Biology HKDSE English Knowledge Base

Paper 1 (75%) | Paper 2 Elective (25%) | SBA. All definitions follow official HKEAA English wording.

考試結構（2024 官方 Public Assessment）

卷别	Section	題型	比重	時長
Paper 1 必修	A 選擇題	MC（課題 I–IV）	18%	2h30m
	B 短題/結構/論述	同上	42%
Paper 2 選修	—	結構題（4 選 2：E1 人體生理學 / E2 應用生態學 / E3 微生物與人類 / E4 生物工程）	20%	1h
SBA	—	A 實驗技能 (8%) + B 探究報告 (12%)	20%	S5–S6

多数学校选 E1 + E4 或 E1 + E2。作答論述題（essay）須用完整句子成段，禁用 bullet points，並結合圖表/曲線描述數據。

Compulsory Part 四大範疇

I 細胞與生命分子（Cells & Molecules of Life）・II 遺傳與進化（Genetics & Evolution）・III 生物與環境（Organisms & Environment）・IV 健康與疾病（Health & Diseases）

出題三大重心（最多人忽略！）

• NOS（Nature of Science）：科學本質、假說驗證、證據可信度
• STSE（Science, Technology, Society, Environment）：科技對社會環境影響的評價題
• SI（Scientific Enquiry）：設計實驗、控制變量、誤差分析

這三類題佔分不低且易拉開差距，溫習時每個課題都要準備「社會/倫理影響」與「實驗設計」角度的英文句式。

想用題型專練鞏固下面每個課題？練習題庫 Biology 卷見 /question-bank/biology/

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Topic 1 Cell Structure & Life Processes ★★★

Term	Official English Definition	中文注解
Cell	The basic structural and functional unit of living organisms	细胞
Diffusion	Net movement of particles from a region of higher to lower concentration due to random motion	扩散
Osmosis	The net movement of water molecules from a less concentrated to a more concentrated solution through a semi-permeable membrane	渗透（必背三关键词）
Active transport	Movement of substances across a membrane against a concentration gradient using energy (ATP)	主动运输

HKEAA 核心定義雙塊（Diffusion / Osmosis / Active transport / Facilitated diffusion）★

diffusion（擴散）★

① HKEAA Official Definition（原版英文，一字不改）

The net movement of particles (molecules or ions) from a region of higher concentration to a region of lower concentration down a concentration gradient, as a result of their random movement.

② 中文對照簡答句

擴散（diffusion）：粒子因隨機運動，沿濃度梯度由高濃度區淨移動至低濃度區，直至分佈均勻。

osmosis（滲透）★

① HKEAA Official Definition（原版英文，一字不改）

The net movement of water molecules from a region of lower solute concentration to a region of higher solute concentration through a partially permeable membrane.

② 中文對照簡答句

滲透（osmosis）：水份子穿過半透膜，由低溶質濃度溶液淨移動至高分子濃度溶液的過程。

active transport（主動運輸）★

① HKEAA Official Definition（原版英文，一字不改）

The movement of substances across a cell membrane against a concentration gradient, using energy released from respiration (ATP) and carrier proteins.

② 中文對照簡答句

主動運輸（active transport）：物質逆濃度梯度穿過細胞膜，需載體蛋白並消耗呼吸作用釋出的能量（ATP）。

facilitated diffusion（協助擴散）★

① HKEAA Official Definition（原版英文，一字不改）

The passive movement of molecules across a cell membrane down a concentration gradient, through carrier proteins or channel proteins, without the use of energy.

② 中文對照簡答句

協助擴散（facilitated diffusion）：分子順濃度梯度、經載體或通道蛋白穿過細胞膜，不消耗能量（仍屬被動運輸）。

** osmosis 陷阱**：水从"less concentrated solution" 流向 "more concentrated solution"（按溶质浓度，不是水浓度！）。

Organelles（识图必考）

• Nucleus: controls cell activities, contains genetic material (DNA)
• Mitochondrion: site of aerobic respiration, ATP production
• Ribosome: site of protein synthesis
• Chloroplast: site of photosynthesis (only plants/algae)
• Cell wall (plant): made of cellulose, gives support

How it works — Core Mechanism ★

Diffusion and osmosis need no energy — they rely on the random motion of particles moving from where they are more crowded (higher concentration) to where they are less crowded (lower concentration) until evenly spread. Active transport is different: it uses ATP to push substances the "wrong way", against their concentration gradient. This is why root hair cells can absorb mineral ions from dilute soil, and why it stops if respiration is blocked (no ATP).

Worked Example — Osmosis Data-analysis ★

Experiment: Equal potato strips placed in sucrose solutions of
increasing concentration. % mass change after 1 h recorded.

Solution (mol dm⁻³) | % mass change
0.0  (pure water)   | +18%
0.2                 | +9%
0.4                 | 0%
0.6                 | −7%
0.8                 | −14%

Step 1: At 0.0 M the solution is HYPOTONIC to the cell sap → water
        ENTERS by osmosis → cells become turgid → strip gains mass (+18%).
Step 2: At 0.4 M, % change = 0 → NO NET MOVEMENT of water.
        This is the ISOTONIC point ≈ concentration of the cell sap.
Step 3: At 0.6–0.8 M the solution is HYPERTONIC → water LEAVES the
        cells → plasmolysis → mass falls (−7%, −14%).

Scoring keywords: hypotonic / hypertonic / isotonic; water enters /
leaves by osmosis; net movement = 0 at the isotonic point.

Common Trap ★

Never say "water moves from high to low concentration". Here concentration means SOLUTE concentration. Water moves from the LESS concentrated solution (low solute) to the MORE concentrated solution (high solute) — i.e. towards the higher solute side. Correct phrase: "Water enters the cell by osmosis because the cell sap is more concentrated than the surrounding solution."

Cell Structure Diagram（細胞結構圖解，必考 label + function）★

Animal cell 標註（無 cell wall / chloroplast / 大液泡）

• Cell membrane (細胞膜)：phospholipid bilayer；controls entry and exit of substances.
• Cytoplasm (細胞質)：jelly-like；site of many metabolic reactions.
• Nucleus (細胞核)：bounded by nuclear envelope with pores；contains chromatin (DNA + protein)；controls all cell activities.
• Mitochondrion (線粒體)：double membrane，inner membrane folded into cristae；site of aerobic respiration，ATP production.
• Ribosome (核糖體)：tiny，free or on rough ER；site of protein synthesis.
• Rough ER (糙面內質網)：studded with ribosomes；transports and processes proteins.
• Smooth ER (滑面內質網)：no ribosomes；lipid and steroid synthesis.
• Golgi body / apparatus (高爾基體)：modifies，sorts and packages proteins into vesicles for secretion.

Plant cell 額外結構

• Cell wall (細胞壁)：outside the membrane，made of cellulose；rigid support and shape.
• Chloroplast (葉綠體)：contains chlorophyll；site of photosynthesis；has its own DNA.
• Permanent vacuole (液泡)：large fluid-filled sac；keeps cell turgid by pushing cytoplasm against the wall.

評卷提示：label 題一定要寫該結構的 specific function，例如 "mitochondrion — site of aerobic respiration where ATP is produced"，不要只寫 "produces energy"。

Worked Example 1.2 — Active Transport (6 marks)

Scenario: A root hair cell absorbs nitrate ions (NO₃⁻) from dilute
soil where the soil solution is LESS concentrated than the cell sap.
Step 1: nitrate ions move FROM a dilute (low) TO a more concentrated
        (high) solution = AGAINST the concentration gradient.  (2 marks)
Step 2: this needs specific CARRIER PROTEINS in the membrane AND
        energy in the form of ATP from respiration.              (2 marks)
Step 3: it is therefore ACTIVE TRANSPORT. It STOPS if the cell is
        poisoned (respiration blocked → no ATP).                 (2 marks)
Scoring keywords: against gradient; carrier protein; ATP / energy
from respiration; stops without ATP.

Worked Example 1.3 — Diffusion Rate & Factors (5 marks)

Data: A dye tablet is dropped into water at two temperatures.
At 20°C the colour spreads across the beaker in 8 min.
At 50°C the colour spreads across the beaker in 3 min.
Step 1: higher temperature → particles have MORE KINETIC ENERGY →
        move and collide more often → FASTER diffusion.      (2 marks)
Step 2: diffusion is also faster with a LARGER surface area, a
        SHORTER diffusion distance, and a STEEPER concentration
        gradient.                                            (2 marks)
Step 3: diffusion needs NO energy (passive) and stops when the
        concentration is EQUAL everywhere (equilibrium).      (1 mark)
Scoring: kinetic energy / faster particle motion; three factors;
no energy needed; equilibrium.

