Hello, everyone. In this lesson, we are going to be talking about the specific adaptations that land plants acquired in their transition from their aquatic environment to their new terrestrial environment. Now, plants had to come up with many complete aquatic environment, to moving to living in a terrestrial environment would be quite dramatically different. So, plants evolved many structural features that allowed them to live on land. Now, what do you think the majority of these new adaptations are going to do? Well, if you go from living in water to not living in water, you're going to find that the majority of these new adaptations that these plants have is going to help them retain water, going to help them not dry out from living in very dry air. So the majority of these adaptations help them retain water. And some of the major adaptations for retaining water are going to be the cuticle, the stomata, and the guard cells. So, the cuticle is going to be the main line of defense against desiccation or drying out. This is going to be a waxy film covering the epidermis, or outer layer of cells, of many plants. You can actually see the cuticle right here. It actually looks like this clear layer of wax. And that's pretty much exactly what it is. It's a clear layer of wax that goes directly over the outer layer of plant cells. It's kind of like a raincoat, But instead of keeping the rain out, it wants to keep the water inside of the tissues of the plant. So the cuticle's main job is to keep water in. So, it keeps the plant cells from losing water. Also, the cuticle is very important for keeping out pathogens, but we'll learn more about that whenever we learn about the immune system that you find inside of plants. All right, so now let's talk about the stomata. Stomata are going to be pores in the tissues of the cells, generally the leaves, that are going to control gas exchange, and they're going to regulate water loss. Stomata are basically pores or holes in the tissues of the plant that are able to open and are able to close. You can actually see a stomata, or a stoma. That is the singular version. Stomata is plural. You can actually see a stoma right here. This is a stoma. This hole in the surface of the leaf. This is a cross-section of a leaf. If you guys were wondering, here's the leaf. Here's the cross-section of the cells of the leaf. And we have a pore in the bottom of the leaf right there, which is a stoma. Now, the stomata are actually able to open and close. And the way that they're able to open and close is because they have these specialized guard cells. And these guard cells are able to change their shape based on their turgidity, which is going to be the amount of water pressure that they have inside of them. And they are able to open and close the stoma. Now, why would a stoma need to open and close? Well, plants need access to the air to do photosynthesis. Photosynthesis requires CO2, and it gets rid of oxygen. So it needs to interact with the gases that are in the air. So the stomata need to open for that particular reason, for gas exchange, for photosynthesis. But because the internal tissues of the plant are interacting with the air, that means that water is actively evaporating out of the leaves, which is bad because we don't want these plants to lose too much water. So, this is why stomata open and close. They open so that the plant can do photosynthesis and exchange gases. But they close so that the plant doesn't lose too much water when it's not doing photosynthesis. In most plants, they're going to close at night when they're not doing photosynthesis because the sun is not out. There are some specialized cases that we will learn about later. Now, I wanted to show you guys how these are actually going to work. So, whenever you have these guard cells, whenever they have low water pressure, so low pressure inside of them, they are going to be closed. So, these are closed guard cells. Meaning that the stomata is closed. So, these guys down here are guard cells. Now, whenever water is actively pumped into these cells they're going to become turgid or have a very high water pressure inside of them. And, they're going to form this, kind of, like, macaroni shape. And this is going to allow the pore to open. So this is going to have high pressure, and this is going to allow the stoma to open. So now we can have these gases, so we can have CO2 entering the plant, and we can have O2 leaving the plant because this stoma is open. And that's high water pressure versus low water pressure. So this is going to be how the stoma actually opens and closes. And, generally, the stomata are going to be found on the bottom of the leaf, as you