---
title: "AP Biology Scientific Investigation FRQ Practice"
description: "145 Scientific Investigation questions written in the AP format, each scored part by part."
canonical: "https://fiveable.me/ap-bio/frqs/scientific-investigation"
type: "frq-type-practice"
subject: "AP Biology"
---

# AP Biology Scientific Investigation FRQ Practice

## What the Scientific Investigation FRQ asks

This is FRQ 3 on the AP Biology exam. You get a research scenario and answer four parts about the experiment: the biology behind it, its procedures, a null hypothesis or prediction, and the reasoning for that prediction.

- **10 min**: suggested writing time
- **4 points**: 1 point for each part
- **50%**: of your score, for all six FRQs

| Part | What it asks | Points |
| --- | --- | --- |
| A: Biology concept | Describe the biology behind the investigation | 1 |
| B: Procedure | Identify or justify a part of the experimental design | 1 |
| C: Hypothesis | State a null hypothesis or predict a result | 1 |
| D: Justification | Justify the prediction with biological reasoning | 1 |

## How Scientific Investigation FRQ practice works

1. **Read the full question.** The scenario and all four parts, A through D, laid out the way the exam shows them.
2. **Write on a 10-minute timer.** The time to plan for on exam day. Pause it or turn it off, and your response saves as you go.
3. **Submit for a score out of 4.** Your response is scored against the scoring guidelines written for that question. Your first score is included.

## All 145 questions

### Unit 1: Chemistry of Life (12)
- [DNA thermal stability across bacterial species](/ap-bio/frq-practice?id=6983ee68ebf1103b6c5281e3&type=frq-3-scientific-investigation-short)
- [Bacterial membrane adaptation to temperature stress](/ap-bio/frq-practice?id=6983ef09ebf1103b6c5281e9&type=frq-3-scientific-investigation-short)
- [Enzyme temperature effects on catalytic activity](/ap-bio/frq-practice?id=6983f12debf1103b6c528200&type=frq-3-scientific-investigation-short)
- [pH effects on myoglobin protein stability](/ap-bio/frq-practice?id=6983f1a8ebf1103b6c528204&type=frq-3-scientific-investigation-short)
- [Protein misfolding and pharmacological stabilization of CFTR](/ap-bio/frq-practice?id=6983f43febf1103b6c52821e&type=frq-3-scientific-investigation-short)
- [DNA thermal stability and base composition relationship](/ap-bio/frq-practice?id=6983f5aeebf1103b6c528232&type=frq-3-scientific-investigation-short)
- [DNA thermal stability and guanine-cytosine base pair composition](/ap-bio/frq-practice?id=6983f8bbebf1103b6c528259&type=frq-3-scientific-investigation-short)
- [Evaporative cooling effectiveness of polar versus nonpolar liquids](/ap-bio/frq-practice?id=6ab29e88ef7fbc2d27b7d71b&type=frq-3-scientific-investigation-short)
- [Amino acid polarity and protein solubility mutations](/ap-bio/frq-practice?id=6ab29ebdef7fbc2d27b7d73d&type=frq-3-scientific-investigation-short)
- [Water transport through xylem and hydrogen bonding](/ap-bio/frq-practice?id=6ab29efaef7fbc2d27b7d768&type=frq-3-scientific-investigation-short)
- [Antifreeze protein structure and freezing point depression](/ap-bio/frq-practice?id=6ab29f7fef7fbc2d27b7d7ad&type=frq-3-scientific-investigation-short)
- [Protein Z disulfide bond mutation immune cell signaling](/ap-bio/frq-practice?id=6ab29ffbef7fbc2d27b7d7f8&type=frq-3-scientific-investigation-short)

