章节大纲

  • 常规

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  • 适应和自然选择

    Lesson Objectives
    ::经验教训目标

    • Describe how characteristics of plants and animals are inherited. Some characteristics can be affected by the environment. 
      ::说明植物和动物的特征是如何继承的,有些特征可能受到环境的影响。

    Lesson Vocabulary
    ::词汇表课程

    • adaptation
      ::适应
    • mutation
      ::突变
    • variation
      ::变化变化

    Why would a living thing match its background? Wouldn't it be better to stand out?
    ::为什么一个活物要符合其背景?

    Some livings things are hard to see. They are able to blend into their background. This is a special trait that helps them survive. They are less likely to be eaten.
    ::有些活物很难看出来, 它们能融入到自己的背景中。 这是一个特殊的特点, 有助于它们生存。 它们被吃掉的可能性较小 。

    Adaptation is a change in a plant or animal traits. These special traits help them survive. Why is it important to adapt special traits? Special traits can help a species survive.
    ::适应是植物或动物特性的改变。 这些特殊特性有助于它们生存。 为什么必须适应特殊特性? 特殊特性可以帮助物种生存。

    The longer they survive, the more offspring they can have. More offspring means a species has a better chance of survival.
    ::它们存活的时间越长,它们的后代就越多。 更多的后代意味着物种的生存机会越大。

    Special traits can be passed from parent to offspring. 
    ::特殊特征可以从父母传给后代。

    Variations
    ::变式

    Every living thing is unique. All living things have adapted traits. These traits are what makes them unique. There are also variations in the traits. Not all organisms of the same species have the same trait. For example, people can have different hair color. Hair can be blonde, brown, black, or even red. Hair color is a trait. Yours is inherited from your parents. 
    ::每个生物都是独特的。所有生物都有适应性的特性。这些特性使它们具有独特性。 这些特性也使它们具有独特性。 特性也各不相同。 不是所有同一物种的生物都有相同的特性。 例如, 人们可以有不同的发色。 头发可以是金发、 棕色、 黑色, 甚至红色。 发色是一种特性。 您的发色是从父母那里继承的。

    Mutations
    ::变异

    Sometimes traits can vary from parent to offspring. These changes are due to mutations. Mutations are a random change. Mutations are natural. Some mutations are harmful. In this case, the organism may not live to reproduce. The trait will not be passed onto offspring. Others variations in traits have no effect on survival. Can some mutations be good for a living thing?
    ::有时,各种特性会因父母和后代而不同。这些变化是由变异引起的。变异是一种随机的变化。变异是自然的。变异是自然的。有些变异是有害的。在这种情况下,生物体可能不会活下来繁殖。特性不会传给后代。其他变异对生存没有影响。有些变异对活的东西是否有益?

    Other mutations can have great benefits. Imagine being the first moth that can blend into its background. It would have a better chance of survival.  A living thing that survives is likely to have offspring. If it does, it may pass the new trait on to its offspring. That’s good news for the offspring. The offspring may be more likely to survive. Mutations are one way living things adapt to new conditions.
    ::其它突变可以带来巨大的好处。 想象一下是第一个能够融入其背景的飞蛾。 它有更好的生存机会。 生存下来的活物很可能有后代。 如果它能生存下来,它可能会将新的特征传给后代。 这对后代来说是好消息。 后代可能更有可能生存下去。 变异是生活事物适应新条件的一种方式。

    Adaptations
    ::适应

    Some traits help a living thing survive. These traits are called adaptations. Some adaptations are better than others. Look at the cactus in  Figure  . Its leaves look like needles. Their shape helps the plant live in dry climates. The needle-like leaves help it to not lose water. Why is that important for a cactus? Cactus live in deserts. Deserts receive very little rainfall.
    ::有些特性有助于活物生存。这些特性被称为适应性。有些适应性优于其他。看看图中的仙人掌。它的叶子看起来像针头。它们的形状有助于植物在干燥的气候中生存。针状的叶子有助于它不失去水。为什么对仙人掌来说这样重要?仙人掌生活在沙漠中。沙漠的降雨量很少。

    Other plants are better suited for locations that are wet and shady. These are opposite conditions to the desert. Palm trees grow in the rainforest. Rainforests have a lot of rainfall. The palm tree has very large leaves. They do not have to worry about losing water through their leaves. As a result, palm leaves are very wide.  
    ::其他植物更适合潮湿和阴暗的地方,与沙漠的条件相反。棕榈树在雨林中生长。雨林中降雨量很大。棕榈树有很大的叶子,不必担心树叶漏水。因此,棕榈叶很宽。

    Plants that live in sunny locations do not need large leaves. If they lived in shady conditions they would need leaves that work extra hard. They need to gather as much sunlight as possible. They gather sunlight in order to make food.
    ::生活在阳光明媚地点的植物不需要大叶子,如果他们生活在阴暗的状态下,他们需要额外艰苦的叶子,他们需要尽可能多的阳光,收集阳光以制造食物。

