Plant Tissues and Meristematic Tissue – Long Answer Questions
Medium Level (Application & Explanation)
Q1. What are plant tissues and why are they important for a plant’s survival and growth?
Answer:
- Plant tissues are groups of cells that do a specific function together.
- They help the plant to grow, develop, and work efficiently.
- They are like teams in a club, each with a special role.
- There are two broad types: meristematic tissue and permanent tissue.
- These tissues work together to keep the plant healthy and strong.
- Without tissues, plants cannot increase in size or repair themselves.
Q2. Describe the main characteristics of meristematic tissue. Explain how each feature helps in growth.
Answer:
- Meristematic tissue has undifferentiated cells that can become many types of cells.
- These cells show high mitosis rate, so they divide rapidly.
- The cells are small and have thin cell walls, which makes division easy and fast.
- Because they are active, they supply new cells for growth.
- They are found at key places like tips and nodes, where growth is needed.
- These features together make plants grow in length and girth.
Q3. Explain apical, lateral, and intercalary meristems with their locations, functions, and one example each.
Answer:
- Apical meristem is at the tips of roots and shoots.
- It causes primary growth, meaning increase in length.
- Example: Top of a growing stem keeps getting longer.
- Lateral meristem is in vascular cambium and cork cambium.
- It causes secondary growth, meaning increase in girth.
- Example: Tree trunk becoming thicker over time.
- Intercalary meristem is at nodes and base of leaves.
- It helps in regrowth after cutting.
- Example: Grass grows back after mowing.
Q4. What is the difference between primary growth and secondary growth in plants? Which meristems cause them?
Answer:
- Primary growth means increase in length of the plant.
- It is caused by the apical meristem at the root and shoot tips.
- It helps new leaves and roots to form and extend.
- Secondary growth means increase in girth or thickness.
- It is caused by lateral meristem like vascular cambium and cork cambium.
- It helps stems and roots become stronger and wider.
Q5. How do meristematic tissues help in plant propagation and regrowth after cutting?
Answer:
- Meristematic cells can divide and make new roots and shoots.
- In cuttings, these cells help form new tissues at the cut end.
- Intercalary meristem helps plants regrow after being cut or grazed.
- Example: Grass quickly grows back after mowing.
- This regrowth is due to active cell division near the nodes or base of leaves.
- Thus, meristems make plant propagation and repair possible.
High Complexity (Analysis & Scenario-Based)
Q6. A lawn is cut very short, but it becomes green again within a week. Analyze the role of intercalary meristem in this regrowth. What if it were absent?
Answer:
- Intercalary meristem is present at nodes and base of leaves in grasses.
- After mowing, these cells divide fast and restore the lost parts.
- This leads to quick regrowth and a fresh green look.
- If intercalary meristem were absent, regrowth would be slow or poor.
- The plant would depend only on apical meristem at the tips.
- But mowing often removes tips, so growth would be limited without intercalary tissue.
Q7. A tree’s trunk gets thicker each year. Explain why this happens. Predict what may happen if the lateral meristem is damaged on one side.
Answer:
- Lateral meristem in the vascular cambium and cork cambium causes girth increase.
- This is secondary growth, which makes the trunk thicker and stronger.
- It adds new vascular tissues and protective cork.
- If the lateral meristem is damaged on one side, growth there will slow or stop.
- The trunk may become uneven or weaker on that side.
- Over time, this can affect the tree’s support and transport in that region.
Q8. The tip of a root is accidentally injured during weeding. Discuss how this affects growth in length and what must remain intact for recovery.
Answer:
- Apical meristem at the root tip drives length growth.
- If this meristem is damaged, the root’s elongation will reduce.
- The plant may struggle to anchor and absorb water well.
- If some meristematic cells remain intact, they can still divide.
- New cells can form and restore the growing tip slowly.
- Protection of the apical region is vital for healthy root growth.
Q9. A student wants to reduce the upward growth of a stem without affecting its thickening. Where should they make a cut, and why will girth still increase?
Answer:
- To reduce upward growth, the cut must remove the apical meristem at the shoot tip.
- This limits primary growth, so length increase slows down.
- Lateral meristem in the vascular cambium remains untouched.
- It will continue secondary growth, so girth still increases.
- Thus, removing the tip affects length, not the thickness.
- The plant will still become wider, even with reduced height growth.
Q10. A stem cutting is placed in soil and kept moist. After some days, new roots and shoots appear. Explain this event using the properties and locations of meristems.
Answer:
- Meristematic cells are undifferentiated and can form new tissues.
- At the cut regions, cells begin rapid division due to high mitosis rate.
- New roots can form near the base, and shoots can arise from growing regions.
- Apical meristems then help in length increase of the new parts.
- As the plant develops, lateral meristem will add girth later.
- This shows how meristems enable regeneration and growth from cuttings.