實驗 1.E1 — 洋蔥表皮細胞觀察（Light microscope，必做 practical）

• Aim 目的：to observe the structure of a plant cell and the effect of a hypertonic solution.
• Method 方法：
  1. Peel a thin layer of epidermis from the inside of an onion scale.
  2. Place it in a drop of water on a slide; add iodine stain; cover with a cover slip.
  3. Observe under low power then high power; draw ONE representative cell with labels.
  4. Place a drop of concentrated sucrose solution at the edge of the cover slip; observe.
• Result 結果：normal cells show a stained nucleus and a clear cell wall; after sucrose the cytoplasm shrinks and pulls away from the wall (plasmolysis).
• Conclusion 結論：plant cells are enclosed by a rigid cell wall; in a hypertonic solution water leaves by osmosis, so the membrane and cytoplasm shrink from the wall.

實驗 1.E2 — Visking tubing 半透膜選擇性（Selectively permeable membrane）

• Aim 目的：to show that a membrane lets small molecules (glucose) pass but blocks large molecules (starch).
• Method 方法：
  1. Fill Visking tubing with a starch + glucose mixture; tie both ends.
  2. Suspend it in a beaker of water; label the water outside.
  3. After 30 min, test the OUTSIDE water for glucose (Benedict's test) and for starch (iodine test).
• Result 結果：Benedict's test on the outside water is POSITIVE (glucose diffused out); iodine test on the outside water is NEGATIVE (no starch outside).
• Conclusion 結論：the Visking membrane is SELECTIVELY PERMEABLE — small glucose molecules pass through, but large starch molecules cannot.

再練滲透與主動運輸，見 /question-bank/biology/

本單元易錯專業詞彙：mitochondrion（單數不是 mitochondria 當單數）、phospholipid、chloroplast、occurred（雙 r）、separate（不是 seperate）

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Topic 2 Nutrition & Respiration ★★★

Photosynthesis

6CO₂ + 6H₂O —[light / chlorophyll]→ C₆H₁₂O₆ + 6O₂

• Light stage: occurs in thylakoid, produces ATP, NADPH, O₂
• Dark stage (Calvin cycle): occurs in stroma, fixes CO₂ using ATP/NADPH

标准句式：Photosynthesis takes place in the chloroplast; light energy is absorbed by chlorophyll and converted into chemical energy stored in glucose.

Aerobic vs Anaerobic Respiration

	Aerobic	Anaerobic
Equation (glucose)	C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + energy	C₆H₁₂O₆ → 2C₂H₅OH + 2CO₂ + energy (plants/yeast)
Site	cytoplasm + mitochondrion	cytoplasm only
ATP yield	large (≈38 ATP)	small
End product (human muscle)	—	lactic acid

HKEAA 核心定義雙塊（Photosynthesis / Aerobic / Anaerobic respiration）★

photosynthesis（光合作用）★

① HKEAA Official Definition（原版英文，一字不改）

The process by which green plants and some other organisms use light energy to synthesize organic compounds (glucose) from carbon dioxide and water, releasing oxygen as a by-product.

② 中文對照簡答句

光合作用（photosynthesis）：綠色植物等利用光能，把二氧化碳和水合成有機物（葡萄糖）並釋出氧氣的過程。

aerobic respiration（有氧呼吸）★

① HKEAA Official Definition（原版英文，一字不改）

The release of energy from glucose (or other organic substrates) in the presence of oxygen, producing carbon dioxide, water and a large amount of ATP.

② 中文對照簡答句

有氧呼吸（aerobic respiration）：在氧氣存在下釋放葡萄糖中的能量，產生二氧化碳、水和大量 ATP。

anaerobic respiration（無氧呼吸）★

① HKEAA Official Definition（原版英文，一字不改）

The release of energy from glucose (or other organic substrates) in the absence of oxygen, producing a small amount of ATP and an organic end product such as lactic acid (in animals) or ethanol and carbon dioxide (in plants and yeast).

② 中文對照簡答句

無氧呼吸（anaerobic respiration）：在缺氧下釋放葡萄糖中的能量，只產生少量 ATP，終產物為乳酸（動物）或乙醇與二氧化碳（植物／酵母）。

• Breathing rate & heart rate rise during exercise to supply more O₂ and remove CO₂/lactic acid
• Lactic acid removed by oxidation in liver or converted back to glucose

How it works — Core Mechanism ★

Photosynthesis stores light energy as chemical energy in glucose; respiration releases that stored energy as ATP for cell work. The two are linked: the O₂ and glucose made in photosynthesis are the raw materials of aerobic respiration, while the CO₂ and H₂O from respiration feed back into photosynthesis. Breathing merely supplies O₂ and removes CO₂ — it is the gas exchange, not the chemical release of energy.

Worked Example — Enzyme Activity vs Temperature ★

Data: Enzyme activity (% of maximum) at different temperatures.
0°C  : 10%
20°C : 55%
37°C : 100%   ← optimum
50°C : 40%
70°C : 5%

Step 1 (0–37°C, rising): higher temperature → more KINETIC ENERGY →
        more frequent successful enzyme–substrate collisions → activity RISES.
Step 2 (37°C): OPTIMUM temperature, maximum rate for a human enzyme.
Step 3 (37–70°C, falling): above optimum the enzyme DENATURES — the
        active site changes SHAPE, substrate no longer fits → activity FALLS sharply.

Scoring keywords: kinetic energy / collision frequency; optimum;
denature / active site / shape change.

Common Trap ★

Do NOT write "respiration makes energy". Energy is not created — respiration releases energy from glucose and stores it in ATP. Also "breathing is respiration" is wrong: breathing is the mechanical exchange of gases; respiration is the chemical release of energy in cells. Use "respiration releases energy / produces ATP".

Leaf & Chloroplast Diagram（葉與葉綠體圖解）★

Cross-section of a leaf (label + function)

• Cuticle (角質層)：waxy；reduces water loss.
• Upper epidermis (上表皮)：transparent；lets light through.
• Palisade mesophyll (柵狀葉肉)：columnar cells packed with chloroplasts；main photosynthesis site.
• Spongy mesophyll (海綿葉肉)：loose cells with air spaces；gas exchange.
• Lower epidermis (下表皮)：contains guard cells and stomata.
• Stoma / stomata (氣孔)：pore controlled by guard cells；CO₂ in, O₂ and water vapour out.
• Xylem (木質部)：transports water and minerals up.
• Phloem (韌皮部)：transports sugars away.

Chloroplast 內部：thylakoid (類囊體，light stage，含 chlorophyll) + stroma (基質，dark / Calvin stage)。

Worked Example 2.2 — Anaerobic Respiration in Yeast (5 marks)

Scenario: Yeast is grown in a sealed tube with glucose and no O₂.
Step 1: without O₂, yeast carries out ANAEROBIC respiration:
        C₆H₁₂O₆ → 2C₂H₅OH + 2CO₂ + (small) energy.      (2 marks)
Step 2: products are ETHANOL (alcohol) and CARBON DIOXIDE;
        ATP yield is SMALL compared with aerobic respiration.
                                                              (2 marks)
Step 3: this is FERMENTATION, used in baking (CO₂ makes dough
        rise) and brewing (ethanol produced).                (1 mark)
Scoring: equation; ethanol + CO₂; small ATP; fermentation use.

Worked Example 2.3 — Limiting Factors of Photosynthesis (6 marks)

Data: rate of photosynthesis at different light intensity (CO₂, temp constant).
Low light → low rate; raising light ↑ rate; at high light, raising
CO₂ ↑ rate further; at high light + high CO₂, raising temp ↑ rate.
Step 1: when light is low, LIGHT is the LIMITING FACTOR.  (2 marks)
Step 2: once light is high, CO₂ becomes limiting until raised;
        then TEMPERATURE (enzyme activity) becomes limiting. (2 marks)
Step 3: a factor is "limiting" when it is in SHORTEST SUPPLY;
        raising it alone increases rate until another becomes
        limiting.                                           (2 marks)
Scoring: identify limiting factor at each stage; definition of
"limiting factor".

