Topic 3: Infection and response
AQA · GCSE · Biology Tema 3 35:38 Narración en inglés · Subtítulos en inglés + 中文 quemados en pantalla
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Transcripción
Pathogens are microorganisms that cause infectious disease — viruses, bacteria, protists and fungi, in animals and in plants.
病原体是引起传染病的微生物——病毒、细菌、原生生物和真菌，感染动物也感染植物。
The body answers with barriers and the immune system, and medicine arms the fight with vaccines, antibiotics and tested drugs.
身体用屏障和免疫系统应战，医学用疫苗、抗生素和经过试验的药物支援。
Monoclonal antibodies and plant disease are biology only, and monoclonals are higher tier.
单克隆抗体与植物病害为仅生物内容，单抗还是高阶内容。
Learn the disease table by heart — it is exam gold.
疾病表格是考试高频考点，务必背熟。
These teacher models are examples, not scale drawings.
这些教师模型仅为示例，并非按比例绘制。
Virus shape and genetic material vary; the fungus model illustrates spore-bearing structures.
病毒的形状与遗传物质可以不同。 真菌模型展示产孢结构。
The mosquito transmits the malarial protist; it is not the pathogen.
蚊子传播疟原虫，本身不是病原体。
A disease is not the name of a pathogen category.
疾病名称不是病原体类别。
A vector carries the cause between hosts.
媒介在宿主之间携带病原体。
This distinction answers the original 2023 vector question.
这个区别对应2023年原题。
Answer before the next frame.
先回答再看下一页。
The original vector question asks for a term, not a named example.
原题要求术语，而不是具体例子。
Do not replace protist with mosquito when the question asks for pathogen type.
询问病原体类别时，不要用蚊子代替原生生物。
Controls must fit the route.
控制措施应对应传播途径。
A generic list of hygiene measures does not explain every named disease.
泛泛列出卫生措施不能解释所有指定疾病。
Answer three separate one-mark parts: the pathogen type, one way measles spreads, and one symptom other than pain.
分开回答三个一分小题：病原体类型、麻疹的一种传播方式，以及疼痛以外的一种症状。
Measles is caused by a virus.
麻疹由病毒引起。
It spreads when droplets from coughs and sneezes are inhaled; just saying 'direct contact' is not enough.
它通过咳嗽和打喷嚏产生的飞沫被吸入而传播；只说“直接接触”是不够的。
The symptoms are fever and a red skin rash, and serious complications can be fatal.
症状是发烧和皮肤红疹，严重的并发症可能致命。
Vaccination reduces how many people can catch it, and so reduces its spread.
接种疫苗减少易感人数，从而减少传播。
How vaccines work comes in the immunity section.
疫苗的作用机制见免疫部分。
These are all viral but have different hosts, routes and effects.
三者都由病毒引起，但宿主、传播与影响不同。
Antiretroviral treatment controls HIV; it is not an antibiotic treatment.
抗逆转录病毒药物控制HIV，不是抗生素治疗。
HIV infection and AIDS are not interchangeable labels for every stage.
HIV感染与艾滋病并非每个阶段都可互换。
Do not suggest casual contact is the specified route.
不要把日常接触当作指定传播途径。
The disease name alone does not explain its effect. Build the full cause-to-growth chain.
仅写疾病名称不能解释影响，需要完整因果链。
Glucose supplies respiratory substrate and building material.
葡萄糖既是呼吸底物也是合成材料。
Calling it only food energy leaves the growth explanation incomplete.
只说食物能量会使生长解释不完整。
Both are bacterial. Different transmission routes need different prevention.
两者都是细菌病，但传播不同，预防也不同。
Penicillin resistance means a treatment may fail, not that the organism became a virus.
青霉素耐药不表示细菌变成病毒。
Only one mark, but it asks for a mechanism: say what the bacteria do in the body to cause these symptoms.
只有一分，但考的是机制：说明细菌在体内做了什么才引起这些症状。
This explanation is separate from food transmission and from vaccination control.
该解释与食物传播、疫苗控制应区分。
Explain how Salmonella is spread, and how the UK controls it, for four marks.
解释沙门氏菌如何传播，以及英国如何控制它，共四分。
Explain transmission in contaminated food, and how vaccinating poultry reduces human exposure.
