CBSE Class 11 Biology – Anatomy of Flowering Plants | Long Answer Questions (NCERT Based)

📘 Course & Examination Details

• Course: CBSE Class 11 Biology
• Unit: Unit II – Structural Organisation in Animals and Plants
• Chapter: Chapter 6 – Anatomy of Flowering Plants
• Question Type: Long Answer Type (120–150 words)
• Total Questions: 25
• Assessment Focus:
  • Labelled diagrams
  • Tissue comparison
  • Structural differentiation
• Exam Relevance:
  • CBSE Class 11 Annual Examination
  • School Term Exams & Unit Tests
  • NCERT-based Conceptual Evaluation

🌱 Section A: Plant Tissues (Q1–Q8)

Q1. Describe meristematic tissue and explain its types.

Answer:
Meristematic tissue consists of actively dividing living cells responsible for plant growth. These cells are small, thin-walled, rich in cytoplasm, and possess a prominent nucleus. They lack intercellular spaces and vacuoles. Based on location, meristems are of three types. Apical meristem is present at root and shoot tips and brings about primary growth by increasing length. Intercalary meristem occurs at the base of internodes or leaves, especially in grasses, and helps in regeneration. Lateral meristem occurs along the sides of stems and roots and is responsible for secondary growth, increasing girth. Meristematic tissues continuously produce new cells that differentiate into permanent tissues, forming the basic plant body structure.

Q2. Explain permanent tissues and their classification.

Answer:
Permanent tissues are derived from meristematic tissues and have lost the ability to divide. These tissues are specialised to perform specific functions. Permanent tissues are classified into simple and complex permanent tissues. Simple permanent tissues consist of only one type of cell and include parenchyma, collenchyma, and sclerenchyma. Parenchyma performs storage and photosynthesis, collenchyma provides flexible support, and sclerenchyma provides mechanical strength. Complex permanent tissues consist of different types of cells working together for conduction. Xylem transports water and minerals, while phloem transports food. Permanent tissues form the bulk of the plant body and play a crucial role in support, transport, and storage.

Q3. Describe parenchyma tissue and its functions.

Answer:
Parenchyma is a simple permanent tissue composed of living, thin-walled cells with large intercellular spaces. These cells are generally isodiametric and contain vacuoles. Parenchyma is widely distributed in plant organs such as roots, stems, leaves, and fruits. Its primary function is storage of food materials like starch. When parenchyma contains chlorophyll, it is called chlorenchyma and performs photosynthesis. In aquatic plants, parenchyma with air spaces is known as aerenchyma, which provides buoyancy. Parenchyma also helps in wound healing and regeneration. Due to its versatility, parenchyma plays an important role in maintaining plant metabolism.

Q4. Explain collenchyma tissue and its significance.

Answer:
Collenchyma is a simple permanent tissue composed of living, elongated cells with unevenly thickened cell walls, particularly at the corners. The thickening is mainly due to cellulose and pectin. Collenchyma is usually found below the epidermis of dicot stems, leaf petioles, and veins. Its main function is to provide mechanical support and flexibility to growing plant parts. Unlike sclerenchyma, collenchyma allows bending without breaking, which is essential for young stems and leaves. It also performs limited photosynthesis when chloroplasts are present. Thus, collenchyma plays a crucial role in supporting actively growing regions of plants.

Q5. Describe sclerenchyma tissue.

Answer:
Sclerenchyma is a simple permanent tissue composed of dead cells with thick, lignified cell walls. These cells have narrow lumen and provide rigidity and mechanical strength to plant parts. Sclerenchyma occurs in two forms: fibres and sclereids. Fibres are long and slender, commonly found in vascular bundles, while sclereids are irregularly shaped and occur in seed coats and nut shells. Due to lignification, sclerenchyma cells are impermeable to water and gases. This tissue helps plants withstand mechanical stress and prevents collapse of plant organs, making it essential for structural support.

Q6. Explain the structure and function of xylem.

