Answers :
1️⃣ Answer: Meristematic tissue 🌱
🧠 Explanation: Meristematic tissue drives plant growth because its cells remain actively dividing. 🔬 Meristematic cells are small, have dense cytoplasm and thin walls, and produce new cells that differentiate into permanent tissues for primary and secondary growth.
2️⃣ Answer: True ✅
🧠 Explanation: Meristematic cells are undifferentiated and capable of continuous division. 🔁 Their high mitotic activity supplies cells for growth, repair, and tissue formation in roots and shoots.
3️⃣ Answer: At root and shoot tips (apical meristems) 📍
🧠 Explanation: Apical meristems at root and shoot tips are responsible for primary (lengthwise) growth. 🌿 These regions contain actively dividing cells that form new tissues for elongation.
4️⃣ Answer: Parenchyma 🍃
🧠 Explanation: Parenchyma cells (especially leaf mesophyll) contain chloroplasts and perform photosynthesis. ☀️ They also store nutrients and aid gas exchange, making them multifunctional in green parts.
5️⃣ Answer: False ❌
🧠 Explanation: Sclerenchyma cells are typically dead at maturity and have thick, lignified walls. 🪵 Their rigidity and lignin content provide structural support, unlike living supportive tissues.
6️⃣ Answer: Xylem 💧
🧠 Explanation: Xylem conducts water and dissolved minerals from roots to shoots using tracheids and vessel elements. 🚰 These structures form continuous tubes that enable efficient upward transport.
7️⃣ Answer: Phloem 🍯
🧠 Explanation: Sieve tube elements and companion cells are components of phloem, which transports sugars and organic nutrients from sources to sinks. ↔️ Companion cells support sieve elements metabolically and enable translocation.
8️⃣ Answer: True ✅
🧠 Explanation: Collenchyma provides flexible support to growing stems and leaves because of its unevenly thickened primary walls. 🧩 Being living and pliable, it supports growth without restricting elongation.
9️⃣ Answer: Small vacuole and thin cell walls 🧫
🧠 Explanation: Meristematic cells have thin primary walls, dense cytoplasm, a prominent nucleus, and small/absent vacuoles. ⚙️ These features support rapid mitotic activity and ongoing division.
1️⃣0️⃣ Answer: Lateral meristem 🔄
🧠 Explanation: Lateral meristems (e.g., vascular cambium) cause secondary growth, increasing stem and root thickness. 🌳 They produce secondary xylem inward and secondary phloem outward.
1️⃣1️⃣ Answer: True ✅
🧠 Explanation: Intercalary meristems—found in grasses at internodes or leaf bases—enable rapid elongation and regrowth after grazing or cutting. 🌾 Their position allows localized lengthening of stems and leaves.
1️⃣2️⃣ Answer: Thick lignified walls 🪵
🧠 Explanation: Sclerenchyma cells are defined by heavily thickened, lignified secondary walls that give rigidity and mechanical strength. 🏗️ They form fibers or sclereids that support mature tissues.
1️⃣3️⃣ Answer: Phloem 🍬
🧠 Explanation: Phloem transports organic nutrients (mainly sucrose) from leaves to growing and storage tissues via sieve tubes and companion cells. 🔁 This source-to-sink translocation fuels growth and storage.
1️⃣4️⃣ Answer: True ✅
🧠 Explanation: Some permanent cells (especially parenchyma) can dedifferentiate and regain meristematic activity during wound healing or tissue culture. 🔬 This plasticity underlies regeneration and vegetative propagation.