说明通过受污染食物传播的途径，以及给家禽接种疫苗如何减少人的接触。
Symptoms do not answer a question about spread and control.
症状不能回答关于传播与控制的问题。
Pause and try it.
暂停并试着回答。
People ingest the bacteria in contaminated food, and poor food hygiene lets the contamination reach the food.
人通过受污染的食物摄入细菌，食品卫生差会使污染进入食物。
In the UK, poultry are vaccinated against Salmonella.
在英国，家禽接种了沙门氏菌疫苗。
Fewer infected animals means fewer bacteria in food, and less human exposure.
受感染的动物减少，食物中的细菌就减少，人接触细菌的机会也减少。
A longer question may add the immune mechanism: specific antibodies and a rapid secondary response, from the immunity section.
更长的题目可能还要求免疫机制：特异性抗体和快速的二次应答，见免疫部分。
Use natural selection, not the idea that bacteria consciously learn resistance.
使用自然选择解释，不要说细菌主动学会耐药。
The population changes over generations.
群体在多代间改变。
The antibiotic selects existing variation; it does not make a useful mutation because bacteria need it.
抗生素筛选已有变异，并非按需要创造有用突变。
Fungicide is not an antibiotic answer for every disease.
杀真菌剂不是所有疾病的抗生素答案。
Destroying infected leaves reduces a source of spores.
销毁感染叶片可减少孢子来源。
Use the original two-mark recall first, then explain the mechanism as a separate teacher extension.
先回答原练习两分回忆题，再独立解释教师拓展机制。
Nets act on contact with the vector; they are not a vaccine or a drug killing protists inside the body.
蚊帐降低媒介接触，不是疫苗，也不是杀死体内疟原虫的药物。
The next two tables complete all seven answers rather than solving only three examples.
接下来两张表给出全部七种疾病，而不是仅解决三个示例。
Match control to route and symptoms to disease.
控制应对应传播，症状应对应疾病。
Do not confuse HIV with late-stage AIDS or penicillin resistance with all antibiotics failing.
区分HIV与晚期艾滋病，青霉素耐药不等于所有抗生素都无效。
Reduced photosynthesis links both named plant diseases to growth.
两种指定植物病都通过减少光合作用影响生长。
In malaria the organism that spreads disease is different from the pathogen.
疟疾媒介与病原体是不同生物。
Non-specific barriers act against many pathogens.
非特异性屏障对多种病原体起作用。
Cilia move mucus towards the throat for swallowing; they do not make antibodies.
纤毛将黏液移向咽部以便吞咽，并不制造抗体。
Give a linked mechanism rather than only naming cilia.
给出连贯机制，不要只写纤毛名称。
Stomach acid acts on swallowed material; it is not secreted into the airways.
胃酸作用于吞下的物质，并不分泌到气道内。
These are different actions.
这些作用不同。
Antibodies do not physically engulf pathogens, and antitoxins are not antibiotics.
抗体不通过吞噬病原体起作用，抗毒素也不是抗生素。
Pause before checking.
先暂停回答。
Specificity explains why the correct antibodies matter.
特异性解释了正确抗体的重要性。
Antigen and antibody are not the same thing: the antibody recognises the antigen.
抗原与抗体不同：抗体识别抗原。
Vaccination stimulates specific antibodies and leaves memory cells.
接种刺激特异性抗体并留下记忆细胞。
On later encounter with the same antigen, the response is faster.
再次遇到同一抗原时反应更快。
The dashed arrow shows memory contributing to the response, not a measured rate.
虚线表示记忆参与应答，而不是测量得到的速率。
Use the syllabus model of dead or inactive pathogen. Not every real-world vaccine is made by that method.
使用大纲中的死或灭活病原体模型；并非现实中每种疫苗都用该方法制成。
Vaccination reduces risk; do not promise that every vaccinated person can never become infected.
接种降低风险，但不能保证每个接种者永不感染。
The original data on the next frames demonstrates this limit.
后面的原题数据展示这一限制。
Give the transmission mechanism rather than the term herd immunity alone.
解释传播机制，不要仅写群体免疫。
Population protection reduces transmission opportunities; it does not guarantee zero infection.
群体保护减少传播机会，并不保证零感染。
Read the key: white is vaccinated, grey is unvaccinated.
