 billion years. A rock holds 12.5 percent of its original potassium-40. Estimate its age. | [
"Note 12.5 percent = (1/2)^3.",
"Count 3 half-lives.",
"Multiply 3 x 1.25 = 3.75 billion years.",
"Recompute: (1/2)^3 = 0.125."
] | biology | Answer: About 3.75 billion years old.
Steps:
1. Note 12.5 percent = (1/2)^3.
2. Count 3 half-lives.
3. Multiply 3 x 1.25 = 3.75 billion years.
4. Recompute: (1/2)^3 = 0.125. | evolution |
V rybníce je asi 600 kaprů; plocha krát hustota dá celkový počet. | null | bio_0550 | worked_example | cs | Rybník má 2 hektary a hustota je 300 kaprů na hektar. Vypočítejte počet kaprů. | [
"Vynásobte 2 x 300 = 600.",
"Přepočítejte: 600 / 2 = 300.",
"Uveďte asi 600 kaprů."
] | biology | Answer: Asi 600 kaprů.
Steps:
1. Vynásobte 2 x 300 = 600.
2. Přepočítejte: 600 / 2 = 300.
3. Uveďte asi 600 kaprů. | ecology |
16.2 km per hour; 1.5 meters times 180 steps each minute scales to hourly speed. | null | bio_0551 | worked_example | en | A runner takes 180 steps per minute with stride 1.5 m. Calculate the speed in km/h. | [
"Multiply 1.5 x 180 = 270 m per min.",
"Scale 270 x 60 = 16200 m per h.",
"Convert to 16.2 km/h.",
"Recompute: 16.2 x 1000 / 60 / 180 = 1.5."
] | biology | Answer: 16.2 km/h.
Steps:
1. Multiply 1.5 x 180 = 270 m per min.
2. Scale 270 x 60 = 16200 m per h.
3. Convert to 16.2 km/h.
4. Recompute: 16.2 x 1000 / 60 / 180 = 1.5. | physiology |
Each amino acid centers on a carbon holding an amino group, a carboxyl group, a hydrogen, and a variable R group that gives each of the 20 types its character. | null | bio_0552 | concept | en | Describe the general structure of an amino acid. | [
"Center on alpha carbon.",
"Attach amino and carboxyl.",
"Vary the R group."
] | biology | Answer: Amino acids share a frame, vary a side chain.
Steps:
1. Center on alpha carbon.
2. Attach amino and carboxyl.
3. Vary the R group. | biochemistry |
Pumping ions unequally across the membrane leaves cells negative inside, a charged battery that nerves discharge to fire signals. | null | bio_0553 | concept | en | Explain how cells maintain a membrane potential. | [
"Pump ions unevenly.",
"Charge inside negative.",
"Fire signals by discharge."
] | biology | Answer: Cells idle as charged batteries.
Steps:
1. Pump ions unevenly.
2. Charge inside negative.
3. Fire signals by discharge. | cell_biology |
Penetrance is the share of carriers showing a trait at all, while expressivity is how strongly it shows; one mutation can hide in some and strike others hard. | null | bio_0554 | concept | en | Distinguish penetrance from expressivity with an example. | [
"Define penetrance as share.",
"Define expressivity as strength.",
"Split one mutation, many fates."
] | biology | Answer: Genes vary in reach and force.
Steps:
1. Define penetrance as share.
2. Define expressivity as strength.
3. Split one mutation, many fates. | genetics |
Darwin tvrdil, že jedinci s výhodnými znaky přežijí a zanechají více potomků, takže se výhodné znaky šíří a druhy se mění; opíral se o pozorování z Galapág. | null | bio_0555 | concept | cs | Vysvětlete Darwinovu teorii přírodního výběru. | [
"Popište různorodost jedinců.",
"Zvýhodněte přežití nejlepších.",
"Šiřte výhodné znaky."
] | biology | Answer: Výběr šíří znaky nejlepších.
Steps:
1. Popište různorodost jedinců.
2. Zvýhodněte přežití nejlepších.
3. Šiřte výhodné znaky. | evolution |
Releasing natural enemies like ladybugs against aphids or parasitoid wasps against caterpillars controls pests without chemicals, though introduced agents can backfire. | null | bio_0556 | concept | en | Explain biological control of pests with examples. | [
"Release natural enemies.",
"Eat pests without spray.",
"Watch for backfire."
