2026年新课标版八年级科学开学摸底卷生命地球与物质变化标准试卷第314套（含答案解析与可打印作答区）

2026年新课标版八年级科学开学摸底卷生命地球与物质变化标准试卷第314套（含答案解析与可打印作答区）学校：________________班级：________________姓名：________________考号：________________考试时间：90分钟满分：100分题量：24题适用：开学摸底答题说明：本卷围绕生命、地球与宇宙、物质变化三个主题，考查基础概念、实验探究、数据分析和综合应用。选择题每题只有一个最佳答案；非选择题请在指定作答区内书写，过程题应写出必要依据、单位和结论。诚信提示：独立完成，书写清楚，保持卷面整洁。题型选择题填空与基础题材料实验题综合解答题分值36分20分32分12分一、选择题（本大题共12题，每题3分，共36分。每题只有一个最佳答案）题号123456789101112答案1.（3分）某同学把一株天竺葵暗处理一昼夜后，将一片叶的一部分用黑纸片遮光，另一部分见光，数小时后脱色并滴加碘液。下列说法正确的是（）A.遮光部分变蓝，说明光合作用不需要光B.见光部分变蓝，说明淀粉是光合作用的产物C.全叶都不变蓝，说明植物只进行呼吸作用D.本实验主要探究二氧化碳对光合作用的影响2.（3分）显微镜下观察洋葱表皮细胞和人的口腔上皮细胞，二者都能看到的结构是（）A.细胞壁、细胞膜、细胞核B.细胞膜、细胞质、细胞核C.叶绿体、液泡、细胞核D.细胞壁、叶绿体、线粒体3.（3分）某草地生态系统中存在“草→蝗虫→青蛙→蛇→鹰”的食物链。若短期内蛇的数量明显减少，最可能首先出现的变化是（）A.青蛙数量减少，鹰数量增加B.青蛙数量增加，鹰可能因食物减少而减少C.草数量增加，蝗虫数量减少D.各种生物数量完全不受影响4.（3分）人体运动后呼吸加快、心跳加快。对此理解正确的是（）A.只为了把更多氧气排出体外B.有利于把氧气和养料更快送到组织细胞，并带走二氧化碳等废物C.说明消化系统停止工作D.说明血液中不含二氧化碳5.（3分）在野外识别矿物时，不能只根据颜色判断种类，主要原因是（）A.矿物没有固定颜色B.同一种矿物可能含杂质而呈现不同颜色，不同矿物也可能颜色相近C.矿物颜色总是随温度快速变化D.颜色只能用于识别植物，不能用于识别矿物

6.（3分）下列现象与水循环中“蒸发—凝结—降水”过程关系最直接的是（）A.河流搬运泥沙B.海水受热形成水蒸气，水蒸气遇冷形成云，云滴增大后降落C.植物根吸收无机盐D.岩石在昼夜温差下破碎7.（3分）地震发生时，正确的避险做法是（）A.在高楼内立即乘电梯下楼B.在室内迅速躲到坚固桌旁或承重墙角，震动间隙再有序撤离C.在玻璃窗旁观察室外情况D.在山坡上靠近陡崖停留8.（3分）某地连续三天记录到气温逐渐降低、气压升高、风力增大，随后出现降雨。该天气变化最可能与（）有关。A.冷空气活动B.长期火山喷发C.月球绕地运动D.地球自转方向改变9.（3分）下列变化中，属于化学变化的是（）A.冰块熔化B.食盐溶于水C.铁钉在潮湿空气中生锈D.玻璃杯破碎10.（3分）把少量蔗糖加入水中搅拌，蔗糖逐渐看不见，但液体仍澄清透明。下列说法正确的是（）A.蔗糖消失了，不再存在B.蔗糖以微粒形式分散在水中，形成溶液C.该液体一定是悬浊液D.水的化学性质已经变成蔗糖的性质11.（3分）密闭容器中点燃镁条，反应后容器内物质总质量与反应前相比（）A.增大，因为生成了新物质B.减小，因为镁被烧掉C.不变，因为密闭条件下反应前后总质量守恒D.无法比较，因为颜色改变12.（3分）甲、乙两个实心小球体积相同，甲的质量大于乙。把它们分别放入足量水中，若二者都完全浸没，则下列判断正确的是（）A.甲的密度一定大于乙B.甲受到的浮力一定大于乙C.乙的密度一定大于甲D.二者受到的重力一定相同二、填空与基础题（本大题共5题，每题4分，共20分）13.（4分）用显微镜观察植物细胞临时装片时，应先用低倍镜找到物像，再换高倍镜观察。若物像偏在视野左上方，应将装片向________移动，使物像移到视野中央；植物细胞外侧较厚、起支持和保护作用的结构是________。________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________14.（4分）人体吸入的氧气进入肺泡后，主要通过________作用进入肺泡周围毛细血管，再随血液运输到组织细胞；组织细胞利用氧气分解有机物释放能量的过程属于________。________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________15.