00:01
Which of these is not an evolutionary trend among plants? developing vascular tissues, becoming seedless, having a dominant diploid generation, producing non -motile gametes, or producing two types of sports.
00:16
Okay, so i'll start with the answer is b, but let's look at all of these.
00:21
So we're looking for trends that develop over the evolutionary history of plants.
00:26
So for the ancestral trait, we can look at plants with a simpler in structure, like mosses and ferns.
00:37
And for the developed, derived trait, we can look at something like gymnospermer and angiosperm.
00:44
So if we look at vascular tissues, so vascular tissues have developed from over time.
00:56
So if you look at a moss, a moss does not have vascular tissue.
01:01
But as you look at other plants, you see more and more vascularization.
01:06
So the fern has a very basic vascular system, and then you get up to the gynosperms, which have a more complex, and then the angiosperm, which brings in more cell type, more cell types, and becomes very complex.
01:21
We'll skip b for now.
01:23
See, the dominant diploid generation.
01:24
So plants have alternation of generations.
01:30
The more ancestral groups, so the older trait is a dominant gametophyte, and the newer one is a dominant sporophyte.
01:44
So if you look at ferns, it's the gametophyte that is the free -living organism, and the sporophyte is dependent on it.
01:52
If you look at the gymnastworms and the angiosperms, the gametophyte is very strong.
01:57
Small and completely dependent on the sporophyte, the sporophyte being the diploid...