] | biology | Answer: Enemies eat pests for free.
Steps:
1. Release natural enemies.
2. Eat pests without spray.
3. Watch for backfire. | ecology |
Waves of muscle contraction squeeze food down the esophagus, working even upside down because nerves, not gravity, drive each push. | null | bio_0557 | concept | en | Explain peristalsis in the esophagus. | [
"Contract muscles in waves.",
"Squeeze food downward.",
"Beat gravity with nerves."
] | biology | Answer: Guts pump food in waves.
Steps:
1. Contract muscles in waves.
2. Squeeze food downward.
3. Beat gravity with nerves. | physiology |
Cohesion chains water molecules into unbroken columns while adhesion grips vessel walls, so transpiration from leaves pulls water up even tall trees. | null | bio_0558 | concept | en | Explain adhesion and cohesion in plant water transport. | [
"Chain water by cohesion.",
"Grip walls by adhesion.",
"Pull columns from leaves."
] | biology | Answer: Sticky chains lift tree water.
Steps:
1. Chain water by cohesion.
2. Grip walls by adhesion.
3. Pull columns from leaves. | biochemistry |
All body cells share one genome yet switch different gene sets on, so identical DNA yields nerves, blood, and bone through selective expression. | null | bio_0559 | concept | en | Explain cell differentiation from one genome. | [
"Share one genome.",
"Switch gene sets selectively.",
"Yield nerves, blood, bone."
] | biology | Answer: One genome, many switched fates.
Steps:
1. Share one genome.
2. Switch gene sets selectively.
3. Yield nerves, blood, bone. | cell_biology |
Mendel na hrachu ukázal, že alely se při tvorbě gamet rozcházejí a geny pro různé znaky se dědí nezávisle; křížení žlutých a zelených semen dalo poměr 3:1. | null | bio_0560 | concept | cs | Vysvětlete Mendelovy zákony na příkladu hrachu. | [
"Popište rozchod alel.",
"Uveďte nezávislou dědičnost.",
"Ukažte poměr 3:1."
] | biology | Answer: Hrách odhalil zákony dědičnosti.
Steps:
1. Popište rozchod alel.
2. Uveďte nezávislou dědičnost.
3. Ukažte poměr 3:1. | genetics |
(D) Mesozoic; dinosaurs ruled the Mesozoic era, between the Paleozoic and the mammal-led Cenozoic. | {
"A": "Cenozoic",
"B": "Paleozoic",
"C": "Precambrian",
"D": "Mesozoic"
} | bio_0561 | multiple_choice | en | Which era is called the age of dinosaurs? | [
"Eliminate mammal era.",
"Eliminate ancient seas.",
"Choose Mesozoic."
] | biology | Answer: (D) Dinosaurs owned the Mesozoic.
Steps:
1. Eliminate mammal era.
2. Eliminate ancient seas.
3. Choose Mesozoic.
Answer: (D) | evolution |
(B) Bee-flower; bees gain nectar while flowers gain pollination, so both partners benefit. | {
"A": "Tapeworm-human",
"B": "Bee-flower",
"C": "Tick-dog",
"D": "Flea-cat"
} | bio_0562 | multiple_choice | en | Which is an example of mutualism? | [
"Eliminate parasites.",
"Spot double benefit.",
"Choose bee-flower."
] | biology | Answer: (B) Bees and blooms trade favors.
Steps:
1. Eliminate parasites.
2. Spot double benefit.
3. Choose bee-flower.
Answer: (B) | ecology |
(A) Medulla; the brainstem medulla drives breathing and heartbeat automatically. | {
"A": "Medulla",
"B": "Cerebrum",
"C": "Cerebellum",
"D": "Thalamus"
} | bio_0563 | multiple_choice | en | Which brain part controls breathing and heartbeat? | [
"Eliminate thinking cortex.",
"Eliminate balance center.",
"Choose medulla."
] | biology | Answer: (A) The medulla runs the vitals.