實驗 2.E1 — 水生植物放氧（Pondweed O₂ collection）

• Aim 目的：to show that light intensity affects the rate of photosynthesis.
• Method 方法：
  1. Place pondweed in a funnel in water; collect gas in an inverted tube.
  2. Put a light at a measured distance; count bubbles / measure O₂ volume per min.
  3. Repeat at increasing distances (lower light intensity).
• Result 結果：closer light → more O₂ per minute; farther light → less O₂.
• Conclusion 結論：light intensity limits photosynthesis; higher light → higher rate (until another factor limits).

實驗 2.E2 — 發芽種子呼吸（Germinating seeds, CO₂ / heat production）

• Aim 目的：to show that respiring seeds release CO₂ and heat.
• Method 方法：
  1. Put germinating seeds in a flask; lead the air through limewater.
  2. Keep a parallel flask with boiled (dead) seeds as control.
  3. Measure temperature inside each flask.
• Result 結果：limewater turns milky (CO₂ present) for live seeds; temperature rises; control shows nothing.
• Conclusion 結論：living seeds respire, producing CO₂ and releasing heat (exothermic).

呼吸與光合作用數據題，見 /question-bank/biology/

本單元易錯專業詞彙：photosynthesis（不是 photosythesis）、respiration（不是 resparation）、occurred（雙 r）、necessary（雙 s 雙 r）、gaseous

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Topic 3 Transport in Humans ★★

• Red blood cells: contain haemoglobin, transport O₂; no nucleus (more space for Hb)
• Double circulation: pulmonary (heart ↔ lung) + systemic (heart ↔ body)
• Artery vs Vein vs Capillary: artery has thick muscular wall, vein has valves
• Blood clot: platelets + fibrin; function = prevent excessive blood loss

How it works — Core Mechanism ★

Blood is the transport medium; the heart is a pump that creates pressure driving blood through two circuits. In pulmonary circulation blood is pumped to the lungs to pick up O₂ and drop CO₂; in systemic circulation it is pumped to the whole body to deliver O₂ and nutrients. Arteries carry blood away from the heart under high pressure (thick walls, no valves); veins return it under low pressure and need valves to stop backflow. Capillaries are thin-walled for exchange.

Worked Example — Heart Rate Data-analysis ★

Data: Resting heart rate = 70 bpm. After 3 min exercise = 140 bpm.
Two minutes after stopping = 80 bpm.

Step 1: Exercise ↑ → muscles need MORE ATP → more AEROBIC RESPIRATION
        → need MORE O₂ and must remove MORE CO₂ / lactic acid.
Step 2: Heart rate RISES to pump blood faster (more O₂ delivered,
        more waste removed) — this is why breathing also speeds up.
Step 3: After stopping, demand falls, heart rate SLOWLY returns to resting
        as O₂ debt / lactic acid is cleared.

Scoring keywords: more O₂ / more ATP; remove CO₂ / lactic acid;
heart pumps faster; gradual recovery.

Common Trap ★

"Veins always carry deoxygenated blood" is FALSE — the pulmonary vein carries OXYGENATED blood from lung to heart. Rule: arteries carry blood AWAY from the heart, veins carry TOWARDS the heart; oxygen level depends on the circuit. Also: RBCs have NO nucleus to maximise space for haemoglobin, so "RBC has a nucleus" is wrong.

Heart & Circulation Diagram（心臟與循環圖解）★

Human heart labels (label + function)

• Right atrium (右心房)：receives deoxygenated blood from body via vena cava.
• Right ventricle (右心室)：pumps deoxygenated blood to lungs via pulmonary artery.
• Left atrium (左心房)：receives oxygenated blood from lungs via pulmonary vein.
• Left ventricle (左心室)：pumps oxygenated blood to whole body via aorta; thickest wall (highest pressure).
• Vena cava (大靜脈)：returns body blood to right atrium.
• Pulmonary artery (肺動脈)：carries deoxygenated blood to lungs (exception!).
• Pulmonary vein (肺靜脈)：carries oxygenated blood from lungs (exception!).
• Aorta (主動脈)：carries oxygenated blood to body.
• Valves (瓣)：prevent backflow; atrioventricular + semilunar valves.

記憶口訣：artery = AWAY from heart；vein = TOWARDS heart。氧合與否看 circuit，不看血管名。

Worked Example 3.2 — Path of a Red Blood Cell (6 marks)

Trace ONE red blood cell from the right ventricle to the left atrium.
Step 1: right ventricle → PULMONARY ARTERY → lung capillaries,
        where it RELEASES CO₂ and picks up O₂.            (2 marks)
Step 2: oxygenated cell → PULMONARY VEIN → LEFT ATRIUM.  (2 marks)
Step 3: this is PULMONARY circulation (heart → lung → heart);
        the cell has now become OXYGENATED.               (2 marks)
Scoring: pulmonary artery; gas exchange in lung; pulmonary vein;
oxygenated; name the circuit.

Worked Example 3.3 — Artery / Vein / Capillary Comparison (5 marks)

Complete the comparison for a STRUCTURED question.
Artery: thick MUSCULAR wall, narrow lumen, NO valves, HIGH pressure,
        carries blood AWAY from heart.
Vein:   thin wall, wide lumen, HAS valves, LOW pressure, carries
        blood TOWARDS heart.
Capillary: ONE cell thick wall, very narrow, site of EXCHANGE
           between blood and tissues.
Step scoring (5 marks): one correct property per vessel type, or
a complete table row for each.

實驗 3.E1 — 脈搏與運動（Pulse rate vs exercise）

• Aim 目的：to investigate how exercise affects pulse (heart) rate.
• Method 方法：
  1. Measure resting pulse for 1 min; record.
  2. Do 3 min stepping exercise; measure pulse immediately after.
  3. Re-measure every 2 min during recovery until resting level.
• Result 結果：pulse rises during exercise, then gradually returns to resting.
• Conclusion 結論：exercise ↑ demand for O₂ / ATP → heart beats faster; recovery as O₂ debt cleared.

循環與血壓題，見 /question-bank/biology/

本單元易錯專業詞彙：haemoglobin（HKDSE 多拼 haem-）、occurred（雙 r）、separate（不是 seperate）、necessary（雙 s 雙 r）

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Topic 4 Coordination & Response ★★★

Term	Official English Definition
Stimulus	A change in the external or internal environment that can be detected
Reflex	A rapid, automatic, involuntary response to a stimulus
Hormone	A chemical messenger secreted by an endocrine gland into the blood

HKEAA 核心定義雙塊（Homeostasis）★

homeostasis（體內平衡）★

① HKEAA Official Definition（原版英文，一字不改）

The maintenance of a relatively stable internal environment despite changes in external conditions, achieved by negative feedback control.

② 中文對照簡答句

體內平衡（homeostasis）：在外界環境變化下，透過負回饋機制維持體內環境相對穩定的狀態。

Reflex arc 顺序（必背）：receptor → sensory neurone → relay neurone (spinal cord) → motor neurone → effector。 Homeostasis 实例：blood glucose regulation by insulin (↓) and glucagon (↑)。

How it works — Core Mechanism ★

Coordination lets the body detect changes (stimuli) and respond to keep conditions stable. Nervous response is fast and short-lived (electrical impulses along neurones); hormonal response is slower but longer-lasting (chemicals carried by blood). Homeostasis uses NEGATIVE FEEDBACK: a receptor detects a deviation, the body triggers a response that reverses it, and the response switches off once the set point is restored — exactly like a room thermostat.

Worked Example — Blood Glucose Negative Feedback ★

Scenario: After a meal, blood glucose rises to 9 mmol/L (normal ≈ 5).
Step 1: pancreas DETECTS high glucose → secretes INSULIN.
Step 2: insulin makes liver & muscle cells take up glucose and store it
        as GLYCOGEN → blood glucose FALLS.
Step 3: when back near 5, insulin secretion STOPS (negative feedback).
        If glucose too LOW → glucagon secreted → glycogen → glucose (rise).

Scoring keywords: detect high glucose; insulin; glucose → glycogen;
negative feedback / returns to set point.

Common Trap ★

A reflex is INVOLUNTARY and bypasses the brain (spinal cord only) — do not say "the brain decides". Also do not confuse: insulin lowers glucose, glucagon raises it. "Hormones are produced by nerves" is wrong — hormones come from endocrine glands, not neurones.

