plant growth Flashcards
What is the role of stem cells in the Root Apical Meristem (RAM)?
Produce all root tissues.
Divide at a low rate to maintain other initial cells.
Send signals to prevent premature differentiation of cells.
What are the 4 developmental zones of the root tip?
1️⃣ Root cap: Protects the meristem, senses gravity (gravitropism).
2️⃣ Meristematic zone: Contains the RAM; produces cells for all root tissues.
3️⃣ Elongation zone: Cells elongate, stop dividing, and reach final size.
4️⃣ Maturation zone: Cells differentiate, form lateral roots and root hairs for water uptake.
How are cells arranged along the root tip?
Cells are arranged in files (rows) along the axis of the root.
Successive stages of differentiation are seen along these files.
How do planes of cell division define three distinct layers in the SAM?
Cells in the SAM divide in different orientations:
Anticlinal divisions: Perpendicular to the surface.
Periclinal divisions: Parallel to the surface.
These divisions create three distinct cell layers in the SAM.
What are the 3 zones of the Shoot Apical Meristem (SAM) and their roles?
1️⃣ Central Zone: Contains slowly dividing stem cells.
2️⃣ Peripheral Zone: Actively dividing cells form organ primordia (e.g., leaves, flowers).
3️⃣ Rib Zone: Actively dividing cells that produce internal stem tissues.
What roles do CLV3 and WUS play in meristem maintenance?
CLV3: A small peptide produced in L1 and L2 layers. It binds receptor kinases, suppressing WUS.
WUS: A transcription factor made in the organizing center. It moves to L1 and L2 to activate CLV3.
Together, CLV3 and WUS maintain a balance in meristem size through a negative feedback loop.
How does the CLV3-WUS feedback loop control stem cell activity in the SAM?
1️⃣ CLV3 peptide binds to receptor kinases.
2️⃣ This suppresses WUS expression.
3️⃣ WUS moves to L1 and L2, activating CLV3 expression.
4️⃣ This feedback maintains meristem size and stem cell population.
What is water potential and how does it affect water movement?
Water potential predicts the direction of water movement.
Water moves from high to low water potential.
Water moves from high to low solute potential.
Water moves from low to high solute concentration.
What factors affect water potential in plants?
1️⃣ Solute potential (Ψs): More solutes = lower water potential.
2️⃣ Pressure potential (Ψp): Turgor pressure pushes water outward.
3️⃣ Water moves from areas of high potential to low potential.
Name 5 key processes related to plant growth and development from this topic.
1️⃣ Root Apical Meristem (RAM): Produces all root tissues.
2️⃣ Root Tip Zones: Root cap, meristematic, elongation, maturation.
3️⃣ Shoot Apical Meristem (SAM): Central, peripheral, and rib zones control shoot development.
4️⃣ CLV3-WUS Loop: Balances stem cell population in the SAM.
5️⃣ Water Potential: Water moves from high to low water potential, affecting water uptake.