Steps:
1. Eliminate thinking cortex.
2. Eliminate balance center.
3. Choose medulla.
Answer: (A) | physiology |
(D) RNA; nucleic acids store and transmit genetic information, unlike sugars, proteins, and fibers. | {
"A": "Glucose",
"B": "Hemoglobin",
"C": "Cellulose",
"D": "RNA"
} | bio_0564 | multiple_choice | en | Which molecule is a nucleic acid? | [
"Eliminate sugars.",
"Eliminate proteins and fibers.",
"Choose RNA."
] | biology | Answer: (D) RNA carries code.
Steps:
1. Eliminate sugars.
2. Eliminate proteins and fibers.
3. Choose RNA.
Answer: (D) | biochemistry |
(C) V chloroplastech; tam chlorofyl zachycuje světlo a skládá cukry. | {
"A": "V mitochondriích",
"B": "V jádře",
"C": "V chloroplastech",
"D": "V ribozomech"
} | bio_0565 | multiple_choice | cs | Kde v rostlinné buňce probíhá fotosyntéza? | [
"Vylučte dýchání a řízení.",
"Přiřaďte světlo chloroplastům.",
"Zvolte chloroplasty."
] | biology | Answer: (C) Fotosyntéza běží v chloroplastech.
Steps:
1. Vylučte dýchání a řízení.
2. Přiřaďte světlo chloroplastům.
3. Zvolte chloroplasty.
Answer: (C) | cell_biology |
(A) AA x aa; every child receives A from one parent and a from the other. | {
"A": "AA x aa",
"B": "Aa x Aa",
"C": "Aa x aa",
"D": "aa x aa"
} | bio_0566 | multiple_choice | en | Which cross always produces heterozygous offspring? | [
"Eliminate mixed squares.",
"Pair A with a only.",
"Choose AA x aa."
] | biology | Answer: (A) AA x aa yields all Aa.
Steps:
1. Eliminate mixed squares.
2. Pair A with a only.
3. Choose AA x aa.
Answer: (A) | genetics |
Carriers are 50 percent; 2pq with p and q both 0.5 gives the maximum 0.5. | null | bio_0567 | worked_example | en | Allele frequencies are p=0.5 and q=0.5 in Hardy-Weinberg equilibrium. Calculate the carrier frequency. | [
"Compute 2pq = 2 x 0.5 x 0.5.",
"Evaluate 2 x 0.25 = 0.5.",
"Convert to 50 percent.",
"Recompute: 0.25+0.25+0.5=1.0."
] | biology | Answer: 50 percent carriers.
Steps:
1. Compute 2pq = 2 x 0.5 x 0.5.
2. Evaluate 2 x 0.25 = 0.5.
3. Convert to 50 percent.
4. Recompute: 0.25+0.25+0.5=1.0. | evolution |
550 deer after one year; 10 percent growth adds 50 fawns to the herd of 500. | null | bio_0568 | worked_example | en | A deer herd of 500 grows 10 percent in a year. Calculate its size after one year. | [
"Compute 500 x 0.10 = 50.",
"Add 500 + 50 = 550.",
"Recompute: 550/500 = 1.10."
] | biology | Answer: 550 deer.
Steps:
1. Compute 500 x 0.10 = 50.
2. Add 500 + 50 = 550.
3. Recompute: 550/500 = 1.10. | ecology |
Total loss is 2.4 liters; 800 mL per hour over 3 hours sums the sweat deficit. | null | bio_0569 | worked_example | en | A hiker sweats 800 mL per hour for 3 hours. Calculate total water loss in liters. | [
"Multiply 800 x 3 = 2400 mL.",
"Convert to 2.4 L.",
"Recompute: 2.4 x 1000 / 3 = 800."
] | biology | Answer: 2.4 L lost.
Steps:
1. Multiply 800 x 3 = 2400 mL.
2. Convert to 2.4 L.
3. Recompute: 2.4 x 1000 / 3 = 800. | physiology |
45 kcal; 5 gramů tuku krát 9 kcal na gram dá energii svačiny. | null | bio_0570 | worked_example | cs | Svačina obsahuje 5 g tuku. Vypočítejte její energii v kcal (tuk 9 kcal na gram). | [
"Vynásobte 5 x 9 = 45.",
"Přepočítejte: 45 / 9 = 5.",
"Uveďte 45 kcal."
] | biology | Answer: 45 kcal.
