问题 选择题

纬度的最大值是(  )

A.0°

B.180°

C.90°

D.60°

答案

纬度的最大值是90°,经度的最大值是180°.

故选:C.

解答题

用某种大小相似的农作物绿色叶片,分组进行实验:已知叶片实验前的重量,在不同温度下分别暗处理1小时,测其重量变化;立刻再光照1小时(光强度相同),再测其与暗处理前的重量变化.得到如下结果:(建议对表中文字重输)

组别
温度27℃28℃29℃30℃
暗处理后的重量变化(mg)*-1-2-3-4
光照后的重量变化(mg)*+3+3+3+2
*指与处理前的重量进行比较,“-”表示减少的重量值,“+”表示增加的重量值
请回答问题:(说明:实际光合速率=净光合速率=总光合速率-呼吸速率)

(1)假如叶片的重量变化都是光合作用所合成的有机物的量,请根据表中所测数据情况计算出27℃时总光合速率是______mg/h,在相同光照强度下,温度从27℃升到30℃的过程中,净光合作用强度的变化情况是______.可能影响的外界因素有______等.

(2)有人认为在相同日温(较适宜)下,夜温低于0℃或高于20℃时,绿叶蔬菜的产量都不理想.请你设计实验,探究日温在29℃夜温控制在多少度范围时,人工大棚中种植绿叶蔬菜,收获的绿叶蔬菜产量较高(怎样控制温度不作要求).

①该实验的自变量是______.

②实验的方法步骤:

第一步:取同种的、枝叶数量、大小、重量和健康状况等相同(或相近)的绿叶蔬菜幼苗若干,均分5组;

第二步:将5组绿叶蔬菜幼苗种植在相同土质中,日温控制在29℃,夜温分别控制在______,光照强度及光照时间、水肥管理等条件完全相同;

第三步:______.

③结果分析:______.

阅读理解

Since the gene , called DAF-16 in worms, was found in many animals and in humans, the finding could open up new ways to affect aging ,immunity and resistance in humans the scientists said.

“We wanted to find out how normal aging is being governed by genes and what effect these genes have on other traits such as immunity,”said Robin May , who led the study.

Populations across the world are aging at a surprising pace , bring potentially big challenges for health and social care systems . A study by Danish scientists last year found that half of babies born in rich world today will live to celebrate their 100th birthday . Scientists are eager to find out how people age to try to develop drugs to help them stay healthier lives extend.

“What we have found is that things like resistance and aging tend go hand in hang “ May said in an interview

May’s team compared longevity ,stress resistance and immunity in four related species of worm. They also looked for differences in the activity of DAV-16 in each of the four species and found that they were all quite distinct.

May said DAF-16 was active in most cells in the body and was very similar to a group of human genes called FOXO genes , which scientists believe play a role in the aging process. “The fact that subtle differences in DAF-16 between species seem to have such an impact on aging and health is very interesting and many explain how differences in lifespan and related traits have arisen during evolution,”May said

小题1:In which section may the text appear in a newspaper?

A  Education   B  Science   C  Entertainment    D  Culture

小题2: According to May ,   

A resistance has a lot of to do with aging    B FOXO genes can be found in worms

C genes play the same role in difference species   D  new drugs will change the genes in older people

小题3:From the text we know that DAF-16   

A is a gene that is only found in worms     B can make people live longer

C has an effect on aging and immunity     D  has been quite familiar to scientists