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  • 案例研究结论:饮食困境

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    Case Study Conclusion: Diet Dilemma
    ::案例研究结论:饮食困境

    After reading this chapter, you should be able to see numerous connections between chemistry, human life, and health. In Joseph’s situation, chemistry is involved in the reasons why his father has diabetes, why his personal risk of getting diabetes is high, and why the dietary changes he is considering could be effective. 
    ::读完本章之后,你应该能看到化学、人命和健康之间的无数联系。 在约瑟夫的形势下,化学涉及到他父亲糖尿病的原因,为什么他个人患糖尿病的风险很高,为什么他考虑的饮食变化可能有效。

    Type 2 diabetes is caused primarily  by a lack of response in the body to the hormone insulin, which causes problems in the regulation of blood sugar, or glucose. Insulin is a peptide hormone, and as you have learned, peptides are chains of amino acids. Therefore, insulin is in the class of biochemical compounds called proteins. Joseph is at increased risk of diabetes partly because there is a genetic component to the disease. DNA, which is a type of chemical compound called a nucleic acid, is passed down from parents to their offspring, and carries the instructions for the production of proteins in units called genes. If there is a problem in a gene (or genes) that contributes to the development of a disease, such as type 2 diabetes, this can get passed down to the offspring and may raise that child’s risk of getting the disease.
    ::2型糖尿病的主要原因是身体对激素胰岛素缺乏反应,这在血糖或葡萄糖的调节方面造成了问题。 胰岛素是一种浸泡激素,正如你们所学的那样,是氨基酸链。 因此,胰岛素属于生物化学化合物类。 约瑟夫患糖尿病的风险增加,部分原因是该疾病有遗传成分。 DNA是一种叫核糖的化学化合物,由父母传给他们的后代,并带有以基因单位生产蛋白质的指令。 如果一种基因(或基因)存在问题,导致2型糖尿病等疾病的发展,这可能会传染给后代,并可能增加儿童感染该疾病的风险。

    But genetics is only part of the reason why Joseph is at an increased risk of diabetes. Obesity itself is a risk factor, and one that can be shared in families due to shared lifestyle factors (such as poor diet and lack of exercise), as well as genetics. Consumption of too many refined carbohydrates (like white bread and soda) may also contribute to obesity and the development of diabetes. As you probably now know, these simple carbohydrates are more easily and quickly broken down in the digestive system into glucose than larger complex carbohydrate molecules, such as those found in vegetables and whole grains. This can lead to dramatic spikes in blood sugar levels, which is particularly problematic for people with diabetes because they have trouble maintaining their blood sugar at a safe level. You can understand why Joseph’s father limits his consumption of refined carbohydrates, and in fact, some scientific studies have shown that avoiding refined carbohydrates may actually help reduce the risk of getting diabetes in the first place.
    ::但遗传学只是约瑟夫患糖尿病风险增加的原因之一。 肥胖本身是一个风险因素,也可以在家庭中分享,因为共同的生活方式因素(如饮食差和缺乏锻炼)以及遗传学。 太多的精炼碳水化合物(如白面包和苏打)的消费也可能导致肥胖和糖尿病的发育。 正如你现在可能知道的那样,这些简单的碳水化合物在消化系统中比在蔬菜和整粒中发现的大型复杂的碳水化合物分子更容易和更快地被分解成葡萄糖。 这可能导致血糖水平的急剧上升,而糖尿病患者尤其会因此难以在安全水平上保持血糖。 你可以理解为什么约瑟夫的父亲限制他消费精制碳水化合物,事实上,一些科学研究表明避免精制碳水化合物实际上有助于降低糖尿病的风险。

    Joseph’s friend recommended eating a low fat, high carbohydrate diet to lose weight, but you can see that the   type of carbohydrate — simple or complex — is an important consideration. Eating lots of white bread and rice may not help Joseph reduce his risk of diabetes, but a healthy diet that helps him lose weight may lower his risk of diabetes, since obesity itself is a factor. Which specific diet will work best to help him lose weight probably depends on a variety of factors, including his biology, lifestyle, and food preferences. Joseph should consult with his doctor about his diet and exercise plan, so that his specific situation can be taken into account and monitored by a medical professional.
    ::约瑟夫的朋友建议吃低脂肪、高碳水化合物饮食来减肥,但你可以看到碳水化合物 — — 简单或复杂 — — 是一个重要考虑因素。 大量吃白面包和大米也许无助于约瑟夫降低糖尿病风险,但有助于他减肥的健康饮食可以降低他患糖尿病的风险,因为肥胖本身是一个因素。 哪种特定饮食能最好地帮助他减肥可能取决于多种因素,包括生物学、生活方式和食物偏好。 约瑟夫应该就他的饮食和锻炼计划咨询他的医生,以便医疗专业人员能够考虑和监测他的具体情况。

