第 1 單元，第 1 課
Exploring Life探索生命
這課一眼看
Cells and the cell theory細胞與細胞學說
- cell細胞: The smallest unit that can carry out the functions of life.
- cell theory細胞學說: Idea that all living things are made of cells, cells are the smallest unit of life, and new cells come from existing cells.
Microscopes顯微鏡
- light microscope光學顯微鏡: Microscope that uses light and lenses to enlarge an image.
- electron microscope電子顯微鏡: Microscope that uses a beam of electrons to magnify objects 100,000 times or more.
Characteristics of life生命的特徵
- unicellular單細胞的: Made of only one cell.
- multicellular多細胞的: Made of two or more cells.
- stimulus刺激: A change in an organism’s surroundings or body that causes a response.
- homeostasis恆定性: The ability to keep steady internal conditions.
Types of cells and classification細胞的種類與分類
- prokaryotic原核的: Describes a cell whose genetic material is not surrounded by a membrane.
- eukaryotic真核的: Describes a cell whose genetic material is surrounded by a membrane.
- organelle胞器: A structure inside a cell with a specialized job.
1Cells and the cell theory細胞與細胞學說
ALiving things are made of cells生物由細胞構成
- Living and nonliving things can look alike. A flame grows, moves, and uses oxygen, but it is not alive. The first thing all living things share is what they are made of: cells.生物和非生物有時看起來很像。火焰會變大、會移動、也會消耗氧氣，但它不是活的。所有生物的第一個共同點是構成它們的東西：細胞。
- A cell is the smallest unit that can carry out the functions of life. Atoms join to form molecules, and molecules make up cells.細胞是能執行生命功能的最小單位。原子結合成分子，分子再構成細胞。
自我檢查
Under a microscope, a cheek sample and an onion sample show small boxlike units, but a salt sample shows only cubes of crystal. What does this tell you?在顯微鏡下，口腔皮膜和洋蔥都看得到一格一格的小單位，鹽卻只看到立方形的晶體。這代表什麼？
看答案
The cheek and onion samples come from living things and are made of cells; salt is nonliving and has no cells.口腔皮膜和洋蔥來自生物，由細胞構成；鹽是非生物，沒有細胞。
BDiscovering cells細胞的發現
- Cells are too small to see with the unaided eye, so they were discovered only after the microscope was invented. In 1665, Robert Hooke looked at thin slices of cork and saw tiny empty boxes. He named them cells.細胞太小，肉眼看不到，所以要等顯微鏡發明後才被發現。1665 年，虎克觀察薄薄的軟木片，看到許多空的小格子，就把它們命名為「細胞」。
- In the late 1600s, Anton van Leeuwenhoek built a single-lens microscope that magnified about 270 times. He was the first to see living single-celled organisms in pond water.1600 年代後期，雷文霍克製作出只有一片透鏡、可放大約 270 倍的顯微鏡，並第一個在池塘水中看到活的單細胞生物。
注意
This is a good example of science depending on engineering: a better tool led directly to new discoveries.這是科學依賴工程的好例子：更好的工具直接帶來新的發現。
CThe three parts of the cell theory細胞學說的三個重點
- Observations by many scientists were combined into the cell theory: (1) all living things are made of one or more cells; (2) the cell is the smallest unit of life; (3) all new cells come from cells that already exist, through cell division.許多科學家的觀察整合成細胞學說：(1) 所有生物都由一個或多個細胞構成；(2) 細胞是生命的最小單位；(3) 新細胞都來自原本就存在的細胞，經由細胞分裂產生。
2Microscopes顯微鏡
ALight and electron microscopes光學顯微鏡與電子顯微鏡
- A light microscope uses light and lenses to enlarge an image, up to about 1,500 times. Specimens often need a dye stain so details show up.光學顯微鏡利用光和透鏡放大影像，最多約 1,500 倍。標本常需要染色，細節才看得清楚。
- An electron microscope focuses a beam of electrons with magnets and can magnify 100,000 times or more. A transmission electron microscope (TEM) sends electrons through a thin sample to show structures inside cells. A scanning electron microscope (SEM) bounces electrons off the surface to make a 3-D image.電子顯微鏡用磁場聚焦電子束，可放大十萬倍以上。穿透式電子顯微鏡（TEM）讓電子穿過很薄的樣本，用來看細胞內部構造；掃描式電子顯微鏡（SEM）讓電子從表面反彈，產生立體影像。
Types of microscopes顯微鏡的種類
| Microscope顯微鏡 | How it works原理 | Magnification放大倍率 | Best for最適合觀察 |
|---|---|---|---|
| Light microscope光學顯微鏡 | Light passes through lenses光穿過透鏡 | Up to about 1,500×最高約 1,500 倍 | Living cells, stained samples活細胞、染色標本 |
| Transmission electron microscope (TEM)穿透式電子顯微鏡（TEM） | Electrons pass through a thin slice電子穿過薄切片 | 100,000× or more10 萬倍以上 | Structures inside cells細胞內部構造 |