    In contrast, the cactus leaves get plenty of sunlight. Its leaves can be much smaller. Deserts receive a lot of sunlight. The cactus does not need really large leaves to collect sunlight.
    ::相反,仙人掌叶的阳光充足,其叶子可能小得多。沙漠得到的阳光也很多。仙人掌并不需要大叶来收集阳光。

    Many adaptations protect living things from harm. The cactus shown below has a large barrel-like body. This trait helps it store water. It may need to go a long time between rainfalls. 
    ::许多适应能保护生命免受伤害。 下面显示的仙人掌有一个巨大的桶状体。 这个特性有助于它储存水。 它可能需要在降雨之间花费很长的时间。

    Cacti have thick, water-retaining bodies that help them conserve water.

    Other adaptations help a living thing. They may help it move or gather food. Reindeer have sponge-like hooves. This helps them walk on snowy ground without slipping and falling. Fish at the bottom of the ocean are tiny. This allows them to use very little energy. This is helpful because there is not much food around.
    ::其它的适应可以帮助活物。 它们可以帮助它移动或收集食物。 驯鹿有海绵般的蹄子。 这可以帮助他们在雪地上行走而不滑落。 海底的鱼非常小。 这使得它们能使用很少的能量。 这很有帮助, 因为周围的食物不多。

    Living things have special features that help them avoid being eaten. Some plants contain poison, or just taste bad. These traits keep animals from eating them. Often their brightly colored flowers serve as a warning. The same is true of some frogs. Some frogs can be poisonous. 
    ::活物有特殊特征,可以避免被食用。有些植物含有毒药,有些只是味道不好。这些特征可以阻止动物吃这些植物。它们的彩色鲜花往往起到警告作用。一些青蛙也是如此。有些青蛙可能是有毒的。

    Poison dart frogs have toxins in their skin. Their bright colors warn potential predators not to take a bite!

    Have you ever heard of the deer mouse? It is one of Nebraska's oldest settlers. It was there long before people. In fact, it lived in Nebraska before the last ice age.  What does this have to do with adaptation? As it turns out, everything. The last ice age event changed the environment. In order to survive, the deer mouse adapted.
    ::你听说过鹿鼠吗?它是内布拉斯加最古老的定居者之一。事实上,它早在人们之前就住在内布拉斯加。事实上,它在上一个冰河时代之前就住在内布拉斯加。这与适应有什么关系?事实证明,所有事情都是如此。上次的冰河时代事件改变了环境。为了生存,鹿鼠经过了适应。

    What color is a mouse? In Nebraska, most mice are brown. In one particular area, they are not the typical brown. Instead, the mice have a lighter color. Why do you think a lighter would be a benefit?
    ::鼠标是什么颜色? 在内布拉斯加州, 大部分老鼠是棕色的。 在某个特定地区, 它们不是典型的棕色。 相反, 小鼠的颜色较轻。 您认为打火机有什么好处?

    During the last ice age, glaciers carried in light colored sand. The sand was deposited on top of the darker soil of the area. This region is now called the Sand Hills area of Nebraska. In this area, the brown mice did not blend in. Their brown color caused them to stand out. As a result, they became easy prey.
    ::在上一个冰河时代,冰川在浅色的沙子中飘动。沙子沉积在该地区较黑暗的土壤之上。这个区域现在被称为内布拉斯加的沙丘地区。在这个地区,棕色老鼠没有混入其中,棕色的颜色使他们露出一身。结果,它们很容易成为猎物。

    Predators could more easily spot the dark mice on this new light colored background. Natural selection favored the light mice. The light colored mice were able to live longer. As a result they had more offspring. Over time, the population became light colored. Today, the mice in the Sand Hills are light in color. This change is due to a change in their environment. 
    ::捕食者可以更容易地在这种新的光彩色背景中发现暗鼠。 自然选择有利于光鼠。 光色小鼠能够活得更长。 结果是它们有较多的后代。 随着时间的推移, 人口变得浅色。 今天, 沙丘的鼠的颜色很浅。 这种变化是由于它们环境的变化造成的。

    Glaciers carried lighter colored material over the area. The Deer mouse adapted to the environment by developing a lighter color. They are now able to blend in.

    Lesson Summary
    ::经验教训摘要

    • Different members of a population may have different inherited traits.
      ::不同的人口成员可能有不同的继承特征。
    • Some of these differences are due to mutations.
      ::其中一些差异是由于突变造成的。
    • Some traits allow an individual living thing to be better adapted to its environment. That individual will be more likely to survive and to reproduce.
      ::某些特性使个体生物能够更好地适应其环境,该个体更有可能生存和繁殖。

    Lesson Review Questions
    ::经验回顾问题

    1. How do adaptations develop?
      ::适应工作如何发展?
    1. What does it mean to say that a living thing is well adapted to its environment?
      ::说一个活物很适合其环境是什么意思?
    1. What is a mutation?
      ::什么是突变?