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What is significance of evolution shown by he flagellated Cycas sperm?
Wiki User
∙ 12y ago
Cycads and other gymnosperms do not have true flowers and their seeds are borne naked. All species of cycads are dioecious. The male reproductive structure, androstrobilus, consists of microsporophylls. Each microsporophyll produces a large quantity of pollen grains on its dorsal surface. The pollen is dispersed by wind or by insects to the gynostrobilus, the female reproductive structure. When a pollen grain lands on the gynostrobilus, it germinates and grows a pollen tube that extends to deep within the multicellular, female haploid gametophyte. Then a sperm cell of the pollen grain swims through the pollen tube using its whip-like tail, or flagella, and fertilizes the egg to form a zygote. The zygote eventually develops into an embryo, and then a seed. Cycad seeds are rich in starch and have a pigmented, fleshy outer layer known as the sarcotesta. The seeds are often dispersed by birds or mammals, which eat them for the nutritious sarcotesta, and later defecate the still-viable seed.
Wiki User
∙ 12y ago
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What are some of the different theories of evolution?
There is only one central "theory of evolution", which is the theory of evolution by natural selection that Charles Darwin pioneered. There have been different theories in the past - such as Jean-baptise Lamarck's theory of acquired traits - but these lost their status of scientific theory when they were shown to be wrong.
What is the biological significance of PGAL?
Calvin Cycle shown in link. PGAL - 1.Used to produce sugars etc.. 2.Used to regenerate the 5 carbon acceptor of CO2 (RuBP).
Why are mutation beneficial to the process of evolution?
Scientists have shown that beneficial mutations do occur to produce brand new alleles(variants of genes) that improve an organism's chances of survival in a particular environment
What is the mutation theory of evolution?
This concept was called saltationism. It posited that organisms could be speciated by " hopeful monster " mutations in one large jump and this concept vied for prominence among biologists, mostly geneticists, with gradualist concepts of how evolution happened and all this in the early 20th century. This concept was shown to have no merit and has been refuted since then.
Why is a tree used to illustrate Darwin's theory of evolution?
Because a tree, or better a bush, shows how evolution actually takes place. The splitting of populations going different directions to species is shown best this way. Where all species at the tip of the branches are equally evolved and connected through the trunk to all other species in the tree.
What channel and when will X men evolution season 5 be shown on?
It won't. X-men: Evolution is cancelled after 4 seasons.
What do fossil forms of evolution show?
The transition of phyla of organisms over time. That is the great strength of the fossil record; evolution shown in the sedimentary rock.
How have bacteria shown proof of evolution?
all bacteria will form and there will be a massive wave of pollution
What is inorganic evolution?
Inorganic evolution is the theory of the creation of the universe, not of the species of animals found on earth (ie organic evolution). It does seem to be a point of contention among a few as how this led to complex compounds. There is no connection as no scientific evidence has shown it, yet.
What was the significance of the Ibis in Ancient Egypt?
The god Thoth was the god of writing and knowledge. He was sometimes shown with a man with an Ibis's head.
When did Eisenhower mandate evolution?
President Eisenhower did not mandate evolution, this is a myth as far as my research has shown. As a matter of fact he was a staunch believer in Creationism. See link: http://www.icr.org/article/presidential-support-for-creationism
What channel will the new x men evolution episodes be on?
There are no new X-men: Evolution episodes and haven't been since 2003. Re-runs used to be shown on Disney XD, but they have since stopped showing them.
What are some of the different theories of evolution?
There is only one central "theory of evolution", which is the theory of evolution by natural selection that Charles Darwin pioneered. There have been different theories in the past - such as Jean-baptise Lamarck's theory of acquired traits - but these lost their status of scientific theory when they were shown to be wrong.
What is the biological significance of PGAL?
Calvin Cycle shown in link. PGAL - 1.Used to produce sugars etc.. 2.Used to regenerate the 5 carbon acceptor of CO2 (RuBP).
In the book The Origin of Species does evolution occur by means of natural selection?
Yes, that is what Darwin thought. However this has never been shown to be true.
What is the significance of red blood cells shown moving single file through the afferent and efferent arteriole and the glomerulus?
It shows how small the blood vessels are
Who is nurse joy's partner in Pokemon?
Nurse Joy's partner is a Chansey. Though, in the anime, she's shown to have other partners, including Chansey's evolution Blissey.