    Drinking enough water is usually good advice for everyone, especially if it replaces sugary drinks like soda. You now know that water is important for many of the chemical reactions that take place in the body. But you can have too much of a good thing — as in the case of marathon runners who can make themselves sick from drinking too much water! As you can see, proper balance, or homeostasis, is very important to the health of living organisms.
    ::饮用水通常对每个人都是一个很好的建议,特别是当它取代了苏打糖类饮料时。你现在知道水对于身体中发生的许多化学反应很重要。但你可以有太多的好东西,比如马拉松赛跑跑跑步者因为喝太多水而生病。 正如你可以看到的那样,适当的平衡或顺从对于活生物体的健康非常重要。

    Finally, you probably now realize that “chemicals” do not have to be scary, toxic substances. All matter consists of chemicals, including water, your body, and healthy fresh fruits and vegetables, like the ones pictured above. When people advocate “clean eating” and avoiding “chemicals” in food, they are usually referring to avoiding synthetic — or man-made — chemical additives, such as preservatives. This can be a healthy way to eat because it involves eating a variety of whole, fresh, unprocessed foods. But there is no reason to be scared of chemicals in general – they are simply molecules and how they react depends on what they are, what other molecules are present, and the environmental conditions surrounding them.
    ::最后,你也许现在意识到,“化学物质”不必是可怕的有毒物质。 所有物质都包含化学物质,包括水、你的身体、健康的新鲜水果和蔬菜,就像上面所描述的。 当人们提倡“清洁饮食”和避免食品中的“化学物质 ” 时,他们通常指避免合成的化学添加物,或者人为的化学添加物,比如防腐剂。 这可能是一种健康的饮食方式,因为它需要吃各种各样的、新鲜的、未经加工的食物。 但没有理由害怕一般的化学物质 — — 它们只是分子,它们的反应取决于它们是什么,其他分子是什么,周围的环境条件。

    Chapter Summary
    ::章次摘要

    By now, you should have a good understanding of the basics of the chemistry of life. Specifically, you have learned:
    ::现在,你应该对生命化学的基本原理有很好的了解。具体地说,你已经学到了:

    • All matter consists of chemical substances. A chemical substance has a definite and consistent composition and may be either an element or a compound.
      ::所有物质均由化学物质组成,化学物质具有确定和一致的成分,既可以是元素,也可以是化合物。
    • An element is a pure substance that cannot be broken down into other types of substances.
      • An atom is the smallest particle of an element that still has the properties of that element. Atoms, in turn, are composed of subatomic particles, including negative electrons, positive protons, and neutral neutrons. The number of protons in an atom determines the element it represents.
        ::原子是一个元素的最小粒子,该元素仍然具有该元素的特性。原子反过来由亚原子粒子组成,包括负电子、正质子和中中中中子。原子中的质子数量决定其所代表的元素。
      • Atoms have equal numbers of electrons and protons, so they have no charge. Ions are atoms that have lost or gained electrons, so they have either a positive or negative charge. Atoms with the same number of protons but different numbers of neutrons are called isotopes.
        ::原子拥有相同数量的电子和质子,因此它们没有电荷。离子是已经丢失或获得电子的原子,因此它们有正电荷或负电荷。质子数量相同的原子,但不同的中子数量被称为同位素。
      • There are almost 120 known elements. The majority of elements are metals. A smaller number are nonmetals, including carbon, hydrogen, and oxygen.
        ::有近120种已知元素,大多数元素是金属,较少的元素是非金属,包括碳、氢和氧。

