CBSE Class 11 Biology Chapter 5: Plant Kingdom NCERT Solutions
This resource provides detailed NCERT Solutions for CBSE Class 11 Biology, Chapter 5, focusing on the Plant Kingdom. It covers the fundamental principles of classifying plants, including algae and their distinct classes (Chlorophyceae, Phaeophyceae, Rhodophyceae), based on pigments, stored food, cell wall composition, and flagellation. The solutions also explain the crucial process of reduction division (meiosis) and where it occurs in the life cycles of various plant groups like liverworts, mosses, ferns, gymnosperms, and angiosperms. These solutions are designed to clarify complex biological concepts, offering step-by-step explanations that aid students in grasping the intricacies of plant diversity and reproduction. They serve as an excellent tool for exam preparation, helping students revise key topics and reinforce their understanding of the plant kingdom's structure and life cycles.
Quick info
| Board | CBSE |
|---|---|
| Class | Class 11 |
| Subject | Biology |
| Session | 2026 |
| Language | English |
| Type | NCERT Solutions |
| Chapter | Chapter 5 |
Chapter summary
Chapter 5 of the NCERT Class 11 Biology textbook delves into the Plant Kingdom, exploring its classification and diversity. These NCERT Solutions break down the criteria used to classify major plant groups, particularly focusing on the three classes of algae: Chlorophyceae, Phaeophyceae, and Rhodophyceae. The solutions also detail the location and timing of reduction division (meiosis) in the life cycles of representative plants from bryophytes (liverworts, mosses), pteridophytes (ferns), gymnosperms, and angiosperms, clarifying the transition between haploid and diploid phases.
Learning outcomes
- Understand the basis for classifying algae into Chlorophyceae, Phaeophyceae, and Rhodophyceae.
- Identify the major photosynthetic pigments, stored food, cell wall composition, and flagellation characteristics for each algal class.
- Explain the significance of reduction division (meiosis) in the plant life cycle.
- Locate where reduction division occurs in the life cycles of liverworts, mosses, ferns, gymnosperms, and angiosperms.
- Differentiate between gametophytic and sporophytic generations in various plant groups.
- Describe the role of sporophytes and gametophytes in the reproduction of different plant types.
Topics covered
Paper topics
- Plant Kingdom Classification
- Algae
- Chlorophyceae
- Phaeophyceae
- Rhodophyceae
- Photosynthetic Pigments
- Stored Food in Plants
- Cell Wall Composition
- Flagella
- Reduction Division (Meiosis)
- Plant Life Cycles
- Gametophyte and Sporophyte
Important topics
- Classification of Algae
- Characteristics of Chlorophyceae, Phaeophyceae, Rhodophyceae
- Location of Reduction Division in Plant Life Cycles
- Alternation of Generations
- Gametophytic vs. Sporophytic Plant Body
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Questions and Solutions
Question 1
Algae are classified into three primary classes: Chlorophyceae (Green algae), Phaeophyceae (Brown algae), and Rhodophyceae (Red algae). The classification is based on a combination of key characteristics:
- Major photosynthetic pigments: The type and abundance of chlorophylls and accessory pigments like carotenoids and phycobilins.
- Form of stored food: The specific carbohydrate compounds synthesized and stored within the cells.
- Cell wall composition: The materials that make up the outer protective layer of the algal cell.
- Number and position of flagella: The presence, number, and attachment point of flagella used for motility.
Here's a breakdown of these characteristics for each class:
Class I – Chlorophyceae (Green algae)
- Major pigments: Chlorophylls a and b.
- Stored food: Primarily starch.
- Cell wall composition: Made of cellulose.
- Flagella: Typically 2 to 8, equal in size, and attached at the apex (apical).
Class II – Phaeophyceae (Brown algae)
- Major pigments: Chlorophylls a and c, along with fucoxanthin (which gives the brown color).
- Stored food: Mannitol and laminarin.
- Cell wall composition: Composed of cellulose and algin.
- Flagella: Usually 2, unequal in size, and attached laterally.
Class III – Rhodophyceae (Red algae)
- Major pigments: Chlorophylls a and d, along with phycoerythrin (which imparts the red color).
- Stored food: Floridean starch.
- Cell wall: Composed of cellulose, pectin, and polysulphate esters.
- Flagella: Absent in all stages.