### Unit 2: Cells (17)
- [Osmotic water movement and contractile vacuole function](/ap-bio/frq-practice?id=69751f5439cb567763bc69db&type=frq-3-scientific-investigation-short)
- [Nitrate transport mechanisms in plant root cells](/ap-bio/frq-practice?id=6983eeb9ebf1103b6c5281e6&type=frq-3-scientific-investigation-short)
- [Aquaporins facilitate water transport across membranes](/ap-bio/frq-practice?id=6983ef4bebf1103b6c5281ec&type=frq-3-scientific-investigation-short)
- [Temperature effects on membrane permeability](/ap-bio/frq-practice?id=6983ef94ebf1103b6c5281ef&type=frq-3-scientific-investigation-short)
- [Temperature effects on membrane permeability and pigment leakage](/ap-bio/frq-practice?id=6983f016ebf1103b6c5281f4&type=frq-3-scientific-investigation-short)
- [Aquaporin-1 protein function and water transport](/ap-bio/frq-practice?id=6983f052ebf1103b6c5281f8&type=frq-3-scientific-investigation-short)
- [Water transport across phospholipid bilayer membranes](/ap-bio/frq-practice?id=6983f16eebf1103b6c528202&type=frq-3-scientific-investigation-short)
- [Aquaporin function and water transport regulation](/ap-bio/frq-practice?id=6983f251ebf1103b6c52820a&type=frq-3-scientific-investigation-short)
- [Bacterial membrane fatty acid composition across temperatures](/ap-bio/frq-practice?id=6983f2d6ebf1103b6c528211&type=frq-3-scientific-investigation-short)
- [Amino acid transport mechanisms across cell membranes](/ap-bio/frq-practice?id=6983f402ebf1103b6c52821b&type=frq-3-scientific-investigation-short)
- [Glucose transport mechanisms in intestinal epithelial cells](/ap-bio/frq-practice?id=6983f433ebf1103b6c52821d&type=frq-3-scientific-investigation-short)
- [Water transport across phospholipid membrane barriers](/ap-bio/frq-practice?id=6983f46cebf1103b6c528222&type=frq-3-scientific-investigation-short)
- [Aquaporin protein function and membrane transport](/ap-bio/frq-practice?id=6983f4abebf1103b6c528227&type=frq-3-scientific-investigation-short)
- [Potassium ion uptake mechanisms in root hair cells](/ap-bio/frq-practice?id=6983f51debf1103b6c52822c&type=frq-3-scientific-investigation-short)
- [Mercury ion effects on aquaporin water transport function](/ap-bio/frq-practice?id=6983f687ebf1103b6c52823d&type=frq-3-scientific-investigation-short)
- [Aquaporin protein function and mercury inhibition effects](/ap-bio/frq-practice?id=6983f6c0ebf1103b6c528240&type=frq-3-scientific-investigation-short)
- [Golgi complex protein processing and secretion](/ap-bio/frq-practice?id=69cffca59fa66019785a959e&type=frq-3-scientific-investigation-short)