读取图例：白色表示接种，灰色表示未接种。
Each bar is a percentage of the full surveyed sample; the four bars total one hundred percent. This is not the percentage within each vaccination group.
每柱表示整个调查样本的百分比，四柱相加为百分之百，而不是各接种组内部的百分比。
Do not use the vaccinated severe bar or treat 45 percent as a percentage only of unvaccinated children.
不要误读接种组重症柱，也不要把45%当作未接种组内的比例。
From the graph, forty-five percent of the surveyed children were unvaccinated with severe illness, and two hundred and forty children were surveyed.
从图中读出，被调查儿童中有百分之四十五是未接种且病情严重的，共调查了二百四十名儿童。
The number equals the percentage over one hundred, times the total.
人数等于百分比除以一百，再乘以总数。
Forty-five over one hundred, times two hundred and forty, is one hundred and eight children.
四十五除以一百，乘以二百四十，得一百零八名儿童。
That is one mark for graph reading, one for the calculation and one for the answer.
读图一分，计算一分，答案一分。
A number of children is a count, not a percentage.
儿童人数是一个计数，而不是百分比。
Give a conclusion and data that directly supports it.
给出结论以及直接支持它的数据。
Severe cases make up three percent vaccinated, against forty-five percent unvaccinated, in the full sample.
在全部样本中，病情严重者中接种的占百分之三，未接种的占百分之四十五。
Use the raw comparative data: the pattern supports lower severity with vaccination.
要使用原始的比较数据：这一规律支持接种疫苗使病情较轻。
But some vaccinated children were infected, so 'never infected' is contradicted.
但也有接种过的儿童被感染，所以“从不感染”的说法不成立。
These are percentages of the whole sample, not the risk within each group, so do not turn them into a vaccine efficacy figure.
这些是占整个样本的百分比，而不是各组内的风险，所以不要把它们换算成疫苗有效率。
For the top marks, link the two parts: the animals' immune response, then how that stops the bacteria reaching people.
要得高分，须把两部分连起来：动物的免疫反应，以及它如何阻止细菌传到人身上。
This is why the disease section signposted immunity rather than substituting symptom facts for the animal response.
因此疾病部分指向免疫机制，而不是用症状事实代替动物免疫应答。
Antibiotics and painkillers answer different needs.
抗生素与止痛药用途不同。
Developing antiviral drugs is difficult because viruses reproduce inside host cells; this does not mean every antiviral must kill host cells.
病毒在宿主细胞内复制使抗病毒药研发困难，但不表示所有抗病毒药都必须杀死宿主细胞。
Avoid the false claim that all medicines act in the same way or that antivirals cannot exist.
不要说所有药物作用相同，也不要说抗病毒药不可能存在。
The first two statements answer the sheet’s two-mark task; symptom relief is a separate clarification.
前两点回答教师练习两分题；症状缓解是单独说明。
Digitalis comes from foxglove and is a heart medicine.
洋地黄来自毛地黄，是一种心脏药物。
Aspirin comes from willow and is a painkiller.
阿司匹林来自柳树，是一种止痛药。
Penicillin comes from Penicillium mould: an antibiotic discovered by Fleming.
青霉素来自青霉菌，是弗莱明发现的抗生素。
Many modern drugs are made synthetically, but the starting chemical may still come from a plant.
许多现代药物是化学合成的，但起始化合物仍可能来自植物。
Think about what could go wrong if an untested drug were given straight to the public.
想一想：未经测试的药物直接给公众使用，可能出什么问题。
A useful-looking effect alone does not establish safety or a suitable dose.
看似有效不能单独证明安全或合适剂量。
The syllabus gives this general sequence.
大纲给出这一概括顺序。
Do not confuse experiments on living tissues in a laboratory with clinical trials in people.
不要混淆实验室活组织实验与人体临床试验。
Preclinical testing comes before any trial on people.
临床前试验在任何人体试验之前进行。
Look for the option that names the test material and where the test is done.
找出写明实验材料和实验场所的选项。
Testing on live tissues in a laboratory is preclinical testing.
在实验室里用活组织进行测试，属于临床前试验。
Testing on healthy volunteers or patients involves people, so it is clinical.
用健康志愿者或病人进行测试，涉及人，属于临床试验。
Safety, efficacy and dose all matter, but a purpose alone, such as 'testing for side effects', may not identify the stage: say how and on whom the drug is tested.
