C. To protect the embryo inside. D. To help the seed float in the air. 相关知识点: 试题来源: 解析 C。解析:种子的种皮的作用是保护内部的胚。选项A,胚乳是为发育中的胚提供食物的,不是种皮,A错误。选项B,种皮不能直接参与光合作用,B错误。选项D,种皮没有帮助种子在空中漂浮的作用,D错误。
sperm cell fertilizes the endosperm nuclei. Thus, the zygote will be diploid whereas the endosperm will be triploid from the union of a sperm cell and two female cells. The zygote develops into an embryo whereas the endosperm develops into nutritive tissue surrounding the embryo within the seed...
However, this exception created by these Regulations is specific to gametes and embryos in the context of artificial reproduction, and does not amount to general uncertainty regarding ownership of human biological material that calls for a case-by-case approach. Social justice and research using ...
Regression analysis using the size of the individual plants demonstrated that large females made smaller investments in inflorescences and larger investments in sexual reproduction than did large males. In contrast, females invested fewer resources in vegetative reproduction than did males. However, the ...
Does seed production of spring ephemerals decrease when spring comes early? To predict the effect of global warming on plant reproductive success, seed-sets of spring ephemerals were compared between a year of extremely warm spring... G Kudo,Y Nishikawa,T Kasagi,... - 《Ecological Research》 ...
Fig. 4.35.The abdomen of the bed bug, containing the reproductive tract. The ectospermalege, a cuticular pouch on the abdomen, is a special reception site for sperm introduced by hemocelic insemination. From Carayon, J., 1966. Traumatic insemination and the paragenital system. In: Usinger,...
Using unique longitudinal demographic records on 140,600 reproducing individuals from the Utah Population Database, we demonstrate a shift from male-biased to female-biased adult lifespans in individuals born before versus during the demographic transition. Only women paid a cost of reproduction in ...
There is a lower chance of using up the resources in a given environment. Sexual reproduction results in variation in the offspring. Sexual reproduction is more cost-effective. Show Solution Which type of life cycle has both a haploid and diploid multicellular stage? asexual life cycles most an...
METHODS: Seeds were collected along a 550 km long transect in Quebec, Canada, and tested for germination. The genetic diversity of a population was determined using polymorphic microsatellite markers to verify whether the species is actually producing new individuals through sexual reproduction. KEY ...
Next consider the situation in a typical heterosporous seed plant species, such as the pea plant (Pisum sativum), an angiosperm. Here the sporophytic individual is bisexual, having two types of sporangia (anther sac/microsporangia in stamen, and ovules/megasporangia in pistils) in which diff...