The excess oxygen is necessary for animals and other organisms to live.
The process of changing light into food and oxygen is called photosynthesis. Besides light energy from the sun, plants also use water and carbon dioxide. The water gets to the plant through its roots. The carbon dioxide enters the leaves through tiny openings called stomata. The carbon dioxide travels to chloroplasts, special cells in the bodies of green plants. This is where photosynthesis takes place. Chloroplasts contain the
chlorophylls that give plants their green color. The chlorophylls are the molecules that trap light energy. The trapped light energy changes water and carbon dioxide to produce oxygen and a simple sugar called glucose.
Carbon dioxide and oxygen move into and out of the stomata. Water vapor also moves out of the stomata. More than 90 percent of water a plant takes in through its roots
escapes through the stomata. During the daytime, the stomata of most plants are open. This allows carbon dioxide to enter the leaves for photosynthesis. As night falls, carbon dioxide is not needed. The stomata of most plants close. Water loss stops.
If photosynthesis ceased, there would be little food or other organic matter on the earth. Most organisms would disappear. The earth’s atmosphere would no longer contain oxygen. Photosynthesis is essential for life on our planet. 词汇：
nutrient n.营养物organism n.生物体，有机体carbon dioxide n.二氧化碳 chloroplast n.叶绿体molecule n.分子vapor n.水蒸气oxygen n.氧气
photosynthesis n.光合作用chlorophyll n.叶绿素glucose n.葡萄糖cease v.停止 Then animals feed upon the plants.动物以植物为食。 1．In the first paragraph，the word “excess” means
A heavyB extra.C green.D liquid.
2．Which of the following does not move through a plant’s stomata? A Carbon dioxide.B Water vapor.C Oxygen.D Food. 3．In the title, the term Essential Scientific Process refers to A photosynthesis.B the formation of glucose.
C global warming.D water getting to the roots of plants. 4．This passage is primarily developed by
A explaining a process.B telling a story.C comparing and contrasting. D convincing the reader of plants’ importance. 5．Another good title for this passage would be
A Oxygen and Carbon Dioxide.B Plants and Their Roots.
C How Photosynthesis Works.D Why Our Earth Needs Water. 答案与题解：
1．B 前文讲到，植物产生的氧气一部分被植物自身消耗了，但植物消耗的氧气量远小于它们产生的氧气，因此可以推测这句话的意思应该是剩余的氧气对于动物以及其他生物体的生存是至关重要的。excess在句中的意思是“超额的”，与extra“额外的”意思相近。 2．D 从第三段的第一、二句得知，二氧化碳、氧气和水蒸气都能从气孔中通过，唯一一个没有提到的是food“养分、食物”，因此该题选D项。
3．A 文章通篇都在讲Photosynthesis，即光合作頌钠作用和重要性，文章结尾又重申了Photosynthesis is essential for life on our planet，因此选A项。B项是光合作用的一个部分，C、D项则毫不相干。
4．A 文章先是介绍了进行光合作用所需的原料和组织，又介绍了光合作用的过程，因此整个逻辑应该是解释过程，而不是讲故事或比较对比。D项是“向读者说明植物的重要性”，这确实是文章的一个目的，但不是文章的组织方式。
5．C 文章的主题是光合作用的基本原理，因此选项C。A、B项在文中有提及，但不是主旨，D项与本文无关。
一个至关重要的科学过程
地球上所有的生命都依靠绿色植物生存。植物利用阳光制造自己的食物，而动物则以植物为食，它们吸收植物制造和储存的营养物质。但是植物能做的还不仅仅这些，它们还能利用阳光产生氧气，这些氧气的一部分被植物自身消耗了，但植物消耗的氧气量远小于它们产生的氧气，这些多余的氧气对于动物以及其他生物体的生存是至关重要的。
植物将光转化为营养物质和氧气的这个过程叫作光合作用，在这一过程中，植物不仅吸收阳光中的能量，还吸收水和二氧化碳。水通过根系进入植物体内，而二氧化碳则通过叶片上的小孔进人植物体，这些小孔叫作气孔。二氧化碳进入植物体内后，到达叶绿体，叶绿体是绿色植物体内的一种特殊细胞。叶绿体是光合作用发生的地方。叶绿体内包含叶绿素，这种物质使得叶子呈现绿色，它是一种能吸收光能的分子，吸收进来的光能将水和二氧化碳转化，产生氧气和一种结构简单的糖——葡萄糖。
二氧化碳和氧气通过气孔进出。水蒸气也是从气孔逸出。植物体通过根系吸收的水分中的90%。白天，大多数植物的气孔都是张开的，使得二氧化碳能进入植物体参与光合作用。到了夜晚，植物不再需要二氧化碳，于是大多数植物的气孔就关闭了，水分散失也停止了。 如果光合作用停止的话，地球上将不会再有食物或其他有机物质，大多数生物体都会消失，地球的大气中的氧气也将消失。光合作用对于地球上的生命来说是至关重要的。
第十篇Young Female Chimps Outlearn Their Brothers
Young female chimps are faster and better learners than young male chimps, suggests a new study, echoing learning differences seen in human girls and boys.
