The Reproductive Lives of Nonvascular Plants: Alternation of Generations - Crash Course Biology #36
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- เผยแพร่เมื่อ 23 ก.ย. 2024
- Hank introduces us to nonvascular plants - liverworts, hornworts & mosses - which have bizarre features, kooky habits, and strange sex lives. Nonvascular plants inherited their reproductive cycle from algae, but have perfected it to the point where it is now used by all plants in one way or another and has even left traces in our own reproductive systems.
Table of Contents
1) Key Traits of Nonvascular Plants 01:42
2) 3 Phyla of Bryophytes 02:52
3) Alternation of Generations 04:33
a) Gametophyte Generation 05:04
b) Sporophyte Generation 05:25
c) In Vascular Plants 07:48
References:
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www.bio.miami.e...
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Can't stand at the fact that this was released 8 years ago.
Recommend you watch the whole video, but if you're in a rush to just get the idea of alternation of generations start at 4:50
You're my hero
yes. yes. yes
It was such a wise decision to dump the lengthy textbook after 5 minutes to watch this!
So much easier to understand.
Thank You, Hank. Thank You.
You are correct! Added an annotation, thanks for letting me know. Not sure how that slipped through.
The animation of mosses really helped me understand how mosses reproduce! I had 2 labs and a whole lecture over this and the 3 minute clip of this taught me more than the 3 hours I spend in lab and lecture. Many thanks!!
A small correction: The capsule holds 1000s of "haploid" spores, not "diploid". :) Loved the video! Great job with the animation!
My science teacher loves you and even assigned your videos as homework. She also likes to watch them in class. Nice videos, good job making them interesting and appealing to all ages. :)
They are great at that
So your science teacher is paid to teach you by showing you TH-cam videos?
Damn. I’d be a great teacher in that case. I watch mostly sciency stuff that I could show kids... Wait... nope I don’t have the patience to deal with kids. Never mind.
At 7:13 I'm pretty sure he meant to say haploid spore not diploid because spores coming from the sporangium are 1n.
yup..u r right..well noted!
But spores have 2 sets of chromosomes...what am I missing?
H
It’s not an mistake they are diploid
They are 2N
You'll never know how happy I was to click on this review guide for part of my final to see my favorite SCI Show guy!! Instantly knew I was set. You da best!
Hank, at 7:15 you made a mistake by saying that the capsule is full of diploid spores. While the sporophyte is diploid, the spores produced should be haploid.
No. The gametaphytes release haploid cells which upon arrival at the archegonia join creating a diploid cell which replicates itself through mitosis until there are thousands of diploid cells (spores) which the calyptra releases and the ones that land on wet ground become bryophytes.
Ruadhan Glynn After fusion of the gametes in the archegonium, the newly formed diploid cells start replicating through mitosis (you're right uptil here) and form a sporophyte, the sporophyte then produces haploid spores through meiosis.
Demba Fofana Demba is correct. The spores couldn't possibly be 2n because they germinate on their own to create gametophytes which are n.
spores can be either haploid or diplod. Mitospores are haploid if made in haploid sporophyte or diploid if made on diploid sporophyte, meiospores are always haploid.
THANK YOU I WAS A BIT CONFUSED AT THAT POINT
I have to take a biology final tomorrow and, as I couldn't sleep, I'm reviewing. I have trouble retaining information due to my head fog, so I was happy to see an easier learning method than books and notes: these videos. Thank you for these. :)
Hank buddy, get me an A on my Bio test.
I believe in you more than I believe in myself.... I shouldn't have played BF4 all night >
pffttt it's all about advanced warfare now
psshhh destiny is life.
loccio il lupo well buddy that's your opinion and i respect it :)
tjtbkgaming lol get a character to lvl 20 and you'll be hooked...
loccio il lupo i played destiny a lot until aw came out i have a lvl 29 hunter, i stopped playing the day aw came out and haven't touched it since then.
this video got me an A on my biology exam
much thank
such hank
broooooooooo
Lil' Zombie Foo Foo Same
After falling asleep through a few mono-toned lectures, this quick video really tied my understanding together, thank you.
Spanish moss is a plant,Tillandsia usneoides. We commonly refer to tillandsias as "air plants"...it is not a lichen.
yee
but i think at the time of making this video spanish moss was believed to be a lichen
I feel like Crash Course should rightfully be sponsored by Google.
ariah johnson I don't care
ariah johnson I agree with you the ariah johnson
@@lichuo No one cares about the fact you don't care
they're sponsored by TH-cam, which is a property of Google
megaKstudios I was so young when I wrote this lol I learned you can make money off of TH-cam since then and I’m 21 now 🤣🤣🤣🤣🤣 whoops!