guys can see right here. So, those are going to be 3 major adaptations for living on land, generally to allow these plants to do gas exchange, but mostly to allow them to retain water. Now, also, we learned that most plants, not all land plants, have vascular tissue. But, vascular plants did, in fact, evolve vascular tissue. Vascular tissue is very, very important because it allows these plants to transport water and nutrients throughout the entire body of the plant. This allows plants to grow quite large because they can transport water and nutrients to their extremities. You can kind of think of this particular system, as an analogy to our blood vessel system. Our blood vessel system actually transports water and nutrients as well to our extremities. Same thing with a plant, except it's a little bit different. They have Vascular Tissue. And, they have one type of Vascular Tissue that is specific for water and one type of Vascular Tissue that is specific for nutrients. And these two types of Vascular Tissue are going to be Xylem and Phloem. Xylem is going to be the transport vascular tissue that transports water and minerals. This is going to be the one that transports for water. Now, wood is very interesting. It is a form of Vascular Tissue, specifically xylem. And, you can look at the Greek word that Xylem came from, so Xylem is the English word. The Greek word is actually Xylon,
Table of contents
- 1. Introduction to Biology2h 40m
- 2. Chemistry3h 40m
- 3. Water1h 26m
- 4. Biomolecules2h 23m
- 5. Cell Components2h 26m
- 6. The Membrane2h 31m
- 7. Energy and Metabolism2h 0m
- 8. Respiration2h 40m
- 9. Photosynthesis2h 49m
- 10. Cell Signaling59m
- 11. Cell Division2h 47m
- 12. Meiosis2h 0m
- 13. Mendelian Genetics4h 41m
- Introduction to Mendel's Experiments7m
- Genotype vs. Phenotype17m
- Punnett Squares13m
- Mendel's Experiments26m
- Mendel's Laws18m
- Monohybrid Crosses16m
- Test Crosses14m
- Dihybrid Crosses20m
- Punnett Square Probability26m
- Incomplete Dominance vs. Codominance20m
- Epistasis7m
- Non-Mendelian Genetics12m
- Pedigrees6m
- Autosomal Inheritance21m
- Sex-Linked Inheritance43m
- X-Inactivation9m
- 14. DNA Synthesis2h 27m
- 15. Gene Expression3h 20m
- 16. Regulation of Expression3h 31m
- Introduction to Regulation of Gene Expression13m
- Prokaryotic Gene Regulation via Operons27m
- The Lac Operon21m
- Glucose's Impact on Lac Operon25m
- The Trp Operon20m
- Review of the Lac Operon & Trp Operon11m
- Introduction to Eukaryotic Gene Regulation9m
- Eukaryotic Chromatin Modifications16m
- Eukaryotic Transcriptional Control22m
- Eukaryotic Post-Transcriptional Regulation28m
- Eukaryotic Post-Translational Regulation13m
- 17. Viruses37m
- 18. Biotechnology2h 58m
- 19. Genomics17m
- 20. Development1h 5m
- 21. Evolution3h 1m
- 22. Evolution of Populations3h 52m
- 23. Speciation1h 37m
- 24. History of Life on Earth2h 6m
- 25. Phylogeny2h 31m
- 26. Prokaryotes4h 59m
- 27. Protists1h 12m
- 28. Plants1h 22m
- 29. Fungi36m
- 30. Overview of Animals34m
- 31. Invertebrates1h 2m
- 32. Vertebrates50m
- 33. Plant Anatomy1h 3m
- 34. Vascular Plant Transport2m
- 35. Soil37m
- 36. Plant Reproduction47m
- 37. Plant Sensation and Response1h 9m
- 38. Animal Form and Function1h 19m
- 39. Digestive System10m
- 40. Circulatory System1h 57m
- 41. Immune System1h 12m
- 42. Osmoregulation and Excretion50m
- 43. Endocrine System4m
- 44. Animal Reproduction2m
- 45. Nervous System55m
- 46. Sensory Systems46m
- 47. Muscle Systems23m
- 48. Ecology3h 11m
- Introduction to Ecology20m
- Biogeography14m
- Earth's Climate Patterns50m
- Introduction to Terrestrial Biomes10m
- Terrestrial Biomes: Near Equator13m
- Terrestrial Biomes: Temperate Regions10m
- Terrestrial Biomes: Northern Regions15m
- Introduction to Aquatic Biomes27m
- Freshwater Aquatic Biomes14m
- Marine Aquatic Biomes13m
- 49. Animal Behavior28m
- 50. Population Ecology3h 41m
- Introduction to Population Ecology28m
- Population Sampling Methods23m
- Life History12m
- Population Demography17m
- Factors Limiting Population Growth14m
- Introduction to Population Growth Models22m
- Linear Population Growth6m
- Exponential Population Growth29m
- Logistic Population Growth32m
- r/K Selection10m
- The Human Population22m
- 51. Community Ecology2h 46m
- Introduction to Community Ecology2m
- Introduction to Community Interactions9m
- Community Interactions: Competition (-/-)38m
- Community Interactions: Exploitation (+/-)23m
- Community Interactions: Mutualism (+/+) & Commensalism (+/0)9m
- Community Structure35m
- Community Dynamics26m
- Geographic Impact on Communities21m
- 52. Ecosystems2h 36m
- 53. Conservation Biology24m
28. Plants
Land Plants
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