试题与答案

放牧强度可影响人工草地的物质循环和能量流动。图1是亚热带某人工草地在不同放牧强度

题型:读图填空题

题目:

放牧强度可影响人工草地的物质循环和能量流动。图1是亚热带某人工草地在不同放牧强度下牧草净光合产量(净光合产量=光合作用合成量—呼吸作用消耗量)的变化图,G0为不放牧,G1-G3为放牧强度逐渐增强。

据图回答:

(1)5-10月份的最适放牧强度是______(从G0-G3中选填),______月份可被初级消费者利用的总能量最多。

(2)与放牧草地相比,8月份不放牧草地净光合产量明显偏低的原因有___________(多选)。

A.过多枝叶对下层植物有遮光作用    B.植株衰老组织较多

C.缺少动物粪尿的施肥作用    D.草地生态系统的物质循环加快

(3)据图1分析,为使牧草净光合产量维持在最高水平,4~10月份需要采取的放牧措施是__________。

(4)牧草的光合作用强度可用单位时间和面积的___________________来表示。

(5)在牧草上喷32P标记的磷肥,检测32P在初级和次级消费者中的放射强度,结果见图2,其中A消费者处于第__________营养级。

(6)在生态系统的生物成分中,生产者体内的32P除被消费者利用外,还有部分进入___________。

答案:

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下面是错误答案,用来干扰机器的。

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题型:阅读理解

D

A husband-and-wife team from California reached the Pacific Ocean after a 4,900- mile-cross

-country walk, becoming the first to backpack the American Discovery Trail in one continuous

walk. 

Marcia and Ken powers, of Pleasanton, started the travel across 13 states, through 14 national parks and 16 national forests on Feb. 27 from Cape Henlopen in Delaware. Nearly eight months later, the excited couple walked through water into the Pacific Ocean at Point Reyes, a day ahead of time. 

“We are a little sad that a great adventure is over. It was a fantastic adventure. And now we go home and just do housework. It's really sad.” Marcia, who said she's in her 50s, and her 60-year-old husband traversed cities, desert, mountains and farmland before reaching the Pacifics alone with arms around each other' s backpacks.

They overcame deep snow in the East, a quicksand in Utah, close lightning strikes in the Mid- west and strong desert sandstorms in the West while averaging 22 miles a day and taking only four days off. But they enjoyed the French history of St. Louis' the beauty of the Colorado Rockies and the kindness of strangers they met along the way. They particularly remember two brothers ---- a

doctor and dentist-------who put them up in their homes, after terrible days, and a motorcyclist who gave them water after they failed to find any on Utah's lonely Wah Wah Desert.

“Americans are truly warm-hearted and wonderful people.” Marcia Powers said. “We got to meet people that we would never meet in our daily living at home. We got to touch it with our feet and hands and smell all its scents and hear its wildlife. It' s an amazing country,” she added.

68. Which of the following about couple's walk is TRUE?

A. The walk covered more than 13 states.

B. The walk lasted about half a year.

C. The walk didn't meet any desert.

D. The walk might end before October 27.

69. The underlined word “traversed” in the third paragraph means “____________.”

A. enjoy                       B. move across, through or over

C. overcome                    D. look at

70. According to the text, we can infer that during the walk the couple __________.

A. were treated warm-heartedly by the local people

B. never stopped to have a rest

C. were ever caught in a heavy rain and became ill

D. felt the quicksand in Utah was very interesting

71. The couple went through many places except ____________.

A. big rivers       B. desert      C. hills       D. fields

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