工作就用美篇工作版","guide_search_desc":"海量模板范文,一键做同款 工作就用美篇工作版","img_beautify_switch":0,"ad_free":0,"text_direction":1,"template":{},"container":{"id":2346795,"user_id":2385561,"container_id":3,"stick_article_id":"","cover_img_url":"","display_name":"浙教版科学七下","description":"","sort":1,"review_state":0,"ip":"","state":0,"create_time":1582472625},"redirect":{"redirect_type":1,"img_url":false,"link_url":"/wap/downloadpage/backpage","button_bg_color":false,"button_desc":false,"redirect_desc":false},"edit_date_str":"更新于 2022-02-23","current_time":1714820094,"font_name":"","rcmd_meipian":0,"hide_article_link":0,"from_wechat":false,"topk_keywords":[{"name":"传粉","score":0.297779},{"name":"异花传粉","score":0.236294},{"name":"雌蕊","score":0.179478},{"name":"花粉","score":0.167316},{"name":"自花传粉","score":0.157529},{"name":"一朵花","score":0.154933},{"name":"父母","score":0.151838},{"name":"雄蕊","score":0.142536},{"name":"正误","score":0.136705},{"name":"柱头","score":0.131898}],"music_name":"","origin_status":0,"password_v2":"","font_id":0,"title_style":"{\"text_color\":{\"color\":\"#191919\",\"index\":0},\"text_size\":\"large\",\"text_style\":[\"bold\"]}","rich_text_title":"","enable_download":1,"cover_thumb":"http://static2.ivwen.com/users/2385561/f010e1939c365d25e04e135b8b12e332.gif-thumb2","has_video":true,"gift_switch":1,"enable_watermark":2,"content":{"article_id":211600339,"content":[{"audio_music_id":0,"img_height":528,"img_url":"https://ss2.meipian.me/users/2385561/91ee194a4e66b0fbf2d1de37ef46ed85.jpg","img_width":663,"is_origin":false,"source":0,"text":"
被子植物的有性生殖
一.复习强化
","type":1},{"audio_music_id":0,"img_height":421,"img_url":"https://ss2.meipian.me/users/2385561/a092bb7170dac7a8e1f51ffe461d73ff.jpg","img_width":703,"is_origin":false,"source":0,"type":1},{"audio_music_id":0,"img_height":396,"img_url":"https://ss2.meipian.me/users/2385561/cdbdb85c59c7787f1da82eeeb8cd96cf.jpg","img_width":761,"is_origin":false,"source":0,"text":"
被子植物六大器官分为两类:生殖器官与营养器官。
生殖器官包括:花、果实、种子;
营养器官包括:根、茎、叶。
有性生殖是指由两性生殖细胞(精子和卵细胞)结合,成为受精卵,再由受精卵发育成为新的个体的生殖方式。
","type":1},{"audio_music_id":0,"img_height":486,"img_width":846,"is_origin":false,"source":0,"source_platform":"local","text":"
本节重点观看","type":3,"video_end_time":0,"video_length":176,"video_origin_path":"","video_start_time":0,"video_thumbnail":"http://static2.ivwen.com/users/2385561/1581521394243.jpg","video_url":"http://video.ivwen.com/users/2385561/1581521330919.mp4"},{"audio_music_id":0,"img_height":352,"img_size":579,"img_url":"https://ss2.meipian.me/users/2385561/f010e1939c365d25e04e135b8b12e332.gif","img_width":500,"is_origin":false,"source":0,"text":"
二、开花
请仔细观察植物开花,花会发生哪些变化呢?
","type":1},{"audio_music_id":0,"img_height":210,"img_size":1648,"img_url":"https://ss2.meipian.me/users/2385561/4d4d7459c7446af8ad9c373ed5c17c6a.gif","img_width":250,"is_origin":false,"source":0,"text":"
答: 萼片和花瓣渐渐张开;雄蕊和雌蕊显露出来;雄蕊伸长,花药裂开,雌蕊也伸长,柱头分泌黏液。
开花是为传粉做准备。
","type":1},{"audio_music_id":0,"img_height":300,"img_size":179,"img_url":"https://ss2.meipian.me/users/2385561/7acc260b6614e4ba8ee443d4c133b471.gif","img_width":400,"is_origin":false,"source":0,"text":"
三.传粉
","type":1},{"audio_music_id":0,"img_height":352,"img_url":"https://ss2.meipian.me/users/2385561/05be20ecfd009895881ad07acbc43c0a.jpg","img_width":749,"is_origin":false,"source":0,"text":"
雄蕊中的花粉就会从花药中散发出来,落到雌蕊的柱头上,这个过程叫做传粉。
","type":1},{"audio_music_id":0,"img_height":238,"img_url":"https://ss2.meipian.me/users/2385561/77ff93919c8c09be541ec434888a7dc6.jpg","img_width":554,"is_origin":false,"source":0,"text":"
豌豆花和棉花的传粉方式有什么区别?
