Chapter 3: Plant Kingdom – Long Answer Type Questions

CBSE Class 11 Biology Long Answer Questions – Chapter 3: Plant Kingdom (NCERT Based)

Course Details

Course: CBSE Class 11 Biology
Syllabus: NCERT
Unit: Unit I – Diversity in Living World
Chapter: Chapter 3 – Plant Kingdom
CBSE Board Examination: Central Board of Secondary Education – Class 11 (School & Annual Examinations)

CBSE Class 11 Biology Chapter 3 Plant Kingdom – 25 Long Answer Questions with Answers (NCERT)

Section A: Introduction & Basis of Classification (Q1–Q3)

Q1. Explain the basis of classification of plants in the Plant Kingdom.

Plants are classified based on level of organisation, presence or absence of vascular tissues, mode of reproduction, and seed formation. Simpler plants like algae have a thalloid body, while higher plants show differentiation into roots, stems, and leaves. Vascular tissue development marks a major evolutionary step seen in pteridophytes and above. Seed habit further divides plants into gymnosperms and angiosperms. These criteria help trace evolutionary trends from simple to complex plant forms.

Q2. Why is the study of Plant Kingdom important in biology?

The Plant Kingdom forms the base of all terrestrial and aquatic ecosystems as plants are primary producers. They convert solar energy into chemical energy, supporting all life forms. Studying plant diversity helps understand evolution, ecological balance, and economic importance. It also provides insight into structural and reproductive adaptations that enabled plants to colonise land successfully.

Q3. Describe the evolutionary trends observed in the Plant Kingdom.

Evolution in plants shows progression from simple aquatic algae to advanced flowering plants. Key trends include development of vascular tissues, seed formation, reduction of gametophyte, and dominance of sporophyte. Dependence on water for fertilisation decreases gradually, reaching complete independence in angiosperms.

Section B: Algae (Q4–Q8)

Q4. Describe the general characteristics of algae.

Algae are simple, photosynthetic organisms with a thalloid body lacking true roots, stems, and leaves. They are mostly aquatic and possess chlorophyll. Reproduction occurs by vegetative, asexual, and sexual methods. Algae show great diversity in pigments, stored food, and habitat.

Q5. Explain the classification of algae with examples.

Algae are classified into Chlorophyceae, Phaeophyceae, and Rhodophyceae based on pigments and stored food. Green algae contain chlorophyll a and b and store starch. Brown algae contain fucoxanthin and store laminarin. Red algae possess phycoerythrin and store floridean starch.

Q6. Write the economic importance of algae.

Algae are used as food, fertilizers, and sources of agar, algin, and carrageenan. They contribute significantly to oxygen production and are used in pharmaceutical and cosmetic industries.

Q7. Describe sexual reproduction in algae.

Sexual reproduction in algae may be isogamous, anisogamous, or oogamous. Fusion of gametes results in a zygote that undergoes meiosis to form spores, completing the life cycle.

Q8. Explain the life cycle pattern seen in algae.

Most algae show a haplontic life cycle where the gametophyte is dominant. The diploid phase is restricted to the zygote, which undergoes meiosis.

Section C: Bryophytes (Q9–Q13)

Q9. Describe the general characteristics of bryophytes.

Bryophytes are small, non-vascular plants growing in moist habitats. They have a dominant gametophyte and a dependent sporophyte. Water is essential for fertilisation, hence they are called amphibians of the plant kingdom.

Q10. Explain the life cycle of bryophytes.

Bryophytes show haplodiplontic life cycle. The gametophyte produces gametes, while the sporophyte produces spores and remains attached to the gametophyte.

Q11. Differentiate between liverworts and mosses.

Liverworts have a thalloid body, while mosses possess a leafy plant body. Moss sporophytes are more differentiated than those of liverworts.

Q12. State the ecological importance of bryophytes.

They prevent soil erosion, aid in soil formation, and maintain moisture in ecosystems. Sphagnum forms peat used as fuel.

Q13. Why are bryophytes restricted to moist habitats?

Bryophytes require water for fertilisation as male gametes swim to reach female gametes, limiting them to moist environments.

Section D: Pteridophytes (Q14–Q17)

Q14. Describe the general characteristics of pteridophytes.

Pteridophytes are the first vascular plants with true roots, stems, and leaves. Sporophyte is dominant and reproduction occurs by spores.

Q15. Explain the importance of vascular tissues in pteridophytes.

Vascular tissues enable efficient transport of water and nutrients, allowing plants to grow taller and adapt to terrestrial habitats.

Q16. Describe heterospory and its significance.

Heterospory involves production of microspores and megaspores. It is an evolutionary step towards seed habit.

Q17. Write the economic importance of pteridophytes.

They are used as ornamentals, soil binders, and contribute to coal formation.

Section E: Gymnosperms (Q18–Q20)

Q18. Describe the general characteristics of gymnosperms.

Gymnosperms are seed-bearing plants with naked seeds. They possess well-developed vascular tissues and reproduce via cones.

Q19. Explain reproduction in gymnosperms.

Male and female cones produce pollen and ovules. Pollination occurs by wind and fertilisation does not require water.

Q20. State the economic importance of gymnosperms.

They provide timber, resins, paper, and medicinal compounds.

Section F: Angiosperms & Life Cycles (Q21–Q25)

Q21. Describe the general characteristics of angiosperms.

Angiosperms are flowering plants with seeds enclosed in fruits. They show advanced vascular tissues and double fertilisation.

Q22. Explain double fertilisation in angiosperms.

One male gamete forms zygote with egg, while the other forms endosperm with polar nuclei, ensuring nourishment of embryo.

Q23. Differentiate between monocots and dicots.

Monocots have one cotyledon and parallel venation, while dicots have two cotyledons and reticulate venation.

Q24. Explain alternation of generations in plants.

Plants alternate between haploid gametophyte and diploid sporophyte phases, ensuring continuity of life cycle.

Q25. Compare life cycle patterns in different plant groups.

Algae show haplontic, bryophytes and pteridophytes haplodiplontic, while gymnosperms and angiosperms show diplontic life cycles.

Exam Relevance

✔ Strictly NCERT-aligned
✔ Ideal for 5-mark CBSE Class 11 questions
✔ Strong focus on evolution, differences & life cycles
✔ Suitable for annual exams and detailed revision