יחידה 4: אנרגיה, סביבה, מיקרוביולוגיה וחיסון
Pearson Edexcel · International A-Level · Biology נושא 4 10:56 קריאת קול באנגלית · תרגום אנגלי + סינית שרוף בתוך הסרטון
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תרגום טקסט
A wheat field intercepts sunlight, fixes carbon, feeds a food chain - and loses energy at every step.
麦田截获阳光、固定碳、供养食物链——而每一步都在损失能量。
This unit follows the energy from photon to ecosystem, then turns to the smallest participants: the microbes that recycle, the pathogens that take, and the immune system that defends.
本单元追踪能量从光子到生态系统的流动，再转向最小的参与者：分解回收的微生物、入侵的病原体，以及防御的免疫系统。
The paper is one hour forty-five minutes, ninety marks, and it is the most calculation-heavy paper after Unit one.
试卷105分钟、90分，是除第一单元外计算量最大的试卷。
Photosynthesis runs in two stages in two places.
光合作用分两个阶段、在两个场所进行。
On the thylakoid membranes, light energy photolyses water - releasing oxygen - photophosphorylates ADP and reduces NADP.
类囊体膜上，光能分解水释放氧气，使ADP光合磷酸化、还原NADP。
In the stroma, rubisco fixes carbon dioxide onto ribulose bisphosphate, and the products are reduced using that ATP and reduced NADP to make GALP: some to glucose, most regenerating RuBP.
基质中，rubisco把二氧化碳固定到核酮糖二磷酸上，产物利用ATP和还原NADP还原成GALP：一部分合成葡萄糖，大部分再生RuBP。
The chloroplast structure matches - stacked thylakoids for absorbing surface, enzyme-packed stroma beside them.
叶绿体结构与之匹配——类囊体堆叠提供吸收面，旁边的基质充满酶。
The absorption spectrum shows what each pigment takes up - chlorophyll a and b in the red and blue, carotenoids spreading the range.
吸收光谱显示各色素吸收什么——叶绿素a和b在红光和蓝光区，类胡萝卜素拓宽范围。
The action spectrum shows what rate of photosynthesis each wavelength drives.
作用光谱显示各波长驱动光合作用的速率。
The two match: strong evidence that these pigments do the work.
两者吻合：这些色素承担工作的有力证据。
Chromatography separates them, and Rf values identify them against standards run in the same solvent.
色谱法分离它们，Rf值对照同溶剂标准品鉴定。
In the field, whichever of light intensity, carbon dioxide concentration or temperature is lowest sets the rate - a greenhouse raises the weakest one.
在田间，光强、二氧化碳浓度或温度中最低者决定速率——温室提升最弱的一项。
Gross primary productivity is the energy photosynthesis fixes; net primary productivity is what remains after the producers own respiration - the energy actually available to herbivores.
总初级生产力是光合作用固定的能量；净初级生产力是扣除生产者自身呼吸后剩余的部分——真正可供草食动物利用的能量。
Each step up the food chain keeps about ten per cent, lost to respiration as heat, egestion, excretion and parts never eaten.
营养级每上升一步只保留约10%，损失于呼吸产热、排遗、排泄和未取食部分。
That arithmetic is why chains are short and top predators rare - and why eating plants feeds more people than eating the animals that ate plants.
这一算术解释了食物链为何短、顶级捕食者为何稀少，也解释了吃植物比吃以植物为食的动物能养活更多人。
Four definitions, precisely: a habitat is where; a population is one species individuals; a community is all the populations; an ecosystem adds the physical environment.
四个定义要精确：栖息地是所在之处；种群是一个物种的个体；群落是所有种群；生态系统再加上物理环境。
Biotic factors - competition, predation, disease - and abiotic factors - light, water, temperature, pH - set distribution and abundance together.
生物因素——竞争、捕食、疾病——与非生物因素——光、水、温度、pH——共同决定分布与多度。
Predator-prey systems cycle with a delay: hares rise, lynx follow with a lag of about a quarter cycle.
捕食者与猎物以滞后的周期波动：野兔上升，猞猁随后滞后约四分之一周期。
On bare ground, succession runs from tolerant pioneer species through grasses and shrubs to the climax community - each stage making the next possible.