Reflex Arc & Neurone Diagram（反射弧與神經元圖解）★

Reflex arc 順序（必背，label each） receptor (受器) → sensory neurone (感覺神經元) → relay neurone (聯絡神經元, in spinal cord) → motor neurone (運動神經元) → effector (動器, muscle / gland).

• Sensory neurone: LONG axon from receptor to cord; ONE dendron.
• Relay neurone: short, many connections in CNS.
• Motor neurone: LONG axon from cord to effector; many dendrites.
• Synapse (突觸)：junction between neurones; impulse crosses by neurotransmitter (chemical), one-way only.

Worked Example 4.2 — Nervous vs Hormonal (6 marks)

Compare the two coordination systems for a STRUCTURED question.
Nervous:
 - transmission: ELECTRICAL impulse along neurones
 - speed: FAST, response rapid
 - duration: SHORT-lived
 - target: precise (specific effector)
Hormonal:
 - transmission: CHEMICAL (hormone) in BLOOD
 - speed: SLOWER
 - duration: LONG-lasting
 - target: widely distributed (any cell with receptor)
Step scoring (6 marks): at least three correct contrasting points,
one per row or paired statement.

Worked Example 4.3 — Thermoregulation Negative Feedback (5 marks)

On a hot day, body temperature tends to rise. Explain control.
Step 1: skin receptors DETECT rise in temperature.          (1 mark)
Step 2: hypothalamus (thermoregulatory centre) coordinates
        a response.                                         (1 mark)
Step 3: EFFECTORS respond: sweat glands release sweat
        (evaporation cools); blood vessels DILATE (vasodilation)
        to lose heat at skin surface.                       (2 marks)
Step 4: temperature returns to set point → response switches
        OFF (negative feedback).                            (1 mark)
Scoring: detect; hypothalamus; sweat + vasodilation; feedback off.

實驗 4.E1 — 簡單反射反應時（Reaction time / knee-jerk）

• Aim 目的：to measure a simple reflex response time.
• Method 方法：
  1. Subject holds ruler; another drops it without warning.
  2. Subject catches; distance fallen → reaction time.
  3. Repeat with eyes closed / after distraction.
• Result 結果：reaction is faster with attention; distraction slows it.
• Conclusion 結論：reflexes are rapid involuntary responses processed via the reflex arc; attention modulates speed.

神經與內分泌比較題，見 /question-bank/biology/

本單元易錯專業詞彙：neurone（HKDSE 英式拼法，不是 neuron）、receptor、necessary（雙 s 雙 r）、occurred（雙 r）

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Topic 5 Genetics & Evolution ★★★

Term	Official English Definition	中文注解
Gene	A short length of DNA that codes for a polypeptide	基因
Allele	One of the alternative forms of a gene	等位基因
Genotype / Phenotype	Genetic makeup / observable characteristics	基因型 / 表现型
Homozygous / Heterozygous	Two identical / different alleles	纯合 / 杂合
Dominant epistasis etc.	—	遗传题按 Punnett square 推导

HKEAA 核心定義雙塊（Gene / Allele / Allele frequency / Natural selection）★

gene（基因）★

① HKEAA Official Definition（原版英文，一字不改）

A short length of DNA that codes for a polypeptide (or a functional RNA molecule).

② 中文對照簡答句

基因（gene）：一段編碼多肽（或功能性 RNA）的 DNA 序列。

allele（等位基因）★

① HKEAA Official Definition（原版英文，一字不改）

One of a number of alternative forms of a gene that arise by mutation and are found at the same locus on homologous chromosomes.

② 中文對照簡答句

等位基因（allele）：同一基因座上、由突變產生的不同版本，決定同一性狀的不同表現。

allele frequency（等位基因頻率）★

① HKEAA Official Definition（原版英文，一字不改）

The proportion of a particular allele among all the alleles of that gene in a population, usually expressed as a decimal or percentage.

② 中文對照簡答句

等位基因頻率（allele frequency）：某特定等位基因佔群體中該基因所有等位基因總數的比例。

natural selection（自然選擇）★

① HKEAA Official Definition（原版英文，一字不改）

The process by which individuals with advantageous heritable characteristics survive and reproduce more successfully, so the frequency of those advantageous alleles in the population increases over generations.

② 中文對照簡答句

自然選擇（natural selection）：具有利遺傳特徵的個體存活與繁殖較成功，使有利等位基因頻率在群體中逐代上升。

Monohybrid cross 步骤：确定亲本基因型 → 写出配子 → Punnett square → 表型比（3:1 显性纯/杂:隐性）。 Meiosis vs Mitosis：

	Mitosis	Meiosis
Daughter cells	2, diploid, identical	4, haploid, genetically different
Purpose	Growth & repair	Gamete formation

Natural selection: variation → selection pressure → survival of fittest → advantageous alleles increase in frequency。

How it works — Core Mechanism ★

Genes are stretches of DNA that code for polypeptides; alleles are alternative versions that create variation. Mitosis copies cells for growth (identical, diploid); meiosis halves the chromosome number to make genetically different gametes (haploid) — this is the source of genetic variation. Inheritance is a matter of chance: each parent gives one allele per gene, and a Punnett square predicts the probability of each offspring genotype, not a guaranteed outcome.

Monohybrid Cross — Full Punnett Square ★

Cross: Tall (T) is dominant over dwarf (t).
Parent phenotypes:  Tall  ×  Tall
Parent genotypes:    Tt   ×   Tt     (both heterozygous)

Gametes from EACH parent:  T  or  t

           T        t
        ----------------
   T  |   TT   |   Tt   |
        ----------------
   t  |   Tt   |   tt   |
        ----------------

Genotypes : TT : Tt : tt  =  1 : 2 : 1
Phenotypes: Tall : Dwarf  =  3 : 1
(3 tall because TT and Tt both show the dominant T; 1 dwarf = tt)

Scoring: show the two gametes per parent, fill the square correctly,
state the 3:1 phenotypic ratio AND explain why (dominant expressed).

Test Cross — Concept & Use ★

TEST CROSS = cross the unknown phenotype (showing the DOMINANT trait)
with a HOMOZYGOUS RECESSIVE individual (tt).

Purpose: to find the UNKNOWN GENOTYPE of the dominant-showing individual.
- If ALL offspring show the dominant trait  → unknown was TT (homozygous).
- If ≈ 1 : 1 dominant : recessive          → unknown was Tt (heterozygous).

Used by plant/animal breeders to confirm whether stock is pure-breeding
(homozygous) before mass propagation.

Worked Example — Ratio from Data ★

Data: Two grey mice are crossed; 192 offspring = 145 grey, 47 white.
Step 1: both parents are grey yet WHITE appears → grey is DOMINANT,
        white is RECESSIVE, so BOTH parents must be HETEROZYGOUS (Gg).
Step 2: ratio 145 : 47 ≈ 3 : 1 → confirms a monohybrid cross Gg × Gg.
Step 3: white offspring must be gg (each received g from both parents).

Scoring: dominant/recessive correctly identified; parents heterozygous;
state and justify the 3:1 ratio.

Common Trap ★

"Meiosis produces identical cells" is wrong — meiosis produces FOUR genetically different haploid cells. A dominant allele does NOT mean "more common" — dominant only means it is expressed over the recessive allele. Never say "gene produces the trait"; say "gene codes for a polypeptide that determines the trait". Also the 3:1 ratio is a PROBABILITY, not a fixed count in small families.

DNA & Chromosome Diagram（DNA 與染色體圖解）★

DNA double helix (label + function)

• Sugar-phosphate backbone (糖-磷酸骨架)：forms the sides of the ladder.
• Base pairs (鹼基對)：A–T, C–G held by weak HYDROGEN bonds; carry the code.
• Two antiparallel strands; sequence of bases = genetic code. Chromosome：DNA wound around histone proteins; in mitosis visible as duplicated chromatids joined at centromere.

