CBSE Class 11 Biology Long Answer Questions – Morphology of Flowering Plants (Chapter 5) | NCERT-Based

Course & Examination Details

Course: CBSE Class 11 Biology
Unit: Unit II – Structural Organisation in Animals and Plants
Chapter: Chapter 5 – Morphology of Flowering Plants
Prescribed By: CBSE Board (As per NCERT syllabus)
Question Type: Long Answer Questions (120–150 words)

Section I: Root (Questions 1–5)

Q1. Describe the structure, functions, and types of roots in flowering plants.

Answer:
The root is the underground part of the plant axis that develops from the radicle of the embryo. It is generally non-green and grows downward into the soil. The primary functions of roots include anchorage, absorption of water and minerals, storage of food, synthesis of plant growth regulators, and vegetative propagation.
Based on origin and structure, roots are classified into three types. Tap root system arises from the radicle and is common in dicots, consisting of a primary root with lateral branches. Fibrous root system replaces the radicle with numerous thin roots and is typical of monocots. Adventitious roots arise from parts other than the radicle, such as stems or leaves, and perform specialized functions like support, respiration, and storage.

Q2. Explain the various modifications of roots with suitable examples.

Answer:
Roots undergo modifications to perform specialized functions beyond absorption and anchorage. Storage roots store reserve food materials, as seen in carrot, radish, turnip, and sweet potato. Supportive roots include prop roots in banyan, which provide mechanical support, and stilt roots in maize and sugarcane that arise from lower stem nodes.
Respiratory roots, called pneumatophores, are found in mangrove plants growing in marshy soils and facilitate gaseous exchange through lenticels. Parasitic plants like Cuscuta possess haustorial roots that absorb nutrients from the host plant. Some adventitious roots also help in vegetative propagation, allowing new plants to develop under favourable conditions.

Q3. Differentiate between tap root system and fibrous root system.

Answer:
Tap root system develops from the radicle and consists of a main primary root with secondary and tertiary branches. It is characteristic of dicotyledonous plants such as mustard and pea. This system provides strong anchorage and often undergoes storage modifications.
Fibrous root system, on the other hand, develops when the radicle is short-lived and replaced by many thin roots arising from the base of the stem. It is common in monocotyledonous plants like wheat and rice. Fibrous roots form a dense mat that efficiently absorbs water and minerals but offers less anchorage compared to tap roots.

Q4. Describe adventitious roots and their significance.

Answer:
Adventitious roots arise from plant parts other than the radicle, such as stem nodes, internodes, or leaves. These roots play an important role in providing additional support, storage, respiration, and vegetative propagation.
Examples include prop roots in banyan for support, stilt roots in maize for stability, pneumatophores in mangroves for respiration, and storage roots in sweet potato. Adventitious roots also help climbers attach to supports and parasitic plants absorb nutrients from hosts. Their adaptability makes them essential for survival under diverse environmental conditions.

Q5. Explain the role of roots in vegetative propagation.

Answer:
In some plants, roots play a significant role in vegetative propagation. Adventitious buds develop on certain roots and give rise to new shoots and plants. Examples include sweet potato and dahlia, where tuberous roots store food and develop buds.
This method of reproduction allows plants to multiply rapidly without seeds, ensuring survival during unfavourable conditions. Vegetative propagation through roots maintains genetic uniformity and is useful in agriculture and horticulture for producing desirable plant varieties.

Section II: Stem (Questions 6–10)

Q6. Describe the structure and functions of the stem.

Answer:
The stem is the ascending aerial part of the plant axis that develops from the plumule of the embryo. It bears nodes and internodes and supports leaves, branches, flowers, and fruits. The stem conducts water and minerals from roots to leaves and transports prepared food from leaves to other plant parts.
Apart from conduction and support, stems may store food, aid in vegetative propagation, and perform photosynthesis in some plants. The presence of buds enables branching and growth, making the stem a vital organ for plant development.

Q7. Explain underground stem modifications with examples.

Answer:
Underground stems are modified to store food, survive adverse seasons, and reproduce vegetatively. Rhizome is a horizontal underground stem with nodes and internodes, as seen in ginger. Tuber is a swollen underground stem bearing eyes, as in potato.
Bulb consists of a short stem with fleshy scale leaves storing food, commonly found in onion. Corm is a solid, vertical underground stem seen in Colocasia. These modifications help plants remain dormant during unfavourable conditions and resume growth when conditions improve.

Q8. Describe aerial stem modifications.