答:花粉是否自己给自己。
(一)自花传粉
一朵花的雄蕊产生的花粉粒,落在同一朵花雌蕊的柱头上。
","type":1},{"audio_music_id":0,"img_height":396,"img_url":"https://ss2.meipian.me/users/2385561/cdbdb85c59c7787f1da82eeeb8cd96cf.jpg","img_width":761,"is_origin":false,"source":0,"text":"
【思考】
请你动脑想一想,自花传粉对花有什么要求?
请向父母描述,父母判断正误。
答:1.是两性花(同一朵花上既有雄蕊,又有雌蕊)。
2.同一朵花的花粉和雌蕊同时成熟。
(二)异花传粉
借助外力作用,一朵花的雄蕊产生的花粉粒,落在另一朵花雌蕊的柱头上。
","type":1},{"audio_music_id":0,"img_height":426,"img_url":"https://ss2.meipian.me/users/2385561/2516227f1eef378f5846ecb4d5548031.jpg","img_width":576,"is_origin":false,"source":0,"text":"
请你动脑想一想,异花传粉的花有什么特点?
请向父母描述,父母判断正误。
答 1.单性花和两性花都可以异花传粉。
2.同一朵花的雄蕊和雌蕊成熟期一般都不相同。
请思考一个问题,一朵花的花粉是如何到另一朵花的柱头上的呢?
异花传粉的动力来自昆虫和风力。
根据传粉的不同途径,可将花分成虫媒花和风媒花。
1.虫媒花
昆虫传粉——虫媒花
昆虫的主要目的是采食花蜜,顺便通过其翅膀、足、口器等搬运花粉,从而帮助花传粉。
","type":1},{"audio_music_id":0,"img_height":272,"img_width":336,"is_origin":false,"source":0,"source_platform":"local","text":"
你觉得虫媒花有什么特点才会吸引昆虫过来帮助传粉啊?
答:花一般较大,有鲜艳的花瓣、芳香的气味、甜美的花蜜,易于吸引昆虫。
花粉粒较大,有黏性,便于黏附在昆虫上。
请你向父母描述一下,虫媒花的这些特点说明了什么?
父母判断正误
答:花的形态、结构与其功能相适应的。
","type":3,"video_end_time":0,"video_length":67,"video_origin_path":"","video_start_time":0,"video_thumbnail":"http://static2.ivwen.com/users/2385561/1581562995108.jpg","video_url":"http://video.ivwen.com/users/2385561/1581562989017.mp4"},{"audio_music_id":0,"img_height":431,"img_url":"https://ss2.meipian.me/users/2385561/951814f8ac52ef078d3865144bd8ef8f.jpg","img_width":609,"is_origin":false,"source":0,"text":"
2.风媒花
风力传粉——风媒花。
主要靠风吹飞花粉,从而帮助花传粉。
例如:玉米、水稻、杨、榆、小麦等。
","type":1},{"audio_music_id":0,"img_height":272,"img_width":336,"is_origin":false,"source":0,"source_platform":"local","text":"
你觉得风媒花又会有什么特点呢?
答:风媒花的花粉多而轻,花丝长,柱头有分叉或成羽毛状,能分泌粘液,并且伸出花瓣外面。
动动脑子,请你向父母描述一下,风媒花的特点对植物传粉有什么作用?
父母判断正误
答:柱头分叉或成羽毛状,能分泌粘液,且伸出花瓣外,便于接受花粉,有助于提高异花传粉的成功率。
","type":3,"video_end_time":0,"video_length":37,"video_origin_path":"","video_start_time":0,"video_thumbnail":"http://static2.ivwen.com/users/2385561/1581563021913.jpg","video_url":"http://video.ivwen.com/users/2385561/1581563017972.mp4"},{"audio_music_id":0,"img_height":467,"img_url":"https://ss2.meipian.me/users/2385561/b3ed1d02067003316ec0da324f718220.jpg","img_width":648,"is_origin":false,"source":0,"text":"
3.人工授粉
【思考1】在植物的上述两种传粉方式-----自花传粉与异花传粉中,你认为哪种传粉方式比较普遍?为什么?