在裸地上，演替从耐逆的先锋物种经草本、灌木到顶极群落——每一阶段为下一阶段创造条件。
Evidence for climate change comes from four archives: direct temperature records, air trapped in ice cores, tree-ring widths in dendrochronology, and pollen layers in peat.
气候变化的证据来自四个档案：直接温度记录、冰芯中的气泡、树木年轮和泥炭中的花粉层。
The physics: solar short-wave radiation arrives, the warm Earth re-emits long-wave infrared, and greenhouse gases absorb and re-emit it downward.
物理机制：太阳短波辐射到达地面，变暖的地球向外发射长波红外，温室气体吸收并向下再发射。
The gases differ - methane is about twenty-eight times CO2 per kilogram but lasts a decade, while CO2 persists for centuries - so short-term and century-scale rankings differ.
气体各不相同——甲烷按千克计约为二氧化碳的28倍，但只存留十来年；二氧化碳存留数百年——因此短期与百年尺度的排名不同。
And extrapolating a trend beyond its data is a judgement that the drivers continue: say the assumption, then its weakness.
把趋势外推到数据之外，等于假设驱动因素不变：先说假设，再说其弱点。
Evolution is defined exactly: a change in allele frequency in a population.
进化的定义很精确：种群中等位基因频率的变化。
Mutation supplies new alleles; selection filters them.
突变提供新等位基因；选择进行筛选。
Directional selection shifts the mean when the environment moves - antibiotic resistance is the textbook case.
环境改变时，定向选择移动均值——抗生素耐药性是教科书案例。
Stabilising selection trims both extremes in a stable environment - human birth weights.
稳定环境中，稳定选择削减两端——人类出生体重。
Speciation needs isolation: allopatric, with a physical barrier, or sympatric, with reproductive isolation in one place - different mating seasons, behaviours or flowers.
物种形成需要隔离：异域隔离有地理屏障；同域隔离在同一地点因繁殖隔离——不同的交配季节、行为或花。
Isolated populations diverge until they cannot interbreed.
被隔离的种群分化直至无法杂交。
Aseptic technique protects you and the culture: flame the loop to red heat, flame the necks, lift lids briefly, seal with tape, and incubate at twenty-five degrees so human pathogens cannot grow.
无菌技术双向保护：接种环烧红，瓶口过火，短暂开盖，胶带封皿，25度培养使人类病原菌无法生长。
Measure growth three ways - colony counts on dilution plates, turbidity in broth, direct cell counts with a haemocytometer.
测量生长有三种方法——稀释平板的菌落计数、肉汤浊度、血细胞计数板直接计数。
The growth curve runs lag, log, stationary, death; in the log phase the growth-rate constant is the log difference divided by 0.301 times the hours - from two times ten to the four to one point six times ten to the seven in five hours gives one point nine three divisions per hour, a doubling every thirty-one minutes.
生长曲线历经延迟、对数、稳定、衰亡四期；对数期增长率常数等于对数差除以0.301乘小时数——从2乘10的4次方到1.6乘10的7次方经5小时，得每小时1.93次分裂，约31分钟翻一番。
Pathogens arrive by routes - respiratory droplets, contaminated food and water, sexual contact, wounds, vectors - and barriers meet them first: intact skin, mucus and cilia, stomach acid, lysozyme in tears, and the clotting cascade sealing breaks.
病原体经多条途径到来——呼吸道飞沫、受污染的食物和水、性接触、伤口、媒介——屏障首先迎敌：完整的皮肤、黏液与纤毛、胃酸、泪液中的溶菌酶，以及封闭破损的凝血级联。
Bacteria are living cells with walls, ribosomes and plasmids; viruses are nucleic acid in a protein capsid, sometimes enveloped, with no metabolism of their own.
细菌是活的细胞，有细胞壁、核糖体和质粒；病毒是蛋白质衣壳包裹的核酸，有时带包膜，没有独立代谢。
Mycobacterium tuberculosis is inhaled and survives inside macrophages; HIV destroys the T helper cells that coordinate immunity, so latent TB reactivates - the classic pairing the exam returns to.
结核分枝杆菌经吸入并在巨噬细胞内存活；HIV破坏协调免疫的T辅助细胞，使潜伏的结核复活——考试反复出现的经典配对。
The specific response has two arms.