Worked Example 5.2 — Dihybrid Cross (8 marks)

Cross: Round (R) dominant to wrinkled (r); Yellow (Y) dominant to
green (y). Parents: RRYY × rryy → F1 all RrYy (round yellow).
Cross F1 × F1 (RrYy × RrYy):
Gametes from each: RY, Ry, rY, ry  (4 types, independent assortment)
Phenotypic ratio = 9 round yellow : 3 round green : 3 wrinkled
yellow : 1 wrinkled green.
Step 1: each gene segregates 3:1; two genes assort INDEPENDENTLY
        (different chromosomes) → 9:3:3:1.                  (3 marks)
Step 2: show a 4×4 Punnett square OR state gamete types.    (3 marks)
Step 3: identify the 1/16 double-recessive class (rryy).    (2 marks)
Scoring: 9:3:3:1; independent assortment; correct gamete set.

Worked Example 5.3 — Sex-linked Inheritance (Red-green colour blindness) (6 marks)

Colour blindness is X-linked RECESSIVE (Xᶜ). A carrier female
(XᴮXᶜ) marries a normal male (XᴮY).
Gametes female: Xᴮ or Xᶜ ; male: Xᴮ or Y.
Offspring:
 XᴮXᴮ (normal female), XᴮXᶜ (carrier female),
 XᴮY (normal male),   XᶜY (colour-blind male).
Step 1: sons get their X from MOTHER only → 50% of sons blind.
                                                              (2 marks)
Step 2: daughters get father's Xᴮ → none blind, 50% carriers.
                                                              (2 marks)
Step 3: trait is MORE common in MALES because they have one X
        (no second normal allele to mask it).                (2 marks)
Scoring: son 50% ; daughter carrier 50% ; male bias explained.

Worked Example 5.4 — Mutation & Natural Selection (5 marks)

Scenario: a population of beetles has mostly green forms; a few
are brown. Birds eat more green beetles on brown soil.
Step 1: brown colour arose by RANDOM MUTATION (gene change).
                                                              (1 mark)
Step 2: on brown soil, brown beetles are BETTER CAMOUFLAGED →
        survive and reproduce MORE (selection pressure).     (2 marks)
Step 3: over generations the BROWN allele FREQUENCY rises in
        the population = EVOLUTION by natural selection.     (2 marks)
Scoring: mutation source; selection advantage; allele frequency
rise = evolution.

實驗 5.E1 — 模型生物遺傳（Model organism cross, e.g. Drosophila / seed）

• Aim 目的：to verify Mendelian ratios by crossing model organisms.
• Method 方法：
  1. Cross pure-breeding parents differing in one or three trait(s).
  2. Grow F1; self- or inter-cross F1 to get F2.
  3. Count phenotypes; compare with predicted 3:1 or 9:3:3:1.
• Result 結果：observed counts approximate predicted ratios (large sample).
• Conclusion 結論：traits assort according to Mendel's laws; large samples reduce chance error.

遺傳題專練（Punnett / test cross），見 /question-bank/biology/

本單元易錯專業詞彙：allele（雙 l）、genotype、phenotype、occurred（雙 r）、separate（不是 seperate）

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Topic 6 Ecosystem & Environment ★★

• Ecosystem = community + abiotic environment
• Trophic levels: producer → primary consumer → secondary consumer → tertiary consumer
• Energy transfer efficiency ≈ 10% between trophic levels (most lost as heat)
• Biomass pyramid: producers base widest
• Pollution & conservation: eutrophication (excess N/P → algal bloom → O₂ depletion); greenhouse effect; biodiversity conservation

HKEAA 核心定義雙塊（Ecosystem / Trophic level）★

ecosystem（生態系統）★

① HKEAA Official Definition（原版英文，一字不改）

A community of living organisms (biotic components) together with the non-living (abiotic) components of their environment, interacting as a system.

② 中文對照簡答句

生態系統（ecosystem）：生物群落（生物成分）與非生物環境（非生物成分）相互作用所構成的系統。

trophic level（營養級）★

① HKEAA Official Definition（原版英文，一字不改）

The position occupied by an organism in a food chain, determined by its feeding relationship (e.g. producer, primary consumer, secondary consumer).

② 中文對照簡答句

營養級（trophic level）：生物在食物鏈中所處的階層，由其攝食關係決定（如生產者、初級消費者）。

How it works — Core Mechanism ★

Energy flows one way through an ecosystem: producers capture sunlight and turn it into biomass, consumers eat and pass on only about 10% of that energy to the next level (the rest is lost as heat in respiration and as undigested matter). Because so little is transferred, food chains rarely exceed four or five trophic levels, and biomass pyramids are bottom-heavy. Unlike energy, materials (C, N, water) are recycled, not lost.

Worked Example — Energy Flow Data-analysis ★

Data: Energy available at each trophic level (kJ m⁻² yr⁻¹)
Producers           : 100 000
Primary consumers   :  10 000
Secondary consumers :   1 000
Tertiary consumers  :     100

Step 1: 10 000 / 100 000 = 10% transfer efficiency (level 1 → 2).
Step 2: only ~10% is transferred; ~90% is LOST as heat (respiration),
        undigested material, and uneaten parts.
Step 3: little energy remains at the top → few organisms can be supported
        → pyramid narrows and long food chains are impossible.

Scoring: calculate 10%; state energy lost as heat; link to pyramid shape
and small top-level population.

Common Trap ★

"Energy is recycled in an ecosystem" is FALSE — energy flows and is lost as heat; only MATERIALS (C, N, water) are cycled. Do not say "producers eat consumers" — producers make their own food by photosynthesis; they are not consumers. Also: the 10% rule is an approximation, so "exactly 10%" phrasing is safer than "always 10%".

Energy Pyramid & Food Web Diagram（能量金字塔與食物網圖解）★

Energy / biomass pyramid

• Base = PRODUCERS (widest, most energy).
• Each level UP loses ~90% as heat → levels get narrower.
• Top carnivore = smallest biomass / fewest individuals. Food web shows interlocking food chains; removal of one species can cascade (trophic cascade).

Worked Example 6.2 — Eutrophication Sequence (6 marks)

Farm fertiliser (nitrates) washes into a lake after heavy rain.
Step 1: excess NUTRIENTS (N, P) stimulate massive ALGAL BLOOM
        on the surface.                                      (2 marks)
Step 2: algae die; DECOMPOSERS (bacteria) break them down,
        using up DISSOLVED OXYGEN in respiration.            (2 marks)
Step 3: low O₂ → fish and aerobic organisms DIE; the lake
        becomes a "dead" zone. = EUTROPHICATION.             (2 marks)
Scoring: nutrient input; algal bloom; decomposers use O₂; fish die.

Worked Example 6.3 — Biomagnification (5 marks)

DDT is sprayed on crops; it does not break down.
Step 1: small amount enters PRODUCERS, then builds up in each
        consumer level (not excreted).                      (2 marks)
Step 2: top predators (eagle) accumulate the HIGHEST
        concentration = BIOMAGNIFICATION.                    (2 marks)
Step 3: this can cause thinning of eggshells / population
        crash at the top.                                   (1 mark)
Scoring: accumulation up levels; highest at top; harmful effect.

實驗 6.E1 — 樣方與樣帶（Quadrat & transect, biodiversity）

• Aim 目的：to estimate species abundance along a gradient.
• Method 方法：
  1. Place a quadrat at regular intervals along a transect line.
  2. Count / identify species inside; record abundance (e.g. % cover).
  3. Repeat; calculate mean for each species.
• Result 結果：species composition changes along the gradient (e.g. shore).
• Conclusion 結論：distribution reflects abiotic factors (light, moisture, salinity).

實驗 6.E2 — 污染水溶氧（Dissolved O₂ vs organic pollution）

• Aim 目的：to test whether a water sample is organically polluted.
• Method 方法：
  1. Collect water from upstream and downstream of a discharge.
  2. Measure dissolved O₂ (e.g. Winkler titration) at each site.
• Result 結果：downstream O₂ is lower (decomposers consume it).
• Conclusion 結論：low O₂ indicates organic pollution supporting heavy bacterial growth.

生態能量流與污染題，見 /question-bank/biology/

本單元易錯專業詞彙：ecosystem、trophic、gaseous、necessary（雙 s 雙 r）、occurred（雙 r）

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Topic 7 Human Physiology & Health ★★

• Immunity: non-specific (skin, phagocytes) vs specific (lymphocytes, antibodies)
• Antibody = protein produced by plasma cells that binds specifically to an antigen
• Vaccination: introduces harmless antigen → memory cell formation → faster secondary response
• Drug abuse / pathogens: HIV attacks T-lymphocytes, weakens immunity

How it works — Core Mechanism ★

The immune system has two lines of defence. Non-specific defence (skin, mucus, phagocytes) blocks or eats any pathogen indiscriminately. Specific defence targets a particular antigen: lymphocytes make antibodies that bind that antigen precisely, and memory cells remember it so a second infection is fought faster and stronger — this is the principle behind vaccination and natural immunity.

