Grade XII Question Bank

Section A: Multiple Choice Questions (1 Mark Each) — Q1 to Q25

  1. (CBSE 2024) The outer layer of a pollen grain, exine, is made up of sporopollenin which is resistant to:
    • (a) High temperature and strong acids only
    • (b) Strong alkalis and enzymes only
    • (c) High temperature, strong acids, alkalis, and enzymes
    • (d) Enzymes only
  2. (CBSE 2023) In a typical angiosperm embryo sac, the functional megaspore undergoes:
    • (a) Three mitotic divisions to form an 8-nucleate, 7-celled embryo sac
    • (b) Three meiotic divisions to form an 8-nucleate embryo sac
    • (c) Two mitotic and one meiotic division
    • (d) Four mitotic divisions
  3. (CBSE 2023) Persistent nucellus in seeds is called perisperm. It is found in:
    • (a) Pea and Bean
    • (b) Black Pepper and Beet
    • (c) Maize and Wheat
    • (d) Groundnut and Castor
  4. (CBSE 2022) What is the ploidy level of the cells of nucellus, microspore mother cell, functional megaspore, and endosperm in a typical angiosperm, respectively?
    • (a) $2n, 2n, n, 3n$
    • (b) $n, 2n, n, 3n$
    • (c) $2n, n, 2n, 3n$
    • (d) $2n, 2n, 2n, n$
  5. (CBSE 2022) Geitonogamy is functionally __________ and genetically __________.
    • (a) Cross-pollination; Autogamy
    • (b) Autogamy; Cross-pollination
    • (c) Self-pollination; Xenogamy
    • (d) Xenogamy; Xenogamy
  6. (CBSE 2021) Filiform apparatus is a characteristic feature of:
    • (a) Antipodal cells
    • (b) Synergids
    • (c) Egg cell
    • (d) Central cell
  7. (CBSE 2020) Which of the following plants produces both chasmogamous and cleistogamous flowers?
    • (a) Vallisneria
    • (b) Viola (Common Pansy)
    • (c) Zostera
    • (d) Rosa
  8. (CBSE 2020) Transfer of pollen grains from the anther to the stigma of another flower of the same plant is called:
    • (a) Autogamy
    • (b) Geitonogamy
    • (c) Xenogamy
    • (d) Cleistogamy
  9. (CBSE 2020) Water pollinated plants like Vallisneria show which of the following features?
    • (a) Female flowers remain submerged in water
    • (b) Pollen grains are light and non-sticky with a mucilaginous covering
    • (c) Flowers produce abundant nectar and fragrance
    • (d) Pollen grains are heavy and sink to the bottom
  10. (CBSE 2019) Embryo sac is to ovule as __________ is to anther.
    • (a) Stamen
    • (b) Filament
    • (c) Pollen grain
    • (d) Microsporangium
  11. (CBSE 2019) In a flowering plant, the total number of mitotic divisions required to form a mature 7-celled embryo sac from a megaspore mother cell is:
    • (a) 1 meiotic and 3 mitotic
    • (b) 3 mitotic
    • (c) 1 meiotic and 2 mitotic
    • (d) 4 mitotic
  12. (CBSE 2018) Coconut water from tender coconut represents:
    • (a) Cellular endosperm
    • (b) Free-nuclear endosperm
    • (c) Endocarp
    • (d) Fleshy mesocarp
  13. (CBSE 2018) The phenomenon in which citrus seeds show multiple embryos is known as:
    • (a) Apomixis
    • (b) Polyembryony
    • (c) Parthenocarpy
    • (d) Parthenogenesis
  14. (CBSE 2017) Seed formation without fertilization in flowering plants involves:
    • (a) Somatic hybridization
    • (b) Apomixis
    • (c) Budding
    • (d) Sporulation
  15. (CBSE 2017) Which component of the pollen grain wall exhibits a wide variety of architecture, shapes, and designs?
    • (a) Intine
    • (b) Exine
    • (c) Germ pore
    • (d) Plasma membrane
  16. (CBSE 2016) The hilum of an ovule represents the junction between:
    • (a) Funicle and chalaza
    • (b) Funicle and body of ovule
    • (c) Integument and nucellus
    • (d) Nucellus and micropyle
  17. (CBSE 2016) Which one of the following is a false fruit?
    • (a) Mango
    • (b) Apple
    • (c) Banana
    • (d) Orange
  18. (CBSE 2015) Pollen tablets are available in the market for:
    • (a) In vitro fertilization
    • (b) Breeding programmes
    • (c) Food supplementation
    • (d) Ex situ conservation
  19. (CBSE 2015) Function of guide cells / filiform apparatus in an angiosperm embryo sac is to:
    • (a) Bring about opening of pollen tube
    • (b) Guide the entry of pollen tube into the synergid
    • (c) Prevent entry of more than one pollen tube
    • (d) Disperse male gametes into the central cell
  20. (CBSE 2014) Attractants and rewards are required for pollination by:
    • (a) Hydrophily
    • (b) Anemophily
    • (c) Entomophily
    • (d) Cleistogamy
  21. (CBSE 2014) Wind pollinated flowers have:
    • (a) Single ovule in each ovary and numerous flowers packed into an inflorescence
    • (b) Large showy colorful petals
    • (c) Abundant sweet nectar
    • (d) Sticky pollen grains and short feathery stigmas
  22. (CBSE 2023) What is the function of germ pores in a pollen grain?
    • (a) Absorption of water
    • (b) Initiation of pollen tube emergence
    • (c) Release of male gametes directly
    • (d) Secretion of sporopollenin
  23. (CBSE 2022) The portion of embryonal axis above the level of cotyledons is:
    • (a) Hypocotyl
    • (b) Epicotyl
    • (c) Radicle
    • (d) Scutellum
  24. (CBSE 2021) In monocot seeds, the single shield-shaped cotyledon is called:
    • (a) Coleoptile
    • (b) Coleorhiza
    • (c) Scutellum
    • (d) Epiblast
  25. (CBSE 2020) Parthenocarpic fruits are developed without fertilization. An example of such fruit is:
    • (a) Apple
    • (b) Strawberry
    • (c) Banana
    • (d) Cashew