Answer:
Xylem is a complex permanent tissue responsible for conduction of water and minerals from roots to aerial parts of the plant. It consists of four elements: tracheids, vessels, xylem fibres, and xylem parenchyma. Tracheids and vessels are dead cells with lignified walls and conduct water efficiently. Xylem fibres provide mechanical strength, while xylem parenchyma is living and helps in storage and lateral conduction. Xylem also contributes to mechanical support due to its rigid structure. The upward movement of water through xylem is essential for photosynthesis and transpiration.

Q7. Describe phloem tissue and its components.

Answer:
Phloem is a complex permanent tissue responsible for transport of organic food materials from leaves to other parts of the plant. It consists of sieve tube elements, companion cells, phloem parenchyma, and phloem fibres. Sieve tube elements form long tubes for food conduction, while companion cells regulate their functions. Phloem parenchyma helps in storage of food, and phloem fibres provide mechanical strength. Except for phloem fibres, all phloem elements are living. Phloem transport is bidirectional, depending on the source and sink relationship within the plant.

Q8. Differentiate between xylem and phloem.

Answer:
Xylem and phloem are complex tissues involved in transport but differ in structure and function. Xylem conducts water and minerals from roots to aerial parts and consists mainly of dead cells except xylem parenchyma. Phloem transports organic food materials and consists mainly of living cells except phloem fibres. Xylem movement is unidirectional, while phloem transport can be bidirectional. Xylem provides mechanical support due to lignified walls, whereas phloem mainly functions in food distribution.

🌿 Section B: Internal Structure of Root, Stem & Leaf (Q9–Q18)

Q9. Describe the internal structure of a dicot root.

Answer:
A dicot root shows a well-defined internal structure. The outermost layer is epiblema bearing root hairs for absorption. Below it lies the cortex made of parenchyma for storage. The innermost cortical layer is endodermis with Casparian strips regulating water movement. Inside the endodermis lies the pericycle, which gives rise to lateral roots and secondary growth. Vascular bundles are radial, with xylem and phloem arranged alternately. Xylem is exarch in nature. The pith is small or absent. This structure supports efficient absorption and conduction.

Q10. Describe the internal structure of a monocot root.

Answer:
A monocot root consists of epiblema, cortex, endodermis, pericycle, vascular bundles, and a large central pith. Root hairs arise from epiblema. Cortex stores food. Endodermis has Casparian strips regulating transport. The pericycle does not produce secondary tissues. Vascular bundles are radial with numerous xylem and phloem strands arranged alternately. Xylem is exarch. A prominent pith is present at the centre. Secondary growth is absent due to lack of cambium. Monocot root structure is adapted mainly for absorption and anchorage.

Q11. Explain the internal structure of a dicot stem.

Answer:
A dicot stem has epidermis covered with cuticle for protection. Beneath it lies collenchymatous hypodermis providing support. Cortex consists of parenchyma. Endodermis is distinct and called starch sheath. Pericycle is made of sclerenchyma. Vascular bundles are arranged in a ring and are conjoint, collateral, and open with cambium present. Xylem lies inside and phloem outside. A large central pith is present. Presence of cambium allows secondary growth, increasing the girth of the stem.

Q12. Describe the internal structure of a monocot stem.

Answer:
Monocot stem shows epidermis with cuticle and sclerenchymatous hypodermis. Ground tissue is undifferentiated into cortex and pith. Numerous vascular bundles are scattered throughout the ground tissue. Each bundle is conjoint, collateral, and closed, lacking cambium. Xylem is endarch and phloem lies outside it. Due to absence of cambium, secondary growth does not occur. This structure provides strength and flexibility to monocot stems.

Q13. Explain the anatomy of a dorsiventral leaf.

Answer:
A dorsiventral leaf has distinct upper and lower surfaces. The upper epidermis is covered with cuticle. Below it lies palisade mesophyll composed of chlorophyll-rich cells for photosynthesis. Spongy mesophyll is present below palisade tissue with air spaces for gaseous exchange. Vascular bundles are embedded in mesophyll and surrounded by bundle sheath. The lower epidermis contains numerous stomata. This structure maximises photosynthesis and gas exchange.

