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AP Environmental Science · CED Unit 1

The Living World:
Ecosystems

生态系统 · 引导型学习册

I'm not here to teach you. I'm here to tell you where to learn it — what to focus on in every CED topic, how much it's worth on the exam, and exactly which video, past paper or vocab set to open next.

📊 6–8% of the exam 📖 11 topics (1.1–1.11) ⭐⭐⭐ Difficulty 🎓 Foundation for all 8 later units
01
GUIDE DECK · 24 SLIDES · AP-STUDY.COM
Unit 1 · 1 / 24
🧭 考纲导航 · Unit Overview
One unit, one idea: matter cycles, energy flows.
Unit 1 is the foundation everything else stands on — pollution (Units 7–8) and climate change (Unit 9) are all Unit 1 concepts with humans added. Learn it as a system, not a list.
📊 Exam Weight
6–8%
📖 CED Topics
1.1 – 1.11
⭐ Difficulty
⭐⭐⭐ Moderate
📝 Common Q's
MCQ · FRQ calc
CED 知识点清单 · All 11 topics
1.1Introduction to Ecosystemspredation · symbiosis · competition
1.2Terrestrial Biomes9 biomes · temp + precip
1.3Aquatic Biomesfreshwater vs marine
1.4The Carbon Cyclesources · sinks · sequestration
1.5The Nitrogen Cycle5 steps · all bacteria
1.6The Phosphorus Cycleno gas phase · limiting
1.7Hydrologic Cyclesun-driven · reservoirs
1.8Primary ProductivityGPP vs NPP
1.9Trophic Levelswho eats whom
1.10Energy Flow & 10% Rulecalculation favourite
1.11Food Chains & Websfeedback · cascade
建议学习路径 · Recommended path
  1. Read this deck once (15 min) — get the map, don't memorise yet
  2. Watch Khan Academy Unit 1 for the topics you don't recognise
  3. Drill past papers on ap-study.com/bank — Unit 1 MCQs
  4. Memorise terms on vocab — APES rewards exact vocabulary
Unit 1 · 2 / 24
🤝
CED Topic 1.1 · 知识引导
Introduction to Ecosystems
Mutualism + / + bee ↔ flower Commensalism + / 0 epiphyte ↔ tree Parasitism + / − tick ↔ deer Competition − / − two warblers Resource partitioning → coexist same habitat, different resource slice — less direct competition
The four interaction types — APES wants the signs, not the story
核心要点
  • Symbiosis = 3 types, read the signs: mutualism +/+, commensalism +/0, parasitism +/−
  • Competition — within a species (intraspecific) vs between (interspecific)
  • Resource partitioning — how species split a niche to coexist
  • Resource availability drives every one of these relationships
📊 Weight
6–8%
⭐ Priority
⭐⭐⭐
📝 Tested as
MCQ scenario
去哪学
Khan Academy — AP Env. Science概念 · interactive→ YouTube — APES 1.1 讲解视频 · 例题→ 真题练习 · Past Papersap-study.com/bank→ 词汇记忆 · Vocabsymbiosis 词族→
💡
引导提问：在校门口找一对 mutualism（互利共生）。找不到？那操场边的那只鸟呢？——APES 喜欢用你身边的例子出 MCQ。
Unit 1 · 3 / 24
🏜️
CED Topic 1.2 · 知识引导
Terrestrial Biomes
Sand dunes, Sahara Desert — the subtropical desert biome
Subtropical desert · ~30° latitude · sinking dry air
核心要点
  • 9 biomes — tundra → taiga → temperate → grassland → desert → tropical
  • Defined by two axes: temperature and precipitation
  • Tropical rainforest = highest NPP & biodiversity; tundra = lowest
  • Climate change is shifting biome boundaries poleward
📊 Weight
6–8%
⭐ Priority
⭐⭐⭐⭐
📝 Tested as
climate graph → biome
去哪学
Bozeman Science — APESbiome 讲解经典→ YouTube — 9 biomes + climatograph视频→ 真题练习 · Past Papersbiome MCQ→
💡
引导提问：给你一张气候图（温度 + 降水），30 秒内说出 biome。练这个反射，比背 9 段描述划算得多。
Unit 1 · 4 / 24
🐠
CED Topic 1.3 · 知识引导
Aquatic Biomes
Colorful coral reef underwater
Coral reefs · the most diverse aquatic biome · extremely sensitive to temperature
核心要点
  • Freshwater: streams, rivers, ponds, lakes, wetlands
  • Marine: oceans, coral reefs, marshlands, estuaries
  • Controlled by salinity, depth, flow, turbidity, nutrients, temperature
  • Estuaries = nurseries & among the most productive biomes
📊 Weight
6–8%
⭐ Priority
⭐⭐⭐
📝 Tested as
MCQ + diagram
去哪学
Khan Academy — Unit 1概念 · interactive→ YouTube — APES 1.3视频→ 真题练习 · Past Papersestuary / wetland→
💡
引导提问：为什么河口（estuary）既是"垃圾场"又是"育婴房"？想通这一句，1.3 就懂了。
Unit 1 · 5 / 24
模块导航 · Checkpoint ①

