问题 解答题

在日常生活中,人们经常利用植物呼吸作用的原理.下面都是一些日常生活中常见的现象,而且都与呼吸作用有关.你能作出正确的解释吗?

(1)为什么要将水果、蔬菜放在冰箱中?______

(2)为什么要给植物松土?______

(3)存放蔬菜的地窖里已经安上了电灯,农民在进入地窖时,为什么手里还要拿着点燃的蜡烛?______

(4)存放时间较长的萝卜,为什么会空心?______

(5)玉米、水稻等在入仓前为什么要晒干?______

(6)关于呼吸作用原理在生活中的应用,你还能举出别的例子吗?______.

答案

(1)温度能影响呼吸作用,主要是影响呼吸酶的活性.一般而言,在一定的温度范围内,呼吸强度随着温度的升高而增强. 根据温度对呼吸强度的影响原理,在生活中贮藏新鲜的蔬菜水果时应该放在冰箱内低温保存,减弱呼吸作用,减少对有机物的消耗.

(2)植物的呼吸作用吸收的是空气中的氧气,给农作物经常松土,保证土壤中有较多的氧气,从而增强根的呼吸作用.

(3)蔬菜进行呼吸作用消耗氧气分解有机物产生二氧化碳和水,使地窖中的氧气减少,二氧化碳增多;拿着一根点燃的蜡烛进入,如蜡烛继续燃烧,表明氧气较多,可以进入;如果蜡烛熄灭,表明氧气较少不能进入.因此拿着一根点燃的蜡烛,是为了检验氧气的多少,不是为了更方便地看见地窖中的道路.

(4)久存的萝卜由于不断地进行呼吸作用,体内的有机物通过呼吸作用被分解了,所以就空心了.

(5)新收获的粮食(种子)含有较多的水分,而潮湿的种子的呼吸作用比较旺盛,消耗的有机物较多,同时还会释放大量的热,容易使种子发热发霉影响种子的寿命,因此收获的粮食应该及时晒干,减少种子的水分以减弱呼吸作用.

(6)农田淹水后,水把土壤缝隙中的空气排挤出来了,使土壤中的氧气过少,根毛无法呼吸,导致根烂掉;因此农田淹水以后必须及时排涝,是为了让植物的根得到足够的氧气,维持根的正常呼吸.

故答案为:(1)低温能抑制植物的呼吸作用;减少水果内有机物的散失;

(2)松土有利于植物根部获得充足的氧气,进行呼吸作用获得生命活动所需的能量;

(3)地窖里的蔬菜进行呼吸作用会消耗氧气,带点燃的蜡烛是为了检测地窖中的氧气.

(4)进行了呼吸作用,消耗了有机物;

(5)晒干可以防止发霉,另外如果种子含有水果会萌发,萌发的过程会呼吸作用增强,会消耗大量种子中的有机物;

(6)旱地里的农作物被水淹没后,要及时排涝,主要是为了促进呼吸作用.

阅读理解

Sometimes the easiest way to get somewhere is on the back of a bike.

More and more people are using cars in many places in Africa today. However, things are different in Malawi( 马拉维 ).Bikes are the most popular in this African country.

Bike riding is a way of life in Malawi. People use them to carry heavy things. They also use bikes to carry people, especially tourists. These years, taking a “ bicycle taxi” to travel around Malawi has become quite popular among tourists from all over the world.

If you go to Malawi, you will find a lot of bike taxis waiting on the sides of the roads. The riders make the bikes comfortable for passengers to sit on . You can jump on a bike taxi and get around at a very low cost.

Alice is a 21-year-old student from Canada. She enjoys the special bike riding a lot. “I really like the bike taxi,” she says. “It’s easy and cheap.” Alice usually pays just $1 for going shopping in town.

28-year-old Panjira Khombe began to ride a bike taxi two years ago. The young man enjoys this job.“I used to make boats for a living, but that’s a hard job. Being a bike taxi rider is easy for me and I don’t mind carrying heavy people,” he says.

小题1:In Malawi ________ are the most popular way for people to get somewhere.

A.cars

B.bikes

C.trains

D.buses小题2:The passage tells us that Alice enjoys the bike taxi because it’s________.

A.on the side of the road

B.popular and heavy

C.all over the country

D.cheap and easy小题3:From the passage we can learn Panjira Khombe thinks that________.

A.going shopping is easy

B.making boats is difficult

C.riding a bike taxi is cheap

D.carrying heavy people is interesting小题4:The best title of the passage may be “________ ” .

A.Bike Riders

B.A Special Country

C.Bike Taxis

D.A Cheap Journey

填空题