      ::元素是无法分解成其他类型物质的纯物质。原子是仍然具有该元素特性的一个元素的最小粒子。原子反过来由亚原子粒子组成,包括负电子、正质子和中中质子。原子中的质子数量决定其所代表的元素。原子拥有等量的电子和质子,因此没有电荷。离子是已经丢失或获得电子的原子,因此它们具有正电荷或负电荷。原子拥有相同数量的质子,但不同的中子数量被称为同位素。有近120个已知元素。大部分元素是金属。较少的元素是非金属,包括碳、氢和氧。
    • A compound is a substance that consists of two or more elements in a unique composition. The smallest particle of a compound is called a molecule. Chemical bonds hold together the atoms of molecules. Compounds can form only in chemical reactions, and they can break down only in other chemical reactions.
      • Biochemical compounds are carbon-based compounds found in living things. They make up cells and other structures of organisms and carry out life processes. Most biochemical compounds are large molecules called polymers that consist of many repeating units of smaller molecules called monomers.
        ::生化化合物是活物中发现的碳基化合物,它们组成细胞和其他生物结构,并进行生命过程,大多数生化化合物是称为聚合物的大型分子,由许多称为单体的较小分子的重复单元组成。
      • There are millions of different biochemical compounds, but all of them fall into four major classes: carbohydrates, lipids, proteins, and nucleic acids.
        ::有数百万种不同的生化化合物,但它们都分为四大类:碳水化合物、脂类、蛋白质和核酸。

      ::化合物是一种由两个或两个以上元素组成的物质,由独特的成分组成。一个化合物的最小粒子称为分子。化学联系将分子原子聚集在一起。化合物只能形成化学反应,只能形成于化学反应中,只能分解于其他化学反应中。生化化合物是活物中发现的碳基化合物。它们组成细胞和其他有机体结构,并进行生命过程。大多数生化化合物是大型分子,称为聚合物,由许多称为单体的较小分子的重复单位组成。有数百万种不同的生物化学化合物,但全部分为四大类:碳水化合物、脂类、蛋白质和核酸。
    • Carbohydrates are the most common class of biochemical compounds. They provide cells with energy, store energy, and make up organic structures, such as the cell walls of plants. The basic building block of carbohydrates is the monosaccharide.
      • Sugars are short-chain carbohydrates that supply us with energy. Simple sugars, such as glucose, consist of just one monosaccharide. Some sugars, such as sucrose (or table sugar) consist of two monosaccharides and are called disaccharides.
        ::糖是为我们提供能量的短链碳水化合物。 简单的糖,如葡萄糖,只包括一种单沙酸。 一些糖,如苏克罗斯(或餐桌糖 ) , 由两种单沙酸组成,被称为非沙酸。
      • Complex carbohydrates, or polysaccharides, consist of hundreds or even thousands of monosaccharides. They include starch, glycogen, cellulose, and chitin.
        • Starch is made by plants to store energy and is readily broken down into its component sugars during digestion.
          ::Starch由植物制成,储存能源,在消化过程中很容易分解成其组成部分的糖。
        • Glycogen is made by animals and fungi to store energy and plays a critical part in the homeostasis of blood glucose levels in humans.
          ::甘蓝素由动物和真菌制成,以储存能量,在人类血液甘蔗糖水平的均匀保持中发挥着关键作用。
        • Cellulose is the most common biochemical compound in living things. It forms the cell walls of plants and certain algae. Humans cannot digest cellulose, but it makes up most of the crucial dietary fiber in the human diet.
          ::纤维素是生命中最常见的生化化合物。 它构成植物和某些藻类的细胞壁。 人类不能消化纤维素,但它是人类饮食中最重要的饮食纤维。
        • Chitin makes up organic structures, such as the cell walls of fungi and the exoskeletons of insects and other arthropods.
          ::Chitin组成有机结构,如真菌的细胞墙和昆虫和其他节肢动物的外骨质素。

        ::复合碳水化合物,或聚碳酸盐,由数百甚至数千个单沙酸化合物组成,包括淀粉、甘醇、纤维素和辣椒。Starch由植物制成,以储存能量,在消化过程中很容易分解成其组成部分的糖。甘醇由动物和真菌制成,以储存能量,在人体血液凝糖水平的均匀状态中发挥着关键作用。细胞素是活物中最常见的生物化学化合物。细胞素是植物和某些藻类的细胞壁。人类不能消化纤维素,但它构成人类饮食中最重要的饮食纤维。Chitin制成有机结构,如真菌细胞壁和昆虫和其他节肢类的外骨质。