答:异花传粉比较普遍。异花传粉比自花传粉更进化,自花传粉遗传性差异小,连续自花传粉,会使后代的生命力衰退。
【思考2】如果某地昆虫大量减少或在植物开花期出现连续下雨、刮大风或无风等情况,对植物的繁殖会有什么影响?
请认真动脑,并向父母描述,父母判断正误。
答:减少传粉的成功率。植物只开花不结果,会导致作物减产。
此时我们就可以采用人工授粉的方式来避免作物减产。
","type":1},{"audio_music_id":0,"img_height":460,"img_url":"https://ss2.meipian.me/users/2385561/b69684494a120818adfd994bc5c66348.jpg","img_width":575,"is_origin":false,"source":0,"text":"
四.受精
","type":1},{"audio_music_id":0,"img_height":268,"img_url":"https://ss2.meipian.me/users/2385561/448f81a20e51ab4bde02b868b1b49fa5.jpg","img_width":631,"is_origin":false,"source":0,"text":"
五、发育
请你的观察验证,受精后,花的结构中先后枯萎或调落的是不是萼片、花瓣、雄蕊以及雌蕊的柱头、花柱。
而不断发育的是子房和胚珠。
最终子房的各部分逐渐发育成果实中相应的结构。
","type":1},{"audio_music_id":0,"img_height":215,"img_url":"https://ss2.meipian.me/users/2385561/4a6abf701ddb25b0154e3e37aca455cc.jpg","img_width":663,"is_origin":false,"source":0,"text":"
认真看下面的框架图,请认真填写好。
","type":1},{"audio_music_id":0,"img_height":221,"img_url":"https://ss2.meipian.me/users/2385561/3997db423f4da181e9fd5666ad7f5236.jpg","img_width":657,"is_origin":false,"source":0,"text":"
填好请交给父母检查
父母判断正误
","type":1},{"audio_music_id":0,"img_height":181,"img_url":"https://ss2.meipian.me/users/2385561/73cf4a92b10759745de7561a0904a52d.jpg","img_width":546,"is_origin":false,"source":0,"text":"
【思维训练】为什么一个桃子里有一粒种子,而一个西瓜里有很多种子?
","type":1},{"audio_music_id":0,"img_height":203,"img_url":"https://ss2.meipian.me/users/2385561/53206dd798748dfc5e225bdcc955e2ee.jpg","img_width":588,"is_origin":false,"source":0,"text":"
认真思考
向父母表达你的观点
父母检查正误
分析:种子既然是由胚珠发育来的,我们就得从胚珠数目的角度去解答。
答:因为一个子房内的胚珠数目不同。
","type":1},{"audio_music_id":0,"img_height":524,"img_url":"https://ss2.meipian.me/users/2385561/8cdc6440a900396631c20dec3c3a2acc.jpg","img_width":635,"is_origin":false,"source":0,"type":1},{"audio_music_id":0,"img_height":518,"img_url":"https://ss2.meipian.me/users/2385561/8e7d0bdd279a735cba98a752359fe16b.jpg","img_width":655,"is_origin":false,"source":0,"text":"
六.小结
","type":1},{"audio_music_id":0,"img_height":600,"img_url":"https://ss2.meipian.me/users/2385561/58545fe55b8de488280f56c6505eceb2.gif","img_width":600,"is_origin":false,"source":0,"text":"
七、练习
1.一朵桃花开后没有结出桃子,最可能被虫子破坏的结构是---------( )
A.花萼 B.花冠 C.雌蕊 D.雄蕊
2.下列有关植物有性生殖的说法,不正确的是( )
A.植物只要开过花,一定能产生种子
B.桃花既能自花传粉,又能进行异花传粉
C.异花传粉主要依靠风、昆虫、鸟类来帮助花粉的传播
D.植物只有经过开花、传粉、受精之后,才能产生种子
2.下列有关植物有性生殖的说法,不正确的是( )
A.植物只要开过花,一定能产生种子
B.桃花既能自花传粉,又能进行异花传粉
C.异花传粉主要依靠风、昆虫、鸟类来帮助花粉的传播
D.植物只有经过开花、传粉、受精之后,才能产生种子
4.西瓜是解暑的佳品,西瓜果实中含有许多粒种子,这是因为花的结构中含有多个---------------( )
A.子房 B.雄蕊 C.花药 D.胚珠
