Good day students. This is the second part of our video discussion in module 1, plant organ systems and functions. Let's proceed to the forms of reproduction in angiosperms.
The types or the forms of reproduction can be a sexual reproduction or a sexual reproduction. When we say asexual reproduction, it occurs when offspring emerge from a single parent. Meaning po, isa lang po ang parent ng ating offspring.
And then, it does not involve the fusion of gametes or fertilization. And the offspring are genetically identical to the parent organism. organism so kung ano ang nasa genetic information or the overall characteristics of the parent will be passed on to the offspring. Let's compare it to the sexual reproduction. When we say sexual reproduction, it may either involve single or self-pollination or two parents which is called as cross-pollination.
And it requires diffusion of a sperm cell and egg cell during fertilization. And it enhances genetic variation because the parents and the offspring are not genetically identical. Compared to the asexual reproduction, there is no genetic variation because na-copy up po lahat ng genetic information from the parents to the offspring.
Okay, so asexual reproduction has different types. Let's start with the apomixis. When we say apomixis, it is a type of asexual reproduction in plants where seeds are produced without meiosis and fertilization. In this process, the unfertilized eggs in ovules produce embryos. Okay, take note po, during apomyxis, it will not undergo meiosis and fertilization.
So kaya wala pong genetic variation na nangyayari. So apomyxis in some species of dandelions allows the production of embryos from unfertilized eggs. eggs in ovules. So for example, the species dandelions, they don't have genetic variation because only one parent is involved in the reproduction and it doesn't undergo meiosis and fertilization.
So, we can see the floral units or the flowers, floral anatomy of the dandelions. And then, this is the mature fruits and seeds. So, kaya po, yung unfertilized eggs po ng dandelions, sa ovules, will produce the embryos. Okay, let's proceed. to the sexual reproduction, specifically vegetative propagation.
When you say vegetative propagation, it is a form of sexual reproduction where plant parts produce buds that develop into new individuals. For example, is our strawberries. So, dito po sa ating figure, this is the main plant, the strawberry plant. And then, we all know that strawberries are runners. So, it will extend the stems, and then it will create an extension of the main plant.
Kaya may budding po ang nangyayari sa... different areas of the soil. So to better visualize So meron po tayong figure here.
These are strawberries or the Fragaria species. These strawberries perform vegetative propagation through the buds that emerge from stolons or runners. So ito po yung main plants.
And then because of its distinct characteristic or ability to um extender stems so you stolen or runners nagkaroon po ng different buds okay from the main plant nagkaroon ng isa dalawa atatlong buds or budding kaya it will para siyang new species or new plant but connected po siya sa ating main plant plant. Yan po yung tinatawag na vegetative propagation. So from the main plant, in layman's term, mukatay or mukron. Ano siya? It will extend and then it will create a new extension or nagkaroon ng buds and then another buds and then another bud.
and then eventually it as it matures it will bear fruits okay i think it's clear already let's proceed to the sexual reproduction specifically the pollen grains sexual reproduction or the pollen grains again as we discuss it oh in the first part pollen grains contain the male gametophytes in angiosperms. Each pollen consists of two sperm nuclei from the generative nucleus and then the tube nucleus will transport the sperm during pollination. So for example, so here in our figure, so this is our pollen grain. pollen grain plus the pollen tube so so i think pollen grain it contains two sperm nuclei or the gametes the long sperm nuclei and then the tube nucleus the tube nucleus will transport the sperm so nakukuha po siya ng ating mga pollinators, agents of pollination, for example, bees, butterflies, towards the stigma.
So, itulak siya pataas and then napapollinate na po siya afterwards. Okay, take note, pollen grains contains the male gametophores. fights in angiosperm gametophytes are haploid okay we have also the ovules so can you now we have the uh male uh male side or the male part now let's proceed to the ovules which contains the female gametes each ovule or embryo stack is the ovary of the flower consists of eight nuclei so you have one two three four five six seven and eight the primary sex cell that is fertilized is the egg nucleus or the egg cells together with the sperm nuclei or the sperm cell and then only the polar nuclei so it's the phone the law and the egg nucleus will have a descendant or will have descendant in feed the but take note ovary will become fruits and then ovules will become fields so you genetic information from the polar nuclei and egg cell will be will be transferred in the form of seeds Okay, so this is what's involved in the sexual reproduction of plants, the pollen grains, and the ovules.
Okay, but there will be instances that... there will be a double fertilization that will happen to the plants. So, for example, pollen grains land on the stigma of the pistil. So, the pollen grains from the answer will be transported to the stigma. And then, the pollen tube extends itself.
Okay? Ma-extend si pollen tube. And then the embryo sac or the ovule, one of the sperm nuclei, fertilizes the egg nucleus to form an embryo. So daraan po si sperm cell rito. And then papasok po siya sa embryo sac.
And then makikita or it will meet the egg nucleus and it will form an embryo. And then the other sperm nucleus, remember may dalawang sperm cell sa pollen grain. Yung isa will be fertilized together with the egg nucleus.