（4分）在生态系统中，绿色植物能制造有机物，通常属于________；细菌和真菌能把动植物遗体中的有机物分解成无机物，通常属于________。________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________16.（4分）地球表面的水在太阳辐射和重力作用下不断循环。水循环能更新淡水资源，也能通过河流径流和地下径流把物质从陆地输送到________；岩石在流水、温度变化、生物活动等作用下逐渐破碎，这种作用称为________。________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________17.（4分）判断物质变化是否属于化学变化，关键看是否有________生成。配制一定质量分数的食盐水时，若需要加快溶解，可采用搅拌、升高温度或________食盐颗粒等方法。________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________三、材料、实验与阅读题（本大题共4题，每题8分，共32分）18.（8分）某兴趣小组探究“光照强弱对水生植物光合作用速率的影响”。他们将等量金鱼藻分别放在距台灯10cm、20cm、30cm处，保持水温、植物长度、溶液体积和照射时间相同，记录5分钟内产生气泡数，结果如下。距离台灯/cm1020305分钟气泡数/个966134水温/℃252525植物长度/cm888（1）本实验的自变量是________________，用气泡数多少近似表示________________。（2）根据数据可得出的结论是：在本实验范围内，________________________________________。（3）若要提高实验可靠性，应如何改进？写出一条具体做法。________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________（4）若水温没有控制相同，可能会怎样影响实验结论？________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________19.（8分）阅读材料：校园旁有一条小河。晴天时河水较清，暴雨后河水变浑，流速增大。科学小组分别在上游林地旁、学校排水口附近、下游浅滩采集水样，观察颜色、气味和小型生物，并测得部分数据。采样点水体外观气味溶解氧/mg·L⁻¹小型水生生物种类数上游林地旁较清无明显异味8.29学校排水口附近略浑轻微异味4.13下游浅滩较清无明显异味6.56（1）从表中看，水生态状况相对较差的采样点是________________，理由是________________________。（2）暴雨后河水变浑，主要说明流水对泥沙具有________作用；长时间看，泥沙在流速变慢处可能发生________。（3）请提出一条保护校园小河生态环境的具体建议。________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________（4）仅凭一次采样能否直接断定排水口一定污染最严重？请说明理由。________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________20.（8分）某小组研究“小苏打与食醋混合后的变化”。他们把小苏打粉末加入装有食醋的锥形瓶中，立即套上气球，发现有大量气泡产生，气球鼓起；反应前后把装置整体放在天平上称量，若装置密闭良好，读数几乎不变。（1）产生气泡、气球鼓起，说明反应过程中生成了________态物质。该变化属于________变化。（2）装置整体质量几乎不变，体现的科学规律是________________________________。（3）若未套气球而直接敞口反应，天平示数可能如何变化？请解释原因。________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________（4）为证明产生的气体可能是二氧化碳，可把气体通入澄清石灰水。若观察到________，可支持判断。________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________21.（8分）某山区修路时发现三种岩石样品。甲岩石有明显层理并含贝壳化石；乙岩石晶粒粗大、质地坚硬，主要由石英、长石等矿物组成；丙岩石呈黑色，多气孔。当地坡面降雨集中，若植被破坏，容易出现滑坡和泥石流。（1）甲岩石最可能属于________岩，判断依据是____________________________。