Root growth occurs in 3 areas, which are found behind the protective covering called the root cap. This protects the apical meristem and amazingly, senses gravity, so that the plant knows which direction to grow its roots in. It also secretes a lubricating polysaccharide that allows the growing root to push through the soil more easily. Now, these three areas are known as the zone, sometimes called area, you know, it doesn't really matter what term you want to use there, zone, area, whatever. But it's the zone of cellular division, and this is where the apical and primary meristems are found, and this is where cells are actively dividing. We also have, behind that, the zone of elongation. This is where these primary meristem tissues, or rather tissues derived from the primary meristems, elongate, and they actually elongate by swelling with water, and this swelling with water provides force to actually push the root cap through the soil. So the root cap is actually forced through the soil by the swelling of the cells in the zone of elongation. Pretty incredible. Then you have, lastly, what's called the zone of cellular maturation. Basically, this is where the cells go to complete their differentiation into whatever tissue type they're going to become, you know, like dermal, vascular, ground tissues, whatever. And it's actually from this area that we see these epidermal outgrowths called root hairs. These are super important. They're the sites of water and nutrient absorption. And here in our diagram, you can see all of these areas labeled, we have our root cap at the bottom, then behind that the area of cell division, behind that elongation, and lastly the area of cell differentiation or zone of cell maturation, it's the same thing. So this is, also the same as zone of maturation, and this is the area where you'll find the root hairs growing. Alright. Looking over here, we can see some of the particular primary meristems we covered, and they've been labeled. So of course, as we saw on the last page, that central area is going to be our, here, it's labeled vascular cambium. I want you guys to think of this as our procambium. And also we have our protoderm on the outside, and then of course the ground meristem in between those two layers. Looking down at this pink image here, it's a really nice picture of the root cap, that's basically what we're looking at here. This is really just a root cap photo, and what I want you to notice here's the root cap. Right? It's, this area in here. Notice all of these dead cells sloughing off the root cap, in this last external area that's marked by the number 4 there. Right? As the root grows and extends, the root cap is actually going to slough off the dead cells. Now lastly, I just want to turn your attention to this image behind my head, and get out of the way. Here you can see our root apex meristem, labeled in this area. It's, of course, found behind our root cap, and I also want you to notice all of these internal tissues. Right? So, here in red and blue, that's our vascular tissue, that's our xylem, and it's actually the red stuff is the phloem in there, so I'll put that in red. Xylem and phloem, and then, of course, we also have our ground tissues in these layers here, that's our ground tissue. So really all I want you to see is how in the root, how the root grows, how those primary meristems are how they're found, how they're located in there, and then, of course, the tissues that they're going to develop into. Alright. With that, let's flip the page and talk about secondary growth.
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
33. Plant Anatomy
Growth
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