刚学完 1.1–1.3 · 接下来是 4 个循环

前三个 topic 在讲"谁和谁在一起"；接下来四个在讲"物质怎么在系统里转"。

✅ 已完成 · Done
  • 1.1 物种互动 4 型
  • 1.2 九大陆地生物群落
  • 1.3 淡水 vs 海洋
🎯 现在做 · Do now
  • 先把 4 个循环的储库记牢
  • 碳：短期 vs 长期储库
  • 磷：没有大气相
一句话记住这一段：碳、氮、磷、水 —— 四个循环，四个考试最爱问的"储库在哪、谁在动它"。
Unit 1 · 6 / 24
🌳
CED Topic 1.4 · 知识引导
The Carbon Cycle
Aerial view of deforestation in the Amazon
Amazon deforestation · long-term carbon store burned into atmospheric CO₂
核心要点
  • Short-term sinks: living things, atmosphere, surface ocean
  • Long-term sinks: fossil fuels, sedimentary rock, deep ocean
  • Photosynthesis ↓ CO₂ · respiration & decomposition ↑ CO₂
  • Burning fossil fuels = fast transfer from long-term to atmosphere
📊 Weight
6–8%
⭐ Priority
⭐⭐⭐⭐⭐
📝 Tested as
FRQ + MCQ
去哪学
Khan Academy — Carbon cycle概念→ YouTube — APES 1.4视频→ 真题练习 · Past Paperscarbon FRQ→
💡
引导提问：汽油加进油箱的时候，那些碳已经在地底待了 3 亿年。你一踩油门，它几秒内上天。——这就是"碳循环被人加速"。
Unit 1 · 7 / 24
🧫
CED Topic 1.5 · 知识引导
The Nitrogen Cycle
N₂ ATMOSPHERE · 78% ① fixation NH₃ / NH₄⁺ ② nitrification NO₂⁻ → NO₃⁻ ③ assimilation PLANTS ④ ammonification waste → NH₄⁺ ⑤ denitrification every arrow = a bacteria doing a job · rhizobia in legume root nodules fix N₂
5 steps · fixation → nitrification → assimilation → ammonification → denitrification
核心要点
  • Atmosphere = 78% N₂ = major reservoir, but plants can't use it
  • Every step has a bacteria — that's the AP's favourite detail
  • Fixation = N₂ → NH₃/NH₄⁺ · Nitrification = NH₄⁺ → NO₃⁻
  • Denitrification returns N to the air (anaerobic, e.g. wetlands)
📊 Weight
6–8%
⭐ Priority
⭐⭐⭐⭐⭐
📝 Tested as
MCQ · FRQ
去哪学
Khan Academy — Nitrogen cycle概念→ YouTube — APES 1.5 五步讲解视频→ 词汇记忆 · Vocab-fication 词族→
💡
引导提问：豆科植物根瘤里的细菌，凭什么让农民少施肥？——想清楚这个，1.5 的核心就通了。
Unit 1 · 8 / 24
🪨
CED Topic 1.6 · 知识引导
The Phosphorus Cycle
⚠️ NO ATMOSPHERIC PHASE — phosphorus never becomes a gas ROCK primary reservoir weathering SOIL PO₄³⁻ for roots uptake ORGANISMS DNA · ATP · bones runoff → SEDIMENT (long-term sink) geologic uplift
Slow, rock-driven, and — unlike the other three — no gas phase at all
核心要点
  • No gas phase — the #1 thing APES checks on this topic
  • Reservoir = rock & sediment; released by weathering
  • Limiting nutrient in freshwater — small additions cause big blooms
  • Fertiliser runoff → eutrophication (connects to Unit 8)
📊 Weight
6–8%
⭐ Priority
⭐⭐⭐⭐
📝 Tested as
MCQ · FRQ link
去哪学
Khan Academy — Phosphorus cycle概念→ YouTube — APES 1.6视频→ 真题练习 · Past Paperseutrophication FRQ→
💡
引导提问：为什么洗衣粉要禁磷？顺着"磷没有气体"这句话往下想，答案自己会出来。
Unit 1 · 9 / 24
💧
CED Topic 1.7 · 知识引导
The Hydrologic (Water) Cycle
Storm clouds forming over a lake
Evaporation feeding condensation — the sun drives every step
核心要点
  • Sun = the engine; 97% of water sits in the ocean
  • Steps: evaporation · transpiration · condensation · precipitation
  • Then: runoff / infiltration → groundwater → uptake
  • Deforestation cuts transpiration → less local rainfall
📊 Weight
6–8%
⭐ Priority
⭐⭐⭐
📝 Tested as
diagram MCQ
去哪学
Khan Academy — Water cycle概念→ YouTube — APES 1.7视频→ 真题练习 · Past Paperswater cycle MCQ→
💡
引导提问：亚马逊雨林"自己造自己的雨"。把树砍了会怎样？——这是 FRQ 里最好写的人类影响之一。
Unit 1 · 10 / 24
模块导航 · Checkpoint ②

