题干

本题共三个小题.

Ⅰ如图甲装置,请回答下列关于光合作用的问题:

(1)测甲叶片光合作用时,除满足充足的光照,适宜的温度外,A液体的作用是____ .测得容器中气体变化量是____ 

(2)叶绿体中色素主要吸收可见光中的____ 光.

(3)如果供给植物H2O18,容器含O18的物质有____ 

Ⅱ如图乙示翻译过程,图丙是甲图方框内部分的放大.思考并回答下列问题:

(1)翻译过程中,肽链上的氨基酸由____  (填mRNA或tRNA)上的三个碱基组成的密码子决定.一种氨基酸可以由____ 种密码子决定.

(2)一种tRNA能携带____ 种氨基酸.图乙中不同的核糖体合成的肽链是否一定相同?____ 

Ⅲ下列是关于变异与育种的一些问题.请思考并回答:

(1)杂交育种过程中,从F2选出的符合需要的优良性状的组合类型,是否一定要经过连续自交获得纯合子才能在生产中推广?____ .如果需要,能大大缩短育种年限的方法是____ ,其原理是____ .

(2)转基因食品是否一定对人体健康有害?____ 

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答案(点此获取答案解析)

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同类题2

阅读理解

    Many children in England get given lunch at school. There are new rules about what children may be given for these lunches. The reason for this is to give children healthier food. There are many foods that children aren't allowed to eat and they're only allowed to eat small amounts of fatty or sweet food. If you were at a school there, you might hear this conversation as you wait for your lunch.

    Josh:        What's for lunch? I want chips!

    Dinner lady: No chips today. You've had chips twice this week already.

    Josh:        Oh! OK, I'll have a chicken pie with gravy.

    Dinner lady: No, sorry. You've had a pastry dish (油酥食品) once this week already.

    Josh:        Really?Oh, yes, on Monday. Well, what can I have? I'd like pasta and sauce.

    Dinner lady: No, sorry. Pasta counts as (算作)a pastry dish. So you can't have that, either.You've had two pastry dishes this week-a meat pie and a pizza. You can have vegetables or salad. The meatballs are nice today.

    Josh:        All right. I'll have meatballs and steamed vegetables. I hope they're tasty.

    Dinner lady: They're good for you!

    Josh:        I miss my chips. They're my favorite. I used to have them every day, before these new rules came in.

Dinner lady: Well, that's why these rules were brought in. Too many children were eating junk food, especially chips. Children like chips, but they aren't a healthy choice.

    Josh:        I'll have an apple juice with that, please.

    Dinner lady: OK, but its only 150 ml. You aren't allowed more than that as juice has sugar in it. The new rules encourage you to drink water. No soft drinks at all.

    Students cannot have more than two portions (价额)a week of food that has been deep-fired.They must have at least three different fruits and three different vegetables every week. Whole grains such as brown bread are to be given,instead of "white" grains.

    These rules are to teach healthy eating and to stop children putting on too much weight. This will make sure that more people are healthy in the future.