向日葵为什么总是向着太阳

导读：　向日葵为什么总是向着太阳(共4篇)向日葵为什么总是向着太阳向日葵为什么总是向着太阳?向日葵的茎部含有一种奇妙的植物生长素。这种生长素非常怕光。一遇光线照射，它就会到背光的一面去，同时它还刺激背光一面的细胞迅速繁殖，所以，背光的一面就比向光的一面生长的快，使向日葵产生了向光性弯曲。向日葵为什么总是向着太阳？(英文版)Why Do Su...

以下是中国招生考试网www.chinazhaokao.com为大家整理的《向日葵为什么总是向着太阳》，希望大家能够喜欢！更多资源请搜索成考报名频道与你分享！

向日葵为什么总是向着太阳
向日葵为什么总是向着太阳(一)

向日葵为什么总是向着太阳?

向日葵的茎部含有一种奇妙的植物生长素。这种生长素非常怕光。一遇光线照射，它就会到背光的一面去，同时它还刺激背光一面的细胞迅速繁殖，所以，背光的一面就比向光的一面生长的快，使向日葵产生了向光性弯曲。

向日葵为什么总是向着太阳？(英文版)
向日葵为什么总是向着太阳(二)

Why Do Sunflowers Follow the Sun?

Blooming sunflower.

It feels good to look at, doesn't it? Something about bright yellow and radial symmetry is so

pleasing to the eyes and mind. Perhaps the visual buzz we get from gazing on sunflowers is due to the arrangement of the flower parts in what is known as Fibbonaci spirals, which I will not

attempt to explain to you, but which you can learn about here in a fascinating animation. No matter how much you understand Fibbonaci spirals, sunflowers are captivating.

The top picture shows a recently-opened sunflower inflorescence, or group of flowers. Each dot in the face of the sunflower is actually a single flower, and the picture above shows sunflowers at the stage of pollination. After pollen has been transported from the male parts of the flower to the female parts of the flower, the female parts of the flower begin to grow into what we know of as sunflower seeds. In the two photographs below, you can see a mature sunflower inflorescence

transitioning to sunflower seeds.

Sunflower finishing blooming and turning to seed.

Sunflower seeds not yet turned black arranged in a Fibbonaci spiral, allowing for maximum packing of seeds.

Above, you can see whitish green sunflower seeds packed together with their pointy end in. The

Fibbonaci spiral arrangement allows the plant to pack as many seeds as possible into the space

available. As this sunflower matures, the seeds will turn striped white and black like what we're accustomed to seeing in the grocery store or birdfeeder. For a more detailed description of

sunflower floral structures, see my older post on aster-type flowers, written when I wrote catchier though less-internet-searchable titles for my posts.【向日葵为什么总是向着太阳】

Sunflowers also do that amazing sun-following trick that makes these plants seem to possess some mystical powers. Well, if you'd like to maintain your sunflower mysticism, I suggest you skip the rest of the text in this post and just look at the pretty pictures.

Sunflowers facing the sun.

What's really going on here is something called heliotropism, and lots of plants do it. Heliotropism means moving toward the sun. If you've ever repositioned yourself periodically during an afternoon of misguided youthful tanning in order to get even sun exposure on all parts of your

previously cancer-free skin, you've done heliotropism yourself. The puzzle with sunflowers is, why do the flowers need to face the sun? To even out tan lines? To look good in a white dress? To appear thinner? To fit in with their friends? Read on.【向日葵为什么总是向着太阳】【向日葵为什么总是向着太阳】

The truth is, the stems of all actively growing sunflower parts - flowers and leaves - grow to face the sun in order to maximize photosynthesis. During the day, the stems elongate on the side away from the sun, tilting leaves and immature flowers toward the sun throughout the day and ending up facing west at sunset. When there's no light (so...night time), the other side of the stem grows, pushing the leaves and flowers back to the east where they will be facing the sun at sunrise.

Growing leaves and immature flowers are green and actively photosynthesizing, and heliotropism provides them with 10-15% more sunlight than just sitting still.

Take a look at the picture below. On the right, you can see an immature sunflower inflorescence covered in green bracts, which are obviously photosynthesizing since they are filled with

chlorophyll and appear green. The younger sunflower has immature leaves held up and facing the sun as well. The lower leaves on the younger sunflower, as well as all parts on the older

sunflower, have matured, and though they are generally facing up, they are not facing the sun. The older sunflower is drooping from the weight of the developing seeds.

