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【单选题】

Passage One
With rapid growth of world population, mainly in developing countries, the available cultivable land per person has declined steadily since 1960 and will decease by half over the next 50 years. Besides, about 400 million women of childbearing age are iron deficient, leaving their babies exposed to various birth defects. As many as 100 million children suffer from vitamin A deficiency. Tens of millions of people suffer from other major ailments and nutritional deficiencies caused by lack of food.
How can biotech help Biotechnologists have developed genetically modified rice fortified with beta carotene (β-胡萝卜素) and additional iron, and they are working on other kinds of nutritionally improved crops. Biotech can also improve farming productivity in places where crop failures are caused by pests, drought, poor soil and crop viruses, bacteria or fungi. Genetically modified, virus-resistant crops can reduce that damage, as can drought-tolerant seeds in regions where water shortages limit the amount of land under cultivation. Biotech can also help solve the problem of soil that contains excess aluminum, which damages roots and causes staple crop failures.
Many scientists believe biotech could raise overall crop productivity in developing countries as much as 25% and help pr the loss of those crops after they are harvested. Yet for all that promise, biotech is far from being the whole answer. In developing countries, lost crops are only one cause of hunger. Poverty plays the largest role. genetically modified crops available will not reduce hunger if farmers cannot afford to grow them or if the local population cannot afford to buy the food those farmers produce.
Nor can biotech overcome the challenge of distributing food in developing countries. Taken as a whole, the world produces enough food to feed everyone--but much of it is in the wrong place. Especially in countries with undeveloped transport infrastructures, geography restricts food availability as dramatically as genetics promises to improve it.
Biotech has its own "distribution" problems. Private-sector biotech companies in rich countries carry out much of the leading-edge research. Their products are often too costly for poor farmers in the developing world, and many of those products won’t even reach the regions where they are most needed. Biotech firms have a strong financial incentive to target rich markets first to help them rapidly recoup the high costs of product development. But some companies are responding to the needs.
Biotechnologists can help illnesses related to nutritional inadequacy by ______.

A.
developing genetically modified or nutritionally improved crops
B.
incorporating pest-resistant or virus-resistant genes into seeds of crops
C.
improving the ability of seeds to resist water shortages in certain regions
D.
identifying genes that helps neutralize aluminum toxicity in crops
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题目标签:胡萝卜素
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参考解析:
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刷刷题刷刷变学霸
举一反三

【单选题】胡萝卜素在体内可转换为

A.
维生素A
B.
维生素B
C.
维生素K
D.
维生素E

【单选题】下列属于维生素A原的类胡萝卜素是

A.
番茄红素
B.
玉米黄素
C.
b-隐黄素
D.
辣椒红素
E.
叶黄素

【单选题】下列有关胡萝卜素的叙述,错误的是[ ]

A.
胡萝卜素是脂溶性色素,宜用石油醚等有机溶剂萃取
B.
胡萝卜素呈橙黄色,是常用的食用色素
C.
胡萝卜素经人体吸收后能在体内转化成维生素A
D.
植物中只有胡萝卜中含有胡萝卜素

【单选题】关于β-胡萝卜素叙述错误的是()

A.
维生素A原
B.
在加氧酶作用下生成2个视黄醇
C.
植物中含量丰富
D.
具有维生素A的活性
E.
儿童缺乏可引起佝偻病

【多选题】下列蔬菜中含胡萝卜素最为丰富的是( )

A.
深色的叶类蔬菜
B.
浅色的茎类蔬菜
C.
深色的茎类蔬菜
D.
浅色的叶类蔬菜