Steps:
1. Vynásobte 5 x 9 = 45.
2. Přepočítejte: 45 / 9 = 5.
3. Uveďte 45 kcal. | biochemistry |
400 cells after 3 hours; two doublings multiply the 100 founders four-fold. | null | bio_0571 | worked_example | en | Yeast double every 90 minutes. Starting from 100 cells, how many are present after 3 hours? | [
"Convert 3 hours = 180 minutes.",
"Count doublings: 180/90 = 2.",
"Compute 100 x 2^2 = 400.",
"Recompute: 400/100 = 4 = 2^2."
] | biology | Answer: 400 cells.
Steps:
1. Convert 3 hours = 180 minutes.
2. Count doublings: 180/90 = 2.
3. Compute 100 x 2^2 = 400.
4. Recompute: 400/100 = 4 = 2^2. | cell_biology |
A karyotype arranges photographed chromosomes by size and banding, exposing extra, missing, or swapped chromosomes behind disorders like Turner syndrome. | null | bio_0572 | concept | en | Explain how karyotypes detect chromosome disorders. | [
"Photograph spread chromosomes.",
"Arrange by size and bands.",
"Spot extra or missing ones."
] | biology | Answer: Karyotypes line up chromosomes for inspection.
Steps:
1. Photograph spread chromosomes.
2. Arrange by size and bands.
3. Spot extra or missing ones. | genetics |
Where similar species overlap, selection pushes their traits apart to cut competition, so coexisting finches evolve clearly different beak sizes. | null | bio_0573 | concept | en | Explain character displacement with the finch example. | [
"Overlap similar species.",
"Compete for one resource.",
"Diverge traits apart."
] | biology | Answer: Neighbors evolve apart to share less.
Steps:
1. Overlap similar species.
2. Compete for one resource.
3. Diverge traits apart. | evolution |
Roads and fields split habitats into isolated patches that lose species, while planted corridors reconnect them so animals can migrate and breed. | null | bio_0574 | concept | en | Explain habitat fragmentation and wildlife corridors. | [
"Split habitats with roads.",
"Isolate shrinking patches.",
"Reconnect with corridors."
] | biology | Answer: Corridors heal cut-up habitats.
Steps:
1. Split habitats with roads.
2. Isolate shrinking patches.
3. Reconnect with corridors. | ecology |
Pravá polovina srdce pumpuje krev do plic pro okysličení a levá do celého těla; chlopně brání zpětnému toku. | null | bio_0575 | concept | cs | Vysvětlete, jak srdce pumpuje krev malým a velkým oběhem. | [
"Pumpujte pravou stranou do plic.",
"Pumpujte levou stranou do těla.",
"Braňte zpětnému toku chlopněmi."
] | biology | Answer: Srdce je dvojité čerpadlo s chlopněmi.
Steps:
1. Pumpujte pravou stranou do plic.
2. Pumpujte levou stranou do těla.
3. Braňte zpětnému toku chlopněmi. | physiology |
Phospholipids pair water-loving heads with water-fearing tails, so in water they self-assemble into the double-layer sheets forming all cell membranes. | null | bio_0576 | concept | en | Explain phospholipids and the membrane bilayer. | [
"Pair heads with tails.",
"Hide tails from water.",
"Sheet into bilayers."
] | biology | Answer: Phospholipids tile membranes in two.
Steps:
1. Pair heads with tails.
2. Hide tails from water.
3. Sheet into bilayers. | biochemistry |
Normal cells halt dividing once touching neighbors, a contact brake that keeps tissues orderly; cancer cells ignore it and pile into tumors. | null | bio_0577 | concept | en | Explain contact inhibition and its failure in cancer. | [
"Touch neighbors, stop dividing.",
"Keep tissues one layer.",
"Pile tumors when brakes fail."
] | biology | Answer: Crowded cells brake; cancers do not.
Steps:
1. Touch neighbors, stop dividing.
2. Keep tissues one layer.
3. Pile tumors when brakes fail. | cell_biology |
Some genes come in three or more alleles, so ABO blood offers IA, IB, and i while rabbit coats span four, though each individual carries only two. | null | bio_0578 | concept | en | Explain multiple alleles with blood group and rabbit examples. | [
"Count three-plus alleles.",
"Type blood IA, IB, i.",
"Carry two each."
