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Plant Kingdom

Alternation of Generations Practice Questions

20 free Alternation of Generations practice questions for the NCERT Biology. Tap an option to answer — you get instant feedback, the correct answer, and a detailed explanation for every question.

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Question 1 of 20 Medium

In the plant life cycle, which of the following processes results in the formation of haploid spores from a diploid sporophyte?

  1. A Mitosis
  2. B Meiosis
  3. C Fertilization
  4. D Fragmentation

Correct answer: Meiosis

The diploid sporophyte produces haploid spores through the process of meiosis. These spores subsequently germinate and grow into the haploid gametophyte phase via mitosis.

Question 2 of 20 Medium

The haploid plant body that produces gametes by mitosis is known as the:

  1. A Sporophyte
  2. B Gametophyte
  3. C Archegonium
  4. D Protonema

Correct answer: Gametophyte

The gametophyte is the haploid stage of the plant life cycle. It produces male and female gametes through mitotic division, maintaining the haploid chromosome number.

Question 3 of 20 Medium

In a haplontic life cycle, which stage is the only diploid stage?

  1. A Gametophyte
  2. B Spore
  3. C Sporophyte
  4. D Zygote

Correct answer: Zygote

In haplontic life cycles, such as in Volvox and Spirogyra, the diploid stage is represented only by the single-celled zygote. There is no multicellular diploid sporophyte; the zygote undergoes meiosis immediately.

Question 4 of 20 Medium

Which of the following organisms typically exhibits a haplontic life cycle?

  1. A Fucus
  2. B Pinus
  3. C Ectocarpus
  4. D Volvox

Correct answer: Volvox

Volvox, Spirogyra, and some species of Chlamydomonas exhibit a haplontic life cycle where the dominant phase is the free-living gametophyte. The diploid phase is restricted to the zygote.

Question 5 of 20 Medium

The diplontic life cycle is characterized by a dominant, independent, and photosynthetic:

  1. A Haploid gametophyte
  2. B Diploid gametophyte
  3. C Haploid spore
  4. D Diploid sporophyte

Correct answer: Diploid sporophyte

In a diplontic life cycle the diploid sporophyte is the dominant, independent and photosynthetic phase, the pattern followed by all seed plants. The haploid gametophytic phase is reduced to a single-celled or few-celled stage that depends entirely on the sporophyte. A gametophyte is haploid by definition, and a zygote is a single cell, so neither can be the dominant photosynthetic body.

Question 6 of 20 Medium

All seed-bearing plants (Gymnosperms and Angiosperms) follow which type of life cycle?

  1. A Haplontic
  2. B Haplo-diplontic
  3. C Diplohaplontic
  4. D Diplontic

Correct answer: Diplontic

Gymnosperms and Angiosperms exhibit a diplontic life cycle. In these plants, the diploid sporophyte is the dominant plant body, and the gametophyte is microscopic and dependent.

Question 7 of 20 Medium

Which plant groups exhibit an intermediate condition called the haplo-diplontic life cycle?

  1. A Bryophytes and Pteridophytes
  2. B Algae and Fungi
  3. C Gymnosperms and Angiosperms
  4. D Monera and Protista organisms

Correct answer: Bryophytes and Pteridophytes

Both Bryophytes and Pteridophytes show a haplo-diplontic life cycle where both haploid and diploid phases are multicellular. However, they differ in which phase is dominant.

Question 8 of 20 Medium

In Bryophytes, the dominant, independent, and photosynthetic phase is the:

  1. A Haploid gametophyte
  2. B Diploid sporophyte
  3. C Zygote
  4. D Capsule and seta complex

Correct answer: Haploid gametophyte

The main plant body of a bryophyte is a haploid gametophyte. The multicellular sporophyte is partially or totally dependent on the gametophyte for its anchorage and nutrition.

Question 9 of 20 Medium

In Pteridophytes, the dominant phase is the:

  1. A Diploid sporophyte
  2. B Haploid gametophyte
  3. C Prothallus
  4. D Zygote

Correct answer: Diploid sporophyte

Unlike bryophytes, the dominant phase in pteridophytes is the diploid sporophyte. It is independent and possesses true vascular tissues (xylem and phloem).

Question 10 of 20 Medium

Although most algae are haplontic, which of the following is an exception that is diplontic?

  1. A Ulva
  2. B Polysiphonia
  3. C Chlamydomonas
  4. D Fucus

Correct answer: Fucus

Fucus is a brown alga that is a notable exception to the general haplontic rule of algae, as it exhibits a diplontic life cycle. Ulva and Polysiphonia are haplo-diplontic, while Chlamydomonas is haplontic.