1️⃣5️⃣ Answer: It produces secondary xylem inward and secondary phloem outward 🔁
🧠 Explanation: The vascular cambium is a lateral meristem that adds secondary xylem (wood) inward and secondary phloem outward, contributing to secondary (thickening) growth and growth rings. 🌲
📚 Topics Covered
What this summary covers — at a glance ✅
- Definition and features of meristematic tissue 🌱
- Types of meristems: apical, lateral, intercalary 📍🔄
- Primary vs secondary growth — role of apical and lateral meristems 🌿🌳
- Permanent tissues: parenchyma, collenchyma, sclerenchyma — structure & function 🍃🪵
- Conducting tissues: xylem (water) & phloem (organic food) 💧🍯
- Key cellular features used in identification (cell wall, vacuole, lignin, living/dead at maturity) 🔬
Core concepts — succinct explanations 🧠
Meristematic tissue
Definition: Groups of undifferentiated, actively dividing plant cells that give rise to new cells for growth. Key: growth & division
- Features: Small cells, dense cytoplasm, large nucleus, thin primary walls, small vacuoles.
- Function: Provide new cells for differentiation into permanent tissues (primary and secondary growth).
Types of meristem
- Apical meristem — at root & shoot tips; responsible for primary growth (lengthening). 📍
- Lateral meristem — vascular cambium & cork cambium; responsible for secondary growth (thickening). 🔄
- Intercalary meristem — at internodes or leaf bases (common in grasses); enables rapid regrowth. 🌾
Permanent tissues — types & roles 🧩
Simple permanent tissues
| Tissue | Structure | Function |
|---|---|---|
| Parenchyma | Thin walls, living cells, chloroplasts in leaves | Photosynthesis, storage, repair, gas exchange |
| Collenchyma | Living cells, unevenly thickened walls | Flexible support in young stems & leaves |
| Sclerenchyma | Thick, lignified secondary walls; often dead at maturity | Rigid support & protection (fibres, sclereids) |
Complex permanent tissues (conducting)
- Xylem — tracheids & vessel elements; conducts water & minerals upward; cells usually dead at maturity. 💧
- Phloem — sieve tube elements & companion cells; transports organic nutrients (sugars) source → sink. 🍬
Important features to remember (Quick facts) ⚡
- Meristematic cells: actively dividing, thin walls, small vacuoles.
- Sclerenchyma: lignified walls → dead support cells (wood/fibres).
- Collenchyma: living support that allows elongation (uneven wall thickening).
- Xylem vs Phloem: xylem = water (root → shoot), phloem = food (source → sink).
- Vascular cambium: lateral meristem producing secondary xylem (inward) and phloem (outward).
How the 15 quiz questions map to the topic 🎯
- Identification of meristematic vs permanent tissues (definition & role).
- Meristematic cell attributes (undifferentiated, mitotic).
- Location of apical meristems (root & shoot tips).
- Function of parenchyma (photosynthesis & storage).
- Sclerenchyma maturity status (dead at maturity).
- Function of xylem (water conduction).
- Components & role of phloem (sieve tubes + companion cells).
- Role of collenchyma (flexible support).
- Typical meristem cell features (small vacuole, thin wall).
- Role of lateral meristem in secondary growth.
- Intercalary meristems in grasses (regrowth).
- Characteristic of sclerenchyma (lignified walls).
- Phloem role in organic nutrient transport.
- Dedifferentiation potential of some permanent cells (parenchyma).
- Vascular cambium function (secondary xylem & phloem formation).
Revision checklist & exam tips ✅
- Memorize distinguishing features of meristematic vs permanent cells (wall thickness, vacuole size, division ability).
- Remember locations: apical → tips, lateral → cambium, intercalary → internodes.
- Be able to match tissue to function: xylem = water, phloem = food, parenchyma = photosynthesis/storage, collenchyma = flexible support, sclerenchyma = rigid support.
- Practice short-answer lines describing one clear feature and one clear function for each tissue (helps in board exams).
- Use labelled diagrams (apical meristem, vascular cambium cross-section) when asked for structure & function.
Key terms (glossary) 🗂️
- Dedifferentiation: permanent cells reverting to a mitotic state (e.g., parenchyma in tissue culture).
- Lignin: complex polymer that strengthens cell walls (characteristic of sclerenchyma and xylem).
- Sieve tube: elongated phloem element that transports sugars; relies on companion cells.
- Vascular cambium: meristematic ring responsible for secondary growth (wood formation).