Answer:
Aerial stem modifications perform functions such as support, protection, and photosynthesis. Tendrils are slender, coiled structures that help climbing plants attach to supports. Thorns are hard, pointed structures that protect plants from grazing animals.
Phylloclades are flattened or cylindrical stems that perform photosynthesis and store water, while leaves are reduced to spines to minimize water loss. Such modifications enable plants to adapt to different environmental conditions.

Q9. What are subaerial stems? Explain their types.

Answer:
Subaerial stems grow partially above the soil surface and help in vegetative propagation. Runner spreads horizontally along the ground, forming new plants at nodes. Stolon grows obliquely and gives rise to new plants.
Sucker arises from underground parts and emerges above the soil, while offset is a short runner with a single internode. These structures allow rapid multiplication and spread of plants.

Q10. Explain the significance of stem modifications.

Answer:
Stem modifications help plants adapt to diverse environments. They assist in food storage, perennation, vegetative propagation, protection, and photosynthesis. Modified stems ensure survival during unfavourable conditions and promote rapid multiplication, making them important from ecological and agricultural perspectives.

Section III: Leaf (Questions 11–15)

Q11. Describe the structure and functions of a leaf.

Answer:
A leaf is a flattened, lateral organ borne on the stem. It consists of leaf base, petiole, and lamina. The lamina contains veins and veinlets for conduction and support.
Leaves are the main photosynthetic organs of plants. They also regulate transpiration and gaseous exchange through stomata. Leaves may modify into tendrils, spines, or storage organs to perform specialized functions.

Q12. Explain venation and its types.

Answer:
Venation refers to the arrangement of veins and veinlets in the leaf lamina. Reticulate venation forms a network and is common in dicots. Parallel venation has veins running parallel and is characteristic of monocots.
Venation provides mechanical support and helps in efficient transport of water, minerals, and food.

Q13. Describe phyllotaxy and its importance.

Answer:
Phyllotaxy is the arrangement of leaves on the stem or branch. It may be alternate, opposite, or whorled. Proper phyllotaxy ensures maximum exposure of leaves to sunlight, improving photosynthesis and reducing shading.

Q14. Differentiate between simple and compound leaves.

Answer:
A simple leaf has an undivided lamina, while a compound leaf has its lamina divided into leaflets. Leaflets lack axillary buds. Compound leaves may be pinnate or palmate.

Q15. Explain leaf modifications with examples.

Answer:
Leaves may modify into tendrils for climbing, spines for protection, storage leaves for food, and insectivorous leaves for trapping insects. These adaptations help plants survive under special conditions.

Section IV: Inflorescence, Flower, Fruit, Seed & Floral Formula (Questions 16–25)

Q16. Explain inflorescence and its types.

Answer:
Inflorescence is the arrangement of flowers on the floral axis. Racemose inflorescence has an indeterminate axis with acropetal succession. Cymose inflorescence has a determinate axis with basipetal succession.

Q17. Describe the structure of a typical flower.

Answer:
A flower consists of four whorls—calyx, corolla, androecium, and gynoecium—arranged on the thalamus. It is the reproductive organ of angiosperms.

Q18. Classify flowers based on symmetry and sexuality.

Answer:
Flowers may be actinomorphic, zygomorphic, or asymmetric based on symmetry. Based on sexuality, they are bisexual or unisexual.

Q19. Explain types of flowers based on ovary position.

Answer:
Flowers are hypogynous, perigynous, or epigynous depending on the position of the ovary relative to other floral parts.

Q20. Describe fruit and its types.

Answer:
Fruit is a mature ovary formed after fertilisation. Fruits may be simple, aggregate, or multiple depending on flower and ovary structure.

Q21. Explain the structure and types of seeds.

Answer:
Seeds consist of seed coat, embryo, and endosperm. Albuminous seeds retain endosperm, while exalbuminous seeds store food in cotyledons.

Q22. Define floral formula and explain its components.

Answer:
Floral formula is a symbolic representation showing flower symmetry, sexuality, number, fusion, and ovary position using standard symbols.

Q23. What is a floral diagram? State its importance.

Answer:
A floral diagram visually represents the arrangement of floral parts. It helps in understanding flower structure and identification.

Q24. Why is morphology important in plant classification?

Answer:
Morphological characters help identify, classify, and understand evolutionary relationships among plants.

Q25. Explain the importance of Morphology of Flowering Plants for CBSE examinations.

Answer:
This chapter is highly scoring as questions are directly NCERT-based, terminology-focused, and diagram-oriented. It forms the foundation for taxonomy and advanced plant studies.