Plant Kingdom — Class 11 Biology NCERT Solutions (Free)
Free step-by-step NCERT solutions for Class 11 Biology chapter "Plant Kingdom" — 8 important questions with detailed answers for CBSE board exam preparation.
TL;DR: Free step-by-step NCERT solutions for Class 11 Biology chapter "Plant Kingdom" — 8 important questions with detailed answers for CBSE board exam prepa…
Written & reviewed by the Syllab.in Academic Team (CBSE/NCERT subject experts) · Updated
NCERT Solutions for Class 11 Biology — Plant Kingdom. Step-by-step answers to all 8 textbook questions from this chapter, written for CBSE board preparation and free to use.
Plant Kingdom — All 8 Questions Solved
Q1. Define bryophytes and state two characteristics.
Bryophytes are small, non-vascular land plants that lack true roots, stems, and leaves. Two characteristics:
1. Absence of vascular tissue (xylem and phloem); water and nutrients absorbed and transported by diffusion.
2. Require moist environments for reproduction; possess flagellated sperms requiring water to swim to egg.
Q2. What is alternation of generations? Explain with reference to ferns.
Alternation of generations is the occurrence of two distinct multicellular forms in the life cycle of an organism: a diploid sporophyte and a haploid gametophyte, each reproducing by different methods.
In ferns:
- Sporophyte (diploid, 2n): The large visible fern plant with roots, stems, and fronds. Produces spores through meiosis in sporangia (located on underside of fronds).
- Gametophyte (haploid, n): The prothallus, a small, heart-shaped green structure. Produces gametes (sperm and egg) through mitosis. Sperms require water to reach eggs.
Q3. Name five adaptations of seed plants to terrestrial life.
Five adaptations of seed plants to terrestrial life:
1. Vascular tissue (xylem and phloem): Allows transport of water, minerals, and nutrients throughout the plant, reducing dependence on external water.
2. Roots: Anchor plant and absorb water and minerals from soil.
3. Waxy cuticle: Reduces water loss through evaporation from leaves.
4. Stomata with guard cells: Regulate gas exchange and water loss.
5. Seeds with protective coat and stored food: Ensure embryo survival in dry conditions and enable dispersal.
Q4. Distinguish between gymnosperms and angiosperms.
Gymnosperms:
- Naked seeds not enclosed in a fruit.
- No flowers; reproductive structures are cones.
- Ovule not enclosed in an ovary.
- Xylem lacks vessels; contains only tracheids.
- Examples: Pines, cedars, spruces.
Angiosperms:
- Seeds enclosed within a fruit.
- Flowers present; reproductive structures specialized for pollination.
- Ovule enclosed in an ovary (pistil).
- Xylem contains both vessels and tracheids.
- Double fertilization produces endosperm.
- Examples: Roses, wheat, beans.
Q5. What is a sporophyll? How does it differ from a vegetative leaf?
A sporophyll is a modified leaf that bears sporangia (structures containing spores). It is specialized for reproduction.
Differences from vegetative leaf:
1. Vegetative leaves perform photosynthesis and gas exchange; sporophylls are primarily reproductive in function.
2. Sporophylls bear sporangia on their surface or margins; vegetative leaves do not.
3. Sporophylls may show reduced blade size and different morphology adapted for spore protection and dispersal.
4. In ferns, sporophylls often appear as the undersurface (abaxial side) of fronds containing sori.
Q6. Describe the structure of a typical angiosperm flower with labeled parts.
A typical angiosperm flower structure:
1. Receptacle: Enlarged tip of floral stalk bearing all flower parts.
2. Sepals (calyx): Leaf-like protective structures, usually green, arranged in a whorl below petals.
3. Petals (corolla): Colorful structures attracting pollinators, arranged in a whorl.
4. Stamens (androecium): Male reproductive organs; each consisting of a filament (stalk) and anther (pollen-producing structure).
5. Carpel/Pistil (gynoecium): Female reproductive organ; consists of stigma (apex, receives pollen), style (connects stigma to ovary), and ovary (contains ovules).
6. Ovules: Structures inside ovary that develop into seeds after fertilization.
Arrangement: Whorls are concentric, with stamens surrounding the central carpel(s).
Q7. Explain the process of double fertilization in angiosperms (5-mark answer).
Double fertilization is a characteristic process of angiosperms occurring after pollination:
1. Pollen grain germinates on stigma; pollen tube grows through style toward ovule.
2. Inside pollen grain: Generative nucleus divides (before or after pollination) to form two sperm cells (male gametes).
3. First fertilization: One sperm fuses with egg cell (female gamete) in the embryo sac, forming the zygote (2n), which develops into the embryo.