Worked Example — Vaccination & Immunity Data ★

Data: Antibody level after 1st and 2nd vaccine dose.
Dose 1: antibody rises to 20, then falls to 5 over 4 weeks.
Dose 2: antibody rises to 80 and stays high.

Step 1: 1st dose → PRIMARY response: B-cells make antibody + MEMORY
        cells formed; level later falls as plasma cells die.
Step 2: 2nd dose → SECONDARY response: memory cells act FAST →
        much higher, longer-lasting antibody (80 vs 20).
Step 3: this is ACTIVE immunity produced by vaccination.

Scoring: primary vs secondary response; memory cells; faster/stronger;
active immunity.

Common Trap ★

"Antibodies kill pathogens directly" is wrong — antibodies bind to antigens and help mark/neutralise them; phagocytes or complement do the killing. "Vaccination gives immediate permanent immunity" is false — it takes time to build and boosters may be needed. HIV attacks T-lymphocytes, weakening specific (not non-specific) immunity.

Immune System Diagram（免疫系統圖解：雙重防線）★

First line — non-specific (先天性, 非專一)

• Skin / mucous membrane：physical barrier.
• Phagocytes (吞噬細胞)：engulf any pathogen.
• Stomach acid / lysozyme：chemical barrier. Second line — specific (適應性, 專一)
• B-lymphocyte：produces ANTIBODIES against a specific antigen.
• T-lymphocyte：cell-mediated; helper & killer roles; HIV targets these.
• Memory cell：long-lived; gives fast secondary response.
• Antibody：Y-shaped protein; binds antigen at its variable region.

Worked Example 7.2 — Antibiotic vs Antiviral (5 marks)

A student has influenza (virus) and takes penicillin (antibiotic).
Step 1: antibiotics target BACTERIAL structures / processes (e.g.
        cell wall synthesis); they do NOT affect viruses.    (2 marks)
Step 2: viruses replicate INSIDE host cells using host
        machinery, so antibiotics cannot stop them.          (2 marks)
Step 3: influenza needs ANTIVIRAL drugs or vaccination; misuse
        of antibiotics causes RESISTANCE.                   (1 mark)
Scoring: antibiotics = bacteria only; viruses inside cells;
resistance from misuse.

Worked Example 7.3 — HIV & Immunity (5 marks)

HIV infects a person and, untreated, leads to AIDS.
Step 1: HIV specifically attacks T-LYMPHOCYTES (helper T cells).
                                                              (2 marks)
Step 2: loss of T-cells weakens SPECIFIC (adaptive) immunity;
        the body cannot coordinate B-cell / killer responses. (2 marks)
Step 3: opportunistic infections then become fatal = AIDS.  (1 mark)
Scoring: T-lymphocyte target; specific immunity weakened;
AIDS = severe immune failure.

實驗 7.E1 — 無菌技術與細菌培養（Aseptic technique & bacterial culture）

• Aim 目的：to culture bacteria and observe growth conditions.
• Method 方法：
  1. Sterilise petri dish & agar; inoculate with a wire loop (flame-sterilised).
  2. Spread bacteria; incubate at 37°C (school: 25°C for safety).
  3. Compare growth on agar with / without antibiotic disk.
• Result 結果：clear zone (no growth) around antibiotic disk = sensitive.
• Conclusion 結論：antibiotics inhibit specific bacteria; aseptic technique prevents contamination.

免疫與傳染病題，見 /question-bank/biology/

本單元易錯專業詞彙：immunity、antibody、occurred（雙 r）、separate（不是 seperate）、necessary（雙 s 雙 r）

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NOS / STSE / SI 三大重心實戰（示例題 + 標準英文句式）★

這三類佔分不低，且最易拉開差距。下面每個角度給 1 道示例題 + 可直接套用的英文句式。

NOS — Nature of Science ★

NOS example: A scientist hypothesises "Enzyme X is inactivated by acid".
Evidence: in pH 3 solution, enzyme activity drops to 5% of normal.

Standard English sentence (to support / reject a hypothesis):
"A hypothesis is SUPPORTED when repeated experiments give results
consistent with its prediction; it may be REJECTED or MODIFIED when
new evidence contradicts it."

Key idea: science is EVIDENCE-BASED; hypotheses are tentative and can
be overthrown by new, reliable data. Mention "repeatable / peer-reviewed"
to show reliability of evidence.

STSE — Science, Technology, Society, Environment ★

STSE example: Discuss genetically modified (GM) crops.

Discussion framework (use balanced "On one hand / On the other hand"):
PROS : higher yield and pest resistance → better food security;
       less pesticide use → lower environmental harm.
CONS : loss of biodiversity; unknown long-term health / ecological risk;
       corporate control of seeds (ethical & social issue).

Standard sentence:
"While the technology brings benefits such as [advantage], it also
raises concerns including [risk]; therefore a cost–benefit assessment
and strict regulation are needed."

SI — Scientific Enquiry (Experimental Design) ★

SI example: Design an experiment to test how TEMPERATURE affects the
activity of catalase (breaks down H₂O₂ → O₂ + H₂O).

You MUST state:
IV (independent variable): temperature (e.g. 10, 20, 37, 50°C)
DV (dependent variable)  : rate of reaction = volume of O₂ collected / min
Predicted result         : rate rises to an optimum (~37°C) then FALLS
                            as the enzyme denatures above optimum.
CV (controlled variables): enzyme concentration, substrate (H₂O₂) conc.,
                            pH, total volume — all kept CONSTANT.
Control                  : a tube with BOILED enzyme (negative control)
                            to show the reaction needs active enzyme.

Standard sentence:
"[IV] is changed systematically while [CV] are kept constant, so that
any change in [DV] can be attributed to [IV] alone. A control is used
to confirm the factor caused the effect."

Common Trap (SI design) ★

In SI design questions, candidates often forget to list CONTROLLED VARIABLES or a CONTROL — missing CV = lost marks. Always name at least two CV and one control. Also state "repeat to improve RELIABILITY" and "use a control to show the factor caused the effect", not just "do it again".

NOS — More Real-world Examples（更多科學本質實例）★

Example A — Theory change: the germ theory replaced spontaneous generation after Pasteur's swan-neck flask experiment. Science is self-correcting.

• Standard sentence: "Scientific theories are revised when new, reproducible evidence contradicts the old theory; a single well-designed experiment can overturn a long-held belief."

Example B — Correlation vs causation: countries with more mobile phones show more brain tumours — but this may reflect better diagnosis, not causation.

• Standard sentence: "A correlation between two variables does NOT prove one causes the other; controlled experiments are needed to establish causation."

Example C — Uncertainty & models: climate and epidemic models give probability ranges, not exact forecasts; uncertainty is normal in science.

• Standard sentence: "Models are simplified representations of reality; they have limits and uncertainties that must be stated honestly."

Example D — Peer review & replication: a single lab's result is not accepted until independently replicated and peer-reviewed.

• Standard sentence: "Reliability of scientific evidence increases when findings are repeated by independent groups and published after peer review."

NOS Exam-style Question (with answer)

Q: "A new study claims 'drinking tea prevents heart disease'.
   How should a scientist evaluate this claim?" (4 marks)
A: Check (1) whether it was a CONTROLLED study or mere correlation;
   (2) sample size and whether it was REPEATED; (3) whether it
   passed PEER REVIEW; (4) whether a plausible biological
   MECHANISM exists.
Standard sentence: "The claim needs controlled, repeated,
peer-reviewed evidence before acceptance; correlation alone is
insufficient to establish cause."
Scoring: controlled vs correlation (1); repetition (1); peer review
(1); mechanism / conclusion (1).

STSE — More Application Debates（更多科技社會環境辯論）★

Topic 1 — Antibiotics overuse: benefits (cure bacterial disease) vs risk (resistant strains, collapsed microbiome, farm runoff).

• Sentence: "While antibiotics save lives, their agricultural and clinical overuse drives natural selection of resistant bacteria, so stewardship and regulation are essential."