      ::碳水化合物是最常见的生物化学化合物。 碳水化合物是最常见的生物化学化合物。 它们提供细胞能量, 储存能量, 并组成有机结构, 如植物的细胞墙。 碳水化合物的基本建筑块是单沙酸。 糖是短链碳水化合物, 为我们提供能量。 糖是短链碳水化合物。 简单的糖, 如葡萄糖, 由一种单沙酸盐组成。 一些糖( 或餐桌糖) , 例如苏克罗斯( 或餐桌糖) 由两种单沙糖组成, 被称为脱硫酸盐。 复杂的碳水化合物, 或多石酸盐, 由数百甚至数千个单沙酸化合物组成。 它们包括恒星、 甘油、 纤维素和 chitin。 Starch是植物储存能量的短链, 在消化过程中很容易分解成糖糖的成分。 液素由动物和真菌组成, 在人体血糖的软体壁中扮演一个关键部分。 细胞是活物中最常见的生物化学化合物化合物化合物化合物化合物化合物化合物化合物化合物的化合物化合物化合物化合物化合物化合物。 它构成人类细胞和某些生物纤维的植物的脂肪的脂肪。
    • Lipids include fats and oils. They store energy, form cell membranes, and carry messages.
      • Lipid molecules consist mainly of repeating units called fatty acids. Fatty acids may be saturated or unsaturated, depending on the proportion of hydrogen atoms they contain. Animals store fat as saturated fatty acids, while plants store fat as unsaturated fatty acids.
        ::脂肪酸可能饱和或不饱和,视其所含氢原子的比例而定; 动物将脂肪作为饱和脂肪酸储存,而植物则将脂肪作为不饱和脂肪酸储存。
      • Types of lipids include triglycerides, phospholipids, and steroids.
        • Triglycerides contain glycerol (an alcohol) in addition to fatty acids. Humans and other animals store fat as triglycerides in fat cells.
          ::人类和其他动物在脂肪细胞中将脂肪作为三甘酸酯储存在脂肪细胞中。
        • Phospholipids contain phosphate and glycerol in addition to fatty acids. They are the main component of cell membranes in all living things.
          ::磷脂除脂肪酸外,还含有磷酸和甘油,是所有生物中细胞膜的主要成分。
        • Steroids are lipids with a four-ring structure. Some steroids, such as cholesterol, are important components of cell membranes. Many other steroids are hormones.
          ::类固醇是四环结构的脂质,一些类固醇,例如胆固醇,是细胞膜的重要成分,许多其他类固醇是荷尔蒙。

        ::脂类包括三甘油、磷素类和类固醇。三甘油类除脂肪酸外,还含有甘油类(一种酒精)。人类和其他动物将脂肪作为三甘油类储存在脂肪细胞中。磷脂类除脂肪酸外,还含有磷酸盐和甘油类。它们是所有生物物质中细胞膜的主要成分。类固醇是四环结构的脂类。一些类固醇,如胆固醇,是细胞膜的重要成分。其他许多类固醇是荷尔蒙。

      ::脂类包括三甘油、磷素和类固醇。三甘醇除脂肪酸外还含有甘油(一种酒精)。人类和其他动物将脂肪作为脂肪细胞中的三甘油的重要成分。磷脂除脂肪酸外,还含有磷酸和甘油。
    • In living things, proteins include enzymes, antibodies, and numerous other important compounds. They help  cells keep their shape, make up muscles, speed up chemical reactions, and carry messages and materials (among other functions).
      • Proteins are made up of small monomer molecules called amino acids.
        ::蛋白质由小型单体分子组成,叫做氨基酸。
      • Long chains of amino acids form polypeptides. The sequence of amino acids in polypeptides makes up the primary structure of proteins. Secondary structure refers to configurations such as helices and sheets within polypeptide chains. Tertiary structure is a protein's overall three-dimensional shape, which controls the molecule's basic function. A quaternary structure forms if multiple protein molecules join together and function as a complex.
        ::氨基酸的长链构成聚虫化物。聚虫化物中的氨基酸序列构成蛋白质的主要结构。次要结构是指聚虫化物链中象象虱子和板块这样的配置。第三层结构是蛋白质的三维整体形状,它控制分子的基本功能。如果多个蛋白分子结合在一起,并作为一个复杂体发挥作用,则四面结构构成。
      • The chief characteristic that allows proteins' diverse functions is their ability to bind specifically and tightly with other molecules.
        ::允许蛋白质发挥不同功能的主要特征是,蛋白质能够与其他分子具体和紧密地结合。