You know what I love? The fact that these biology crash course videos are following my biology course at school down to the T. I've got a bio test on thursday that I need to revise for... was feel pretty annoyed about that, but then I realised it gives me an excuse to watch crashcourse! :D
This is so amazing! As he was talking my thoughts actually started to align surrounding all the textbook stuff I've read - he makes it so easy to understand!!! :)
The examples of the ones that do not have a vascular system would be the liverworts, hornworts, and mosses but they have bizarre features for their reproduction systems but they need the requirement of water presented. They undergo gametophyte in which the sperm and egg meet and undergo mitosis then later releases spores into the air hoping it would fertilize another egg. - Great video!
Shouldn't plant taxonomy use Divisons instead of Phyla?
Anyway you saved my morning, I didn't feel like studying for my Botany test, but this is a good compromise ;)
I cant help but laugh!
So refreshing to see humor and quick explanations for what may seem like complicated topics! Wonderful videos. My son and I truly enjoy them (13 yrs old). As a future Science teacher it is something I will share and link to my pages, thank you!
I just wanted to say thank you SO much Hank for Crash Course Biology, because of it I passed my end of term Biology test in the top 10% of the year group, when last year I was in the bottom 10%! SCIENCE, OH YEAH.
Next week - don't miss Hank explaining how grass grows! He makes everything entertaining!!! Keep up the amazing work!
When Hank explained the concept of alternation of generations, I immediately understood it thanks to the Aliens franchise. Facehuggers are like sporophytes. Yay!
Thank you for this! I have an exam on this tomorrow.
Do you have any quick tips on remembering the life cycles of gymnosperms and angiosperms?
so happy that i have this to help me study for my test tomorrow!
hey CC, at one point (5:41) you say the spores are haploid, and at (7:12) you say they are diploid. This is a pretty confusing topic so please fix. other than that, thank you sooo much for your collection of awesome videos! you're my hero!
+Gabriela Garcia The spores are actually haploids, in case you needed that. An easy way to remember it is how the fused gamete is diploid, so haploid spores are produced.
My guy explained something my bio teacher would have taken 4hrs to explain and made me understand with in 20 mins frrrr
Great Video Series I'm learning lots, though it can be a lots of information at once so I really appreciate visual aids and Crashcourse's are great when there used. I have to add this one was confusing, there are comparison and cycles and different processes, it hard to keep it all straight. I watched parts four times now (which I learn something each time) but I'm still missing something.
Hey Hank, first of all, Thanks for all these great videos, they're helping a lot with the AP Bio test review. I have one question though, so if the gametophytes produce gametes through mitosis, how is genetic variation produced, how are gametes haploid, and how is gender detirmined? Thanks again for the videos!
How can something that seems so complicated in lecture be explained in like 3 minutes. Thank you!
Love this guy! Using his catalog of videos to teach our outdoor classroom in the Hamilton Gardens - good stuff!!!
Thanks for wrapping this up for me! I have so much more understanding of all of this now!
These videos are so amazing and Hank you are so funny! Thank you very much!
no one expects the spanish moss
I really really really like this comment
These are such great episodes!! Please keep it up!
This was in my classroom today! I fangirled so much lmao
+Phoebe Smith I would too if I were in your place!
These shows are fantastic. I love how you (Hank) and John present information. I hope you do more such as physics, because it is a misunderstood and a fun study.
I feel smarter everytime I watch one of these videos.
You've probably already realized this, but Crash Course puts out about one video a week on each active course. Biology and Ecology have ended and Hank is working on Chemistry now. (You can find the playlists at the Crashcourse page.) His brother, John, has finished World History and Literature, and is working on US HIstory. All the courses are worth watching. Have fun learning!
Hank you are doing a fine job
Every video of yours I watch Hank I am just so grateful for, you make learning bio easy and straightforward, thank you!
Love the video! Was trying to review my knowledge of non-vascular plants and got a kick out of this while also accomplishing my goal. Thanks!
I am wondering if there is an error in this video - at 7:14 he says that the capsule is full of "diploid spores" - but aren't the spores haploid since they then go on to become a gametophyte?
Hi! I wanted to know if nonvascular plants and vascular plants both had cuticles. I read on a few websites that they did have small waxy ones, but others say no. Thank you!
This is so going to help me pass bio 2 lab and lecture I'm so happy !!!! 🤗
I know this video is old but I'd like to say that your channel has helped me so much through highschool. You make learning fun.
@2:15 Are we supposed to know what osmosis and diffusion are at this point? Which previous videos explain those? It looks like it's a core difference between vascular and non-vascular plants and I would like to understand it better. Kelp, for example, seems to be able to grow pretty tall too.