Section B: Assertion-Reason Questions (1 Mark Each) — Q26 to Q40

Directions: In the following questions (26-40), a statement of Assertion (A) is followed by a statement of Reason (R). Choose the correct option:

  • (a) Both (A) and (R) are true and (R) is the correct explanation of (A).
  • (b) Both (A) and (R) are true but (R) is NOT the correct explanation of (A).
  • (c) (A) is true but (R) is false.
  • (d) (A) is false but (R) is true.
  1. (CBSE 2024)
    • Assertion (A): Sporopollenin is one of the most resistant organic materials known.
    • Reason (R): It can withstand high temperatures, strong acids, and alkalis, and no enzyme that degrades sporopollenin is known.
  2. (CBSE 2024)
    • Assertion (A): Cleistogamous flowers produce assured seed set even in the absence of pollinators.
    • Reason (R): Cleistogamous flowers do not open at all, ensuring self-pollination.
  3. (CBSE 2023)
    • Assertion (A): Endosperm development precedes embryo development in angiosperms.
    • Reason (R): The cells of endosperm tissue are filled with reserve food materials to provide nutrition to the developing embryo.
  4. (CBSE 2023)
    • Assertion (A): Geitonogamy is functionally cross-pollination involving a pollinating agent.
    • Reason (R): Genetically, geitonogamy is similar to autogamy since pollen grains come from the same plant.
  5. (CBSE 2022)
    • Assertion (A): Pollen grains can be well preserved as fossils.
    • Reason (R): The intine layer of pollen grains is made up of cellulose and pectin.
  6. (CBSE 2022)
    • Assertion (A): Apple and cashew are classified as false fruits.
    • Reason (R): In false fruits, the thalamus also contributes to fruit formation along with the ovary.
  7. (CBSE 2021)
    • Assertion (A): Apomictic seeds are highly advantageous to the hybrid seed industry.
    • Reason (R): Apomixis prevents segregation of desirable traits in hybrid progeny across generations.
  8. (CBSE 2021)
    • Assertion (A): Hydrophily is limited to about 30 genera, mostly monocotyledons.
    • Reason (R): Aquatic plants like water lily and lotus are pollinated by water currents.
  9. (CBSE 2020)
    • Assertion (A): Microspore mother cell undergoes meiosis to form microspore tetrad.
    • Reason (R): Microspore mother cells are haploid ($n$).
  10. (CBSE 2020)
    • Assertion (A): Castor is an endospermic (albuminous) seed while bean is a non-endospermic seed.
    • Reason (R): Endosperm is completely consumed by the developing embryo in castor before seed maturation.
  11. (CBSE 2019)
    • Assertion (A): Emasculation is not required in female parent flowers if they produce unisexual flowers.
    • Reason (R): Bagging is done to prevent contamination of stigma with unwanted pollen grains.
  12. (CBSE 2018)
    • Assertion (A): Synergids show prominent filiform apparatus at their micropylar tip.
    • Reason (R): Filiform apparatus guides the pollen tube into the synergid cell.
  13. (CBSE 2017)
    • Assertion (A): Tapetum is the innermost layer of microsporangium wall that nourishes developing pollen grains.
    • Reason (R): Cells of tapetum possess dense cytoplasm and generally have more than one nucleus.
  14. (CBSE 2016)
    • Assertion (A): Wind pollinated flowers produce massive quantities of pollen grains.
    • Reason (R): A large number of pollen grains are lost during wind transport.
  15. (CBSE 2015)
    • Assertion (A): Double fertilization is a characteristic feature unique to angiosperms.
    • Reason (R): It involves two events: syngamy (fertilization of egg cell) and triple fusion (formation of primary endosperm nucleus).