| Scanning electron microscope (SEM)掃描式電子顯微鏡（SEM） | Electrons bounce off the surface電子從表面反彈 | 100,000× or more10 萬倍以上 | 3-D images of surfaces表面的立體影像 |
3Characteristics of life生命的特徵
AUnicellular and multicellular organisms單細胞與多細胞生物
- A unicellular organism is made of one cell, which carries out every function needed to live. A multicellular organism is made of many cells organized into groups with special jobs. A human body has about 37 trillion cells.單細胞生物只由一個細胞構成，這個細胞要負責所有生存所需的功能。多細胞生物由許多細胞構成，細胞分成不同群組，各有專門的工作。人體大約有 37 兆個細胞。
BThe seven characteristics七個生命特徵
- All living things share seven characteristics: they are made of cells; they are organized; they grow and develop; they reproduce; they respond to stimulus (changes inside or outside the body); they maintain steady internal conditions; and they use energy.所有生物都有七個共同特徵：由細胞構成、有組織、會生長與發育、會繁殖、會對刺激（身體內外的變化）產生反應、能維持穩定的體內狀態，以及會利用能量。
- Growth means getting bigger; development means the changes an organism goes through during its life. Keeping steady internal conditions, such as body temperature, is called homeostasis.生長是指變大；發育是指生物一生中經歷的各種改變。維持穩定的體內狀態（例如體溫）稱為恆定性。
- Most organisms get energy from food. Some, like plants, use energy from the Sun to make their own food; others get energy by eating other organisms.大多數生物從食物獲得能量。有些生物（例如植物）利用太陽能自己製造食物；其他生物則靠吃別的生物取得能量。
注意
Something must show all seven characteristics to be living. A flame grows and uses energy, but it is not made of cells and cannot reproduce on its own.一定要七個特徵全部具備才算生物。火焰會變大、也會用能量，但它不是由細胞構成，也不能自己繁殖。
4Types of cells and classification細胞的種類與分類
AProkaryotic and eukaryotic cells原核細胞與真核細胞
- All cells contain genetic material, the information passed from one generation to the next. In a prokaryotic cell, the genetic material is not surrounded by a membrane. Prokaryotic cells are small, have few parts, and usually form unicellular organisms called prokaryotes.所有細胞都含有遺傳物質，也就是一代傳給下一代的資訊。原核細胞的遺傳物質沒有被膜包住。原核細胞小、構造少，通常形成單細胞生物，稱為原核生物。
- In a eukaryotic cell, the genetic material is surrounded by a membrane, and the cell has other membrane-bound structures called organelles. Eukaryotic cells are about ten times larger. Plants, animals, fungi, and protists are eukaryotes.真核細胞的遺傳物質被膜包住，細胞內還有其他有膜包圍的構造，稱為胞器。真核細胞大約大十倍。植物、動物、真菌和原生生物都是真核生物。
BDomains and kingdoms域與界
- Organisms are classified using evidence such as cell type, habitat, how they get food, their structures, and common ancestry. Every organism belongs to one of three domains (Bacteria, Archaea, Eukarya) and then to one of six kingdoms.生物依據細胞類型、棲地、取得食物的方式、構造和共同祖先等證據來分類。每一種生物都屬於三個域（細菌域、古菌域、真核生物域）之一，再分到六個界之一。
Domains and kingdoms域與界
| Domain域 | Kingdom界 | Cell type細胞類型 | Features特徵 |
|---|---|---|---|
| Bacteria細菌域 | Bacteria細菌界 | Prokaryotic原核 | Simple, unicellular構造簡單、單細胞 |
| Archaea古菌域 | Archaea古菌界 | Prokaryotic原核 | Unicellular; often in extreme environments單細胞；常在極端環境 |
| Eukarya真核生物域 | Protists原生生物界 | Eukaryotic真核 | Unicellular or multicellular; more complex than bacteria單細胞或多細胞；比細菌複雜 |
| Eukarya真核生物域 | Fungi真菌界 | Eukaryotic真核 | Unicellular or multicellular; absorb food單細胞或多細胞；吸收養分 |
| Eukarya真核生物域 | Plants植物界 | Eukaryotic真核 | Multicellular; make their own food多細胞；自己製造養分 |
| Eukarya真核生物域 | Animals動物界 | Eukaryotic真核 | Multicellular; take in food多細胞；攝取食物 |
注意
Bacteria and Archaea are unicellular prokaryotes; many archaea live in extreme places such as hot springs. The classification system is still being revised as new evidence appears.細菌和古菌都是單細胞原核生物；許多古菌生活在溫泉等極端環境。分類系統會隨新證據持續修訂。
CAre viruses alive?病毒是生物嗎？
- A virus has an organized structure and makes copies of itself, but only by taking over a living host cell and using the host’s energy. It is not made of cells, does not grow, and does not maintain homeostasis, so most scientists say viruses are not living things.病毒有組織化的構造，也會複製自己，但只能靠入侵活的宿主細胞、使用宿主的能量。它不是由細胞構成，不會生長，也不維持恆定性，所以大多數科學家認為病毒不是生物。
這課的重點字
- cell細胞
- cell theory細胞學說
- light microscope光學顯微鏡
- electron microscope電子顯微鏡
- unicellular單細胞的
- multicellular多細胞的
- stimulus刺激
- homeostasis恆定性