四个循环讲完 · 现在轮到能量

物质会循环（matter cycles）。能量不会——它单向流、边走边丢（energy flows）。这是全单元最重要的一句话。

✅ 已完成 · Done
  • 1.4 碳循环
  • 1.5 氮循环 · 5 步
  • 1.6 磷循环 · 无气相
  • 1.7 水循环
🎯 现在做 · Do now
  • 默写氮循环 5 步
  • 记住：NPP = GPP − Ra
  • 区分"循环"与"流动"
高频失分点：写"能量在生态系统中循环（recycled）"直接错。能量单向流动并以热的形式散失（热力学第二定律），只有物质循环。
Unit 1 · 11 / 24
☀️
CED Topic 1.8 · 知识引导
Primary Productivity
Sunlight streaming through a green forest canopy
Tropical rainforest canopy · the highest terrestrial NPP on Earth
核心要点
  • GPP = total energy captured by photosynthesis
  • NPP = GPP − respiration ← what's actually left for consumers
  • Units: kJ/m²/yr or g/m²/yr — per area, per time
  • Highest NPP: rainforest, estuaries, wetlands · Lowest: desert, open ocean
📊 Weight
6–8%
⭐ Priority
⭐⭐⭐⭐⭐
📝 Tested as
calculate NPP
去哪学
Khan Academy — Primary productivity概念→ YouTube — GPP/NPP 计算视频 · 例题→ 真题练习 · Past PapersNPP 计算→
💡
引导提问：开放海洋被太阳晒了 24 小时，为什么 NPP 还这么低？提示：没有"土壤"这个养分库。
Unit 1 · 12 / 24
🐺
CED Topic 1.9 · 知识引导
Trophic Levels
A grey wolf — a top-level consumer
Apex predator · tertiary consumer · sits on the narrowest energy tier
核心要点
  • Producer → primary → secondary → tertiary consumer
  • Herbivore / carnivore / omnivore / detritivore / decomposer
  • Decomposers recycle matter, they don't "return energy"
  • Higher level = less energy, fewer individuals, more toxins
📊 Weight
6–8%
⭐ Priority
⭐⭐⭐⭐
📝 Tested as
pyramid · MCQ
去哪学
Khan Academy — Trophic levels概念→ YouTube — APES 1.9视频→ 词汇记忆 · Vocab-vore 词族→
💡
引导提问：为什么地球上从没出现过"五级消费者"？——用 1.10 的 10% 规则自己算一遍就明白了。
Unit 1 · 13 / 24
⚡
CED Topic 1.10 · 知识引导
Energy Flow & the 10% Rule
TERTIARY · 10 J SECONDARY · 100 J PRIMARY · 1,000 J PRODUCERS · 10,000 J ↑ only 10% moves up 90% lost as heat, respiration, waste each step ÷ 10
10% rule · the single most-tested calculation in Unit 1
核心要点
  • Only ~10% of energy moves up a level; 90% is lost
  • Lost to: heat, respiration, movement, waste, uneaten parts
  • So: 10,000 → 1,000 → 100 → 10 J (each arrow ÷ 10)
  • Consequence: food chains rarely exceed 4–5 levels
📊 Weight
6–8%
⭐ Priority
⭐⭐⭐⭐⭐
📝 Tested as
FRQ calculation
去哪学
Khan Academy — Energy flow概念→ YouTube — 10% rule 习题视频 · 例题→ 真题练习 · Past Papers10% FRQ→
💡
引导提问：反过来想：养 10 亿人吃牛肉，和直接吃作物，土地要差多少？——10% 规则就是这道题。
Unit 1 · 14 / 24
🕸️
CED Topic 1.11 · 知识引导
Food Chains & Food Webs
PRODUCERS RABBITS MICE HAWKS SNAKES KEYSTONE REMOVED hawk ↓ → rabbit ↑ → plants ↓ a web = many chains · remove one node and the feedback ripples outward
Food web + trophic cascade — the AP's favourite "what if we remove X" question
核心要点
  • Food web = interlocking chains — more paths = more resilience
  • Positive feedback: change amplifies · Negative: change dampens
  • Trophic cascade: removing a top predator reshapes everything below
  • Humans simplify webs → less stable (monoculture, overfishing)
📊 Weight
6–8%
⭐ Priority
⭐⭐⭐⭐
📝 Tested as
MCQ scenario
去哪学
Khan Academy — Food webs概念→ YouTube — Yellowstone 狼的生态级联案例 · 强推→ 真题练习 · Past Paperscascade MCQ→
💡
引导提问：黄石公园重新引入狼，居然让河边树变多了。这条因果链，你能一口气画出来吗？
Unit 1 · 15 / 24
模块导航 · Checkpoint ③