] | biology | Answer: Populations hold more alleles than individuals.
Steps:
1. Count three-plus alleles.
2. Type blood IA, IB, i.
3. Carry two each. | genetics |
Some lineages barely change for hundreds of millions of years, so coelacanths and horseshoe crabs swim today nearly as their fossil ancestors did. | null | bio_0579 | concept | en | Explain evolutionary stasis in living fossils. | [
"Define near-zero change.",
"Swim coelacanths unchanged.",
"Credit stable niches."
] | biology | Answer: Living fossils outwaited change.
Steps:
1. Define near-zero change.
2. Swim coelacanths unchanged.
3. Credit stable niches. | evolution |
Voda se vypařuje z oceánů, v oblacích kondenzuje, padá jako déšť a řekami a podzemím se vrací zpět do moře. | null | bio_0580 | concept | cs | Popište koloběh vody v přírodě. | [
"Odpařte vodu z oceánů.",
"Zkondenzujte ji v oblacích.",
"Vraťte ji deštěm a řekami."
] | biology | Answer: Moře krmí oblaka, která je vracejí.
Steps:
1. Odpařte vodu z oceánů.
2. Zkondenzujte ji v oblacích.
3. Vraťte ji deštěm a řekami. | ecology |
(C) Insulin; the pancreas releases insulin to store glucose when blood sugar runs high. | {
"A": "Glucagon",
"B": "Adrenaline",
"C": "Insulin",
"D": "Thyroxine"
} | bio_0581 | multiple_choice | en | Which hormone lowers blood sugar? | [
"Eliminate sugar raisers.",
"Spot storage signal.",
"Choose insulin."
] | biology | Answer: (C) Insulin banks sugar.
Steps:
1. Eliminate sugar raisers.
2. Spot storage signal.
3. Choose insulin.
Answer: (C) | physiology |
(A) 7; neutral pH sits midway between acidic 0 and basic 14. | {
"A": "7",
"B": "1",
"C": "14",
"D": "0"
} | bio_0582 | multiple_choice | en | Which pH value is neutral? | [
"Eliminate strong acid.",
"Eliminate strong base.",
"Choose 7."
] | biology | Answer: (A) Neutral is 7.
Steps:
1. Eliminate strong acid.
2. Eliminate strong base.
3. Choose 7.
Answer: (A) | biochemistry |
(D) Lysosome; acid-filled lysosomes digest worn parts and swallowed invaders. | {
"A": "Ribosome",
"B": "Chloroplast",
"C": "Mitochondrion",
"D": "Lysosome"
} | bio_0583 | multiple_choice | en | Which organelle digests waste inside the cell? | [
"Eliminate builders.",
"Eliminate energy makers.",
"Choose lysosome."
] | biology | Answer: (D) Lysosomes digest debris.
Steps:
1. Eliminate builders.
2. Eliminate energy makers.
3. Choose lysosome.
Answer: (D) | cell_biology |
(B) 3:1; the Aa x Aa square yields three dominant-phenotype offspring for each recessive one. | {
"A": "1:1",
"B": "3:1",
"C": "9:7",
"D": "1:2:1"
} | bio_0584 | multiple_choice | en | What is the phenotype ratio of Aa x Aa with complete dominance? | [
"Build the Aa square.",
"Count 3 dominant to 1.",
"Choose 3:1."
] | biology | Answer: (B) Dominant wins three to one.
Steps:
1. Build the Aa square.
2. Count 3 dominant to 1.
3. Choose 3:1.
Answer: (B) | genetics |
(D) Darwin; přírodní výběr jako hybatele evoluce popsal roku 1859. | {
"A": "Mendel",
"B": "Linné",
"C": "Lamarck",
"D": "Darwin"
} | bio_0585 | multiple_choice | cs | Kdo popsal evoluci přírodním výběrem? | [
"Vylučte genetika a taxonomy.",
"Přiřaďte výběr Darwinovi.",
"Zvolte Darwina."
] | biology | Answer: (D) Výběr popsal Darwin.