Topic 2 — IVF & stem cells: benefits (treat infertility, replace damaged tissue) vs ethical concerns (embryo status, access inequality, commercialisation).

• Sentence: "The technology offers medical benefit, yet raises ethical questions about embryo use and fair access that society must regulate."

Topic 3 — Renewable biofuels: benefits (lower net CO₂ than fossil fuel) vs cost (land for fuel competes with food, biodiversity loss, fertiliser runoff).

• Sentence: "Biofuels reduce net emissions but compete with food production; a full life-cycle assessment is required before scale-up."

Topic 4 — Genetic screening: benefits (early disease prevention) vs risk (privacy, discrimination by insurers/employers).

• Sentence: "Screening improves prevention, but genetic data must be legally protected against misuse and discrimination."

STSE Exam-style Question (with answer)

Q: "Discuss the release of genetically modified (GM) mosquitoes
   to control dengue fever." (6 marks)
A: Pros: reduces mosquito population → fewer dengue cases, less
   insecticide sprayed, lower health cost.
   Cons: ecological risk to food webs, potentially irreversible
   gene flow to wild populations, and communities must give
   informed consent.
   Balanced conclusion + call for monitoring and strict
   regulation.
Scoring: pros (2) + cons (2) + balanced conclusion with
regulation (2).

SI — More Experimental Design Drills（更多實驗設計演練）★

Drill 1 — Effect of pH on amylase: IV = pH (5, 7, 9); DV = time to digest starch (iodine test endpoint); CV = temperature, enzyme & starch concentration; control = boiled amylase (no digestion). Predicted: optimum near pH 7, slower / stopped far from optimum.

Drill 2 — Effect of light colour on photosynthesis: IV = filter colour (red / green / blue); DV = O₂ production rate; CV = light intensity, distance, temperature, CO₂; control = no plant. Predicted: red / blue high, green low (green light reflected).

Drill 3 — Investigating a disinfectant: IV = disinfectant concentration; DV = zone of inhibition (mm); CV = bacterial strain, incubator temperature, time; control = water only. Predicted: higher concentration → larger clear zone.

Drill 4 — Effect of exercise on breathing rate: IV = exercise duration / intensity; DV = breaths per minute; CV = age, fitness, temperature; control = resting subject. Predicted: more exercise → higher breathing rate to clear CO₂ / supply O₂.

SI 設計題常忘記：control + ≥2 controlled variables + repeat for reliability。每次作答都列出這三項。

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Cross-business Value（升学关联）

本组合（Bio + Chem + Econ）对应大学交叉赛道：

• 医疗投资 / 生物科技商业化：懂机理 + 懂商业逻辑
• 制药企业管理、医疗咨询
• ESG 可持续金融：生态 / 环境评估知识支撑碳核算理解

详见 经济+生化交叉商科解析。

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Common Wrong-expression Correction Table

✗ Wrong	✓ Correct
water goes from high to low concentration	water moves from less concentrated to more concentrated solution
respiration makes energy	respiration releases energy / produces ATP
photosynthesis occurs in chloroplast (vague)	in chloroplast; light stage in thylakoid, dark stage in stroma
gene produces trait	gene codes for a polypeptide that determines the trait
meiosis produces identical cells	meiosis produces genetically different haploid cells

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實驗大題標準五段英文模板（填空即拿滿分）

實驗大題（Structured / Essay）若寫不滿五段會被扣分。熟記下列五段骨架，考試時直接填空即可拿滿分。

Purpose（目的）：The aim of this experiment is to [investigate / compare / find out] how [IV] affects [DV] / whether [factor] causes [effect].

Procedure（步驟）：[Sample / apparatus set-up] was prepared. [IV] was changed at [list levels], while [CV1], [CV2] and [CV3] were kept constant. [Measurement method] was used to record [DV]. A [control] was included. The experiment was repeated [n] times.

Observation（觀察）：It was observed that [describe result: e.g. the solution turned from blue to brick-red / gas bubbles were produced / a white precipitate formed / O₂ volume increased with light intensity].

Explanation（解釋）：This is because [biological principle: e.g. light provides energy for photosynthesis, so a higher light intensity raises the rate of O₂ production until another factor becomes limiting].

Source of error（誤差來源）：The error may arise from [e.g. heat loss to the surroundings / incomplete reaction / human error in timing / uneven light intensity / gas dissolved in water], which could make the recorded [DV] [higher / lower] than the true value.

Worked Example — Testing a leaf for starch（葉片澱粉測試，填空示範）★

Purpose：The aim of this experiment is to find out whether a leaf has carried out photosynthesis and produced starch.

Procedure：A leaf was boiled in water, then in ethanol to remove chlorophyll, and rinsed in warm water. The leaf was spread on a tile and iodine solution was added. A covered (non-green) part of the same leaf and a leaf kept in darkness were used as comparisons. The experiment was repeated with three leaves.

Observation：The green part of the leaf turned blue-black with iodine, while the covered part and the dark-kept leaf stayed brown / yellow (no colour change).

Explanation：This is because photosynthesis needs light and chlorophyll; the green exposed part made starch which reacts with iodine to give blue-black, but the covered / dark part could not photosynthesise, so no starch was present.

Source of error：The error may arise from incomplete decolourisation (residual chlorophyll masking the colour) or uneven iodine spreading, which could make the blue-black colour difficult to judge.

更多實驗設計演練見 NOS / STSE / SI 章節，與 /question-bank/biology/

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歷屆真題演練（HKDSE Past-paper Style，附評卷參考）

改編自 HKEAA 公開試，括號內為當屆考生表現，助你判斷「易錯陷阱」。

Q1（MC · 物質運輸）正答率 52%

A red blood cell is placed in pure water. What happens and why?

• A. It shrinks because water leaves by osmosis. (18%)
• B. It swells and may burst because water enters by osmosis. (52%) ✅
• C. It stays the same size because the membrane is impermeable. (14%)
• D. It shrinks because solute enters the cell. (16%)

評卷筆記：紅血球內溶液濃度高於純水 → 水經滲透進入細胞 → 膨脹甚至破裂（lysis）。選 A 是反向陷阱，記住「低滲環境水進細胞」。

Q2（MC · 酵素）正答率 61%

At which temperature is an enzyme from a human body MOST active?

• A. 0°C (7%)
• B. 37°C (61%) ✅
• C. 60°C (22%)
• D. 100°C (10%)

評卷筆記：人體酶最適溫約 37°C；60°C 以上變性（denature），100°C 完全失活。

Q3（Structured · 光合作用實驗）8 分

A student puts a pondweed in water with indicator. Under bright light the indicator turns purple (CO₂ removed); in darkness it turns yellow (CO₂ added). (a) Explain the colour change in light. (3) (b) Explain the colour change in darkness. (3) (c) Name one controlled variable. (2)

答案與評分點： (a) In light, pondweed photosynthesises, using up CO₂ from water → indicator shows low CO₂ = purple. (3 分：光合作用 + 消耗 CO₂ + 顏色對應) (b) In darkness, no photosynthesis; plant respires, releasing CO₂ → indicator shows high CO₂ = yellow. (3 分：呼吸作用 + 釋放 CO₂ + 顏色對應) (c) E.g. temperature / light intensity / amount of pondweed kept constant. (2 分)

Q4（Data · 呼吸速率）數據分析

A graph shows oxygen consumption of a small mammal rising from 2 mL/h at 10°C to 10 mL/h at 30°C, then falling at 35°C. Explain the shape. (4)

答案：Rate rises with temperature (more kinetic energy, faster metabolism) up to an optimum near 30°C; above 35°C enzymes denature, so oxygen use falls. (4 分：上升因溫度 + 下降因變性)

Q5（Structured · Cell Transport 渗透）8 分

A student placed equal-sized cubes of fresh potato into three beakers: A = distilled water, B = 0.3 M sucrose, C = 0.6 M sucrose. After 2 h the masses changed: A +12%, B +2%, C −9%. (a) State and explain the change in A. (3) (b) What does B suggest about the potato cell sap concentration? (2) (c) Explain the change in C. (3)

答案與評分點： (a) A is hypotonic to the cell sap → water enters by osmosis → cells become turgid → mass +12%. (3 分：hypotonic + 水進入/滲透 + turgid) (b) B shows near-zero change → 0.3 M is close to isotonic with the cell sap, so little net water movement. (2 分：isotonic + 無淨移動) (c) C is hypertonic to the cell sap → water leaves by osmosis → cells plasmolysed → mass −9%. (3 分：hypertonic + 水離開/滲透 + plasmolysis)