While young male chimps pass their time playing. Young female chimps carefully study their mothers. As a result, they learn how to fish for tasty termite snacks over two years before the boys.
Elizabeth Lonsdorf, now at Lincoln Park Zoo in Chicago, US, and colleagues at the
University of Minnesota, Saint Paul spent four years watching how young chimpanzees in the Gombe National Park in Tanzania learned “cultural behavior”.
The sex differences in learning behavior were “consistent and strikingly apparent”, says the team. The researchers point out that similar differences are seen in human children with regard to skills such as writing. “A sex-based learning differences may therefore date back at least to the last common ancestor of chimpanzees and humans.” they write in the journal Nature.
Chimps make flexible tools from vegetation and then insert them into termite mounds, extract them and then munch the termites clinging onto the tool. The researchers used video cameras to record this feeding behavior and found that each chimp mother had her own technique, such as how she used tools of different lengths.
Analysis of the six infants whose ages were known showed that girl chimps were an average of 31 months old when they succeeded in fishing out their termites, where the boy chimps were aged 58 months on average. Females were also more skillful at getting out more termites with every dip and used techniques similar to their mothers while males did not.
Instead of studying their mothers, the boy chimps spent a significantly greater amount of time frolicking around the termite mound. Behaviors such as playing or swinging might help the male infants later in life when typically male activities like hunting or fighting for
dominance become important, suggest the researchers.
Lonsdorf adds that there just two main sources of animal protein for chimps — the
termites or colobus monkeys. “Mature males often hunt monkeys up trees, but females are almost always either pregnant or burdened with a clinging infant. This makes hunting difficult,” she says .“Adult females spend more time fishing for termites than males.” So becoming proficient at termite fishing could mean adult females eat better, “They can watch their offspring at the same time. The young of both sexes seen to pursue activities related to their adult sex roles{10} at a very young age.”
练习: 1. Why do young female chimps learn faster than young male chimps at fishing for termites?
A Because young female chimps don’t play with their brothers. B Because young female chimps begin to study their mothers earlier. C Because young male chimps never learn to fish for termites. DBecauseyoung male chimps are not interested in termites. 2. What are the tools with which chimps fish for termites?
A Tree branches.B Vegetation.C Fruits.D Grass.
3. Which of the Following is true about chimps fishing for termites according to paragraph 6?
A Males often compete with females in fishing for termites. B Males could get out more termites with every dip. C Females could get out more termites with every dip.
D Males are good at mastering technique for fishing for termites.
4. How did the researchers explain the fact that boy chimps spent more time on playing? A They like hunting. B They enjoy fighting.
C It helps them to stay fit. D It will make them good fighters and hunters in the future.
5. According to the last paragrnph, which of the following is NOT true? A Adult chimps hunt monkeys while young chimps fish for termites. B The main source of animal protein for male chimps is colobus monkeys. C The main source of animal protein for female chimps is termites.
D Female chimps fish for termites while watching their children.