11 个 topic 全部过完 · 进入考试模式

内容你已经有了地图。剩下的不是"学更多"，而是"练得更准"。

✅ 已完成 · Done
  • 1.1–1.3 互动 + 生物群落
  • 1.4–1.7 四大循环
  • 1.8–1.11 能量流
🎯 现在做 · Do now
  • 合上幻灯片，画出
  • 碳→氮→磷→水的储库
  • 画不出就回第 6 页
APES 的得分逻辑：精确词汇 > 理解大意。写 "nitrogen fixation by rhizobia" 得分，写 "bacteria help plants" 不得分。这就是为什么词汇页在后面等你。
Unit 1 · 16 / 24
计算引导 · The math you must own

Unit 1 只考两种计算

APES 现在允许用计算器，并会发公式表。你要练的是"知道用哪条"，不是心算。

① Net Primary Productivity
NPP = GPP − Ra
GPP = total captured by producers · Ra = producer respiration
NPP is the energy actually available to consumers
陷阱：题目给 GPP 和 Ra，问你"consumer 能拿到多少能量"——必须先减出 NPP，再喂给下一级。直接拿 GPP 除以 10 是最常见的错。
② The 10% Rule
Enext = Ecurrent × 0.10
10,000 J producers → 1,000 → 100 → 10 J
Each arrow up divides by 10
考试变体：① 给 producers 能量求 tertiary；② 反过来，给 top predator 能量反推 producers（×10 三次 = ×1,000）；③ 求第 n 级后剩余百分比（0.1n）。
🧮
练一道：producers 有 250,000 kJ，问 tertiary consumers 拿到多少？
→ 250,000 → 25,000 → 2,500 → 250 kJ。三箭头，三除法。
Unit 1 · 17 / 24
自测 · MCQ 1

点一下就判分

A food chain transfers 500 kJ of energy to primary consumers. Using the 10% rule, how much energy reaches the tertiary consumers?

A0.5 kJ
B5 kJ
C50 kJ
D500 kJ
✅ 答案 B。500 kJ 是 primary consumers 手里的能量。到 secondary = ÷10 = 50 kJ，到 tertiary = 再 ÷10 = 5 kJ。选 A 的人多除了一次（四级），选 C 的人只除了一次。看清"从哪一级开始算"是这个考点的全部难度。
Unit 1 · 18 / 24
自测 · MCQ 2

点一下就判分

Which reservoir stores carbon for the longest period of time?

