CBSE Class 11 Biology Morphology of Flowering Plants Assignments

Very Short Answer Questions (1 mark each)

Question 1. Which part of opuntia is modified to form spines ?
Answer: Leaves are modified into spines in Opuntia to reduce transpiration and provide protection against herbivores.
In simple words: Leaves become sharp spines to save water and protect the plant.

Exam Tip: Remember that leaf modifications in xerophytes primarily serve to conserve water.

Question 2. Name one plant in which leaf is pinnately compound.
Answer: Neem (or Rose, Acacia) is a plant with a pinnately compound leaf where leaflets are arranged on a common axis called the rachis.
In simple words: Neem has leaves divided into many small leaflets along a central stalk.

Exam Tip: Keep common examples like Neem and Rose handy for compound leaf questions.

Question 3. In mangroves, pneumatophores are the modified adventitious roots. How are these roots helpful to the plant ?
Answer: Pneumatophores grow vertically upwards out of the water-logged soil and help the plant get oxygen for respiration.
In simple words: They act like breathing roots in muddy, oxygen-poor soil.

Exam Tip: Link pneumatophores directly with gaseous exchange in halophytes.

Question 4. Which part of mango fruit is edible ?
Answer: The mesocarp (fleshy middle layer) of the fruit is edible in mango.
In simple words: The juicy, pulpy part we eat is the mesocarp.

Exam Tip: Be precise about fruit layers: epicarp (skin), mesocarp (fleshy edible part), and endocarp (hard stone).

Question 5. Why do various plants have different type of phyllotaxy ?
Answer: Different types of phyllotaxy ensure that each leaf receives maximum sunlight for photosynthesis without shading other leaves.
In simple words: It helps every leaf get enough sunlight.

Exam Tip: Mention light capture as the primary adaptive significance of phyllotaxy.

Question 6. State the main function of leaf tendril.
Answer: Leaf tendrils help weak-stemmed plants climb up supports.
In simple words: They coil around objects to support climbing plants.

Exam Tip: Distinguish between stem tendrils and leaf tendrils based on their origin.

Question 7. Which plant family represent the following floral formula: \(\oplus \widehat{P}_{3+3} A_{3+3} \underline{G}_{(3)}\)
Answer: Liliaceae family.
In simple words: This formula belongs to the lily family.

Question 8. The endosperm is formed as a result of double fertilisation (triple fusion). What is its function ?
Answer: The primary function of the endosperm is to store food and provide nourishment to the developing embryo.
In simple words: It acts as a food store for the growing baby plant.

Exam Tip: Mention triple fusion and its triploid nature (\(3n\)) for complete credit.

Question 9. Which type of venation do you observe in dicot leaf ?
Answer: Reticulate venation, where veinlets form a network.
In simple words: Dicot leaves have a net-like web of veins.

Question 10. In pea flower, the aestivation in corolla is known as vexillary. Give reason.
Answer: In vexillary aestivation, there are five petals: the largest posterior petal (standard) overlaps two lateral petals (wings), which in turn overlap the two smallest anterior petals (keel).
In simple words: The petals overlap in a specific overlapping pattern characteristic of legumes.

Exam Tip: Use the terms standard (banner), wings, and keel when describing vexillary aestivation.

Question 11. What is the name given to the cotyledon in case of Monocots
Answer: Scutellum.
In simple words: The single cotyledon in monocots is called the scutellum.

Question 12. Flower is a modified shoot. Justify.
Answer: A flower is considered a modified shoot because the shoot apical meristem changes to a floral meristem, internodes do not elongate, the axis gets condensed, and different floral appendages (sepals, petals, stamens, and carpels) arise at successive nodes instead of leaves.
In simple words: The stem stops growing long and packs its leaves closely together to form floral parts.

Question 13. Name the type of root for the following :
(a) Roots performing the function of photosynthesis.
(b) Roots come above the surface of the soil to absorb air.
(c) The pillar like roots developed from lateral branches for providing mechanical support.
(d) Roots coming out of the lower nodes of the stem and provide the support to the plant.
Answer:
(a) Assimilatory roots
(b) Respiratory roots (Pneumatophores)
(c) Prop roots
(d) Stilt roots
In simple words: Different roots perform special jobs like breathing, climbing support, and extra mechanical strength.

Question 14. Fill up the blank spaces (a), (b), (c) and (d) in the table given below :

Answer:
(a) Floral parts are situated below the ovary.
(b) Half inferior.
(c) Epigynous.
(d) Floral parts are situated above the ovary.
In simple words: The terms describe how floral parts are placed relative to the ovary.

Exam Tip: Practice drawing diagrams of hypogynous, perigynous, and epigynous flowers.

Question 15. Provide the scientific terms for the following :
(i) The leaf without a petiole (stalk).
(ii) The flat and expanded portion of a leaf.
(iii) Orderly arrangement of leaves on the node.
(iv) Lateral appendages on either side of the leaf.
Answer:
(i) Sessile
(ii) Lamina (Leaf blade)
(iii) Phyllotaxy
(iv) Stipules
In simple words: These are standard botanical terms for leaf structures.