And then the other one or the other sperm nucleus fertilizes the polar nuclei. Remember, polar nuclei will... together with the egg nucleus, will have a descendant in seeds.
So, si polar nuclei will be fertilized by the other sperm to produce an endosperm. Yung isa, dalawang first set, will produce an embryo, and the second set will produce an endosperm. And then, the double fertilization produces a diploid embryo and triploid endosperm. Okay? To better understand, may figure tayo rito.
The fate of the sperm nuclei, egg nucleus, and polar nuclei during double fertilization in angiosperm. So, ito. Si egg nucleus, pollen tube ito, and then, The sperm nuclei will be fertilized. And then, the other sperm together with the two polar nuclei will be fertilized. And then after...
After fertilization, the embryo came from this one, the union of sperm and the egg cell. And then the endosperm, so ito po siya, the result of the fertilization of the two polar nuclei and the other sperm cell. Kaya yung karoon ng triploid endosperm. sperm and the deployed embryo.
So yan po siya ang ating double-fertilization. Okay. So si pollen tube, as you can see here, it's served as a barrier para hindi po lalabas yung mga gamets. So nandyan siya sa opening ng ovule. Okay.
I hope you understood the discussion. Let's proceed to the plant development. Okay. Plants have different tissues. We have the short apical meristem.
So, it's here at the top. This is the short apical meristem. um it allows the continuous upward growth of the plant apical class because upward growth and development of the plant then we have oh i'm sorry okay i think okay sorry for the inconvenient let's proceed to the Cambiums The cambium allows further growth of stems and roots by increasing their thickness.
So, the short apical mary stem horizontally raises the plants. Si core cambium naman will allow the further growth of the stem, the thickness of the plants or yung pagkakadevelop vertically. So cambium has different types.
We have the core cambium and the vascular cambium. Si core cambium, yan po yung, for example, sa mga trees, yan po yung nag-create ng mga woody parts ng plant. So, there are woody or sturdy parts of plants.
And the vascular cambium, the one mentioned in the first part, which are the phloem and the xylem. Xylem transports water and then phloem transports the organic nutrient or food all throughout the different parts of the... plants and then we have also the root apical meristem it allows the continuous downward growth of out of the plants roots so ito po ang ating mga root system so um it can be fibrous or top root So, this is the root apical meristem, the root hairs, and the root apical meristem again, and then the root cap. Okay.
Let's proceed to embryogenesis. So, this is the fate of different floral structure upon the maturity into a fruit. Now, upon maturity, the seeds from the...
yung ovules enclosed inside the embryos or the embryo ay nagiging seeds. Take note, si ovary class will become a fruit. And then the ovules or seeds inside the ovary will become, the ovules will become seeds.
and then the differentiation of the ovary wall into exocarp mesocarp and endocarp in different types of fruits so this one, apple has pericarp and then seed endocarp kaya dinatawag siyang foam and then we have the peach it contains endocarp seed exocarp and mesocarp next we have the grape or grapes these are berries grape is a berry it has a it has seeds mesocarp mesocarp or the flesh or the pulp And then the exocarp, meaning the skin. And then we have the orange. These are hesperidium. May mesocarp, stigs po sa middle. And then the juices are the vesicles.
Yung parang may mga veins, yan po siya. Okay. Let's proceed to the organogenesis.
During germination, when we say germination again, this is the sprouting of the seed. Lalabas po dyan si cotylidon or the embryonic leaf. During germination, water is imbibed or it will undergo imbibition which ruptures the seed coat.
Okay, this is the seed coat. From a normal seed And then it will rooted sa ating soil. And then it will undergo germination. And then it will be imbibed. Kaya lalabas po ang radical.
Magkakaroon ng radical. The radical emerges from the seed which becomes the root of the plant. Okay?
Tutusya. from a normal seed because of germination and inhibition um radical so your root non-acting plants and then after that the hypochotile emerges from the seed okay ito hypocotyl and it will become the stem So, si radical is the root. Si hypocotyl will become the stem. And then after that, the cotyledons serve as the primary embryonic leaves in the seedlings.
Okay, recap. Radical will become the root. Hypocotyl will become the stem.
Cotyledon will become the embryonic leaf. And then eventually, the epicotyl from the plumule gives rise to the mature leaves. So from the embryonic leaf or the cotyledon, so ang cotyledon, and then as it matures, naggaroon po. ng epicotyl and si epicotyl nandyan po ang mga mature leaves.
So, dito tayo titingin. Again, radical will become the root. Hypocotyl will become the stem. And then, cotylidon will become the embryonic leaf. And then, epicotyl contains the mature leaf.
Okay? So, that's our organogenesis. So, this is the fate of the plumule, hypocotyl, cotylidons, radical, and epicotyl in the developing seedlings. And then, after it became or it became a seedling, it will become a mature or adult plant. I think we're done with our discussion.
Unfortunately, we will not have this checkpoint or multiple choice quiz. Okay, so, the questions are here and the answer keys. These are our resources.
Thank you for listening. If you have questions, you can reach me at this email. And you can also message in our group chat.
We'll see you in our next discussion. I hope face-to-face na. Okay, have a good day.