Question 2
Reduction division, also known as meiosis, is a critical process in the life cycle of plants as it reduces the chromosome number by half, leading to the formation of haploid spores or gametes. The timing and location of this division vary across different plant groups:
Liverwort: In liverworts, the dominant plant body is the haploid gametophyte. The sporophyte generation develops on the gametophyte. Reduction division occurs within the capsule of the sporophyte, producing haploid spores that germinate to form new gametophytes.
Moss: Similar to liverworts, mosses have a dominant haploid gametophyte. The sporophyte, consisting of a foot, seta, and capsule, grows on the gametophyte. Reduction division takes place inside the capsule of the sporophyte, generating haploid spores.
Fern: Ferns exhibit a dominant diploid sporophyte generation. Specialized leaves called sporophylls bear sporangia. Reduction division occurs within the sporangia (specifically, the spore mother cells within the sporangia) on the sporophylls, resulting in the formation of haploid spores.
Gymnosperm: In gymnosperms, the plant body is a diploid sporophyte. Reduction division occurs in the microsporangia (within the anthers of pollen cones) to produce microspores (which develop into pollen grains) and in the megasporangia (within ovules on ovuliferous cones) to produce megaspores.
Angiosperm: Angiosperms also have a dominant diploid sporophyte generation. Reduction division occurs in the anthers of the stamen (male reproductive part) to form microspores (pollen grains) and within the ovule in the ovary of the pistil (female reproductive part) to form megaspores.
Common mistakes
- Confusing the specific pigments or stored food types for different algal classes.
- Incorrectly identifying the stage where reduction division occurs in the life cycle of various plant groups.
- Difficulty in distinguishing between the gametophyte and sporophyte generations.
- Misunderstanding the role of spores and gametes in plant reproduction.
Revision tips
- Create a table summarizing the key characteristics of Chlorophyceae, Phaeophyceae, and Rhodophyceae.
- Draw simplified life cycle diagrams for each plant group mentioned, clearly marking where reduction division occurs.
- Focus on understanding the ploidy level (haploid/diploid) of different plant structures.
- Use the provided solutions to trace the process of alternation of generations in plants.
Practice MCQs
Q1. Which class of algae is commonly known as 'Green Algae'?
Explanation: Chlorophyceae are known as green algae due to the presence of chlorophylls a and b as major photosynthetic pigments.
Q2. Fucoxanthin is a major photosynthetic pigment found in which algal group?
Explanation: Fucoxanthin, along with chlorophylls a and c, is characteristic of Phaeophyceae, the brown algae.
Q3. Reduction division (meiosis) in ferns primarily occurs within:
Explanation: In ferns, the main plant body is sporophytic, and reduction division to produce spores takes place within the sporangia.
Q4. Floridean starch is the stored food material in:
Explanation: Floridean starch is a characteristic stored food reserve found in Rhodophyceae, the red algae.
Q5. In gymnosperms and angiosperms, reduction division occurs during the formation of:
Explanation: Reduction division in seed plants (gymnosperms and angiosperms) leads to the formation of microspores (pollen grains) and megaspores, which are precursors to gametes.
Frequently asked questions
What are the main criteria used to classify algae in NCERT Class 11 Biology?
Algae are classified into three main classes—Chlorophyceae, Phaeophyceae, and Rhodophyceae—based on their major photosynthetic pigments, the form of stored food, cell wall composition, and the number and position of flagella.
Where does reduction division (meiosis) occur in the life cycle of a liverwort?
In liverworts, reduction division occurs inside the capsule of the sporophyte, which develops on the gametophyte, to produce haploid spores.
What is the difference between the location of reduction division in ferns and mosses?
In ferns, reduction division occurs within the sporangia on the sporophylls of the sporophyte. In mosses, it occurs within the capsule of the sporophyte, which develops on the gametophyte.
How does the life cycle of gymnosperms and angiosperms differ regarding reduction division from ferns?
In ferns, reduction division occurs in sporangia to form spores. In gymnosperms and angiosperms, reduction division occurs in microsporangia (forming pollen) and megasporangia (forming megaspores), which are directly involved in producing gametes or their precursors.
Why is understanding reduction division important for studying the Plant Kingdom?
Reduction division is crucial as it produces haploid spores or gametes, initiating the gametophytic generation and enabling sexual reproduction. Understanding its timing and location clarifies the alternation of generations in different plant groups.
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