### Unit 3: Cellular Energetics (27)
- [Light-dependent photosynthesis reactions and oxygen production](/ap-bio/frq-practice?id=69751f2739cb567763bc69d7&type=frq-3-scientific-investigation-short)
- [Amino acid interactions, tertiary structure, enzyme catalysis](/ap-bio/frq-practice?id=697593bc2649156a48dc1e00&type=frq-3-scientific-investigation-short)
- [Enzyme temperature adaptation and protein structure functionality](/ap-bio/frq-practice?id=6983efdaebf1103b6c5281f1&type=frq-3-scientific-investigation-short)
- [Nitrate uptake mechanism in plant root cells](/ap-bio/frq-practice?id=6983f2dfebf1103b6c528212&type=frq-3-scientific-investigation-short)
- [Enzyme activity and pH effects on protein structure](/ap-bio/frq-practice?id=6983f311ebf1103b6c528213&type=frq-3-scientific-investigation-short)
- [Enzyme temperature effects on starch hydrolysis](/ap-bio/frq-practice?id=6983f3a7ebf1103b6c528217&type=frq-3-scientific-investigation-short)
- [Enzyme activity and pH effects on protein digestion](/ap-bio/frq-practice?id=6983f481ebf1103b6c528224&type=frq-3-scientific-investigation-short)
- [Contractile vacuole function and osmotic water regulation](/ap-bio/frq-practice?id=6983f4e4ebf1103b6c528228&type=frq-3-scientific-investigation-short)
- [Mitochondrial respiration disruption by chemical uncouplers](/ap-bio/frq-practice?id=6983f666ebf1103b6c52823b&type=frq-3-scientific-investigation-short)
- [Rotenone's effect on mitochondrial respiration rates](/ap-bio/frq-practice?id=6983f6a5ebf1103b6c52823f&type=frq-3-scientific-investigation-short)
- [Enzyme thermal stability across climate-adapted plant species](/ap-bio/frq-practice?id=6983f6e8ebf1103b6c528242&type=frq-3-scientific-investigation-short)
- [Enzyme structure and pH effects on peroxidase activity](/ap-bio/frq-practice?id=6983f742ebf1103b6c528245&type=frq-3-scientific-investigation-short)
- [Rotenone inhibition of mitochondrial electron transport chain](/ap-bio/frq-practice?id=6983f788ebf1103b6c52824b&type=frq-3-scientific-investigation-short)
- [Temperature effects on yeast cellular respiration rates](/ap-bio/frq-practice?id=6983f7ceebf1103b6c52824d&type=frq-3-scientific-investigation-short)
- [Enzyme catalysis and pH effects on peroxidase activity](/ap-bio/frq-practice?id=6983f817ebf1103b6c528252&type=frq-3-scientific-investigation-short)
- [Brown adipose tissue heat generation mechanisms](/ap-bio/frq-practice?id=6983f8b1ebf1103b6c528258&type=frq-3-scientific-investigation-short)
- [Enzyme inhibition effects on glycolysis reaction rates](/ap-bio/frq-practice?id=6983f92febf1103b6c52825f&type=frq-3-scientific-investigation-short)
- [Light intensity effects on photosynthetic oxygen production](/ap-bio/frq-practice?id=6983fa4eebf1103b6c52826a&type=frq-3-scientific-investigation-short)
- [Light intensity effects on photosynthetic rate](/ap-bio/frq-practice?id=6983faf5ebf1103b6c528271&type=frq-3-scientific-investigation-short)
- [Beetle toxin inhibition of bird digestive enzyme](/ap-bio/frq-practice?id=6983fb56ebf1103b6c528277&type=frq-3-scientific-investigation-short)
- [Fungicide inhibition of yeast fermentation and ATP production](/ap-bio/frq-practice?id=6983fba2ebf1103b6c52827a&type=frq-3-scientific-investigation-short)
- [Enzyme inhibition mechanisms and activation energy effects](/ap-bio/frq-practice?id=6983fcf9ebf1103b6c528286&type=frq-3-scientific-investigation-short)
- [Fungicide effects on aerobic cellular respiration rates](/ap-bio/frq-practice?id=6983fdd1ebf1103b6c528290&type=frq-3-scientific-investigation-short)
- [Yeast fermentation and anaerobic glucose metabolism](/ap-bio/frq-practice?id=6983febeebf1103b6c528296&type=frq-3-scientific-investigation-short)
- [Carbohydrate substrate effects on yeast fermentation rates](/ap-bio/frq-practice?id=6983ff01ebf1103b6c52829a&type=frq-3-scientific-investigation-short)
- [Herbicide effectiveness on photosynthetic electron transport chain](/ap-bio/frq-practice?id=69cffb3636501e32bda0a02b&type=frq-3-scientific-investigation-short)
- [Glucose availability effects on lactic acid fermentation](/ap-bio/frq-practice?id=69cffc077dd82dadf8c9e37b&type=frq-3-scientific-investigation-short)