      ::在生物物质中,蛋白质包括酶、抗体和许多其他重要化合物。它们帮助细胞保持形状、肌肉、加速化学反应和传递信息与材料(包括其他功能)。蛋白质由称为氨基酸的小型单体分子组成。氨基酸的长链形成聚苯醚。聚苯醚中的氨基酸序列构成蛋白质的主要结构。次要结构是指象热利和聚极物链内板块等配置。三级结构是蛋白质的三维整体形状,它控制分子的基本功能。如果多种蛋白分子结合在一起,并作为一个复杂功能,则四面形结构形式。允许蛋白质多种功能的主要特征是它们与其他分子具体和紧密结合的能力。
    • Nucleic acids include DNA and RNA. They encode instructions for making proteins, helping make proteins, and passing the encoded instructions from parents to offspring.
      • Nucleic acids are built of monomers called nucleotides, which bind together in long chains to form polynucleotides. DNA consists of two polynucleotides, and RNA consists of one polynucleotide.
        ::核心酸由称为核酸的单体组成,它们以长链结合形成多核酸。 DNA由两种核酸组成,RNA由一种多核酸组成。
      • Each nucleotide consists of a sugar molecule, phosphate group, and nitrogen base. Sugars and phosphate groups of adjacent nucleotides bind together to form the "backbone" of the polynucleotide. Bonds between complementary bases hold together the two polynucleotide chains of DNA and cause it to take on its characteristic double helix shape.
        ::每一种核酸都由糖分子、磷酸盐组和氮基组成。 糖和磷酸组相邻的核酸类聚在一起形成聚核酸的“后骨 ” 。 互补基点之间的债券将DNA的两个多核酸链连接在一起,并导致它以其特有的双螺旋形状形成。
      • DNA makes up genes, and the sequence of nitrogen bases in DNA makes up the genetic code for the synthesis of proteins. RNA helps synthesize proteins in cells. The genetic code in DNA is also passed from parents to offspring during reproduction, explaining how inherited characteristics are passed from one generation to the next.
        ::DNA构成基因,而DNA中的氮基序列构成蛋白质合成的遗传代码。 RNA帮助细胞中合成蛋白质。DNA中的遗传代码在生殖过程中也从父母传给后代,解释遗传特征是如何一代传给下一代的。