Steps:
1. Vylučte genetika a taxonomy.
2. Přiřaďte výběr Darwinovi.
3. Zvolte Darwina.
Answer: (D) | evolution |
(A) Shark; as a meat-eating hunter it is a carnivore, unlike the grazing mammals listed. | {
"A": "Shark",
"B": "Cow",
"C": "Sheep",
"D": "Deer"
} | bio_0586 | multiple_choice | en | Which animal is a carnivore? | [
"Eliminate grazers.",
"Spot the hunter.",
"Choose shark."
] | biology | Answer: (A) Sharks hunt meat.
Steps:
1. Eliminate grazers.
2. Spot the hunter.
3. Choose shark.
Answer: (A) | ecology |
Drink 1.5 liters; food covers 1 of the 2.5 liters needed each day. | null | bio_0587 | worked_example | en | Daily water need is 2.5 L and food provides 1 L. Calculate how much water to drink. | [
"Subtract 2.5 - 1 = 1.5 L.",
"Recompute: 1.5 + 1 = 2.5.",
"Report 1.5 L."
] | biology | Answer: 1.5 L.
Steps:
1. Subtract 2.5 - 1 = 1.5 L.
2. Recompute: 1.5 + 1 = 2.5.
3. Report 1.5 L. | physiology |
29.25 grams; half a mole times 58.5 grams per mole gives the mass. | null | bio_0588 | worked_example | en | Table salt (NaCl) has molar mass 58.5 g/mol. Calculate the mass of 0.5 mol. | [
"Multiply 0.5 x 58.5 = 29.25 g.",
"Recompute: 29.25 / 58.5 = 0.5.",
"Report 29.25 g."
] | biology | Answer: 29.25 g.
Steps:
1. Multiply 0.5 x 58.5 = 29.25 g.
2. Recompute: 29.25 / 58.5 = 0.5.
3. Report 29.25 g. | biochemistry |
300 cells per mL; 30 colonies from 0.1 mL scale tenfold to a full milliliter. | null | bio_0589 | worked_example | en | A 0.1 mL sample grows 30 colonies on a plate. Estimate cells per mL in the original. | [
"Divide 30 / 0.1 = 300.",
"Recompute: 300 x 0.1 = 30.",
"Report 300 cells per mL."
] | biology | Answer: 300 cells per mL.
Steps:
1. Divide 30 / 0.1 = 300.
2. Recompute: 300 x 0.1 = 30.
3. Report 300 cells per mL. | cell_biology |
Pravděpodobnost je 1/2, tedy 50 procent; křížení Dd x dd dá Dd a dd stejně často. | null | bio_0590 | worked_example | cs | Při křížení Dd x dd vypočítejte pravděpodobnost potomka s genotypem Dd. | [
"Vypište potomky: Dd nebo dd.",
"Přiřaďte stejné šance 1/2.",
"Převeďte na 50 procent.",
"Přepočítejte: 1/2 + 1/2 = 1."
] | biology | Answer: 1/2, tedy 50 procent.
Steps:
1. Vypište potomky: Dd nebo dd.
2. Přiřaďte stejné šance 1/2.
3. Převeďte na 50 procent.
4. Přepočítejte: 1/2 + 1/2 = 1. | genetics |
The frequency rises by 0.02 per generation on average; a 0.3 gain over 15 generations gives the rate. | null | bio_0591 | worked_example | en | An allele rises in frequency from 0.3 to 0.6 over 15 generations. Calculate the average change per generation. | [
"Subtract 0.6 - 0.3 = 0.3.",
"Divide 0.3 / 15 = 0.02.",
"Recompute: 0.3 + 15 x 0.02 = 0.6."
] | biology | Answer: 0.02 per generation.
Steps:
1. Subtract 0.6 - 0.3 = 0.3.
2. Divide 0.3 / 15 = 0.02.
3. Recompute: 0.3 + 15 x 0.02 = 0.6. | evolution |
Returning wolves to Yellowstone scared elk from valleys, letting willows regrow and beavers return in a trophic cascade that rebuilt the ecosystem. | null | bio_0592 | concept | en | Explain rewilding and trophic cascades with the Yellowstone wolves. | [
"Return top predators.",
"Shift grazing prey.",
"Cascade through food web."
] | biology | Answer: Wolves rebuilt Yellowstone top-down.