（2）丙岩石多气孔，说明其形成时可能与岩浆喷出后气体逸出有关，丙更可能属于________岩。（3）从地表过程看，降雨集中、坡度较大、植被减少会增强流水的________和搬运作用。（4）请提出一条降低山区道路旁滑坡风险的措施，并说明科学依据。________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________四、综合解答题（本大题共3题，每题4分，共12分）22.（4分）小明想判断一块小石块的密度。他用天平测得石块质量为54g，把石块放入量筒中，水面由40mL升至60mL。请计算石块密度，并判断它放入水中是沉入水底还是可能漂浮。计算可用公式：ρ＝m÷V（密度＝质量÷体积）。________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________23.（4分）学校建设“生物友好型校园”，准备在角落设置小型生态池。池中计划放入水生植物、螺、小鱼和少量底泥，并保持适当光照。请从能量来源、物质循环和生物多样性三个角度说明这样设计的科学意义。________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________24.（4分）某厨房中同时发生三种现象：①铁锅表面出现锈斑；②冰箱取出的玻璃杯外壁有小水珠；③加热糖水时水分逐渐减少，糖液变浓。请分别判断三种现象主要属于物理变化还是化学变化，并任选其中一种说明判断依据。________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________备用作答区如需补充材料题论证、综合题计算过程或修改答案，请在横线处注明题号后继续作答。________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

参考答案与解析说明：参考答案按题号逐题对应，非选择题同义表述、科学依据正确且表达清楚均可酌情给分。一、选择题题号123456789101112答案BBBBBBBACBCA1.B。暗处理可消耗叶片原有淀粉；遮光与见光形成对照，滴加碘液后见光部分变蓝，说明见光部分进行了光合作用并产生淀粉。A与现象相反，D不是本实验变量。诊断要点：本题要求把现象、变量和科学概念对应起来，答题时应先抓住题干中的控制条件，再判断选项是否与证据一致。2.B。植物细胞和动物细胞共有细胞膜、细胞质、细胞核等基本结构；细胞壁、叶绿体和明显大液泡主要见于植物细胞，口腔上皮细胞没有细胞壁。诊断要点：本题要求把现象、变量和科学概念对应起来，答题时应先抓住题干中的控制条件，再判断选项是否与证据一致。3.B。蛇减少后，蛇对青蛙的捕食压力降低，青蛙短期可能增加；鹰以蛇等为食，蛇减少可能使鹰食物不足而减少。生态系统各成分相互影响，不会完全不变。诊断要点：本题要求把现象、变量和科学概念对应起来，答题时应先抓住题干中的控制条件，再判断选项是否与证据一致。4.B。运动时细胞呼吸增强，需要更多氧气和养料，同时产生更多二氧化碳等废物；呼吸和循环加快有利于物质运输，血液中也会运输二氧化碳。诊断要点：本题要求把现象、变量和科学概念对应起来，答题时应先抓住题干中的控制条件，再判断选项是否与证据一致。5.B。矿物鉴别要综合颜色、条痕、光泽、硬度、晶形等特征。颜色容易受杂质、风化等影响，单凭颜色判断可靠性低。诊断要点：本题要求把现象、变量和科学概念对应起来，答题时应先抓住题干中的控制条件，再判断选项是否与证据一致。6.B。海水蒸发成水蒸气，水蒸气遇冷凝结成云，云滴增大后以雨雪等形式降落，正是水循环的重要环节。诊断要点：本题要求把现象、变量和科学概念对应起来，答题时应先抓住题干中的控制条件，再判断选项是否与证据一致。7.B。地震时室内应就近避险，远离玻璃和易坠物，在震动间隙有序撤离。乘电梯、靠近玻璃或陡崖都增加危险。诊断要点：本题要求把现象、变量和科学概念对应起来，答题时应先抓住题干中的控制条件，再判断选项是否与证据一致。8.A。冷空气活动常使气温下降、气压升高、风力增大，并可能带来降水；其他选项与短期天气过程关系不直接。诊断要点：本题要求把现象、变量和科学概念对应起来，答题时应先抓住题干中的控制条件，再判断选项是否与证据一致。9.C。铁生锈生成了与铁性质不同的铁锈，有新物质生成，是化学变化；熔化、溶解、破碎通常没有新物质生成。诊断要点：本题要求把现象、变量和科学概念对应起来，答题时应先抓住题干中的控制条件，再判断选项是否与证据一致。10.B。蔗糖溶于水后以微小粒子分散在水中，形成均一、稳定的溶液；蔗糖并未消失，水的化学性质也没有变成蔗糖的性质。诊断要点：本题