2026 ACT科学实验设计仿真真题集

2026ACT科学实验设计仿真真题集Passage1酶催化反应（基础难度｜2026高频生物化学实验）背景：淀粉酶可以分解淀粉。研究者探究温度对淀粉酶催化速率的影响。

实验1

准备5组试管，每组加入5mL2%淀粉溶液+1mL淀粉酶溶液，分别置于20℃、30℃、40℃、50℃、60℃水浴。

各组pH统一=6.8，反应时间统一10min。反应结束后检测剩余淀粉浓度，淀粉剩余越少=催化速率越快。

实验2

固定温度40℃，设置5组不同pH（4.0、5.2、6.8、8.1、9.3），其余条件同实验1，检测剩余淀粉浓度。Questions1–6WhatistheindependentvariableinExperiment1?

A.Remainingstarchconcentration

B.Temperatureofwaterbath

C.pHofsolution

D.ReactiontimeWhichofthefollowingwasacontrolledvariableinbothExperiment1andExperiment2?

F.Temperature

G.pH

H.Volumeofstarchsolution

J.RemainingstarchThedependentvariablemeasuredinbothexperimentswas:

A.Amylaseconcentration

B.Reactiontime

C.Remainingstarchconcentration

D.WaterbathtemperatureAnegativecontrolgroupforthisstudywouldmostlikelyincludewhichsetup?

F.Starchsolution+water(noamylase)at40℃,pH6.8

G.Starch+amylaseat0℃

H.Wateronly,nostarchoramylase

J.Amylaseonly,nostarchSupposetheresearcherswanttotestifamylaseconcentrationaffectsreactionrate.Whichfactorshouldremainconstant?

A.Amylaseconcentration

B.Massofamylaseadded

C.TemperatureandpH

D.AmountofproductformedIfat60℃thestarchremainingwasnearlyequaltothenegativecontrol,themostreasonableconclusionis:

F.60℃maximizesenzymeactivity

G.Theenzymeisdenaturedat60℃

H.HigherpHisneededat60℃

J.Starchcannotdissolveat60℃✅Passage1答案+解析

1.B自变量：人为改变的变量（温度）

2.H两组都固定：淀粉溶液体积；F/G在两组中是变量

3.C因变量：测量指标（剩余淀粉浓度）

4.F阴性对照：不含酶，其余条件一致，排除淀粉自发分解

5.C单一变量原则，温度pH保持不变

6.G和空白对照接近→酶失去活性（变性）Passage2植物蒸腾作用（中等难度｜2026生物高频）背景：植物通过叶片气孔散失水分（蒸腾）。研究者测试光照强度和风速对绿萝蒸腾速率的影响。蒸腾速率=单位时间植物散失水的质量

Study1

4株长势一致绿萝，土壤含水量相同，环境温度25℃，无风。4组光照：0lux、500lux、1000lux、2000lux，记录24h失水质量。

Study2

4株相同绿萝，固定光照1000lux、温度25℃。风速：0m/s、0.5m/s、1.0m/s、1.5m/s，记录24h失水质量。Questions7–12WhatquestionwasStudy2designedtoanswer?

A.Doestemperatureaffecttranspiration?

B.Howdoeswindspeedaffecttranspirationrate?

C.Doeslightintensityaffectstomatasize?

D.Howdoessoilwatercontentchangeover24h?WhichvariablewasheldconstantinStudy1?

F.Lightintensity

G.Windspeed

H.Massofwaterlost

J.TranspirationrateIfthescientistswanttotestthecombinedeffectoflightandwind,theyshould:

A.Varybothlightandwindatthesametime

B.Changetemperaturewhilekeepinglightandwindfixed

C.Onlychangesoilwatercontent

D.RemoveleavesfromsomeplantsWhichofthefollowingisthedependentvariableinbothstudies?

F.Lightintensity

G.Windspeed

H.Massofwaterlost

J.AirtemperatureIfhigherwindspeedincreasestranspiration,whattrendwillthedatainStudy2show?