Steps:
1. Return top predators.
2. Shift grazing prey.
3. Cascade through food web. | ecology |
Glomeruli squeeze water and small solutes from blood into nephron tubules, which then reabsorb useful goods and leave concentrated urine behind. | null | bio_0593 | concept | en | Explain how kidneys filter blood and form urine. | [
"Squeeze filtrate at glomeruli.",
"Reabsorb useful goods.",
"Excrete leftover urine."
] | biology | Answer: Kidneys filter wide, reclaim most.
Steps:
1. Squeeze filtrate at glomeruli.
2. Reabsorb useful goods.
3. Excrete leftover urine. | physiology |
Chaperone proteins cradle new chains and guide their folding, rescuing misshapes that would otherwise clump into useless or harmful aggregates. | null | bio_0594 | concept | en | Explain how chaperone proteins help folding. | [
"Cradle new chains.",
"Guide correct folds.",
"Rescue misshapes."
] | biology | Answer: Chaperones coach proteins into shape.
Steps:
1. Cradle new chains.
2. Guide correct folds.
3. Rescue misshapes. | biochemistry |
Buněčná membrána je dvojvrstva fosfolipidů s bílkovinami; propouští vybrané látky a drží tvar a rovnováhu buňky. | null | bio_0595 | concept | cs | Popište buněčnou membránu a její funkci. | [
"Popište dvojvrstvu s bílkovinami.",
"Vysvětlete výběrovou propustnost.",
"Uveďte držení rovnováhy."
] | biology | Answer: Membrána je výběrová hranice buňky.
Steps:
1. Popište dvojvrstvu s bílkovinami.
2. Vysvětlete výběrovou propustnost.
3. Uveďte držení rovnováhy. | cell_biology |
XX embryos default to female while a Y chromosome triggers male development, so fathers determine each child's sex by passing X or Y sperm. | null | bio_0596 | concept | en | Explain sex determination in humans. | [
"Default XX to female.",
"Trigger male with Y.",
"Pass sex via father."
] | biology | Answer: Fathers deal X or Y.
Steps:
1. Default XX to female.
2. Trigger male with Y.
3. Pass sex via father. | genetics |
Greenish warblers ring Tibet with interbreeding neighbors whose opposite ends cannot mate, showing one species splitting into two around a barrier. | null | bio_0597 | concept | en | Explain ring species with the greenish warbler. | [
"Ring a central barrier.",
"Breed neighbor to neighbor.",
"Fail mating end to end."
] | biology | Answer: Rings show speciation mid-split.
Steps:
1. Ring a central barrier.
2. Breed neighbor to neighbor.
3. Fail mating end to end. | evolution |
The ozone layer absorbs harmful ultraviolet light, but CFC chemicals thinned it into an Antarctic hole now healing under the global ban. | null | bio_0598 | concept | en | Explain the ozone layer, its hole, and recovery. | [
"Block ultraviolet with ozone.",
"Thin it with CFCs.",
"Heal it by global ban."
] | biology | Answer: The ozone shield thins, then heals.
Steps:
1. Block ultraviolet with ozone.
2. Thin it with CFCs.
3. Heal it by global ban. | ecology |
Heat triggers sweating and widened vessels that dump warmth, while cold triggers shivering and narrowed vessels that save it, holding 37 C steady. | null | bio_0599 | concept | en | Explain human thermoregulation in heat and cold. | [
"Dump heat by sweat.",
"Save heat by shiver.",
"Hold 37 C steady."
] | biology | Answer: Bodies air-condition near 37 C.
Steps:
1. Dump heat by sweat.
2. Save heat by shiver.
3. Hold 37 C steady. | physiology |
Enzymy jsou bílkovinné katalyzátory: snižují aktivační energii, urychlují reakce a samy se nespotřebují; každá reakce má svůj enzym. | null | bio_0600 | concept | cs | Vysvětlete, co jsou to enzymy a jak fungují. | [
"Definujte bílkovinné katalyzátory.",
"Snižte aktivační energii.",
"Urychlete reakce bez spotřeby."
] | biology | Answer: Enzymy zrychlují reakce bez spotřeby.
Steps:
1. Definujte bílkovinné katalyzátory.
2. Snižte aktivační energii.
3. Urychlete reakce bez spotřeby. | biochemistry |
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