Otho Boniface
more than 1 week ago
Describe the process of primary growth in plants
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Google Gemini AI
more than 1 week ago
Primary Growth
Primary growth in plants involves the elongation and differentiation of tissues in the axial organs (stems and roots) primarily due to the activity of apical meristems.
Apical Meristems
- Shoot apical meristem (SAM): Located at the tip of the shoot, produces leaf primordia and stem tissue.
- Root apical meristem (RAM): Located at the tip of the root, produces root primordia and root cap.
Process of Primary Growth
1. Cell Division in Apical Meristem:
- Apical meristematic cells undergo rapid cell division, producing a pool of undifferentiated cells.
2. Cell Expansion and Differentiation:
- Undifferentiated cells elongate and differentiate into specific tissues:
- Protoderm: Develops into epidermis
- Procambium: Develops into vascular tissue (xylem and phloem)
- Ground meristem: Gives rise to cortex and pith
3. Formation of Leaf Primordia:
- Small bumps (leaf primordia) are formed at the SAM.
- Leaf primordia grow and develop into leaves.
4. Formation of Root Primordia:
- Small bumps (root primordia) are formed at the RAM.
- Root primordia grow and develop into roots.
5. Elongation and Tissue Maturation:
- Cells produced by apical meristems elongate, pushing the plant upwards and downwards.
- Tissues mature as they differentiate and acquire their specialized functions.
6. Internodal Elongation:
- Cells in the internodes (regions between leaves on stems) elongate rapidly, resulting in the extension of the stem.
7. Formation of Nodes and Leaves:
- At the nodes (points where leaves attach to the stem), leaf primordia develop into leaves.
- Leaf expansion and maturation contribute to the increase in photosynthetic surface area.
8. Lateral Root Formation:
- Lateral roots emerge from the procambium of older roots, allowing the plant to absorb more nutrients and water from the soil.
Primary growth in plants involves the elongation and differentiation of tissues in the axial organs (stems and roots) primarily due to the activity of apical meristems.
Apical Meristems
- Shoot apical meristem (SAM): Located at the tip of the shoot, produces leaf primordia and stem tissue.
- Root apical meristem (RAM): Located at the tip of the root, produces root primordia and root cap.
Process of Primary Growth
1. Cell Division in Apical Meristem:
- Apical meristematic cells undergo rapid cell division, producing a pool of undifferentiated cells.
2. Cell Expansion and Differentiation:
- Undifferentiated cells elongate and differentiate into specific tissues:
- Protoderm: Develops into epidermis
- Procambium: Develops into vascular tissue (xylem and phloem)
- Ground meristem: Gives rise to cortex and pith
3. Formation of Leaf Primordia:
- Small bumps (leaf primordia) are formed at the SAM.
- Leaf primordia grow and develop into leaves.
4. Formation of Root Primordia:
- Small bumps (root primordia) are formed at the RAM.
- Root primordia grow and develop into roots.
5. Elongation and Tissue Maturation:
- Cells produced by apical meristems elongate, pushing the plant upwards and downwards.
- Tissues mature as they differentiate and acquire their specialized functions.
6. Internodal Elongation:
- Cells in the internodes (regions between leaves on stems) elongate rapidly, resulting in the extension of the stem.
7. Formation of Nodes and Leaves:
- At the nodes (points where leaves attach to the stem), leaf primordia develop into leaves.
- Leaf expansion and maturation contribute to the increase in photosynthetic surface area.
8. Lateral Root Formation:
- Lateral roots emerge from the procambium of older roots, allowing the plant to absorb more nutrients and water from the soil.
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