### Unit 4: Cell Communication and Cell Cycle (17)
- [Ligand receptor binding and cell division signaling](/ap-bio/frq-practice?id=6975a9d04af6063408f963d8&type=frq-3-scientific-investigation-short)
- [BCR-ABL fusion protein and targeted kinase inhibition](/ap-bio/frq-practice?id=6983f672ebf1103b6c52823c&type=frq-3-scientific-investigation-short)
- [p53 tumor suppression and DNA damage response](/ap-bio/frq-practice?id=6983f6c0ebf1103b6c528241&type=frq-3-scientific-investigation-short)
- [EGF signaling pathway and cell cycle regulation](/ap-bio/frq-practice?id=6983f762ebf1103b6c528249&type=frq-3-scientific-investigation-short)
- [KRAS mutation, signal transduction, cell division inhibition](/ap-bio/frq-practice?id=6983f88febf1103b6c528257&type=frq-3-scientific-investigation-short)
- [Cell cycle regulation, DNA damage response, p53 function](/ap-bio/frq-practice?id=6983f96eebf1103b6c528262&type=frq-3-scientific-investigation-short)
- [Cell cycle regulation via membrane receptor signaling](/ap-bio/frq-practice?id=6983fa05ebf1103b6c528266&type=frq-3-scientific-investigation-short)
- [Bacterial quorum sensing and bioluminescence regulation](/ap-bio/frq-practice?id=6983fa80ebf1103b6c52826e&type=frq-3-scientific-investigation-short)
- [Bacterial quorum sensing and competitive inhibitor mechanisms](/ap-bio/frq-practice?id=6983fb49ebf1103b6c528275&type=frq-3-scientific-investigation-short)
- [Cancer drug targeting cell cycle checkpoint regulation](/ap-bio/frq-practice?id=6983fb8bebf1103b6c528278&type=frq-3-scientific-investigation-short)
- [Growth factor signaling and cell cycle checkpoint regulation](/ap-bio/frq-practice?id=6983fd97ebf1103b6c52828d&type=frq-3-scientific-investigation-short)
- [Cell cycle regulation and density-dependent inhibition mechanisms](/ap-bio/frq-practice?id=6984008eebf1103b6c5282a2&type=frq-3-scientific-investigation-short)
- [Quorum sensing and bacterial virulence factor regulation](/ap-bio/frq-practice?id=69840111ebf1103b6c5282a4&type=frq-3-scientific-investigation-short)
- [Signal transduction, second messengers, cAMP degradation](/ap-bio/frq-practice?id=6ab29e8bef7fbc2d27b7d71d&type=frq-3-scientific-investigation-short)
- [Cyclin B degradation and cell cycle checkpoint regulation](/ap-bio/frq-practice?id=6ab29f19ef7fbc2d27b7d779&type=frq-3-scientific-investigation-short)
- [Signal transduction pathway negative feedback regulation](/ap-bio/frq-practice?id=6ab29f91ef7fbc2d27b7d7c0&type=frq-3-scientific-investigation-short)
- [Mitotic spindle regulation and cancer cell cycle arrest](/ap-bio/frq-practice?id=6ab2a008ef7fbc2d27b7d803&type=frq-3-scientific-investigation-short)