A.Waterlossdecreasesaswindspeedincreases

B.Waterlossincreasesaswindspeedincreases

C.Waterlossstaysthesame

D.WaterlossfirstrisesthenfallswithnorelationtowindAconfoundingvariablethatcouldbiastheresultswouldbe:

F.Sameplantspecies

G.Differentinitialleafareaamong4plants

H.Constantroomtemperature

J.Identicalsoilmoisture✅Passage2答案+解析

7.BStudy2唯一变量是风速，探究风速和蒸腾关系

8.GStudy1固定无风（风速不变），光照是变量

9.A联合效应实验，同时改变两个自变量

10.H两组测量指标都是失水量

11.B风速越大蒸腾越强，失水更多

12.G叶片总面积不同会干扰结果，属于混杂变量Passage3金属腐蚀速率（中等偏难｜2026化学材料类热门）背景：金属在含盐水中更容易生锈。实验探究NaCl浓度和pH对铁腐蚀速率的影响。腐蚀速率通过72h后铁片质量损失衡量。

ExpA

5个烧杯，放入相同铁片，20℃，pH=7，NaCl浓度：0g/L,2g/L,4g/L,6g/L,8g/L。72h后称重计算质量损失。

ExpB

5个烧杯，相同铁片，20℃，NaCl固定4g/L，pH分别为3,5,7,9,11，同样测72h质量损失。Questions13–18InExpA,whatistheindependentvariable?

A.Masslossofiron

B.NaClconcentration

C.pHvalue

D.DurationofthetestWhichconditionservedascontrolinExpA?

F.0g/LNaCl

G.pH=3

H.8g/LNaCl

J.72hoursIfExpBfindsmasslosshighestatpH=3,thissuggests:

A.Alkalinesolutionacceleratescorrosion

B.Acidicsolutionacceleratescorrosion

C.NaClhasnoeffectonrusting

D.HigherpHincreasesmasslossWhatmustbeidenticalforallironsamples?

F.Initialmassandsurfacearea

G.NaClconcentration

H.pH

J.FinalmasslossResearchersaddanExpCtotesttemperatureeffect.Whichsettingiscorrect?

A.Varytemperature;keepNaCl=4g/L,pH=7

B.VarytemperatureandpHtogether

C.ChangeNaClwhiletemperaturechanges

D.UsedifferentmetalsheetsSupposeatNaCl=8g/L,masslossnolongerincreases.Thebestexplanationis:

F.Highersaltfullystopscorrosion

G.Otherfactorslimitcorrosionrate

H.Theironsampleisheavier

J.pHautomaticallyrises✅Passage3答案+解析

13.BExpA人为改变NaCl浓度

14.F0g/L盐（纯水组）空白对照

15.BpH=3酸性条件腐蚀最严重

16.F铁片初始质量、表面积必须统一，否则无法对比

17.A单一变量原则，仅改变温度，其余固定

18.G盐浓度饱和后，不再是限制因素，速率不再上升Passage4小球沉降速率（难题｜物理实验，2026常考多实验对比）背景：小球在黏性液体中下沉，沉降速率受液体黏度、小球直径影响。

Trial1

液体A（黏度高），4种不同直径塑料小球，测量沉降时间（越长=速率越慢）

Trial2

液体B（黏度低），使用和Trial1完全相同4组小球直径，测量沉降时间Questions19–24WhatwasthepurposeofTrial2?

A.Totesthowliquidviscosityaffectssettlingrate

B.Totesthowballmasschangeswithdiameter

C.TomeasuretemperatureofLiquidA

D.TochangethematerialofballsWhichvariablewaskeptthesamebetweenTrial1andTrial2?

F.Liquidviscosity

G.Balldiameters

H.Settlingtime

J.LiquidtypeIfLiquidBhaslowerviscosity,forthesameballdiameterweexpect:

A.LongersettlingtimeinB

B.ShortersettlingtimeinB

C.Identicalsettlingtime

D.SettlingtimeunrelatedtoliquidWhatisthedependentvariableforbothtrials?

F.Balldiameter

G.Liquidviscosity

H.Settlingtime

J.LiquidvolumeIfanewtrialusesLiquidAbutmetalballs(densityhigherthanplastic),thiswouldtest:

A.Effectofballdensityonsettlingrate

B.Effectofliquidviscosity

C.Effectofballdiameter

D.EffectoftemperatureWhichmodificationwouldbestimprovethereliabilityofdata?

F.Repeateac