Young sunflower parts following the sun, old sunflower parts stuck in place.

为什么向日葵问题向着太阳生长
向日葵为什么总是向着太阳(三)

为什么向日葵问题向着太阳生长

五年级二班 刘静心 我是一个爱看书的女孩，从书中我经常看到有关向日葵的资料，它告诉我向日葵这种植物总是向着有太阳的地方生长。我心中百思不得其解，我不明白为什么向日葵总是向有太阳的地方生长呢？这其中又蕴含着什么奥秘呢？于是，我开始了对向日葵的调查。

刚开始，我去访问了一下爸爸，他对我说：“向着太阳生长，能够刺激细胞分裂，加快生长繁殖。”我听后，虽然在表面上点了点头，但脑子里还是有一个大大的问号，于是，我又去问妈妈，妈妈说：“背光，遇到光线照射，背光部分的生长素会比向着太阳的那部分多。”我听了之后，顿时傻眼了，爸爸、妈妈的回答不统一，我该怎么办呢？对了，可以上网上搜索嘛！

从网上的查询中，我知道了向日葵朝阳的这个特点是因为它的花盘下面的茎部含有一种奇妙的植物生长素，一遇到光线照射，生长素就会转移到背光的一面去，并且刺激背光一面的细胞迅速增殖，于是，背光一面就比向着太阳的一面生长得快，使向日葵产生了向光性弯曲。所以向日葵始终向着太阳。

为 增加资料的真实性，我还做了一个针对向日葵的这个特点的实验。首先，我准备了两盆向日葵，第一盆，我把它放在朝太阳的一边，另一盆放在背光的一面，让其自由生长。

一个星期过去了，我发现：向着太阳生长的那一盆发育良好，另一盆转向了有太阳的那一面，生长较好。

通过查询资料，并结合自己的实验，我知道了向日葵喜欢充足的阳光，其幼苗、叶片和花盆都有很强的向光性。我还知道了向日葵又称为葵花，朝阳花或转日莲，是众所周知的会向太阳“鞠躬”的植物，这次实验，让我知道了向日葵是一种喜热又耐寒的植物，它能够坚强

地生长。

向日葵为什么总是向着太阳的？
向日葵为什么总是向着太阳(四)

向日葵又称做葵花和朝阳花。我们一般所说的花盘并不是一朵花，而是一个花序，就是头状花序，它由短缩肥厚的花轴以及密布其上的小花共同组成。而且向日葵的花盘有个奇怪的现象:花盘总是向着太阳转动。
向日葵总是朝太阳转动的原因是什么?
大约在18世纪末，英国著名生物学家达尔文就开始对这个现象产生浓厚兴趣，并做了些相关研究。向日葵为什么总是向着太阳的？。他开始发现，种在屋子里的一些花草，茎叶有时也会向着透光的窗子那边倾斜。他也曾把花草幼苗的顶芽切去一小部分，虽然幼苗还会向上生长，却再也不会向着太阳了。于是他就断定，在幼苗的顶端一定有某种物质使幼苗倾向太阳。
后来，许多科学家们经过进一步深入研究探索，在植物顶端终于找到了一种可以刺激细胞生长的激素，把它叫做生长素。从这里也初步开始揭开了向日葵向阳之谜。
原来，这些生长素主要是在茎尖以上形成的，/>近几年来，随着科学技术水平的不断提高，科学家还对向日葵向阳种种现象的解释做出了新的相关补充。他们不但从向日葵的茎叶生长区内发现了新的有较高浓度的叶黄氧化素。这种物质同生长素相反，可以阻止细胞伸长。科学实验不断表明:当光由茎的一侧照射30分钟后，向日葵幼苗生长区的两侧，它的叶黄氧化素的浓度主要分布为:向光的一侧浓度相当高，背光的一侧浓度相当低。这正好与生长素的浓度分布相关规律相反。这样说来，向日葵的向阳性和叶黄氧化素也有十分大的关系。即向日葵的向阳是生长素和叶黄氧化素共同作用的重要结果。

以上就是中国招生考试网http://www.chinazhaokao.com/带给大家的精彩成考报名资源。想要了解更多《向日葵为什么总是向着太阳》的朋友可以持续关注中国招生考试网，我们将会为你奉上最全最新鲜的成考报名内容哦! 中国招生考试网，因你而精彩。

相关热词搜索：向日葵为什么向着太阳 向日葵向着太阳的原因

1、向日葵为什么能够向着太阳(2016-05-05)