### Unit 5: Heredity (13)
- [Genotype, environment, phenotype interactions](/ap-bio/frq-practice?id=6975a5a7b95e1995e5360618&type=frq-3-scientific-investigation-short)
- [Temperature-dependent sex determination in reptiles](/ap-bio/frq-practice?id=6983f867ebf1103b6c528253&type=frq-3-scientific-investigation-short)
- [Linked genes, crossing over, temperature effects](/ap-bio/frq-practice?id=6983fa3febf1103b6c528269&type=frq-3-scientific-investigation-short)
- [Temperature-dependent sex determination in sea turtles](/ap-bio/frq-practice?id=6983fc55ebf1103b6c528280&type=frq-3-scientific-investigation-short)
- [Linked genes, recombination frequency, temperature effects](/ap-bio/frq-practice?id=6983fe4eebf1103b6c528294&type=frq-3-scientific-investigation-short)
- [Linked genes, recombination frequency, maternal age effects](/ap-bio/frq-practice?id=6983fed8ebf1103b6c528298&type=frq-3-scientific-investigation-short)
- [Paclitaxel effects on meiosis and aneuploidy formation](/ap-bio/frq-practice?id=69840123ebf1103b6c5282a5&type=frq-3-scientific-investigation-short)
- [Phenotypic plasticity in genetically identical organisms](/ap-bio/frq-practice?id=69840281ebf1103b6c5282a9&type=frq-3-scientific-investigation-short)
- [Temperature-dependent sex determination in alligator embryos](/ap-bio/frq-practice?id=698402daebf1103b6c5282aa&type=frq-3-scientific-investigation-short)
- [Soil pH, aluminum availability, flower color phenotype](/ap-bio/frq-practice?id=6ab29e54ef7fbc2d27b7d6fd&type=frq-3-scientific-investigation-short)
- [Reciprocal crosses, chloroplast versus nuclear inheritance](/ap-bio/frq-practice?id=6ab29e9cef7fbc2d27b7d72a&type=frq-3-scientific-investigation-short)
- [Gamete viability, independent assortment, and test cross analysis](/ap-bio/frq-practice?id=6ab29ef8ef7fbc2d27b7d765&type=frq-3-scientific-investigation-short)
- [Genetic recombination through crossing over and meiosis](/ap-bio/frq-practice?id=6ab29f91ef7fbc2d27b7d7c2&type=frq-3-scientific-investigation-short)

### Unit 6: Gene Expression and Regulation (16)
- [Transcription factor binding and gene expression regulation](/ap-bio/frq-practice?id=69751f5f39cb567763bc69dc&type=frq-3-scientific-investigation-short)
- [Bacterial toxin gene regulation by iron availability](/ap-bio/frq-practice?id=6983f743ebf1103b6c528246&type=frq-3-scientific-investigation-short)
- [Heat shock protein gene regulation and temperature response](/ap-bio/frq-practice?id=6983f79bebf1103b6c52824c&type=frq-3-scientific-investigation-short)
- [Heat shock protein expression regulation under stress](/ap-bio/frq-practice?id=6983f7deebf1103b6c52824f&type=frq-3-scientific-investigation-short)
- [Iron-dependent translational regulation of ferritin](/ap-bio/frq-practice?id=6983fa75ebf1103b6c52826d&type=frq-3-scientific-investigation-short)
- [Galactose metabolism regulation in yeast cells](/ap-bio/frq-practice?id=6983fab8ebf1103b6c52826f&type=frq-3-scientific-investigation-short)
- [Heat shock protein expression under thermal stress](/ap-bio/frq-practice?id=6983fafcebf1103b6c528272&type=frq-3-scientific-investigation-short)
- [Gene regulation through transcription factors and thermal stress response](/ap-bio/frq-practice?id=6983fbd1ebf1103b6c52827c&type=frq-3-scientific-investigation-short)
- [Gene regulation through transcription factor binding](/ap-bio/frq-practice?id=6983fc67ebf1103b6c528282&type=frq-3-scientific-investigation-short)
- [Bacterial iron homeostasis and gene regulation](/ap-bio/frq-practice?id=6983fdd5ebf1103b6c528291&type=frq-3-scientific-investigation-short)
- [Bacterial bioluminescence regulation through quorum sensing](/ap-bio/frq-practice?id=6983ff32ebf1103b6c52829c&type=frq-3-scientific-investigation-short)
- [Epigenetic modifications and maternal diet effects on gene expression](/ap-bio/frq-practice?id=6983ffd3ebf1103b6c52829e&type=frq-3-scientific-investigation-short)
- [Heat shock protein operon negative regulation](/ap-bio/frq-practice?id=69840017ebf1103b6c52829f&type=frq-3-scientific-investigation-short)
- [Cyclin D regulation and cancer cell cycle control](/ap-bio/frq-practice?id=6984006cebf1103b6c5282a1&type=frq-3-scientific-investigation-short)
- [Glutamate-dependent gene regulation in bacteria](/ap-bio/frq-practice?id=69840170ebf1103b6c5282a6&type=frq-3-scientific-investigation-short)
- [MicroRNA regulation of developmental gene expression](/ap-bio/frq-practice?id=6ab2a037ef7fbc2d27b7d81b&type=frq-3-scientific-investigation-short)

