a-level生物考试答题(a-level生物自学课程)

A-Level生物考试，近年来也越来越多的被考生选择，而关于生物考试的知识点，不知道大家在平时有积累吗？其实在自然环境中，有一类生物是通过无性繁殖的，今天小编就为大家介绍一下相关的生物知识，希望对大家有所帮助，下面一起来看看。

　　Asexual reproduction

　　无性生殖

　　Asexual Reproduction: Imagine this. What if you could possibly reproduce without a partner? Wouldn’t that be great?

　　As they say, life always finds a way; and for instance, perhaps parthenogenesis is just one of these life’s tricks.

　　从字面意思也能看出这是一个无性的生殖过程，世界上人类，很多动物，甚至很多植物都是有性生殖。

　　我们可以想象一下无性生殖又是怎么回事呢？也许单性生殖是生命做出的的一个把戏。我们一起来来学习一下什么叫无性生殖吧~

　　Asexual Reproduction Definition

　　Asexual reproduction occurs when an organism makes more of itself without exchanging genetic information with another organism through sex.

　　无性繁殖不涉及生殖细胞，不需要经过受精过程，直接由母体的一部分直接形成新个体的繁殖方式。

　　Asexual reproduction is practiced by most single-celled organisms including bacteria, archaebacteria, and protist. It is also practiced by some plants, animals, and fungi.

　　普遍在单细胞生物，比如细菌，原始细菌和原生生物。甚至还有些植物，动物和真菌。

　　evolution and animal life

　　Advantages of Asexual Reproduction

　　Rapid population growth.

　　No mate is needed to found a new population.

　　Lower resource investment.

　　Disadvantages of Asexual Reproduction

　　lack of diversity

　　Because members of an asexually reproducing population are genetically identical except for rare mutants, they are all susceptible to the same diseases, nutrition deficits, and other types of environmental hardships.

　　Virus hazard

　　There are many different ways to reproduce asexually.

　　These include :

　　1. Binary fission.(bacteria and archaebacteria.)

　　2. Budding.(plants and sea creatures, and some single-celled eucaryotes such as yeast.)

　　3. Vegetative propagation.( Strawberries....)

　　4. Sporogenesis

　　介绍完无性繁殖的相关知识，下面我们一起来认识一下新的动物，开开眼界！

　　The first organism to be included in this asexual reproduction organisms list is the“zebra shark”.

　　无性生殖的动物名单里的第一个动物就是斑马鱼。

　　The second organism to be included in this asexual reproduction organisms list is the “Water Flea”.Is characterized by the hopping motion of a flea, only underwater.

　　无性生殖的动物名单里的第二个动物就是水焰。它是以跳跃运动为特征的，只在水下。

　　Intriguingly, during most of the wet phase of the vernal pond, the population of water fleas is all composed of females.

　　有趣的是，在春季池塘的大部分潮湿阶段，水蚤的数量都是由雌性组成的。

　　The third organism to be included in this asexual reproduction organisms list is the“ Walnut Gulch Scorpion”.

　　第三个要认识的动物就是，胡桃沟蝎子。看起来也是挺恐怖的！

　　This animal is “ Parasitic Flatworms”.

　　这个动物就是“寄生的扁虫”

　　以上就是本文有关A-Level生物考试无性繁殖相关知识点的介绍了，希望对大家备考有所帮助，了解更多alevel考试报名时间、alevel考试大纲等相关知识，可咨询在线客服。