📚 KS3 CIE Year 7 Genes Scheme of Work | KS3 CIE 七年级基因教学大纲
This unit introduces Year 7 learners to the idea that living organisms pass on information from one generation to the next. Pupils explore where genes are located, how they influence characteristics, and why individuals of the same species show variation. The scheme of work builds scientific vocabulary and simple models for inheritance without requiring detailed molecular biology.
本单元向七年级学生介绍生物体将信息从一代传递到下一代的概念。学生将探索基因的位置、基因如何影响性状，以及为什么同一物种的个体会表现出差异。本教学大纲帮助学生积累科学词汇并建立简单的遗传模型，不涉及过于详细的分子生物学。
1. Genes and characteristics | 基因与性状
A gene is a unit of inherited information. Genes carry the instructions that help decide many of an organism’s characteristics, such as eye colour, hair colour and whether earlobes are attached. Although genes are not visible under a school microscope, their effects can be observed in living things.
基因是遗传信息的单位。基因携带决定生物体许多性状的指令，例如眼睛颜色、头发颜色以及耳垂是否粘连。虽然基因在学校显微镜下不可见，但它们的作用可以在生物体中观察到。
In Year 7, learners should describe a gene as a section of DNA that controls a characteristic. It is useful to think of a gene as a recipe in a cookbook: the whole cookbook is the genetic material, and each recipe is one gene that contributes to building the organism.
在七年级，学生应将基因描述为控制某种性状的一段 DNA。可以把基因想象成食谱中的一道菜谱：整本食谱是遗传物质，每道菜谱则是一个基因，共同参与构建生物体。
2. Where genes are found: DNA and chromosomes | 基因在哪里：DNA 和染色体
Genes are located in the nucleus of most plant and animal cells. Inside the nucleus, genetic information is organised into thread-like structures called chromosomes. Each chromosome is made of a chemical called DNA, and genes are small sections of this DNA.
基因位于大多数动植物细胞的细胞核中。在细胞核内，遗传信息被组织成称为染色体的线状结构。每条染色体由一种叫做 DNA 的化学物质组成，基因就是 DNA 上的小片段。
Humans usually have 46 chromosomes in each body cell, arranged as 23 pairs. One chromosome in each pair is inherited from the biological mother and the other from the biological father. This pairing helps explain why offspring resemble both parents.
人类每个体细胞通常有 46 条染色体，组成 23 对。每对染色体中一条来自生物学母亲，另一条来自生物学父亲。这种成对现象有助于解释为什么后代会同时像父母双方。
3. The cell nucleus: control centre | 细胞核：控制中心
The nucleus acts as the control centre of a cell because it stores the genetic information needed for cell activities and for making new cells. If the nucleus is removed from a cell, the cell cannot divide normally or produce the same kind of organism.
细胞核是细胞的控制中心，因为它储存着细胞活动和产生新细胞所需的遗传信息。如果从细胞中移除细胞核，细胞就无法正常分裂或产生相同类型的生物体。
Not all cells have a nucleus. Bacterial cells do not have a true nucleus; their genetic material is loose in the cytoplasm. However, the Year 7 scheme focuses mainly on plant and animal cells where genes are held in the nucleus.
并非所有细胞都有细胞核。细菌细胞没有真正的细胞核，其遗传物质游离在细胞质中。不过，七年级教学大纲主要关注植物和动物细胞，基因位于细胞核内。
4. Inherited characteristics | 遗传性状
Inherited characteristics are features passed from parents to offspring through genes. Examples include natural eye colour, natural hair colour, blood group, dimples, tongue rolling and certain genetic conditions. These features are present at birth, although some become visible later.
遗传性状是通过基因从父母传递给后代的特征。例如天生的眼睛颜色、天生的头发颜色、血型、酒窝、卷舌能力以及某些遗传病。这些特征在出生时就已存在，但有些会稍后才显现出来。
Learners often investigate their own class as a sample. They record whether they can roll their tongue or whether their earlobes are attached. This is a simple way to observe inherited traits, but teachers should point out that the exact genetics of tongue rolling is more complex than a single gene in real life.