### Unit 7: Natural Selection (22)
- [Genetic variation, natural selection, triclosan resistance](/ap-bio/frq-practice?id=69751f6839cb567763bc69de&type=frq-3-scientific-investigation-short)
- [Sexual selection and predation on guppy coloration](/ap-bio/frq-practice?id=6983f8bdebf1103b6c52825a&type=frq-3-scientific-investigation-short)
- [Predator-driven selection on coat color phenotypes](/ap-bio/frq-practice?id=6983f907ebf1103b6c52825d&type=frq-3-scientific-investigation-short)
- [Predation pressure and sexual selection on guppy coloration](/ap-bio/frq-practice?id=6983f95cebf1103b6c528261&type=frq-3-scientific-investigation-short)
- [Copper tolerance evolution in yellow monkeyflower populations](/ap-bio/frq-practice?id=6983f9f3ebf1103b6c528265&type=frq-3-scientific-investigation-short)
- [Copper tolerance evolution in plant populations](/ap-bio/frq-practice?id=6983fa28ebf1103b6c528268&type=frq-3-scientific-investigation-short)
- [Copper tolerance evolution in monkeyflower populations](/ap-bio/frq-practice?id=6983fa6bebf1103b6c52826c&type=frq-3-scientific-investigation-short)
- [Evolutionary adaptation to copper contamination](/ap-bio/frq-practice?id=6983fb0eebf1103b6c528273&type=frq-3-scientific-investigation-short)
- [Sexual selection versus predation pressure on guppy coloration](/ap-bio/frq-practice?id=6983fb50ebf1103b6c528276&type=frq-3-scientific-investigation-short)
- [Copper tolerance adaptation through natural selection](/ap-bio/frq-practice?id=6983fb91ebf1103b6c528279&type=frq-3-scientific-investigation-short)
- [Fur color evolution through natural selection in mice](/ap-bio/frq-practice?id=6983fbd5ebf1103b6c52827d&type=frq-3-scientific-investigation-short)
- [Adaptive evolution and copper tolerance in plant populations](/ap-bio/frq-practice?id=6983fc1febf1103b6c52827e&type=frq-3-scientific-investigation-short)
- [Camouflage, predation, phenotypic variation in populations](/ap-bio/frq-practice?id=6983fc6aebf1103b6c528283&type=frq-3-scientific-investigation-short)
- [Predation-driven coat color evolution in mouse populations](/ap-bio/frq-practice?id=6983fcacebf1103b6c528284&type=frq-3-scientific-investigation-short)
- [Predation, sexual selection, guppy coloration evolution](/ap-bio/frq-practice?id=6983fd04ebf1103b6c528287&type=frq-3-scientific-investigation-short)
- [Pyrethroid resistance evolution in agricultural pest populations](/ap-bio/frq-practice?id=6983fd54ebf1103b6c52828b&type=frq-3-scientific-investigation-short)
- [Armor reduction evolution in stickleback fish populations](/ap-bio/frq-practice?id=6983fd95ebf1103b6c52828c&type=frq-3-scientific-investigation-short)
- [Predation pressure and sexual selection on guppy coloration](/ap-bio/frq-practice?id=6983fe19ebf1103b6c528293&type=frq-3-scientific-investigation-short)
- [Stickleback spine evolution under predation pressure](/ap-bio/frq-practice?id=6983feb3ebf1103b6c528295&type=frq-3-scientific-investigation-short)
- [Pesticide resistance evolution in diamondback moth populations](/ap-bio/frq-practice?id=6983fef5ebf1103b6c528299&type=frq-3-scientific-investigation-short)
- [Reproductive isolation through divergent selective pressures](/ap-bio/frq-practice?id=69cffa97b18d8b78791ab71e&type=frq-3-scientific-investigation-short)
- [Glyphosate resistance and evolutionary trade-offs in weeds](/ap-bio/frq-practice?id=69cffba288333991eee3c027&type=frq-3-scientific-investigation-short)