4. Second fertilization: Second sperm fuses with two polar nuclei (or central cell) in the embryo sac, forming the primary endosperm nucleus (3n), which develops into the triploid endosperm.
5. Endosperm: Nutritive tissue storing food reserves (starch, proteins, oils) used by the developing embryo and seedling.
Significance: Double fertilization ensures nourishment for the developing embryo and is a unique feature of angiosperms, providing reproductive advantage.
Q8. What are heterosporous plants? Give examples and explain their significance.
Heterosporous plants are plants that produce two morphologically distinct types of spores: microspores and megaspores.
Characteristics:
1. Microspores (smaller): Develop into male gametophytes (pollen grains), each producing sperm cells.
2. Megaspores (larger): Develop into female gametophytes (embryo sac), producing egg cells.
Examples: All seed plants (gymnosperms and angiosperms), some advanced ferns.
Significance:
1. Represents evolutionary advancement toward sexual specialization.
2. Microspores can be produced in larger numbers and dispersed easily, increasing pollination efficiency.
3. Megaspore development is protected inside ovule, reducing exposure to environmental stress.
4. Heterospory is a stepping stone in plant evolution toward the sporophyte dominance and gametophyte reduction seen in seed plants.
Plant Kingdom — Practice MCQs with Answers
Attempt these 20 multiple-choice questions after working through the solutions above. Each carries the correct option and the reasoning behind it, so a wrong answer tells you which idea to revisit.
MCQ 1. Which of the following classification systems is based on a few superficial morphological characters like habit, colour, number, and shape of leaves?
- A. Natural system
- B. Phylogenetic system
- C. Artificial system
- D. Numerical taxonomy
Answer: C. Artificial system — Artificial systems of classification used only a few superficial morphological characters. For example, Linnaeus's system was based on the androecium structure.
MCQ 2. Which classification system considers natural affinities among organisms, taking into account both external and internal features like ultrastructure, anatomy, embryology, and phytochemistry?
- A. Artificial system
- B. Natural system
- C. Phylogenetic system
- D. Chemical taxonomy
Answer: B. Natural system — Natural systems of classification are based on natural affinities among the organisms and consider both external and internal features, providing a more comprehensive view.
MCQ 3. In which class of algae are phycobilins (like phycoerythrin) the major photosynthetic pigments?
- A. Chlorophyceae
- B. Phaeophyceae
- C. Rhodophyceae
- D. Xanthophyceae
Answer: C. Rhodophyceae — Phycobilins, particularly phycoerythrin, are the characteristic pigments found in red algae (Rhodophyceae), contributing to their distinct red colour.
MCQ 4. Food in green algae is commonly stored as which of the following?
- A. Starch
- B. Mannitol
- C. Laminarin
- D. Floridean starch
Answer: A. Starch — Green algae (Chlorophyceae) typically store food in the form of starch, often associated with pyrenoids in their chloroplasts.
MCQ 5. Isogamous sexual reproduction with non-flagellated gametes is characteristic of which of the following algae?
- A. Volvox
- B. Fucus
- C. Spirogyra
- D. Ulothrix
Answer: C. Spirogyra — Spirogyra exhibits isogamous sexual reproduction where both fusing gametes are similar in size and non-motile (non-flagellated).
MCQ 6. Which of the following is a colonial form of green algae?
- A. Ulothrix
- B. Spirogyra
- C. Chlamydomonas
- D. Volvox
Answer: D. Volvox — Volvox is a well-known example of a colonial green alga, forming spherical colonies of many cells that can move synchronously.
MCQ 7. Bryophytes are often called 'amphibians of the plant kingdom' primarily because:
- A. They can live in water and on land.
- B. They require water for sexual reproduction.
- C. They have both male and female reproductive organs.
- D. Their life cycle includes both a sporophyte and a gametophyte.
Answer: B. They require water for sexual reproduction. — Bryophytes are called amphibians of the plant kingdom because, despite living on land, they depend on water for sexual reproduction, as their motile male gametes need water to swim to the egg.
MCQ 8. The dominant, independent, photosynthetic phase in the life cycle of a bryophyte is the:
- A. Sporophyte
- B. Gametophyte
- C. Protonema
- D. Prothallus
Answer: B. Gametophyte — The dominant, independent, photosynthetic thalloid or erect phase in bryophytes is the gametophyte, which bears the sex organs and produces gametes.
MCQ 9. Which part of the bryophyte sporophyte is directly involved in the production and dispersal of spores?
- A. Foot
- B. Seta
- C. Capsule
- D. Rhizoids
Answer: C. Capsule — The capsule (also called sporangium) of the bryophyte sporophyte is where spores are produced by meiosis and subsequently released for dispersal.