安全性、有效性和剂量都很重要，但只写一个目的（例如“测试副作用”）可能无法确定是哪个阶段：要说明药物是如何测试、在谁身上测试的。
A placebo is one possible comparison; the right control depends on what the trial is testing.
安慰剂只是一种对照；合适的对照取决于试验要检验什么。
Blinding does not mean scientists never know the code, and a placebo is not an antibiotic.
双盲不表示研究者永远不知道编码，安慰剂也不是抗生素。
A company's report on its own drug may be biased.
一家公司关于自己药物的报告可能存在偏见。
Explain why, and say how such claims are checked.
解释原因，并说明这类说法如何被核查。
Name the possible financial interest, and separate peer review from advertising.
说出可能的经济利益，并把同行评议与广告区分开。
Saying only that the report was not peer reviewed does not explain the bias.
只说报告未经同行评议，并不能解释偏见。
Pause and try it.
暂停并试着回答。
The final step summarises the sheet’s drug-testing account without treating trial labels as proof of a successful treatment.
最后一步概括练习中的药物测试解释，不把试验名称当作药物成功的证据。
Biology only, higher tier.
仅生物高阶。
A mouse lymphocyte supplies a specific antibody-producing ability; a tumour cell supplies repeated division in culture. The hybridoma combines both.
小鼠淋巴细胞提供特异性抗体生产能力，肿瘤细胞提供培养中反复分裂的能力，杂交瘤结合两者。
Activated lymphocytes can divide; the problem is sustained production in culture, not a universal inability to divide.
活化淋巴细胞可以分裂，问题是持续培养生产，而不是普遍不能分裂。
The original figure labels are a route to the biological roles; do not memorise letters instead of the process.
原图字母应帮助识别生物作用，而不是代替理解过程。
A mouse lymphocyte makes the specific antibody needed.
小鼠的淋巴细胞产生所需的特异性抗体。
A tumour cell can divide again and again in culture.
肿瘤细胞能在培养中不断分裂。
The fused hybridoma cell both divides and makes the antibody.
融合形成的杂交瘤细胞既能分裂又能产生抗体。
The mouse is stimulated with the relevant antigen, for a liver test, a liver antigen or liver cells, not just 'a pathogen'.
要用相关的抗原刺激小鼠，例如肝脏检测要用肝抗原或肝细胞，而不只是“病原体”。
The hybridoma has already formed.
杂交瘤细胞已经形成。
Describe how monoclonal antibodies are then made, for three marks.
描述之后如何生产单克隆抗体，共三分。
Explain the cloning into identical cells, and how the antibody is collected and purified.
说明克隆成相同的细胞，以及如何收集和纯化抗体。
Just naming the hybridoma again earns nothing: say what happens next.
只是再写一遍杂交瘤的名称不得分：要说明接下来发生什么。
Pause and try it.
暂停并试着回答。
For three marks, give three of these: cloning, identical cells, the same antibody, and purification.
三分答案写出其中三点：克隆、相同的细胞、相同的抗体、纯化。
A four-mark answer on producing the antibodies also starts earlier, with stimulating the lymphocyte and fusing it with a tumour cell.
四分的生产题还要从更早讲起：刺激淋巴细胞，并让它与肿瘤细胞融合。
One clone means identical antibody-producing cells, so the same antibody is made.
一个克隆是指产生抗体的细胞完全相同，所以产生的是同一种抗体。
Its binding site is complementary to one site on the antigen, so it recognises the intended target.
它的结合部位与抗原上的一个位点互补，所以能识别预定的目标。
That selective binding is specificity: it can detect or target one particular substance.
这种选择性结合就是特异性：它能检测或作用于某一种特定物质。
Complementary does not mean the same shape, and say complementary, not just 'specific'.
互补并不是形状相同；答题时要写“互补”，而不只是“特异”。
The specification asks for mechanisms from supplied information, not memorising one named commercial test or treatment.
大纲要求根据提供信息解释机制，而不是背诵某个商业检测试剂或治疗名称。
This is an ideal targeted-delivery model, not a promise that every antibody treatment has no side effects.
这是理想靶向递送模型，不表示所有抗体治疗都没有副作用。
The sheet’s without harming other cells wording is conditional on its ideal target-only model.