Section C: Short Answer Type I (2 Marks Each) — Q41 to Q65

  1. (CBSE 2024) State the function of tapetum in a microsporangium. Give two structural features of tapetal cells.
  2. (CBSE 2024) Name the organic substance of which exine of pollen grain is composed. Mention two of its distinct properties.
  3. (CBSE 2023) Differentiate between Chasmogamous and Cleistogamous flowers.
  4. (CBSE 2023) Explain the term ‘Pollen-Pistil Interaction’. Why is it called a dynamic process?
  5. (CBSE 2023) What is self-incompatibility? Why is it considered an effective outbreeding device in plants?
  6. (CBSE 2022) Draw a labeled diagram of a 2-celled mature pollen grain. Mention the function of the vegetative cell and generative cell.
  7. (CBSE 2022) What is triple fusion? Where does it occur in an embryo sac? Name the product formed after triple fusion.
  8. (CBSE 2021) Mention two characteristic floral adaptations observed in anemophilous (wind-pollinated) flowers.
  9. (CBSE 2021) Differentiate between Perisperm and Endosperm across two parameters: (a) Origin, (b) Ploidy level.
  10. (CBSE 2020) Why is apple called a false fruit? Which part of the flower forms the edible fleshy part of the fruit?
  11. (CBSE 2020) Explain the phenomenon of Apomixis. How does it differ from Parthenocarpy?
  12. (CBSE 2019) Name the mechanism that prevents self-pollination in a hermaphrodite flower by ensuring that anther and stigma mature at different times. Name its two variants.
  13. (CBSE 2019) What is polyembryony? Give one natural example of a plant species where it is commonly observed.
  14. (CBSE 2018) Write the functions of the following structures:
    • (a) Coleoptile
    • (b) Coleorhiza
  15. (CBSE 2018) Mention the advantage and disadvantage of cleistogamous flowers to a plant.
  16. (CBSE 2017) How does the floral structure of Vallisneria facilitate pollination by water?
  17. (CBSE 2017) List two steps involved in artificial hybridization in hermaphrodite flowers. Explain the significance of each step.
  18. (CBSE 2016) Explain the dynamic role of filiform apparatus during fertilization in angiosperms.
  19. (CBSE 2016) Differentiate between albuminous and non-albuminous seeds with one example of each.
  20. (CBSE 2015) What are germ pores? What is their functional importance during pollen germination?
  21. (CBSE 2015) Why is tender coconut water considered a free-nuclear endosperm? What is the white kernel surrounding it?
  22. (CBSE 2014) Mention the site of microsporogenesis in an angiosperm stamen. Write the ploidy level of microspore tetrad cells.
  23. (CBSE 2014) Why do farmer hybrid seed growers need to purchase expensive hybrid seeds every year? How can apomixis solve this issue?
  24. (CBSE 2020) Explain why endosperm development precedes embryo development in angiosperm seeds.
  25. (CBSE 2019) Define pericarp. Mention its origin and name two types of dry pericarp fruits.