### Unit 8: Ecology (21)
- [Foundation species habitat complexity and biodiversity](/ap-bio/frq-practice?id=69751f6f39cb567763bc69df&type=frq-3-scientific-investigation-short)
- [Honeybee foraging behavior and pesticide exposure effects](/ap-bio/frq-practice?id=6983f8c4ebf1103b6c52825b&type=frq-3-scientific-investigation-short)
- [Salt marsh ecosystem trophic interactions and population dynamics](/ap-bio/frq-practice?id=6983f916ebf1103b6c52825e&type=frq-3-scientific-investigation-short)
- [Phenological mismatch between predators and prey](/ap-bio/frq-practice?id=6983f9d6ebf1103b6c528264&type=frq-3-scientific-investigation-short)
- [Mutualism intensity between acacia trees and ants](/ap-bio/frq-practice?id=6983fa57ebf1103b6c52826b&type=frq-3-scientific-investigation-short)
- [Invasive garlic mustard disrupting mycorrhizal symbiosis](/ap-bio/frq-practice?id=6983fae3ebf1103b6c528270&type=frq-3-scientific-investigation-short)
- [Nutrient limitation and phytoplankton growth in freshwater lakes](/ap-bio/frq-practice?id=6983fb2eebf1103b6c528274&type=frq-3-scientific-investigation-short)
- [Nutrient limitation and algal bloom impacts](/ap-bio/frq-practice?id=6983fbb7ebf1103b6c52827b&type=frq-3-scientific-investigation-short)
- [Nitrate pollution effects on Daphnia populations](/ap-bio/frq-practice?id=6983fc63ebf1103b6c528281&type=frq-3-scientific-investigation-short)
- [Energy transfer through freshwater lake trophic levels](/ap-bio/frq-practice?id=6983fcf5ebf1103b6c528285&type=frq-3-scientific-investigation-short)
- [Nitrogen fertilizer runoff and aquatic eutrophication effects](/ap-bio/frq-practice?id=6983fd31ebf1103b6c52828a&type=frq-3-scientific-investigation-short)
- [Invasive species disrupting plant-fungal mutualistic relationships](/ap-bio/frq-practice?id=6983fdb1ebf1103b6c52828e&type=frq-3-scientific-investigation-short)
- [Nutrient limitation and algal growth in freshwater ecosystems](/ap-bio/frq-practice?id=6983fde6ebf1103b6c528292&type=frq-3-scientific-investigation-short)
- [Phenotypic plasticity in nutrient-limited environments](/ap-bio/frq-practice?id=6983feceebf1103b6c528297&type=frq-3-scientific-investigation-short)
- [Nitrogen fertilizer effects on algal population growth](/ap-bio/frq-practice?id=6983ff19ebf1103b6c52829b&type=frq-3-scientific-investigation-short)
- [Nitrogen eutrophication, algal blooms, aquatic oxygen depletion](/ap-bio/frq-practice?id=6983ff58ebf1103b6c52829d&type=frq-3-scientific-investigation-short)
- [Keystone species removal and trophic cascade effects](/ap-bio/frq-practice?id=6984002cebf1103b6c5282a0&type=frq-3-scientific-investigation-short)
- [Invasive garlic mustard, mycorrhizal fungi, plant competition](/ap-bio/frq-practice?id=69840103ebf1103b6c5282a3&type=frq-3-scientific-investigation-short)
- [Carnivorous plant nutrient acquisition in nitrogen-poor environments](/ap-bio/frq-practice?id=69840193ebf1103b6c5282a7&type=frq-3-scientific-investigation-short)
- [Nitrogen eutrophication, algal growth, dissolved oxygen depletion](/ap-bio/frq-practice?id=69840229ebf1103b6c5282a8&type=frq-3-scientific-investigation-short)
- [Plant defense trade-offs and reproductive allocation](/ap-bio/frq-practice?id=69cffd0c7983a36a847f5f55&type=frq-3-scientific-investigation-short)

## Sample question

**DNA thermal stability across bacterial species**

Certain bacteria, such as *Thermus aquaticus*, thrive in high-temperature environments like hot springs, while others, such as *Escherichia coli*, inhabit moderate environments like the mammalian gut. The stability of biological macromolecules, including DNA, is critical for survival in these diverse habitats.