AThe atmosphere
BLiving terrestrial plants
CFossil fuels and sedimentary rock
DThe surface ocean
✅ 答案 C。化石燃料与沉积岩是长期储库，碳能被锁住数千万到数亿年。A、B、D 都是短期储库——周转快，几年到几十年。APES 几乎每年都会用"长期 vs 短期储库"出一道题，1.4 的核心就这一条分界线。
Unit 1 · 19 / 24
FRQ 引导 · 3 种问法

Unit 1 在 FRQ 里只穿三件衣服

Section II 占 40% 分数，3 道题 70 分钟。Unit 1 的知识几乎一定会在某道 FRQ 里出现。

① Identify / Explain
"Identify the reservoir…" · "Explain why phosphorus is a limiting nutrient."
答法：精确名词 + 一句因果。
② Calculate
10% rule 或 NPP。
答法：写出公式 → 代入 → 带单位。没单位丢分。
③ Justify / Propose
"Propose a solution to reduce fertilizer runoff and justify it."
答法：具体手段（buffer zone）+ 为什么有效。
打分逻辑：FRQ 按 rubric 逐点给分。写"具体名词"才得分：写 "contour farming" 得分，写 "a farming method" 不给分。空着 = 0 分，猜一个具体答案至少有机会。
去哪练
College Board — 官方 FRQ + 评分标准AP Central→ 历年真题 · Past Papersap-study.com/bank→
Unit 1 · 20 / 24
高频陷阱 · Common mistakes

六个最常丢分的地方

  • "能量循环" ❌
    能量单向流动并以热散失；只有物质循环。
  • NPP 忘了减呼吸 ❌
    NPP = GPP − Ra，题目一定埋这个坑。
  • 混淆 fixation 与 nitrification
    fixation: N₂→NH₄⁺ · nitrification: NH₄⁺→NO₃⁻。
  • "磷有大气相" ❌
    磷循环没有气体阶段，储库是岩石。
  • 10% 规则算错起点
    先确认题目给的是哪一级的能量。
  • 只靠温度判断 biome ❌
    必须同时看降水——两条轴缺一不可。
🎯
自查：这六条里，哪一条你刚才还需要想一下？把它写进你的错题本——APES 的分就在这些"差一点"上。
Unit 1 · 21 / 24
词汇引导 · Must-know terms

Unit 1 必背术语（能定义，不是眼熟）

APES 的 3 分和 5 分之间，隔的就是这些词的精确度。

  • resource partitioning — 划分资源以共存
  • mutualism / commensalism / parasitism
  • estuary — 河口，高生产力育幼场
  • sequestration — 碳被长期储存
  • nitrogen fixation / nitrification / denitrification
  • eutrophication — 养分过量 → 藻华 → 缺氧
  • limiting nutrient — 限制生产力的养分
  • GPP / NPP — 总生产 / 净生产
  • trophic cascade — 顶级捕食者引发的连锁反应
  • feedback loop — 正反馈放大 · 负反馈稳定
去哪背
AP 词汇系统 · Vocabap-study.com/vocab→ 在真题里见到这些词context > 孤立背诵→
Unit 1 · 22 / 24
资源总页 · Resources

这一页就够了

按顺序用：先 Khan 补概念 → 再 OCT/Bozeman 加固 → 真题收尾。

视频课
Khan Academy — AP Env. Science与 CED 逐条对齐 · 首选→ Bozeman Science — APES短平快 · 每个 topic 一条→ YouTube — Unit 1 总复习考前冲刺→
官方
College Board — Course page考试结构 · 官方说明→ CED + 官方 FRQAP Central · 最权威→
本站
Past Papers · 真题库15 科 · 1200+ 份→ Vocab · 词汇系统背精确词→ Review · 复习中心所有科目入口→
Unit 1 · 23 / 24
覆盖清单 · Coverage

CED Unit 1 · 11 个 topic 全覆盖

  • 1.1 互动 4 型 + 资源划分 (slide 3)
  • 1.2 九大陆地生物群落 (slide 4)
  • 1.3 淡水 vs 海洋 (slide 5)
  • 1.4 碳循环 · 长短储库 (slide 7)
  • 1.5 氮循环 · 5 步 (slide 8)
  • 1.6 磷循环 · 无气相 (slide 9)
  • 1.7 水循环 (slide 10)
  • 1.8 GPP / NPP (slides 12, 17)
  • 1.9 营养级 (slide 13)
  • 1.10 能量流 + 10% 规则 (slides 14, 17–18)
  • 1.11 食物网 · 反馈 · 级联 (slide 15)
  • 技能 MCQ×2 · FRQ×3 型 · 陷阱 · 词汇 (18–22)
🎓
Unit 1 完成。下一册：Unit 2 — The Living World: Biodiversity（6–8%）：生态耐受、演替、岛屿生物地理学、瓶颈效应。Unit 1 是它的地基。
Unit 1 · 24 / 24
Unit 1 1 / 24 The Living World: Ecosystems