练习中不伤害其他细胞的说法依赖理想的靶标仅在癌细胞上模型。
The specification also explicitly requires evaluating side effects.
大纲也明确要求评价副作用。
Do not replace the supplied blocking model with a toxic-payload explanation from the cancer example.
不要把题目提供的阻断模型替换成癌症例子中的毒性药物递送。
'Same shape' earns no mark, and neither does 'specific' on its own.
写“形状相同”不得分，只写“特异性”也不得分。
Use the mechanism the question gives you; it is not how every transplant drug works.
按题目给出的机制作答；这并不是所有移植药物的作用方式。
hCG is the pregnancy-test target.
hCG是验孕检测靶标。
The diagram and explanation define a teacher model; use any different mechanism provided by an actual exam question.
图与解释定义教师模型，实际试题若提供不同机制，应以题目为准。
The control zone checks the test process.
对照区检查检测过程。
A test line alone cannot validate a strip without its control.
缺少对照线时，单独测试线不能证明试纸有效。
Two lines indicate target detected in this model. Control only means no target detected under the test conditions.
此模型两线表示检出靶标，仅对照线表示在检测条件下未检出。
No control means invalid, even if a test line appears.
没有对照线即无效，即使测试线出现也不能解释为有效结果。
Do not equate target not detected with guaranteed absence in every real test.
未检出不等于任何真实检测中都保证完全没有靶标。
A test strip shows no control line.
一张检测试纸没有出现质控线。
Should it be recorded as 'target absent'?
应该记录为“未检出目标”吗？
State what the control line demonstrates, and give a possible failure, such as the liquid not moving along or a reagent not binding.
说明质控线证明了什么，并给出一种可能的失败原因，例如液体没有沿试纸移动，或试剂没有结合。
Pause and try it.
暂停并试着回答。
The reason is a suggestion supported by the mechanism, not a claim that one failure cause has been proved.
原因是根据机制提出的可能解释，不表示已经证明某个失败原因。
The source key represents blue dye with grey shading.
原图用灰色阴影表示蓝色染料。
The upper area is control and the lower area is test.
上方为对照区，下方为测试区。
The original diagram is preserved, including its letters and key.
保留原图字母和图例。
The source Figure 5 says test area captures antibody–steroid complex and control captures free antibodies.
原图5说明测试区捕获抗体—类固醇复合物，对照区捕获游离抗体。
Both areas change colour on binding.
结合时两区均显色。
Evidence is an observation; the reason is a supported possibility. The two are separate marks.
证据是观察，原因是有依据的可能性，两者分别得分。
A: control present, test absent, a valid result with the target not detected.
A：有质控线、无检测线，是有效结果，未检出目标。
B: no control, so invalid.
B：没有质控线，无效。
C: a test signal but no control, still invalid.
C：有检测信号但没有质控线，仍然无效。
D: both control and test lines, a valid positive.
D：质控线和检测线都有，是有效的阳性结果。
The answer is D; C shows why a test signal alone is not enough.
答案是D；C说明仅有检测信号是不够的。
The specification says monoclonal antibodies have produced more side effects than originally expected.
大纲指出单克隆抗体曾出现超出预期的副作用。
Specific binding alone does not settle overall safety.
特异性结合不能单独决定总体安全。
Do not infer a side-effect-free cure from the word monoclonal. Link the judgement to the drug-testing criteria already taught.
不要从单克隆一词推断无副作用治愈，应联系前面学过的药物测试标准。
Detection and identification are HT.
病害检测与鉴定为高阶内容。
Start with observations before proposing a cause.
先观察，再提出病因。
Yellowing and poor growth are evidence of a problem, but neither uniquely names the cause.
叶黄和生长不良提示问题，但不能唯一确定病因。
The question asks for two ways to identify a disease, not two symptoms.
题目要求两种鉴定病害的方法，而不是两种症状。
Method one: consult a gardening manual, or a gardening website or app.
方法一：查阅园艺手册，或园艺网站、应用程序。
Method two: take an affected plant to a laboratory or an expert.
方法二：把患病植物送到实验室或交给专家。
Another option is a testing kit containing monoclonal antibodies.
另一种选择是使用含单克隆抗体的检测试剂盒。
Any two methods earn the marks, but a vague 'search the internet' does not.
