问题 解答题

如图1、图2所示是蚕豆种子外形和结构图,根据图回答问题.

(1)蚕豆种子由______和胚两部分组成,胚又由______和子叶组成.

(2)子叶能被稀碘液染成蓝色,这说明子叶中有______(填营养物质名称).

(3)蚕豆种子播种后,种子的胚芽将发育成______;胚根将发育成根;子叶贮存营养物质;胚轴连接胚根、胚芽和子叶,可以将子叶贮存的营养物质输送给______,供它们生长发育的需要.

答案

(1)蚕豆种子有种皮和胚两部分组成,种皮质地坚硬,具有保护作用,胚由子叶、胚芽、胚轴、胚根组成.

(2),蚕豆种子的营养物质储存在子叶中,淀粉有遇碘变蓝的特性,子叶能被稀碘液染成蓝色,这说明子叶中有淀粉.

(3)种子萌发时,吸水膨胀,种皮变软,呼吸作用增强,将储存在子叶内的营养物质逐步分解,转化为可以被细胞吸收利用的物质,输送到胚的胚轴、胚根和胚芽.萌发时,胚根生长最快,首先突破种皮向地生长,并发育成根,随后胚轴伸长,胚芽突破种子背地生长,发育成茎和叶. 

故答案为:(1)种皮    胚芽、胚轴、胚根   (2)淀粉  (3)茎和叶  胚根、胚芽、胚轴

完形填空

The teacher stood before his class and was going to hand out the final exam papers. “I know how   1   you have all worked to prepare for this test,” he said. “And because I know you can do it well, I am willing to offer a B to anyone who would   2   not to take the test. ”

Many students jumped up to   3   the teacher and left the classroom.  The teacher looked at the   4   students and said, “Does anyone else want to get a B? This is your last   5   . ” Two more students decided to go.     Seven students remained.  The teacher then handed out the   6   .  There were only three sentences typed on the paper: Congratulations! You have just   7   an A in this class.  Keep believing in yourself.     I never had a teacher like that, but I think it is a test   8   any teacher could and should give.  Students who are not   9   in what they have learned are B students at best(充其量). The same is   10   in real life.  The A students are those who believe in what they are doing because they have   11   both successes and failures.  They have learned life’s lessons, either from normal education   12   from events in their lives, and have become   13   people.      Scientists say that by the age of eight, 80% of what we believe about ourselves has already been formed.  You are a big kid now, and you   14   that  you have some limits (限制).  However, there is   15   you can’t do or learn or be.  Sir Edmund Hillary, the first person to reach the summit of Mount Everest said, “It’s not the mountain we conquer(克服) but ourselves. ”

小题1:A.  luckily        B.  terribly        C.  hard

小题2:A.  dislike        B.  help            C.  prefer

小题3:A.  thank         B.  praise          C.  fight

小题4:A.  following     B.  relaxing      C.  remaining

小题5:A.  chance        B.  trouble         C.  test

小题6:A.  results        B.  presents        C.  papers

小题7:A.  given         B.  sent            C.  received

小题8:A.  where         B.  that            C.  what

小题9:A.  confident     B.  necessary       C.  mysterious

小题10:A.  unusual        B.  impossible      C.  true

小题11:A.  broken off     B.  dreamed of      C.  learned from

小题12:A.  and           B.  or            C.  but

小题13:A.  ruder         B.  cuter           C.  better

小题14:A.  decide        B.  forget          C.  realize

小题15:A.  something     B. anything        C.  nothing

单项选择题