I usually watch these to review after I finish reading the chapters that go with it in the textbook and it usually helps but this is made me super confused after I thought I understood. According to this video, the sporophyte generation produces asexually-- but it produces haploid spores from diploid cells. Doesn't that mean meiosis occured? I'm so lost.
I know this video is older, but I’d like to correct one part for anyone who is still watching:
3:30 He mentioned that Spanish Moss is a lichen. Spanish moss (as depicted in the picture at 3:38) is actually a Bromeliad which is the same taxonomic family as pineapples and succulents. The scientific name is Tillandsia usneoides.
Interestingly enough, this is a common mistake, as the species name ‘usneoides’ means ‘to resemble usnea’.
Usnea IS in fact a lichen, otherwise known as the beard lichen, which is an amazing interesting fellowship between Cyanobacteria or Algae and Fungus.
I hope this helps someone!
Meiosis is the process where a diploid cell undergoes divisions to produce 4 haploid cells, yes. In the bryophytes featured in this video, the dominant stage (the plant you see carpeting the rock) is a haploid gametophyte. Since it's already haploid, the sperm and eggs are produced via mitosis on the antheridium and archegonium respectively. The archegonium (w/ eggs) is fertilized and produces a diploid sporophyte that releases, via meiosis, haploid spores. Those spores grow into gametophytes.
Do you think you could (at some point) do a video on plants that seem to be geared entirely on very rapid reproduction and choking out all other plants? We have some non-native species on the Eglin Reserve that are very interesting and do this. They're generally a problem for the forest, as well as controlled burning (since they ignite like gasoline during fires).
Nice video although at 7:21 you say that you need high humidity levels for spore release whereas dry conditions are actually needed ;)
Hank, you actually just saved me for tomorrows test:) You are the best!!! Thank you soooooooooo much.
Thanks. Took my AP test today- NOTHING about ecology 90% of it was just graphs- and I saw EVERY video.
Thank you from me as well, Hank. Will be sad to see this end in four weeks. Would be excellent if you two could start a new series, but since this is offered to us for free? I have absolutely no right to complain if you don't.
I told my Biology teacher about CrashCourse Biology and we might start watching them in class! Hooray!
decomposer is normally a term used in relation to a wide range of organisms that break down organic matter as I'm sure you are aware, the partner in the litchen is in fact a photo-, or more often, a chemoautotroph.
7:11 it is haploid not diploid. I think the whole video needs some editing on haploid vs diploid generations. We need to be able to follow how genetic info is being passed on to better understand what's happening.
For instance, sporophytes are made of diploid cells, spores are haploid gametes that grow into haploid gametophytes.
Love this just like all of the rest! Just found a tiny edit...can you put a word blip that says "haploid" in, where you talk about spores? The sporangium is diploid, but the spores, produced via meiosis, are haploid, not diploid. I'm sure it was just a verbal slip - bound to happen!
Instead of relying on my ancient textbook to do my independent study unit, I can come here and not be bored to death. Thanks for making it interesting, Hank! :D
This could possibly be my favorite response I've read in a long time. Thank you for making my day.
Hank! Why weren't you making these 20 years ago? Never mind, silly question. However I would have been inspired to pursue Biology (in more ways than the usual one, heh). You and your brother are brilliant presenters and teachers.
Isn't the taxon Division used for Plant taxonomy, instead for term Phylum/Phyla which is used in Animal Taxonomy?
Only Hank could get me to click on a video titled "The Sex Lives of Nonvascular Plants: Alternation of Generations"
Would it be possible to feature Bryozoa in a video at some point?
7:12 he means HAPLOID spores!!!!!!!!!!!! confusing but actually helped me learn it from getting confused and figuring it out
Literally just stepped out of my algae/moss lab in my bio class. THANKS HANK!!!!!!
I swear Hank shows up in almost every science TH-cam channel I visit.
The capsule on the bryophyte sporophyte will release it's spores when humidity levels are LOW, not high. When the air is dry, spores may be dispersed more widely and over greater distances than when the air is wet.
example 4:22 gives a comparison of animals vs plants then Alternation of Generations then algae vs plants then there are those flailing arms LOL (after watching 4X those arms are dangerous).Animations are awesome and help to digest all that great info please keep it up. Keywords are fine, but I like suggest maybe flow charts or bullet point with your lecture and sometimes less info is more retained information. Your Knowledge ---Giveme! Giveme! Giveme! Thanks Crashcourse
At 7:19 he says: "If humidity levels are high enough the capsule will let the spores go to meet their fate." In other literature I have read that the capsule actually remains closed when humidity levels are relatively high, and it only opens up when the air is dry enough for the spores to spread far away from the mother plant by means of wind. To me, this explanation sounds more plausible. What do you think?