Section D: Short Answer Type II (3 Marks Each) — Q66 to Q85

  1. (CBSE 2024)
    • (a) Describe the structure of a typical microsporangium of an angiosperm anther with reference to its wall layers.
    • (b) Name the innermost wall layer and state its functional significance.
  2. (CBSE 2024) Trace the development of a microspore mother cell into a mature 2-celled pollen grain in an angiosperm.
  3. (CBSE 2023)
    • (a) Draw a neat labeled diagram of a typical anatropous ovule showing its six main constituent parts.
    • (b) Define chalaza and micropyle.
  4. (CBSE 2023) Trace the steps involved in megasporogenesis in an angiosperm ovule leading to the formation of a functional megaspore.
  5. (CBSE 2022) Describe the structure of a mature 7-celled, 8-nucleate female gametophyte (embryo sac) in angiosperms. Mention the location and cellular arrangement of egg apparatus, central cell, and antipodals.
  6. (CBSE 2022)
    • (a) Describe pollination mechanism in Zostera (sea grass).
    • (b) How do pollen grains protect themselves from water damage in aquatic hydrophilous plants?
  7. (CBSE 2021) Explain three distinct outbreeding devices that flowering plants have evolved to prevent self-pollination (autogamy) and encourage cross-pollination.
  8. (CBSE 2021)
    • (a) Define double fertilization in angiosperms.
    • (b) Name the two nuclear fusion events that constitute double fertilization and mention the products formed with their respective ploidy levels.
  9. (CBSE 2020) Describe the step-by-step procedure of Artificial Hybridization technique carried out in:
    • (a) Bisexual flower
    • (b) Unisexual female flower
  10. (CBSE 2020) Describe the post-fertilization changes occurring in an angiosperm ovule that transform it into a mature seed, highlighting changes in integuments, nucellus, zygote, and primary endosperm nucleus (PEN).
  11. (CBSE 2019)
    • (a) Differentiate between Free-Nuclear Endosperm and Cellular Endosperm.
    • (b) Illustrate using tender coconut as an example.
  12. (CBSE 2019) Draw a neat labeled diagram of a mature dicotyledonous embryo (e.g., Capsella) and label the following parts:
    • Epicotyl
    • Hypocotyl
    • Radicle
    • Cotyledons
    • Root Cap
  13. (CBSE 2018) Compare the structural features of a Dicot Embryo and a Monocot (Grass) Embryo. Detail the position and identity of cotyledon(s) in both.
  14. (CBSE 2018)
    • (a) Explain how apomictic seeds can be produced without fertilization from nucellar cells.
    • (b) State the significance of apomixis in agriculture.
  15. (CBSE 2017) Describe the process of pollen grain germination on stigma leading to the entry of pollen tube into the embryo sac through micropyle.
  16. (CBSE 2017)
    • (a) What is seed dormancy? State two environmental factors that trigger germination upon breaking dormancy.
    • (b) Write one ecological/evolutionary advantage of seed dormancy in land plants.
  17. (CBSE 2016)
    • (a) How do insect-pollinated (entomophilous) flowers attract insect vectors? List two floral rewards offered to pollinators.
    • (b) Give an example of a symbiotic relationship where a flower provides a safe place for egg-laying in exchange for pollination service.
  18. (CBSE 2016) Describe the structural organisation of a mature anther in transverse section (T.S.). Why is an angiosperm anther described as bilobed and dithecous?
  19. (CBSE 2015)
    • (a) What happens to antipodal cells and synergids after double fertilization?
    • (b) Trace the development of Primary Endosperm Nucleus ($3n$) into a mature endosperm tissue.
  20. (CBSE 2014) Explain why:
    • (a) Pollen grains are well-preserved in fossil layers for millions of years.
    • (b) Pollen banks store pollen grains in liquid nitrogen at $-196^\circ\text{C}$.
    • (c) Pollen grains of some species (e.g., Parthenium) cause severe respiratory allergies.