学生通常以自己班级为样本进行调查。他们记录自己是否能卷舌或耳垂是否粘连。这是观察遗传性状的简单方法，但教师应指出，真实情况中卷舌的遗传基础比单基因模型更复杂。
5. Variation within a species | 物种内的变异
Variation means the differences between individuals of the same species. No two individuals are exactly alike, even if they are related. Variation is caused partly by differences in genes and partly by differences in the environment.
变异是指同一物种个体之间的差异。没有两个个体是完全相同的，即使它们有亲缘关系。变异部分由基因差异引起，部分由环境差异引起。
Recognising variation is important because it allows living things to adapt to changing conditions. In a population, some individuals may be better suited to survive when the environment changes, which is a key idea in natural selection.
认识变异很重要，因为它使生物能够适应不断变化的环境。在一个种群中，当环境发生变化时，某些个体可能更适应生存，这是自然选择的关键思想。
6. Continuous and discontinuous variation | 连续变异与不连续变异
Continuous variation is when a characteristic can take any value within a range. Height, hand span and foot length are examples. These traits are usually influenced by many genes and by the environment.
连续变异是指某种特征在一个范围内可以取任意值。身高、手掌宽度和脚长都是例子。这些性状通常受多个基因和环境的影响。
Discontinuous variation is when a characteristic falls into distinct groups with no intermediate values. Examples include blood group, ability to roll the tongue and attached or free earlobes. Discontinuous traits are often controlled by a small number of genes.
不连续变异是指某种特征分为明显不同的类别，没有中间值。例子包括血型、卷舌能力以及粘连或游离的耳垂。不连续性状通常由少数基因控制。
| Type of variation | Examples | Pattern |
|---|---|---|
| Continuous | Height, hand span, foot length | Range of values |
| Discontinuous | Blood group, tongue rolling, earlobe type | Separate groups |
7. Environmental and genetic variation | 环境变异与遗传变异
Some differences between individuals are mainly genetic, meaning they are determined by the genes inherited from parents. Other differences are environmental, caused by factors such as diet, climate, sunlight, exercise, disease and lifestyle.
个体之间的一些差异主要是遗传的，即由从父母那里继承的基因决定。另一些差异是环境的，由饮食、气候、阳光、运动、疾病和生活方式等因素引起。
Many characteristics are influenced by both genes and the environment. For example, a person’s maximum possible height may be influenced by genes, but poor nutrition during childhood can prevent them from reaching that height.
许多特征同时受基因和环境的影响。例如，一个人的最大可能身高可能受基因影响，但儿童时期营养不良会使其无法达到该身高。
8. Sexual reproduction and inheritance | 有性生殖与遗传
In sexual reproduction, specialised cells called gametes are produced. In humans, the male gamete is the sperm cell and the female gamete is the egg cell. Each gamete carries half the number of chromosomes of a normal body cell.
在有性生殖中，会产生称为配子的特殊细胞。在人类中，男性配子是精子细胞，女性配子是卵细胞。每个配子携带正常体细胞一半数量的染色体。
At fertilisation, a sperm and an egg join together. The resulting fertilised egg cell has the full number of chromosomes again, with half of its genetic material from each parent. This is why offspring inherit a mix of characteristics from both sides of the family.
在受精过程中，精子和卵子结合。形成的受精卵细胞又恢复了完整的染色体数目，其中一半遗传物质来自父母双方。这就是为什么后代会从家庭双方遗传混合特征的原因。
9. Using models to predict inheritance | 用模型预测遗传
A simple genetic model uses letters to represent different versions of a gene, called alleles. For example, the allele for brown eyes could be written as B and the allele for blue eyes as b. A capital letter represents a dominant allele, while a lower-case letter represents a recessive allele.
简单的遗传模型用字母表示基因的不同版本，即等位基因。例如，棕色眼睛的等位基因可以写成 B，蓝色眼睛的等位基因写成 b。大写字母表示显性等位基因，小写字母表示隐性等位基因。
If an individual has at least one dominant allele, the dominant characteristic is usually shown. A recessive characteristic only appears when the individual has two recessive alleles. This can be modelled using a Punnett square, but Year 7 learners
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