Scientists conducted an experiment to investigate the thermal stability of DNA from these two species. They extracted purified DNA from *T. aquaticus* and *E. coli* and suspended samples of each in a buffer solution. The scientists slowly heated the DNA samples from 25°C to 95°C while monitoring the absorbance of UV light. As the two strands of the DNA double helix separate (denature), UV absorbance increases. The temperature at which 50% of the DNA strands have separated is defined as the melting temperature (Tₘ). The scientists observed that the genomic DNA of *T. aquaticus* has a significantly higher Tₘ than the genomic DNA of *E. coli*.

Part A (1 point):
  Prompt: **Describe** the specific chemical interaction that connects the nitrogenous bases of complementary DNA strands and holds the double helix together.
  Verb: describe

Part B (1 point):
  Prompt: **Identify** one variable, other than the rate of heating, that the scientists must keep constant between the two DNA samples to ensure the validity of the results.
  Verb: identify

Part C (1 point):
  Prompt: **State** the null hypothesis for the experiment comparing the melting temperatures (Tₘ) of the DNA from the two bacterial species.
  Verb: state

Part D (1 point):
  Prompt: The scientists claim that the DNA of *T. aquaticus* contains a higher percentage of guanine-cytosine (G-C) base pairs than the DNA of *E. coli*. Based on the chemical structure of DNA, **justify** the scientists' claim.
  Verb: justify

## Questions

**How many responses can I get scored?**

You can read every question without a plan. Your first scored response is included. A plan unlocks unlimited scoring.

**How is a null hypothesis different from a prediction?**

A null hypothesis says there’s no difference or relationship between the variables. A prediction states the result you expect and its direction.

**How long should each part be?**

Two to four focused sentences usually does it. Each part is worth 1 point, so answer every part.

**How is this different from the Data Analysis FRQ?**

This question asks how an experiment is designed: its variables, controls, and predictions. The Data Analysis FRQ asks you to describe data and use it to evaluate a hypothesis.

## Related

- [Scientific Investigation FRQ exam guide](/ap-bio/ap-biology-exam/ap-bio-frq-short/study-guide/ap-bio-frq-short)
- [AP Biology Experimental Results FRQ practice](/ap-bio/frqs/experimental-results)
- [AP Biology Graphing FRQ practice](/ap-bio/frqs/graphing)
- [AP Biology Conceptual Analysis FRQ practice](/ap-bio/frqs/conceptual-analysis)
- [AP Biology Model Analysis FRQ practice](/ap-bio/frqs/model-analysis)
- [AP Biology Data Analysis FRQ practice](/ap-bio/frqs/data-analysis)
- [AP Biology FRQs](/ap-bio/frqs)
- Any question by id: the `get_frq` tool on the [Fiveable MCP server](/mcp/docs)

## About This Document

Canonical Fiveable pages are available as Markdown at the same path plus `.md`.

- [llms.txt](https://fiveable.me/llms.txt): index of Fiveable's sections and URL patterns
- [llms-full.txt](https://fiveable.me/llms-full.txt): complete subject and unit listing
- [MCP server](https://fiveable.me/mcp): call Fiveable as tools instead of fetching pages (`https://fiveable.me/api/mcp`)
- [MCP server for AP teachers](https://fiveable.me/mcp/teachers): a teacher's classes, assignments and AP-rubric grading (`https://fiveable.me/api/mcp/teacher`)