MCQ 10. Pteridophytes are commonly known as which of the following?
- A. Mosses
- B. Liverworts
- C. Ferns
- D. Conifers
Answer: C. Ferns — Ferns are the most common and widely recognized group within Pteridophytes, although the group also includes horsetails and club mosses.
MCQ 11. Which of the following groups are considered the first terrestrial plants to possess vascular tissues?
- A. Bryophytes
- B. Pteridophytes
- C. Gymnosperms
- D. Algae
Answer: B. Pteridophytes — Pteridophytes are the first terrestrial plants to possess xylem and phloem, the vascular tissues, which allowed them to grow taller and occupy diverse terrestrial habitats.
MCQ 12. If a pteridophyte produces two different types of spores (megaspores and microspores), it is termed:
- A. Homosporous
- B. Heterosporous
- C. Monoecious
- D. Dioecious
Answer: B. Heterosporous — Heterosporous pteridophytes produce two kinds of spores, megaspores (larger, female) and microspores (smaller, male), which germinate into female and male gametophytes, respectively.
MCQ 13. The term 'gymnosperm' literally means:
- A. Covered seeds
- B. Naked seeds
- C. Flowering plants
- D. Seedless plants
Answer: B. Naked seeds — Gymnosperm comes from Greek words 'gymnos' (naked) and 'sperma' (seeds), referring to plants with ovules that are not enclosed by an ovary wall.
MCQ 14. Which of the following gymnosperms is often referred to as a 'living fossil' due to its ancient lineage and persistent primitive characteristics?
- A. Pinus
- B. Cycas
- C. Sequoia
- D. Gnetum
Answer: B. Cycas — Cycas is widely considered a living fossil because it has maintained many primitive characteristics and belongs to a group with a very long evolutionary history.
MCQ 15. Which of the following statements about Pinus is INCORRECT?
- A. It is a monoecious plant.
- B. Male and female cones are borne on the same tree.
- C. It typically has an unbranched stem.
- D. It possesses needle-like leaves.
Answer: C. It typically has an unbranched stem. — Pinus typically has branched stems, unlike Cycas which often has an unbranched stem. Pinus is monoecious, with both male and female cones on the same plant, and has characteristic needle-like leaves.
MCQ 16. A life cycle in which the diploid sporophyte is the dominant, photosynthetic, and independent phase, and the gametophyte is represented by a single to few-celled stage, is called:
- A. Haplontic
- B. Diplontic
- C. Haplo-diplontic
- D. Isomorphic
Answer: B. Diplontic — In a diplontic life cycle, the diploid sporophyte is the dominant, photosynthetic, independent plant body, while the haploid gametophytic phase is very short-lived and usually represented only by gametes.
MCQ 17. Which of the following organisms exhibits a haplo-diplontic life cycle?
- A. Volvox
- B. Fucus
- C. Ectocarpus
- D. Spirogyra
Answer: C. Ectocarpus — Ectocarpus, Polysiphonia, and kelps are examples of algae that exhibit a haplo-diplontic (intermediate) life cycle, where both sporophyte and gametophyte are multicellular and often free-living.
MCQ 18. The presence of archegonium as a female sex organ is NOT a characteristic feature of which plant group?
- A. Bryophytes
- B. Pteridophytes
- C. Gymnosperms
- D. Angiosperms
Answer: D. Angiosperms — Archegonia are female sex organs found in bryophytes, pteridophytes, and gymnosperms. Angiosperms do not have archegonia; their female gametophyte (embryo sac) contains an egg cell within an ovule.
MCQ 19. Which pigment is primarily responsible for the characteristic red colour of red algae (Rhodophyceae)?
- A. Chlorophyll b
- B. Fucoxanthin
- C. Phycoerythrin
- D. Carotenoids
Answer: C. Phycoerythrin — Phycoerythrin is the dominant red pigment found in Rhodophyceae, allowing them to absorb blue-green light that penetrates deeper into water.
MCQ 20. Which of the following is a common example of a liverwort?
- A. Funaria
- B. Marchantia
- C. Sphagnum
- D. Polytrichum
Answer: B. Marchantia — Marchantia is a well-known representative example of a liverwort, belonging to the class Hepaticopsida of bryophytes.
How to Use These Solutions
Attempt each question yourself first and only then compare with the worked answer. Marks in the CBSE board exam are awarded for the METHOD as much as the final result, so reproduce the steps rather than memorising the last line. Where a solution states a law, a formula or a definition, learn that wording — examiners look for it.
Related practice for this chapter: chapter MCQs, previous-year questions, revision notes and sample papers.