Section E: Long Answer Type (5 Marks Each) — Q86 to Q100

  1. (CBSE 2024)
    • (a) Draw a schematic transverse section (T.S.) of a mature microsporangium of an angiosperm anther and label four wall layers.
    • (b) Explain microsporogenesis detailing the cytological events from Microspore Mother Cell (MMC) to microspore tetrad.
    • (c) Describe the development of a microspore into a mature 3-celled pollen grain.
  2. (CBSE 2024)
    • (a) Trace the development of female gametophyte (embryo sac) from Megaspore Mother Cell (MMC) in angiosperms with the help of neat labeled diagrams (Polygonum type).
    • (b) Why is this development described as monosporic?
    • (c) Explain why a mature embryo sac is 7-celled but 8-nucleate.
  3. (CBSE 2023)
    • (a) Explain the events of Pollen-Pistil interaction starting from deposition of pollen on stigma up to the release of male gametes in synergids.
    • (b) Draw a schematic diagram showing L.S. of pistil illustrating pollen tube growth entering the ovule through micropyle into an embryo sac.
  4. (CBSE 2023)
    • (a) Define Double Fertilization. Explain Syngamy and Triple Fusion in detail.
    • (b) Mention the fate of the following flower parts after fertilization:
      • Ovary
      • Ovule
      • Outer Integument
      • Inner Integument
      • Zygote
      • Primary Endosperm Nucleus
  5. (CBSE 2022)
    • (a) Explain the mechanisms of Pollination by different agencies:
      • Anemophily (Wind)
      • Hydrophily (Water)
      • Entomophily (Insects)
    • (b) Give one example plant species for each type of pollination agency.
    • (c) Why are wind and water pollinated flowers not brightly colored and lack nectar?
  6. (CBSE 2022)
    • (a) Compare Autogamy, Geitonogamy, and Xenogamy based on pollination mechanism, floral requirement, and genetic variation in offspring.
    • (b) List four structural, physiological, or genetic devices developed by plants to prevent autogamy.
  7. (CBSE 2021)
    • (a) Describe the step-by-step post-fertilization development of an angiosperm embryo in a dicot seed.
    • (b) Draw a neat labeled diagram of a L.S. of a mature dicot embryo.
    • (c) Distinguish between Epicotyl and Hypocotyl.
  8. (CBSE 2020)
    • (a) Describe endosperm development in angiosperms. Explain why free-nuclear division is followed by cell wall formation with reference to coconut.
    • (b) Differentiate between Albuminous (Endospermic) and Exalbuminous (Non-endospermic) seeds with two examples each.
    • (c) What is perisperm? Give two plant species where persistent perisperm is observed.
  9. (CBSE 2020)
    • (a) Define Artificial Hybridization. Describe emasculation, bagging, controlled pollination, and re-bagging steps.
    • (b) Under what condition is emasculation step skipped during artificial hybridization?
    • (c) State the commercial significance of artificial hybridization in crop plant improvement.
  10. (CBSE 2019)
    • (a) Explain the development of seed and fruit in angiosperms.
    • (b) Differentiate between True Fruits, False Fruits, and Parthenocarpic Fruits with one example of each.
    • (c) State three biological advantages offered by seeds to angiosperms for colonization and survival.
  11. (CBSE 2018)
    • (a) What is Apomixis? Explain two distinct pathways through which apomictic seeds develop in nature without fertilization.
    • (b) What is Polyembryony? Explain how nucellar polyembryony occurs in Citrus fruits.
    • (c) Explain why agricultural scientists are conducting active research to introduce apomictic genes into commercial hybrid crops.
  12. (CBSE 2017)
    • (a) Draw a labeled diagram of L.S. of a monocot (maize) grain.
    • (b) Label the following parts:
      • Pericarp + Seed coat fusion
      • Aleurone layer
      • Endosperm
      • Scutellum
      • Coleoptile
      • Coleorhiza
    • (c) Explain the functional roles of Scutellum, Coleoptile, and Coleorhiza during monocot seed germination.
  13. (CBSE 2016)
    • (a) Trace the complete path of a pollen tube from its growth on the stigma through style, entering the ovary, passing through micropyle into synergid, up to double fertilization.
    • (b) What guides the entry of pollen tube into synergid?
    • (c) Name the contents discharged by the pollen tube into the cytoplasm of synergid cell.
  14. (CBSE 2015)
    • (a) Describe the structure of a mature 2-celled pollen grain and 3-celled pollen grain. In what percentage of angiosperms are pollen grains shed at 2-celled stage?
    • (b) Explain pollen viability. State two factors that influence pollen viability period.
    • (c) Write a note on pollen allergy and pollen products available in commercial markets.
  15. (CBSE 2014)
    • (a) Describe the structural organisation of a mature angiosperm ovule (Anatropous Ovule) with a neat labeled diagram.
    • (b) Explain the process of megasporogenesis that leads to the formation of a functional megaspore.
    • (c) State the fate of the three degenerate megaspores formed during meiotic division of Megaspore Mother Cell.