      ::核酸包括DNA和RNA。 它们将蛋白质制作、 帮助制造蛋白质、 帮助制造蛋白质, 并将父母的编码指令传递给后代。 核酸是由称作核糖核酸的单体组成的, 它们在长链中结合, 形成多核酸。 DNA由两个多核素组成, 核酸核酸由一个聚核素组成。 每个核酸由糖分子、 磷酸组和氮基组成。 相邻核糖核酸的糖和磷酸盐组结合在一起, 形成聚核糖核酸的“ 后骨” 。 补充基的组合将两个DNA的聚核酸链连接在一起, 并导致它以其特性的双螺旋素形状形成。 DNA组成基因, DNA基中的氮基序列构成蛋白质合成的基因代码。 RNA 帮助细胞中的合成蛋白质。 DNA的遗传代码也由父母传给后代, 解释遗传特性如何从一代传到下一代。
    • A chemical reaction is a process that changes some chemical substances into others. A substance that starts a chemical reaction is called a reactant, and a substance that forms in a chemical reaction is called a product. During the chemical reaction, bonds break in reactants and new bonds form in products.
      ::化学反应是一种将某些化学物质改变为其他化学物质的过程。 开始化学反应的物质被称为反应剂,而化学反应中形成的一种物质被称为产品。 在化学反应中,债券断裂反应器和产品中的新债券形式。
    • Chemical reactions can be represented by chemical equations. According to the law of conservation of mass, mass is always conserved in a chemical reaction, so a chemical equation must be balanced, with the same number of atoms of each type of element in the products as in the reactants.
      ::化学反应可以用化学方程式来表示。 根据质量保护法,质量总是在化学反应中加以保护,因此化学方程式必须平衡,产品中每种元素的原子数量与反应物中的原子数量相同。
    • Many chemical reactions occur all around us each day, such as iron rusting and organic matter rotting, but not all changes are chemical processes. Some changes, such as ice melting or paper being torn into smaller pieces, are physical processes that do not involve chemical reactions and the formation of new substances.
      ::我们周围每天都会发生许多化学反应,例如铁锈和有机物腐烂,但并非所有变化都是化学过程。 一些变化,如冰融化或纸张被撕成小块,是物理过程,不涉及化学反应和新物质的形成。
    • All chemical reactions involve energy, and they require  activation energy to begin. Exothermic reactions release energy. Endothermic reactions absorb energy.
      ::所有化学反应都涉及能量,它们需要激活能量才能开始。 异热反应释放能量。 异热反应吸收能量。
    • Biochemical reactions are chemical reactions that take place inside living things. The sum of all the biochemical reactions in an organism is called  metabolism. Metabolism includes catabolic reactions (exothermic reactions) and anabolic reactions (endothermic reactions).
      ::生物化学反应是生命中发生的化学反应。 生物体中所有生物化学反应的总和被称为新陈代谢。 新陈代谢包括新陈代谢反应(异温反应)和新陈代谢反应(异温反应 ) 。 新陈代谢反应包括新陈代谢反应(异温反应)和新陈代谢反应(异温反应 ) 。
    • Most biochemical reactions require  a biological catalyst called an enzyme to speed up the reaction by reducing the amount of activation energy needed for the reaction to begin. Most enzymes are proteins that affect just one specific substance, called the enzyme's substrate.
      ::大部分生物化学反应都需要一种叫作酶的生物催化剂来通过减少反应开始所需的活性能量来加速反应。 大多数酶都是只影响一种特定物质的蛋白质,即酶基质。
    • Virtually all living things on Earth require liquid water. Only a tiny percent of Earth's water is fresh liquid water. Water exists as a liquid over a wide range of temperatures, and it dissolves many substances. These properties depend on water's polarity, which causes water molecules to "stick" together.
      ::地球上几乎所有生物都需要液态水。地球水中只有很小的一小部分是淡水。水作为液体存在于广泛的温度上,它溶解了许多物质。这些特性取决于水的极性,它使水分子“粘合在一起 ” 。
    • The human body is about 70 percent water (outside of fat). Organisms need water to dissolve many substances and for most biochemical processes, including photosynthesis and cellular respiration.
      ::人体大约是70%的水(脂肪外)。 生物需要水来溶解许多物质和大部分生化过程,包括光合作用和细胞呼吸。
    • A solution is a mixture of two or more substances that has the same composition throughout. Many solutions consist of water and one or more dissolved substances.
      ::一种溶液是由两个或两个以上物质混合而成,其成分自始至终相同,许多溶液由水和一种或多种溶解物质组成。
    • Acidity is a measure of the hydronium ion concentration in a solution. Pure water has a very low concentration and a pH of 7, which is the point of neutrality on the pH scale. Acids have a higher hydronium ion concentration than pure water and a pH lower than 7. Bases have a lower hydronium ion concentration than pure water and a pH higher than 7.
      ::纯水浓度非常低,pH值为7,这是pH值的中点。酸的氢离子浓度高于纯水,pH值低于7。基底的氢离子浓度低于纯水,pH值高于7。
    • Many acids and bases in living things are secreted to provide the proper pH for enzymes to work properly.  
      ::许多酸和活物的基底被秘密保存,以便为酶正常工作提供适当的pH值。

    Now you understand the chemistry of the molecules that make up living things. In the next chapter, you will learn how these molecules make up the basic unit of structure and function in living organisms — cells — and you will be able to understand some of the crucial chemical reactions that occur within cells. 
    ::现在你了解构成活物的分子的化学成分。在下一章,你将了解这些分子如何构成活生物体——细胞——的基本结构和功能单位,你将能够理解细胞中发生的一些关键化学反应。

    Chapter Summary Review
    ::" 概述 " 章次

    1. The four major classes of biochemical compounds are: carbohydrates, lipids, proteins, and nucleic acids. For each of the substances below, identify which of these classes includes the substance.
    ::1. 生物化学化合物的四大类是:碳水化合物、脂类、蛋白质和核酸,对以下每种物质,标明其中哪类物质包括该物质。

    a. enzymes
    ::a. 酶

    b. fructose
    ::b. 纤维化

    c. DNA
    ::c. DNA

    d. RNA
    ::d. RNA

    e. steroids
    ::e. 类固醇

    2. The chemical formula for the complex carbohydrate glycogen is C 24 H 42 O 21 .
    ::2. 复合碳水化合物甘油的化学公式为C24H42O21。

    a. What are the elements in glycogen?
    ::a. 甘油成分是什么?

    b. How many atoms are in one molecule of glycogen?
    ::b. 甘油分子中有多少原子?

    c. Is glycogen an ion? Why or why not?
    ::c. 甘油是离子吗?

    d. Is glycogen a monosaccharide or a polysaccharide? Besides memorizing this fact, how would you know this based on the information in the question?
    ::d. 甘油是单沙律还是聚沙律?除了记住这一事实外,你如何根据问题的信息知道这一点?

    e. What is the function of glycogen in the human body?
    ::e. 人体中甘基体的功能是什么?