Exam Tip: Learn exact morphological terminology for full marks in definitions.

Short Answer Questions - I (3 marks each)

Question 16. Observe the given figure showing various types of placentation. Identify the type of plancentation. Give one example of each.
Answer:
(a) Marginal placentation - Example: Pea
(b) Parietal placentation - Example: Mustard / Argemone
(c) Axile placentation - Example: China rose / Tomato / Lemon
In simple words: Placentation is how ovules are attached inside the ovary.

Exam Tip: Distinguish axile (multilocular with central axis) from free central (unilocular without septa).

Question 17. 'Potato is a stem and sweet potato is a root.' Justify the statement on the basis of external features.
Answer: Potato is a modified underground stem (tuber) because it possesses nodes (eyes) containing buds subtended by leaf scars, and can sprout new shoots. Sweet potato is a modified adventitious root (tuberous root) because it lacks nodes, internodes, and true buds.
In simple words: Potato has buds and eyes like a stem, while sweet potato has none, acting like a swollen root.

Exam Tip: The presence of nodes and buds is the definitive proof of a stem.

Question 18. Define aestivation. Which type of aestivation is found in China rose, Calotropis Gulmohar and pea.
Answer: Aestivation is defined as the mode of arrangement of sepals or petals in a floral bud with respect to other members of the same whorl.
- China rose: Twisted aestivation
- Calotropis: Valvate aestivation
- Gulmohar: Imbricate aestivation
- Pea: Vexillary aestivation
In simple words: Aestivation is how floral petals or sepals overlap inside the bud.

Exam Tip: Memorize the four main types of aestivation with their textbook examples.

Question 19. Explain the different types of phyllotaxy. Give one example of each type.
Answer:
1. Alternate phyllotaxy: A single leaf arises at each node in an alternate manner. Example: China rose, Mustard.
2. Opposite phyllotaxy: A pair of leaves arise at each node and lie opposite to each other. Example: Calotropis, Guava.
3. Whorled phyllotaxy: More than two leaves arise at a node and form a whorl. Example: Alstonia, Nerium.
In simple words: Phyllotaxy tells us how leaves are arranged along the stem.

Exam Tip: Use clear diagrams or bullet points for differences in leaf arrangements.

Question 20. Differentiate between :
(a) Actinomorphic flower and Zygomorphic flower
(b) Apocarpous ovary and Syncarpous ovary
(c) Racemose inflorescence and Cymose inflorescence
Answer:
(a) Actinomorphic flower can be divided into two equal radial halves in any radial plane passing through the centre (e.g., Mustard). Zygomorphic flower can be divided into two similar halves only in one particular vertical plane (e.g., Pea).
(b) Apocarpous ovary has multiple free carpels (e.g., Nelumbo). Syncarpous ovary has fused carpels (e.g., Tomato).
(c) Racemose inflorescence has unlimited main axis growth with flowers borne in acropetal succession. Cymose inflorescence has limited main axis growth terminating in a flower with basipetal succession.
In simple words: These are structural differences in flower symmetry, ovary carpel fusion, and flower cluster growth patterns.

Exam Tip: Contrast acropetal (younger flowers at top) with basipetal (younger flowers at base) succession.

Question 21. In the given structure of a Monocotyledonous seed label the parts a, b, c, d, e. Give the function of part 'a'
Answer:
(a) Endosperm
(b) Plumule
(c) Coleoptile
(d) Coleorhiza
(e) Scutellum
Function of (a) Endosperm: Stores food and provides nourishment to the developing embryo during seed germination.
In simple words: Parts of a monocot seed include the food-storing endosperm and protective sheaths.

Exam Tip: Learn coleoptile (protects plumule) and coleorhiza (protects radicle) carefully.

Long Answer Questions (5 marks each)

Question 22. Describe various stem modifications associated with food storage, climbing and protection.
Answer:
1. Food Storage: Underground stems like rhizomes (ginger), tubers (potato), bulbs (onion), and corms (colocasia) store food and help tide over unfavorable conditions.
2. Climbing: Stem tendrils develop from axillary buds and help weak stems climb, such as in cucumbers, grapevines, and watermelons.
3. Protection: Axillary buds of stems get modified into woody, straight, and pointed thorns to protect plants from grazing animals, as seen in Bougainvillea and Citrus.
In simple words: Stems can change their form to store food, help the plant climb, or protect against animals.

Exam Tip: Give precise examples for each modification to secure full marks.

Question 23. Give the distinguishing morphological features of gynoecium of family Fabaceae, Solanaceae and Liliaceae. Draw floral diagrams of Fabaceae and Solanaceae.
Answer:
- Family Fabaceae: Ovary superior, monocarpellary, unilocular with many ovules along the marginal suture, single style.
- Family Solanaceae: Ovary superior, bicarpellary, syncarpous, bilocular, ovary swollen with many ovules on axile placentation.
- Family Liliaceae: Ovary superior, tricarpellary, syncarpous, trilocular with many ovules on axile placentation.
In simple words: Each family has a distinct carpel number, chamber count, and placenta layout in the ovary.

Exam Tip: Practice drawing standard floral diagrams and writing floral formulas for these three families.