搜题请搜索小程序“爱下问搜题”
问题 单项选择题

乳酸脱氢酶在骨骼肌中主要是催化生成（）

A.丙酮酸

B.乳酸

C.3-磷酸甘油醛

D.3-磷酸甘油酸

E.磷酸烯醇式丙酮酸

答案

参考答案：B

解析：乳酸脱氢酶催化的反应为可逆反应，丙酮酸和乳酸既是底物又是产物，在骨骼肌中往往为缺氧环境，产物向乳酸方向进行。

单项选择题

Most plants can make their own food from sunlight, (1) some have discovered that stealing is an easier way to live. Thousands of plant species get by (2) photosynthesizing, and over 400 of these species seem to live by pilfering sugars from an underground (3) of fungi(真菌). But in (4) a handful of these plants has this modus operandi been traced to a relatively obscure fungus. To find out how (5) are (6) , mycologist Martin Bidartondo of the University of California at Berkeley and his team looked in their roots. What they found were (7) of a common type of fungus, so (8) that it is found in nearly 70 percent of all plants. The presence of this common fungus in these plants not only (9) at how they survive, says Bidartondo, but also suggests that many ordinary plants might prosper from a little looting, too.

Plants have (10) relations to get what they need to survive. Normal, (11) plants can make their own carbohydrates through photosynthesis, but they still need minerals. Most plants have (12) a symbiotic relationship with a (13) network of what are called my corrhizal fungi, which lies beneath the forest (14) . The fungi help green plants absorb minerals through their roots, and (15) , the plants normally (16) the fungi with sugars, or carbon with a number of plants sharing the same fungal web, it was perhaps (17) that a few cheaters—dubbed epiparasites—would evolve to beat the system. (18) , these plants reversed the flow of carbon, (19) it into their roots from the fungi (20) releasing it as "payment.\

20（）

A. instead of

B. in spite of

C. in place of

D. by contrast of
查看答案
单项选择题

啤酒花叶片形状随品种及生长部位而异，从（）到5个裂片的缺刻状。

A、心脏形

B、柳叶形

C、三角形

D、手掌型
查看答案