5.吃玉米棒子和葵花籽时,常发现玉米果穗再现“秃顶”、葵花籽出现空瘪现象。其主要原因都是( )
A.传粉不足 B.光照不足
C.开得花较少 D.肥料不足
6.一般开花植物进行有性生殖时,需经下列步骤:①精子和卵细胞结合;②长出花粉管;③长出新个体;④花粉传到雌蕊;⑤胚珠形成种子。它们的先后顺序是------( )
A.④→①→②→⑤→③ B.③→④→①→⑤→②
C.④→②→①→⑤→③ D.④→②→⑤→①→③
请拿出纸笔认真练习。
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被子植物的有性生殖
一.复习强化
","type":1},{"audio_music_id":0,"img_height":421,"img_url":"https://ss2.meipian.me/users/2385561/a092bb7170dac7a8e1f51ffe461d73ff.jpg","img_width":703,"is_origin":false,"source":0,"type":1},{"audio_music_id":0,"img_height":396,"img_url":"https://ss2.meipian.me/users/2385561/cdbdb85c59c7787f1da82eeeb8cd96cf.jpg","img_width":761,"is_origin":false,"source":0,"text":"
被子植物六大器官分为两类:生殖器官与营养器官。
生殖器官包括:花、果实、种子;
营养器官包括:根、茎、叶。
有性生殖是指由两性生殖细胞(精子和卵细胞)结合,成为受精卵,再由受精卵发育成为新的个体的生殖方式。
","type":1},{"audio_music_id":0,"img_height":486,"img_width":846,"is_origin":false,"source":0,"source_platform":"local","text":"
本节重点观看","type":3,"video_end_time":0,"video_length":176,"video_origin_path":"","video_start_time":0,"video_thumbnail":"http://static2.ivwen.com/users/2385561/1581521394243.jpg","video_url":"http://video.ivwen.com/users/2385561/1581521330919.mp4"},{"audio_music_id":0,"img_height":352,"img_size":579,"img_url":"https://ss2.meipian.me/users/2385561/f010e1939c365d25e04e135b8b12e332.gif","img_width":500,"is_origin":false,"source":0,"text":"
二、开花
请仔细观察植物开花,花会发生哪些变化呢?
","type":1},{"audio_music_id":0,"img_height":210,"img_size":1648,"img_url":"https://ss2.meipian.me/users/2385561/4d4d7459c7446af8ad9c373ed5c17c6a.gif","img_width":250,"is_origin":false,"source":0,"text":"
答: 萼片和花瓣渐渐张开;雄蕊和雌蕊显露出来;雄蕊伸长,花药裂开,雌蕊也伸长,柱头分泌黏液。
开花是为传粉做准备。
","type":1},{"audio_music_id":0,"img_height":300,"img_size":179,"img_url":"https://ss2.meipian.me/users/2385561/7acc260b6614e4ba8ee443d4c133b471.gif","img_width":400,"is_origin":false,"source":0,"text":"
三.传粉
","type":1},{"audio_music_id":0,"img_height":352,"img_url":"https://ss2.meipian.me/users/2385561/05be20ecfd009895881ad07acbc43c0a.jpg","img_width":749,"is_origin":false,"source":0,"text":"
雄蕊中的花粉就会从花药中散发出来,落到雌蕊的柱头上,这个过程叫做传粉。
","type":1},{"audio_music_id":0,"img_height":238,"img_url":"https://ss2.meipian.me/users/2385561/77ff93919c8c09be541ec434888a7dc6.jpg","img_width":554,"is_origin":false,"source":0,"text":"
豌豆花和棉花的传粉方式有什么区别?
答:花粉是否自己给自己。
(一)自花传粉
一朵花的雄蕊产生的花粉粒,落在同一朵花雌蕊的柱头上。
","type":1},{"audio_music_id":0,"img_height":396,"img_url":"https://ss2.meipian.me/users/2385561/cdbdb85c59c7787f1da82eeeb8cd96cf.jpg","img_width":761,"is_origin":false,"source":0,"text":"
【思考】
请你动脑想一想,自花传粉对花有什么要求?