Q14. Describe the anatomy of an isobilateral leaf.

Answer:
An isobilateral leaf has similar upper and lower surfaces. Epidermis is present on both sides, with stomata distributed on both surfaces. Mesophyll is not differentiated into palisade and spongy tissues. Bulliform cells are present in the upper epidermis and help in leaf rolling during water stress. Vascular bundles are surrounded by bundle sheath. This structure is commonly found in monocot leaves.

Q15. Differentiate between dorsiventral and isobilateral leaves.

Answer:
Dorsiventral leaves have distinct upper and lower surfaces with differentiated mesophyll, while isobilateral leaves have similar surfaces and undifferentiated mesophyll. Palisade tissue is present only in dorsiventral leaves. Bulliform cells are present in isobilateral leaves but absent in dorsiventral leaves. Stomata are mainly on the lower surface in dorsiventral leaves, but present on both surfaces in isobilateral leaves.

Q16. Explain the role of endodermis in plant organs.

Answer:
Endodermis is the innermost layer of cortex in roots and stems. In roots, it contains Casparian strips that regulate movement of water and minerals into vascular tissues. In stems, it acts as starch sheath storing reserve food. Endodermis plays a vital role in selective absorption and controlled transport within the plant body.

Q17. Describe vascular bundles and their types.

Answer:
Vascular bundles consist of xylem and phloem arranged together for conduction. They are classified as radial, conjoint, collateral, bicollateral, open, or closed. Radial bundles occur in roots, while conjoint bundles occur in stems and leaves. Open bundles contain cambium and show secondary growth, while closed bundles lack cambium.

Q18. Explain the importance of tissue comparison in anatomy.

Answer:
Tissue comparison helps in understanding structural differences between roots, stems, and leaves of monocots and dicots. It aids in identification, classification, and diagram-based questions. Comparative study enhances conceptual clarity and improves exam performance.

🌳 Section C: Secondary Growth (Q19–Q25)

Q19. Define secondary growth and explain its significance.

Answer:
Secondary growth refers to increase in thickness or girth of stems and roots due to activity of lateral meristems. It is significant as it strengthens plants, supports tall growth, and increases conductive capacity. Secondary growth is mainly observed in dicot plants and gymnosperms.

Q20. Explain the role of vascular cambium in secondary growth.

Answer:
Vascular cambium forms a continuous ring and produces secondary xylem inward and secondary phloem outward. Continuous cell division increases girth of stem and root. Secondary xylem forms wood, while secondary phloem helps in food transport.

Q21. Describe cork cambium and periderm formation.

Answer:
Cork cambium or phellogen arises in the cortex during secondary growth. It produces cork cells outward and secondary cortex inward. These tissues together form the periderm, replacing epidermis and protecting older plant parts.

Q22. Explain formation of annual rings.

Answer:
Annual rings are formed due to seasonal activity of vascular cambium. Rapid growth in spring produces lighter spring wood, while slow growth in winter forms darker autumn wood. Each ring represents one year of growth.

Q23. Differentiate between sapwood and heartwood.

Answer:
Sapwood is the outer, light-coloured, active xylem involved in water conduction. Heartwood is inner, dark-coloured, inactive xylem providing mechanical strength. Heartwood contains waste materials.

Q24. Why is secondary growth absent in monocots?

Answer:
Secondary growth is absent in monocots due to absence of vascular cambium. Their vascular bundles are closed, preventing formation of secondary tissues.

Q25. Explain the importance of labelled diagrams in this chapter.

Answer:
Labelled diagrams help visualise internal structure of plant organs. They are frequently asked in CBSE exams and aid in better understanding and retention of anatomical details.

✅ Final Note

✔ Fully NCERT-based
✔ Ideal for 5-mark CBSE long answers
✔ Strong focus on tissue comparison & diagrams