    3. What is the difference between an ion and a polar molecule? Give an example of each in your explanation.
    ::3. 离子和极分子有什么区别?请在解释中举例说明其中的每一种。

    4. Define monomer and polymer.
    ::4. 界定单体和聚合物。

    5. For each of the following polymers, identify the name of its monomers.
    ::5. 对于下列每一种聚合物,应标明其单体名称。

    a. RNA
    ::a. RNA

    b. protein
    ::b. 蛋白质

    c. complex carbohydrate
    ::c. 复杂的碳水化合物

    6. What is the difference between a protein and a polypeptide?
    ::6. 蛋白质和聚石化之间有什么区别?

    7. People with diabetes have trouble controlling the level of glucose in their bloodstream. Knowing this, why do you think it is often recommended that people with diabetes limit their consumption of carbohydrates?
    ::7. 糖尿病患者难以控制血液中的葡萄糖含量,知道这一点,你为什么认为经常建议糖尿病患者限制对碳水化合物的消费?

    8. Identify each of the following reactions as endothermic or exothermic.
    ::8. 确定以下每种反应为内热或异热反应。

    a. cellular respiration
    ::a. 细胞呼吸

    b. photosynthesis
    ::b. 光合作用

    c. catabolic reactions
    ::c. 代谢反应

    d. anabolic reactions
    ::d. 新陈代谢反应

    9. Pepsin is an enzyme in the stomach that helps us digest protein. Answer the following questions about pepsin.
    ::9. Pepsin是一种有助于我们消化蛋白质的胃酶,回答以下有关pepsin的问题。

    a. What is the substrate for pepsin?
    ::a. pepsin 的基质是什么?

    b. How does pepsin work to speed up protein digestion?
    ::b. pepsin如何加速蛋白消化?

    c. Given what you know about the structure of proteins, what do you think are some of the products of the reaction that pepsin catalyzes?
    ::c. 根据你对蛋白质结构的了解, 你认为Pepsin催化器反应的一些产品是什么?

    d. The stomach is normally acidic. What do you think would happen to the activity of pepsin and protein digestion if the pH is raised significantly?
    ::胃通常是酸性的,如果pH值显著提高,你认为pepsin和蛋白分解的活动会怎样?

    10. What defines a neutral pH? What is the numerical value of a neutral pH?
    ::10. 中性pH是什么定义?中性pH的数值值是多少?

    11. True or False:  Unsaturated fatty acids have straight chains.
    ::11. 真实或假:不饱和脂肪酸有直链。

    12. True or False:  The DNA code carries instructions for the correct sequence of nucleic acids in a protein.
    ::12. 真实或假:DNA代码载有蛋白质核酸正确序列的指示。

    13. True or False:  Phospholipids make up cell membranes.
    ::13. 真实或假:磷脂构成细胞膜。

    14. The function of proteins can include
    ::14. 蛋白质的功能可包括:

    a. helping cells keep their shape
    ::a. 帮助细胞保持其形状

    b. helping to destroy foreign substances
    ::b. 帮助销毁外国物质

    c. speeding up biochemical reactions
    ::c. 加速生化反应

    d. all of the above
    ::d. 以上所有情况

    15. Which of the following is not part of a nucleotide?
    ::15. 以下哪一种不是核糖核酸的一部分?

    a. a nitrogen base
    ::a. 氮基

    b. a cellulose molecule
    ::b. 纤维素分子

    c. a sugar molecule
    ::c. 糖分子

    d. a phosphate group
    ::d. 磷酸酯组

    16. The “push” needed to start a chemical reaction is the
    ::16. 开始化学反应所需的 " 推进 " 是:

    a. enzymatic energy
    ::a. 酶能

    b. endothermic energy
    ::b. 内热能

    c. activation energy
    ::c. 激活能量

    d. reactant energy
    ::d. 反应能