Volvox, like Chlamydomonas,has been
investigated in depth because it is capable of existing as a unicellular plant or in a spherical colony of several thousand cells. Volvox carteri is thus a useful subject if you want to study the evolution of multicellularity, which has evolved many times inplants, let alone independently in plants and animals. (查看原文)
It may be that the 50%increase in carbon dioxide levels at the end of the Younger Dryas Event helped by making agriculture photosynthetically supportable. (查看原文)
It is important to this story to consider what is meant by cultivation and domestication. The former is simply the deliberate growing or protection of a wild plant. Growing begins with a propagule such as a seed or cutting, while protection is where a particular plant is preserved and nurtured because it has something that is wanted. (查看原文)
These improvements are known as domestication syndromes. Some of the characters are obviously better for the farmer. These include compact growth, making the plant more resilient, simultaneous ripening allowing one harvest, loss of seasonal flowering and/or germination permitting sowing at various times of year, and … (查看原文)
It has to be noted that these female gametophytes are a sad apology for a gametophyte compared to everything that has been produced by other land
plants. These angiosperm female gametophytes consists of just a few haploid cells(one of which is the egg cell that has been produced without the aid of an archegonium)and one cell that has two haploid nuclei. (查看原文)