Hi, this was very useful but I'm wondering how this works in vascular plants. Ex. I used to grow tomatoes and to my knowledge they never had spores and we needed seeds to make our plants grow. For now I'm going to assume this only applies to non-vascular plants or that there are several exceptions to this but he did infer that vascular plants use this. Can someone give me clarification?
Addition: I've been thinking about it some and I believe I may have clumped two cycles into one. So if the first generation is my "plant" and my sporophyte is the flower. The flower mates and makes the fruit which becomes my new "plant." My one question is how the plants mate for the first cycle. I'll assume this gets answered in next episode but if someone knows if this is right or not it would be greatly appreciated.
"The mosses... Mmmm, fuzzy."
n_n
The gametophytes are haploid, so the gametes are in fact made through mitosis. The gametophytes come from the germination of spores (haploid) which are produced by the sporophytes (diploid because they come from the fecundation of gametes ) through meiosis. Sorry if it's a bit confusing...
you are my only hope at doing well on my midterm today. thank you for being here haha
unexpected slide whistles make everything better
6:07 is where it's at. Turn on the captions if necessary.
Quick question why isn't Ulva considered a plant? It photosynthesizes with Chlorophyll A&B, it has the alternation of generation life cycle, it has cell walls made of cellulose. Yes it does not have roots, stems and, leaves, but non-vascular plants don't either.
a long stalk with a cap on top called calyptra... beautifully helpful for remembering.
Right. Okay. That makes sense. He probably could've explained it better in the video though. So which part exactly is the actual spore? Would that be the (n) "gametes" you described that are created by the sporophyte?
Spanish moss actually Bromeliad! A flowering plant, though it does look like a lichen to be sure.
Good. Any time something in science can be made simpler, we should take the opportunity. It's complicated enough without having two names for the same thing for no apparent reason.
They're plants functionally, but not systematically! They're symbiotic associations that consist of a fungus that forms the body and an alga (and/or cyanobacterium) that photosynthesizes.
When we say "plant" we either mean "thing that photosynthesizes" (includes lichens, algae and whatnot) or we mean "kingdom Plantae" which is a lot more specific. It's tricky. :D
Hank, can you do a botany series!?
You are correct. What he said on that was mistaken. Mitosis can ONLY make an exact copy of a cell. Meiosis is what happens when gametes are made to mix up the gene pool. It's the same in both animals and plants regardless.
I was looking for a way to procrastinate since this is the lazy person I am.Then I stumbled upon this gem here and voil´a!I can actually revise for my botany exam while kind of relaxing my brain at the same time!
Depends on what taxonomist you ask. Bryophyta, Anthocerophyta and Hepatophyta are all recognized as phyla or have been at some point. But yeah, unranked divisions are more common in botanical taxonomy these days.
You're right. The pods the queen lays is more like the sporophytes, and the facehuggers are the spores, except the spores are a further generation that seeks out an appropriate growth environment for the gestation of the new xenomorph, which also incorporates DNA from that environment (aka host). So it's a three-generational cycle. :O
*lichen
And they're colonies of algae living within colonies of fungus, similar to coral, but not nearly as sturdy. They reproduce via spores that contain both the protective mold and the food-making algae, and also increase the diameter of their patch about one inch per year (although this may be skewed due to reindeer loving to eat lichen).
This is a good review for my IB Botany test for HL Bio.
Gametes/haploid cells can be made from mitosis when they are coming from cells that are already haploid in the first place (like the gametophytes). When they come from diploid cells, then its meiosis taking place.
Could you explain marsupial reproduction, either here or in scishow?
So, how does the gametophyte get down to the haploid ? I think I missed something... is there a meiosis process that takes the diploid down to haploid?
Wait, I'm confused. He said the gametophytes produce gametes that will fuse and eventually give rise to sporophytes which are asexual (5:25), but isn't the fusion of gametes sexual?
I hear that John Green wrote a few books. I think that one got tried at being banned. What were those books?
Thank goodness! Posted a day before our practicals and long tests *O* Thanks!
Yup. Are you gonna be ok?
Thank you! This was extremely helpful
We don't know the specifics at all (like, AT ALL), but we have a couple good ideas. For one thing, the first life would've been chemosynthetic rather than photosynthetic, so it may have been something like what lives around deep-sea volcanic vents.
For another thing, there's some evidence that RNA was the central molecule to begin with, and that DNA and proteins emerged secondarily. A lot of ancient cellular functions are still handled by RNA. Google ribozymes for more information. :)