请向父母描述,父母判断正误。
答:1.是两性花(同一朵花上既有雄蕊,又有雌蕊)。
2.同一朵花的花粉和雌蕊同时成熟。
(二)异花传粉
借助外力作用,一朵花的雄蕊产生的花粉粒,落在另一朵花雌蕊的柱头上。
","type":1},{"audio_music_id":0,"img_height":426,"img_url":"https://ss2.meipian.me/users/2385561/2516227f1eef378f5846ecb4d5548031.jpg","img_width":576,"is_origin":false,"source":0,"text":"
请你动脑想一想,异花传粉的花有什么特点?
请向父母描述,父母判断正误。
答 1.单性花和两性花都可以异花传粉。
2.同一朵花的雄蕊和雌蕊成熟期一般都不相同。
请思考一个问题,一朵花的花粉是如何到另一朵花的柱头上的呢?
异花传粉的动力来自昆虫和风力。
根据传粉的不同途径,可将花分成虫媒花和风媒花。
1.虫媒花
昆虫传粉——虫媒花
昆虫的主要目的是采食花蜜,顺便通过其翅膀、足、口器等搬运花粉,从而帮助花传粉。
","type":1},{"audio_music_id":0,"img_height":272,"img_width":336,"is_origin":false,"source":0,"source_platform":"local","text":"
你觉得虫媒花有什么特点才会吸引昆虫过来帮助传粉啊?
答:花一般较大,有鲜艳的花瓣、芳香的气味、甜美的花蜜,易于吸引昆虫。
花粉粒较大,有黏性,便于黏附在昆虫上。
请你向父母描述一下,虫媒花的这些特点说明了什么?
父母判断正误
答:花的形态、结构与其功能相适应的。
","type":3,"video_end_time":0,"video_length":67,"video_origin_path":"","video_start_time":0,"video_thumbnail":"http://static2.ivwen.com/users/2385561/1581562995108.jpg","video_url":"http://video.ivwen.com/users/2385561/1581562989017.mp4"},{"audio_music_id":0,"img_height":431,"img_url":"https://ss2.meipian.me/users/2385561/951814f8ac52ef078d3865144bd8ef8f.jpg","img_width":609,"is_origin":false,"source":0,"text":"
2.风媒花
风力传粉——风媒花。
主要靠风吹飞花粉,从而帮助花传粉。
例如:玉米、水稻、杨、榆、小麦等。
","type":1},{"audio_music_id":0,"img_height":272,"img_width":336,"is_origin":false,"source":0,"source_platform":"local","text":"
你觉得风媒花又会有什么特点呢?
答:风媒花的花粉多而轻,花丝长,柱头有分叉或成羽毛状,能分泌粘液,并且伸出花瓣外面。
动动脑子,请你向父母描述一下,风媒花的特点对植物传粉有什么作用?
父母判断正误
答:柱头分叉或成羽毛状,能分泌粘液,且伸出花瓣外,便于接受花粉,有助于提高异花传粉的成功率。
","type":3,"video_end_time":0,"video_length":37,"video_origin_path":"","video_start_time":0,"video_thumbnail":"http://static2.ivwen.com/users/2385561/1581563021913.jpg","video_url":"http://video.ivwen.com/users/2385561/1581563017972.mp4"},{"audio_music_id":0,"img_height":467,"img_url":"https://ss2.meipian.me/users/2385561/b3ed1d02067003316ec0da324f718220.jpg","img_width":648,"is_origin":false,"source":0,"text":"
3.人工授粉
【思考1】在植物的上述两种传粉方式-----自花传粉与异花传粉中,你认为哪种传粉方式比较普遍?为什么?
答:异花传粉比较普遍。异花传粉比自花传粉更进化,自花传粉遗传性差异小,连续自花传粉,会使后代的生命力衰退。
【思考2】如果某地昆虫大量减少或在植物开花期出现连续下雨、刮大风或无风等情况,对植物的繁殖会有什么影响?