特异性免疫有两条臂。
Humoral: an antigen binds a B cell, clonal selection expands it into antibody-secreting plasma cells and long-lived B memory cells.
体液免疫：抗原结合B细胞，克隆选择使其扩增为分泌抗体的浆细胞和长寿的B记忆细胞。
Cellular: T helper cells release signals that activate macrophages and B cells; T killer cells destroy infected cells outright.
细胞免疫：T辅助细胞释放信号激活巨噬细胞和B细胞；T杀伤细胞直接裂解被感染细胞。
The antibody is four chains with a variable region forming one binding site.
抗体由四条链组成，可变区形成一个结合位点。
The second encounter with an antigen is faster, higher and longer than the first - memory cells divide at once - which is what vaccination schedules exploit.
再次遇到同一抗原时应答更快、更高、更持久——记忆细胞立即分裂——疫苗程序正是利用这一点。
Active immunity is your own antibodies; passive is given antibodies - immediate but fading.
主动免疫是自身抗体；被动免疫是外源抗体——立即起效但会消退。
Bacteriostatic antibiotics stop bacteria dividing - the immune system must clear them; bactericidal antibiotics kill outright, which is what a weakened immune system needs.
抑菌抗生素阻止细菌分裂——需要免疫系统清除；杀菌抗生素直接杀灭——免疫力弱的患者所需。
Resistance arises by mutation and spreads by selection: a half-finished course kills the sensitive cells and leaves the resistant ones to multiply, and plasmids carry the genes horizontally between species.
耐药性经突变产生、经选择扩散：疗程未完成杀死敏感菌，留下耐药菌繁殖，质粒还把耐药基因在物种间水平传递。
Hospital-acquired infections thrive where vulnerable patients, invasive devices and resistant strains meet.
院内感染在易感患者、侵入性器械与耐药菌株相遇处滋生。
The counter-measures are systems, not heroics: hand hygiene, sterile procedures, isolating carriers, targeted rather than blanket antibiotics.
对策是系统而非个人英雄主义：手卫生、无菌操作、隔离携带者、有针对性的而非全覆盖的抗生素使用。
Decomposers recycle what communities leave - carbon dioxide back to the air, nitrogen back to the soil.
分解者回收群落的残余——二氧化碳回到空气，氮回到土壤。
The polymerase chain reaction amplifies DNA in cycles of denaturation, primer annealing and extension: n cycles give two-to-the-n copies.
聚合酶链式反应以变性、退火、延伸循环扩增DNA：n个循环得到2的n次方拷贝。
Gel electrophoresis separates fragments by length - short ones run furthest - and the band profile identifies individuals and relatedness.
凝胶电泳按长度分离片段——短的跑得最远——条带图谱可识别个体与亲缘。
Time of death narrows by four clocks: body temperature falling about one degree per hour, rigor mortis setting then passing, decomposition stage, and the insects that colonise a body in sequence.
死亡时间由四个时钟缩小范围：体温每小时约降1度、尸僵出现后消退、分解阶段、以及按顺序在尸体上定殖的昆虫。
Each clock carries its assumptions - clothing, build, air temperature - and exam answers state them.
每个时钟都有假设——衣物、体型、气温——答题时要写明。
Close where the paper starts: with numbers.
以试卷开头的方式收尾：数字。
The action spectrum matches the absorption spectrum because the pigments that absorb a wavelength are the ones driving photosynthesis at it.
作用光谱与吸收光谱吻合，因为吸收某波长的色素正是在该波长驱动光合作用的色素。
Forty thousand kilojoules of NPP: one transfer keeps four thousand, a second four hundred - the third consumer sees four hundred kilojoules per square metre per year.
四万千焦的NPP：一次传递保留四千，再传递四百——第三营养级获得每年每平方米四百千焦。
Sixteen in a thousand recessive gives q squared of zero point zero one six, q about zero point one two six, carriers two p q about twenty-two per hundred.
千分之十六的隐性表型使q平方为0.016，q约0.126，携带者比例约22%。
And a weakened immune system cannot clear static bacteria, so the drug must kill them itself - bactericidal.
而免疫力弱的患者无法清除被抑制的细菌，药物必须亲自杀灭——用杀菌药。