答出任意两种方法即可得分，但笼统的“上网搜索”不得分。
This version is worth four marks: for each of two ways, give the method and explain how it helps identify the problem.
本题四分：两种方法，每种都写出方法，并说明它如何帮助找出问题。
Do not turn a symptom match into certainty. Laboratory and kit findings must be interpreted for the cause they investigate.
症状相似不是确诊，实验室与试剂结果应按检测范围解释。
Aphids are insect pests. They are not a fifth category of disease-causing microorganism.
蚜虫是昆虫害虫，不是第五类致病微生物。
Use both symptoms together to choose the most likely disease.
把两个症状结合起来，选出最可能的病害。
The answer is rose black spot; another correct disease, such as rust, would also be accepted.
答案是玫瑰黑斑病；其他正确的病害，例如锈病，也可以。
The evidence: spots together with leaf loss match its typical pattern of symptoms.
证据是：斑点加上落叶，符合它典型的症状特征。
But a likely identification from symptoms is not the same as laboratory confirmation.
但根据症状作出的可能判断，并不等于实验室确诊。
Notice the word 'may': yellow leaves have more than one possible cause.
注意“可能”一词：叶片发黄的原因不止一种。
The cause: a shortage of magnesium ions.
原因：缺少镁离子。
The mechanism: magnesium is needed to make chlorophyll, so less chlorophyll causes yellowing, called chlorosis.
机制：合成叶绿素需要镁，叶绿素减少就会使叶片发黄，称为失绿症。
Lack of light can also cause chlorosis, so yellow leaves alone do not prove a magnesium shortage.
缺光也会导致失绿，所以仅凭叶片发黄不能证明缺镁。
Several causes of yellow leaves are accepted: a mineral shortage, problems with light, water or pH, or an infection.
叶片发黄可以有多种原因：缺少矿物质，光照、水分或酸碱度出了问题，或者感染。
Both deficiency mechanisms are biology-only content at both tiers. Do not swap the molecules each ion is needed to make.
两种缺素机制均为生物两档要求，不要混淆合成物质。
Three marks: carry the explanation past 'the leaves turn yellow', all the way to reduced growth.
三分解释要从“叶片发黄”一直推到生长减少。
Respiration releases energy from glucose. Avoid saying that the plant makes energy.
呼吸从葡萄糖释放能量，不是制造能量。
Teacher leaf-surface schematic, not to scale. Trace the outer cuticle and the cellulose walls; they resist pathogen entry.
教师叶表结构示意图，角质层和纤维素细胞壁阻止病原体进入。
Give one physical and one chemical defence, and learn what each example does for the plant.
写出一种物理防御和一种化学防御，并理解每个例子对植物有什么作用。
Name the feature and what it does. “Protects the plant” alone gives little biological explanation.
应说明结构或物质及作用，不能只说保护植物。
For each feature, name its defence category and say how it benefits the plant.
每个特征都写出防御类别，并说明它给植物带来的益处。
Plants do not choose to act. Touch-induced movement is a response that can discourage feeding.
植物不是主动决定行动，触碰引起的反应可阻止取食。
A kit detects only the antigen it targets.
试剂盒只检测它针对的抗原。
Use the kit's instructions to decide what a negative result can and cannot show.
按试剂说明判断：阴性结果能说明什么，不能说明什么。
A valid result supports interpretation for the kit’s specified target. It does not test all possible causes of poor growth.
有效结果只涉及指定靶标，并不检测所有生长不良原因。
Final checklist. Name the four pathogen types and three spread routes. Recite each named disease with pathogen, spread, symptom and control. List the four barriers and the three white-cell actions. Explain vaccination for the individual and for the population. Distinguish antibiotics from painkillers and say why viruses resist both. Order the drug-testing stages with the placebo and the double-blind. For biology: build a hybridoma and give four uses of its antibody, then read plant signs and the two ion deficiencies.
最后清单：说出四类病原体和三种传播途径；逐个疾病背出病原体、传播、症状和控制；列出四道屏障和白细胞三招；解释疫苗对个人和人群的作用；区分抗生素与止痛药并说明病毒为何两者都不怕；按顺序说出药物试验阶段及安慰剂与双盲；仅生物部分：构建杂交瘤并给出其抗体的四种用途，读懂植物病症和两种缺素。