请认真动脑,并向父母描述,父母判断正误。
答:减少传粉的成功率。植物只开花不结果,会导致作物减产。
此时我们就可以采用人工授粉的方式来避免作物减产。
","type":1},{"audio_music_id":0,"img_height":460,"img_url":"https://ss2.meipian.me/users/2385561/b69684494a120818adfd994bc5c66348.jpg","img_width":575,"is_origin":false,"source":0,"text":"
四.受精
","type":1},{"audio_music_id":0,"img_height":268,"img_url":"https://ss2.meipian.me/users/2385561/448f81a20e51ab4bde02b868b1b49fa5.jpg","img_width":631,"is_origin":false,"source":0,"text":"
五、发育
请你的观察验证,受精后,花的结构中先后枯萎或调落的是不是萼片、花瓣、雄蕊以及雌蕊的柱头、花柱。
而不断发育的是子房和胚珠。
最终子房的各部分逐渐发育成果实中相应的结构。
","type":1},{"audio_music_id":0,"img_height":215,"img_url":"https://ss2.meipian.me/users/2385561/4a6abf701ddb25b0154e3e37aca455cc.jpg","img_width":663,"is_origin":false,"source":0,"text":"
认真看下面的框架图,请认真填写好。
","type":1},{"audio_music_id":0,"img_height":221,"img_url":"https://ss2.meipian.me/users/2385561/3997db423f4da181e9fd5666ad7f5236.jpg","img_width":657,"is_origin":false,"source":0,"text":"
填好请交给父母检查
父母判断正误
","type":1},{"audio_music_id":0,"img_height":181,"img_url":"https://ss2.meipian.me/users/2385561/73cf4a92b10759745de7561a0904a52d.jpg","img_width":546,"is_origin":false,"source":0,"text":"
【思维训练】为什么一个桃子里有一粒种子,而一个西瓜里有很多种子?
","type":1},{"audio_music_id":0,"img_height":203,"img_url":"https://ss2.meipian.me/users/2385561/53206dd798748dfc5e225bdcc955e2ee.jpg","img_width":588,"is_origin":false,"source":0,"text":"
认真思考
向父母表达你的观点
父母检查正误
分析:种子既然是由胚珠发育来的,我们就得从胚珠数目的角度去解答。
答:因为一个子房内的胚珠数目不同。
","type":1},{"audio_music_id":0,"img_height":524,"img_url":"https://ss2.meipian.me/users/2385561/8cdc6440a900396631c20dec3c3a2acc.jpg","img_width":635,"is_origin":false,"source":0,"type":1},{"audio_music_id":0,"img_height":518,"img_url":"https://ss2.meipian.me/users/2385561/8e7d0bdd279a735cba98a752359fe16b.jpg","img_width":655,"is_origin":false,"source":0,"text":"
六.小结
","type":1},{"audio_music_id":0,"img_height":600,"img_url":"https://ss2.meipian.me/users/2385561/58545fe55b8de488280f56c6505eceb2.gif","img_width":600,"is_origin":false,"source":0,"text":"
七、练习
1.一朵桃花开后没有结出桃子,最可能被虫子破坏的结构是---------( )
A.花萼 B.花冠 C.雌蕊 D.雄蕊
2.下列有关植物有性生殖的说法,不正确的是( )
A.植物只要开过花,一定能产生种子
B.桃花既能自花传粉,又能进行异花传粉
C.异花传粉主要依靠风、昆虫、鸟类来帮助花粉的传播
D.植物只有经过开花、传粉、受精之后,才能产生种子
2.下列有关植物有性生殖的说法,不正确的是( )
A.植物只要开过花,一定能产生种子
B.桃花既能自花传粉,又能进行异花传粉
C.异花传粉主要依靠风、昆虫、鸟类来帮助花粉的传播
D.植物只有经过开花、传粉、受精之后,才能产生种子
4.西瓜是解暑的佳品,西瓜果实中含有许多粒种子,这是因为花的结构中含有多个---------------( )
A.子房 B.雄蕊 C.花药 D.胚珠
5.吃玉米棒子和葵花籽时,常发现玉米果穗再现“秃顶”、葵花籽出现空瘪现象。其主要原因都是( )
A.传粉不足 B.光照不足
C.开得花较少 D.肥料不足
6.一般开花植物进行有性生殖时,需经下列步骤:①精子和卵细胞结合;②长出花粉管;③长出新个体;④花粉传到雌蕊;⑤胚珠形成种子。它们的先后顺序是------( )
A.④→①→②→⑤→③ B.③→④→①→⑤→②
C.④→②→①→⑤→③ D.④→②→⑤→①→③
请拿出纸笔认真练习。
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