Question 11 of 20 Medium

Which of the following algae exhibit a haplo-diplontic life cycle?

  1. A Ectocarpus and Kelps
  2. B Volvox and Spirogyra
  3. C Fucus and Chlamydomonas
  4. D Sargassum only

Correct answer: Ectocarpus and Kelps

Ectocarpus, Polysiphonia, and Kelps are examples of algae that deviate from the haplontic pattern and instead show a haplo-diplontic life cycle. This involves multicellularity in both generations.

Question 12 of 20 Medium

The multicellular sporophyte in bryophytes is:

  1. A Short-lived and dependent on the gametophyte
  2. B Independent and photosynthetic
  3. C Produced by meiosis of the zygote
  4. D The dominant, independent, and photosynthetic stage

Correct answer: Short-lived and dependent on the gametophyte

The sporophyte in bryophytes is attached to and dependent on the photosynthetic gametophyte for nutrition. It consists of a foot, seta, and capsule, where spores are produced.

Question 13 of 20 Medium

In pteridophytes, the haploid spores germinate to give rise to a small, inconspicuous, multicellular, free-living gametophyte called:

  1. A Prothallus
  2. B Protonema
  3. C Archegonium
  4. D Rhizoid

Correct answer: Prothallus

The gametophyte of pteridophytes is known as the prothallus. It is typically photosynthetic and requires cool, damp, and shady places to grow and facilitate fertilization.

Question 14 of 20 Medium

The shift from a haploid gametophyte to a diploid sporophyte occurs through the process of:

  1. A Syngamy
  2. B Meiosis
  3. C Gametogenesis
  4. D Sporogenesis

Correct answer: Syngamy

Syngamy, or the fusion of male and female gametes, results in the formation of a diploid zygote. This zygote marks the beginning of the sporophytic generation.

Question 15 of 20 Medium

Which of the following statements regarding the gametophytic phase is FALSE?

  1. A It is always haploid
  2. B It produces gametes via mitosis
  3. C It typically originates from a haploid spore
  4. D It is the dominant phase in gymnosperms

Correct answer: It is the dominant phase in gymnosperms

In gymnosperms, the sporophyte is the dominant phase, while the gametophyte is highly reduced and dependent. The gametophyte is dominant only in bryophytes and most algae.

Question 16 of 20 Medium

In the life cycle of a moss, the first stage of the gametophyte is the:

  1. A Leafy stage
  2. B Protonema
  3. C Seta
  4. D Zygote

Correct answer: Protonema

A moss spore germinates into a creeping, green, branched, and filamentous stage called the protonema. The second stage is the leafy stage, which develops from the secondary protonema as a lateral bud.

Question 17 of 20 Medium

The relationship between the gametophyte and sporophyte in ferns (Pteridophytes) is that:

  1. A The sporophyte is dependent on the gametophyte
  2. B Both are independent and free-living
  3. C The gametophyte is dependent on the sporophyte
  4. D The sporophyte is unicellular

Correct answer: Both are independent and free-living

In ferns, both the sporophyte (the large, familiar plant) and the gametophyte (the small prothallus) are independent and free-living. This is a unique feature of the haplo-diplontic cycle in pteridophytes.

Question 18 of 20 Medium

What is the primary evolutionary trend observed in the alternation of generations from bryophytes to angiosperms?

  1. A Progressive elaboration of the gametophyte generation
  2. B Increasing dominance and complexity of the sporophyte
  3. C Complete loss of the sporophytic generation over time
  4. D Progressive transition from diploidy to haploidy

Correct answer: Increasing dominance and complexity of the sporophyte

Evolution shows a clear trend toward the reduction of the gametophytic phase and the increasing dominance, size, and vascular complexity of the diploid sporophytic phase.

Question 19 of 20 Medium

The cells of a sporophyte have twice the number of chromosomes as the cells of a gametophyte because of:

  1. A Triple fusion during seed formation
  2. B Fertilization of two haploid gametes
  3. C Meiotic division of spore mother cells
  4. D Asexual reproduction via fragmentation

Correct answer: Fertilization of two haploid gametes

Fertilization involves the fusion of two haploid (n) gametes to form a diploid (2n) zygote. All subsequent cells of the sporophyte produced by mitosis from this zygote remain diploid.

Question 20 of 20 Medium

In which stage of the plant life cycle does genetic recombination occur?

  1. A Mitosis in the gametophyte
  2. B Meiosis in the sporophyte
  3. C Budding of the protonema
  4. D Spore germination in soil

Correct answer: Meiosis in the sporophyte

Genetic recombination occurs during meiosis, which in plants takes place within the sporophyte's sporangia to produce haploid spores. This ensures genetic diversity in the next gametophytic generation.

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