1. B 根据第二段的内容，雄性小猩猩将时间用来玩要，而雌性小猩猩则研究她们母亲的行为，因此，她们比雄性小猩猩早两年学会捕食白蚁。 A、D文中没有提到， C与问题没有关系。
2. B第五段的第一个句子告诉我们，猩猩用植物作成方便的工具，用来捕食白蚁。 A、C和 D均是错误的。
3. C 该段告诉我们，对六只小猩猩的分析表明，雌性小猩狠不但较早学会捕食白蚁 .
而且能比雄性小猩猩更为熟练地捕食到更多的白蚁。所以， B和 D都不是正确选项。 A项内容文中没有提到。
4. D A、B和 C都是错误的，因为文中没有捉到雄性小猩猩喜欢猎食和打斗，也没有提及玩耍能使他们更健康。D是正确答案。第七段昀后一句说，他们喜欢玩耍的行为有助于他们长大后的生活，因为，到那时，他们要猎食和争权夺位。
5. A 根据昀后一段的内容，成年雄猩猩主要猎食生活在树上的一种叫做 colobus（疣猴）的猴子，而雌性猩猩捕食白蚁。所以 A是正确选项。 B、C和 D的内容均可在该段中找到。
第十篇 年轻雌猩猩学习优于她们的弟兄
一项新的研究显示，与年轻雄性相比，年轻雌黑猩猩是更快更好的学习者，这与人类的两性学习差异相仿。
在小雄猩猩玩乐嬉闹时候，雌猩猩却在悉心向母亲学习。结果她们比“男孩们”提早两年学会捕获美味小吃——白蚁。
美国芝加哥林肯公司动物园的Elizabeth Lonsdorf 和她在圣保罗市明尼苏达大学的同事们用了4年时间观察坦桑尼亚Gombe 自然公园的年轻黑猩猩学习它们的“文化行为”。 学习行为的性别差异是“一贯和惊人显著的”，观察小组报告说。研究人员指出，类似的差别也存在于人类儿童写作等技巧的学习过程。他们在《自然》杂志中写道，“基于性别的学习差异因而可以上溯到人类和黑猩猩最近的共同始祖。”
黑猩猩用植物制造灵巧的工具，将它们插入蚁丘把白蚁驱赶出来，再津津有味地享用粘在工具上的白蚁。研究人员用摄像机记录下这种捕食行为，发现每位猩猩母亲在诸如怎样使用不同长度的工具等方面都有她们自己的诀窍。
分析研究六只已知年龄的幼猩猩显示，雌猩猩在平均31个月大时就能成功捕获白蚁，而雄猩猩则需要到58个月时才能学会。雌性每次都能熟练地收获更多的白蚁，并能采用与母亲相似的技巧，而雄性却做不到。
“男孩们”不向母亲学习，却花费大量时间在蚁丘周围嬉戏。研究人员认为玩耍、摇荡等活动或许对公幼兽后来的诸如捕猎、争夺领导权等典型的雄性活动大有裨益。
Lonsdorf 补充说，黑猩猩食物中动物蛋白的主要来源有两个——白蚁和疣猴。“成熟雄性常在树间抓捕疣猴，而雌性则总是因为怀孕或身上吊着小猩猩而难以捕猎，”她说，“成年雌性比雄性花更多的时间捕食白蚁。”因此娴熟地捕获白蚁意味着雌性比雄性吃得更好，“并且可以同时看护后代。雌雄两性似乎都是在十分年幼的时候就开始了与成年后性别角色有关的活动。”
第十一篇：When Our Eyes Serve Our Stomach
Our senses aren’t just delivering a strict view of what’s going on in the world；they’re affected by what’s going on in our heads1. A new study finds that hungry people see food-related words more clearly than people who’ve just eaten.
Psychologists have known for decades that what’s going on inside our head affects our senses. For example, poorer children think coins are larger than they are, and hungry people think pictures of food are brighter. Remi Radel of University of Nice Sophia-Antipolis2, France, wanted to investigate how this happens. Does it happen right away as the brain receives signals from the eyes or a little later as the brain’s high-level thinking processes get involved.
Radel recruited 42 students with a normal body mass index3. On the day of his or her test, each student was told to arrive at the lab at noon after three or four hours of not eating. Then they were told there was a delay. Some were told to come back in 10
minutes; others were given an hour to get lunch first. So half the students were hungry when they did the experiment and the other half had just eaten.
For the experiment, the participant looked at a computer screen. One by one, 80 words flashed on the screen for about l/300th of a second each. They flashed at so small a size that the students could only consciously perceive. A quarter of the words were food-related. After each word, each person was asked how bright the word was and asked to choose which of two words they’d seen — a food-related word like cake or a neutral word like boat. Each word appeared too briefly for the participant to really read it. Hungry people saw the food-related words as brighter and were better at identifying food-related words. Because the word appeared too quickly for them to be reliably seen, this means that the difference is in perception4, not in thinking processes, Radel says.
“This is something great to me. Humans can really perceive what they need or what they strive for. From the experiment, I know that our brain can really be at the disposal of5 our motives and needs,” Radel says.
词汇：threshold / ’θre?h??ld/ n．起点，开端；门檻 neutral / ’nju:tr?l / adj．中性的；中立的strive / stra?v/ v．努力，力求；斗争 disposal / d?s’p??z?l / n．处理，处置；配置motive/ ’m??t?v/ n．动机，目的
1．Our senses aren’ t just delivering a strict view of ... in our heads：这个句子的大概意思是：我们的五官感觉不仅仅让我们感知世界；五官感觉还受大脑活动的影响。 2．University of Nice Sophia-Antipolis：法国尼斯·索菲亚·安提波利斯大学，简称尼斯大学，1965年经法国政令正式宣布成立。尼斯大学在尼斯市设有7处主校园，另外，还在索菲亚·安提波利斯市（Sophia Antipolis）、戛纳市（Cannes）和芒东市（Menton）设有校区。索菲亚·安提波利斯是位于尼斯市西南侧的科技园区，是许多髙等学府的所在地。
3．body mass index：身体质量指数4．in perception ：感知 5．at the disposal of：受到……的控制
1．What does the new study mentioned in Paragraph 1 find? A Hungry people see every word more clearly than ordinary people. B Hungry people are always thinking of food-related words.
C Hungry people are more sensitive to food-related words than stomach-full people.
D Hungry people do not have lower-level of thinking process. 2．Why was there a delay on the day of the experiment? A Because hungry people needed time to fill their stomach.
B Because Radel wanted to create two groups of testees, hungry and non-hungry. C Because noon was not the right time for any experiment.
D Because Radel needed time to select participants in terms of body mass index. 3．What does the writer want to tell us?