Q6（Structured · Genetics 孟德爾）8 分

In pea plants, round seed (R) is dominant to wrinkled (r). A round-seeded plant is crossed with a wrinkled-seeded plant. All 80 offspring have round seeds. (a) What is the genotype of the wrinkled parent? (1) (b) Deduce the genotype of the round parent. Explain. (3) (c) Draw a Punnett square for a cross between two of the round F1 offspring; state the phenotypic ratio. (4)

答案與評分點： (a) rr (homozygous recessive). (1 分) (b) Round parent = RR. Because ALL offspring are round (none wrinkled), and a wrinkled offspring would need r from each parent, the round parent must supply only R → RR. (3 分：RR + 理由：全部顯性表示無 r 配子) (c) F1 are all Rr. Rr × Rr →

      R      r
   ------------
R |  RR  |  Rr  |
   ------------
r |  Rr  |  rr  |
   ------------

Genotypes 1 RR : 2 Rr : 1 rr; phenotypes 3 round : 1 wrinkled. (4 分：配子 + 方格 + 3:1 表型比)

Q7（Data · Ecosystem 能量流）數據分析

A food chain: grass → grasshopper → frog → snake. Energy at each level: 50 000, 5 000, 480, 45 kJ. (a) Calculate the energy transfer efficiency from grass to grasshopper. (1) (b) Explain why the efficiency is low and why the snake population is small. (3)

答案與評分點： (a) 5 000 / 50 000 = 10%. (1 分) (b) Only ~10% is transferred; ~90% is lost as heat in respiration, plus undigested and uneaten material. So little energy reaches the top → few snakes can be supported → small population / short chain. (3 分：10% + 熱能散失 + 頂層數量少)

Q8（Structured · Immunity 免疫）6 分

Explain how vaccination protects a person from a later infection with the same pathogen. (6)

答案與評分點： Vaccine contains a harmless antigen (weakened or dead pathogen). It stimulates B-lymphocytes to produce antibodies and form memory cells. On later infection, memory cells trigger a fast, strong secondary response, making antibodies quicker and in greater amount, so the pathogen is cleared before illness. This is active immunity. (6 分：antigen + B-cells + antibodies + memory cells + 更快更強次級反應 + active immunity)

Q9（MC · 細胞器功能）正答率 58%

Which structure is the site of protein synthesis?

• A. Mitochondrion
• B. Ribosome (58%) ✅
• C. Nucleus
• D. Golgi body

評卷筆記：ribosome 是蛋白質合成位點；mitochondrion 是呼吸作用位點；Golgi 負責包裝。

Q10（Structured · 主動運輸）6 分

Explain how root hair cells absorb mineral ions from dilute soil. (6)

答案與評分點： Soil solution is LESS concentrated than cell sap, so ions move AGAINST the gradient (1). Carrier proteins in the membrane are needed (2). Energy (ATP) from respiration drives the process = active transport (2). It stops if respiration is blocked (1). (6 分：逆梯度 + 載體蛋白 + ATP/呼吸作用 + 受阻條件)

Q11（Data · 酶最適 pH）數據分析

Amylase activity at pH 3, 5, 7, 9, 11: 5, 40, 100, 60, 10. Explain the shape. (4)

答案與評分點： Activity rises to a peak at pH 7 (optimum), then falls (3 分：上升→最適→下降). Far from optimum the active site changes shape (denaturation) so activity drops (1 分：變性/活性位點改變).

Q12（Structured · 神經反射）6 分

Describe the reflex arc involved when you touch a hot object. (6)

答案與評分點： Receptor in skin detects heat → sensory neurone → relay neurone in spinal cord → motor neurone → effector (muscle) contracts, hand withdraws (4 分：完整五站). Bypasses brain = involuntary, rapid (2 分：非自主+快速).

Q13（MC · 生態能量）正答率 49%

Why are food chains rarely longer than 5 levels?

• A. Producers are few
• B. ~90% energy lost as heat at each level (49%) ✅
• C. Consumers eat each other
• D. Decomposers remove energy

評卷筆記：只有約 10% 傳遞，頂層能量不足維持更多層級；materials 會循環但 energy 不會。

Q14（Structured · 疫苗與記憶細胞）6 分

Why does a booster dose give a stronger, faster response than the first? (6)

答案與評分點： 1st dose → primary response, memory cells formed (2 分). 2nd dose → memory cells trigger SECONDARY response: faster and greater antibody production (3 分：更快更強次級反應). This is active immunity (1 分).

Q15（Structured · 滲透與植物細胞）8 分

A student places red blood cells and plant cells separately in 1.0 M sucrose. Describe what happens to EACH and explain. (8)

答案與評分點： Red cell: solution is HYPERTONIC → water LEAVES by osmosis → cell SHRINKS (crenation) (4 分：高滲+水離開+收縮). Plant cell: also hypertonic → water leaves → cytoplasm pulls from wall = PLASMOLYSIS (4 分：高滲+水離開+質壁分離).

Q16（Data · 人口與資源）數據分析

A country's CO₂ per person is 12 t, but its ecological footprint needs 4 Earths at world population. Discuss one STSE solution. (4)

答案與評分點： e.g. shift to renewable energy lowers per-capita CO₂; combined with efficiency and conservation this reduces footprint (2). But equity and technology transfer to developing regions are needed (2). Balanced, with regulation/behaviour change. (4 分：方案+社會/公平層面)

更多仿 HKEAA 題型與評分點，見 /question-bank/biology/

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生理過程標準英文描述句式（細胞/光合/呼吸/遺傳/稳态統一套用）★★★

標準句式模板（L1 背誦）：

The XX physiological process takes place inside [cell / organ structure]. Under specific environmental conditions, raw materials are converted into target products via a series of enzyme-controlled chemical reactions, resulting in the final physiological outcome of ...

適用場景：長篇解釋生理機理大題，句式規整貼合閱卷學術英文偏好。

各大生理過程高頻標準英文長句仿寫範例（L2 仿寫）

• 光合作用 Photosynthesis：Photosynthesis takes place inside chloroplasts. Under light, carbon dioxide and water are converted into glucose and oxygen via light-dependent and light-independent reactions, providing chemical energy for the plant.
• 呼吸作用 Respiration：Cellular respiration takes place inside mitochondria. Glucose is broken down with oxygen to release ATP, carbon dioxide and water through glycolysis, the Krebs cycle and oxidative phosphorylation.
• 體液調節 Homeostasis：Insulin is secreted by the pancreas when blood glucose rises, promoting glucose uptake by cells and lowering blood sugar back to the normal range.

生物圖表數據答題三段式高分模板（圖表大題必考）★★★

1. Describe the overall trend of the curve within the whole experimental period；
2. Combine biological knowledge to explain the internal mechanism causing such changing trend；
3. Analyse abnormal data points and give a reasonable experimental error explanation.

生物實驗答題通用規範 ★★★

• 對照組、實驗組區分描述，不寫明對照組設計實驗設計題直接丟失過半採分點；
• 變量控制書寫規範（independent / dependent / controlled variable 分列）；
• 實驗結論必須緊扣實驗目的作答，不可過度外延推導。

實驗答題扣分潛規則（與化學通用，參見化學頁）★★★

1. 實驗誤差分析只寫籠統 "human error" 不得分，必須寫明具體誤差來源（如 incomplete mixing / evaporation of solution）；
2. 實驗組不作對照組說明，設計題丟失過半採分點；
3. 生物專業術語拼寫錯誤（mitochondrion / chloroplast / photosynthesis）直接扣採分點。

理化生主觀題自查表（寫完必逐項勾選）★★★

專業單詞拼寫 ✅｜實驗步驟動詞正式學術寫法 ✅｜現象描述客觀寫實 ✅｜原理匹配知識點 ✅｜圖表數據解讀邏輯通順 ✅

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Act as an official HKDSE Biology examiner. For the topic I specify, set 5 questions in English: 2 definitions + 2 data-analysis (graph/experiment) + 1 structured explanation.
After I answer, check English academic expression accuracy, identify missing scoring points (especially labelled diagrams and process keywords), and give targeted review advice pointing to this page's relevant section.

Topic: [e.g. Nutrition & Respiration]