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Plant Kingdom: questions with answers

Class 11 Biology, Chapter 3 (NCERT). 15 questions by concept. Open “Show answer” for the answer and why.

How to teach this chapter · Common misconceptions & worked visual for this chapter

Changing systems of plant classification

Question 1

Earlier classifications placed fungi and cell-walled members of Monera and Protista with plants. Which comparison with the modern plant kingdom is correct?

  1. (a)Only fungi were excluded; cyanobacteria remain true algae in Plantae because of their older name.
  2. (b)The modern boundary includes all members of Monera and Protista but excludes flowering plants.
  3. (c)The boundary is unchanged because every cell-walled organism is still a plant.
  4. (d)The modern boundary excludes those groups; cell-wall presence and the name blue-green algae no longer decide whether a group belongs to Plantae.
Show answer

(d) The modern boundary excludes those groups; cell-wall presence and the name blue-green algae no longer decide whether a group belongs to Plantae.

The modern plant kingdom excludes fungi and the cell-walled members of Monera and Protista that were formerly grouped with plants. Cyanobacteria are therefore not treated as true algae in Plantae.

Question 2

A learner says, 'Cyanobacteria have cell walls and are called blue-green algae, so they are true algae in Plantae.' Which diagnosis is correct?

  1. (a)The placement is wrong only because cyanobacteria lack both photosynthesis and cell walls.
  2. (b)The placement is correct because the name blue-green algae makes cyanobacteria true algae in Plantae.
  3. (c)The placement is correct because every cell-walled organism belongs to Plantae.
  4. (d)Both reasons are faulty: a cell wall does not define Plantae, and cyanobacteria are prokaryotes in Monera rather than true algae.
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(d) Both reasons are faulty: a cell wall does not define Plantae, and cyanobacteria are prokaryotes in Monera rather than true algae.

The claim relies on two insufficient cues: cell-wall presence and an older common name. Cyanobacteria are prokaryotes placed in Monera and are not algae in the modern plant kingdom.

Question 3

Which statement accurately distinguishes artificial, natural, and phylogenetic classification systems?

  1. (a)Artificial uses a few convenient traits; natural combines external and internal affinities; phylogenetic emphasises evolutionary relationships.
  2. (b)Artificial and phylogenetic use only chemical constituents, while natural uses no internal features.
  3. (c)All three use the same evidence; only their names and the taxa they produce differ.
  4. (d)Artificial emphasises common ancestry; natural uses only colour and habit; phylogenetic uses chromosome number alone.
Show answer

(a) Artificial uses a few convenient traits; natural combines external and internal affinities; phylogenetic emphasises evolutionary relationships.

Artificial systems use a few convenient characters, natural systems consider external and internal affinities, and phylogenetic systems organise taxa by evolutionary relationships and common ancestry. Their evidence bases therefore cannot be treated as identical.

Bryophyte structure and gametophyte-dominant life cycle

Question 4

Under suitable conditions, how does a detached Marchantia gemma form a new plant?

  1. (a)By germination
  2. (b)By releasing spores
  3. (c)By fusion with another gemma
  4. (d)By meiosis
Show answer

(a) By germination

Marchantia gemmae are multicellular asexual buds. After detaching, they germinate under suitable conditions to form new plants. This process does not involve fusion of gametes.

Question 5

Which comparison of a Marchantia gemma, a moss protonema, and a bryophyte sporophyte is correct?

  1. (a)Gemma—an asexual bud; protonema—the diploid moss sporophyte; sporophyte—an attached dependent diploid body
  2. (b)Gemma—a sexual gamete; protonema—a haploid gametophyte stage; sporophyte—an attached dependent diploid body
  3. (c)Gemma—an asexual bud; protonema—a haploid gametophyte stage; sporophyte—an attached dependent diploid body
  4. (d)Gemma—an asexual bud; protonema—a haploid gametophyte stage; sporophyte—the dominant independent bryophyte plant
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(c) Gemma—an asexual bud; protonema—a haploid gametophyte stage; sporophyte—an attached dependent diploid body

A gemma is a multicellular asexual bud that can detach and form a new liverwort individual. Protonema is the first haploid gametophyte stage formed from a moss spore, whereas the diploid bryophyte sporophyte stays attached to and dependent on the photosynthetic gametophyte.

Question 6

Which structures attach a moss gametophyte to the substratum?

  1. (a)Setae
  2. (b)Rhizoids
  3. (c)Capsules
  4. (d)True roots
Show answer

(b) Rhizoids

Multicellular rhizoids attach a moss gametophyte to the substratum. Rhizoids are not true roots; bryophytes lack true roots.

Pteridophytes, vascular tissues, and heterospory

Question 7

A learner says, ‘Selaginella is heterosporous only because it makes large and small spores. Both spores have the same fate, and this pattern has no evolutionary link to seed habit.’ Which correction is complete?

  1. (a)Small microspores form male gametophytes and large megaspores form female gametophytes; female-gametophyte retention and embryo development are precursor features of seed habit.
  2. (b)The spores differ only in size and have the same developmental fate, although retention hints at seed habit.
  3. (c)Small microspores form male gametophytes and large megaspores form female gametophytes, but this developmental pattern has no evolutionary link to seed habit.
  4. (d)Selaginella is homosporous because both spore types eventually contribute to the dominant sporophyte.
Show answer

(a) Small microspores form male gametophytes and large megaspores form female gametophytes; female-gametophyte retention and embryo development are precursor features of seed habit.

Selaginella produces two kinds of spores: small microspores develop into male gametophytes, and large megaspores develop into female gametophytes. Retention of the female gametophyte and development of the embryo within it are steps associated with the evolutionary origin of seed habit. Selaginella itself does not produce seeds.

Question 8

Pteridophytes have xylem and phloem. Which vascular tissues are present in bryophytes?

  1. (a)No vascular tissues
  2. (b)Xylem and phloem
  3. (c)Xylem only
  4. (d)Phloem only
Show answer

(a) No vascular tissues

Bryophytes lack vascular tissues. Pteridophytes possess xylem and phloem, which transport water and food.

Question 9

Which statement best explains why heterospory in some pteridophytes is linked to the evolution of seed habit?

  1. (a)The two spore types form sex-specific gametophytes, but their retention and embryo development have no link to seed habit
  2. (b)The two spore types form sex-specific gametophytes, and retention of the female gametophyte permits embryo development on the parent
  3. (c)The two spore types differ only in size and have no different developmental fates
  4. (d)The two spore types immediately become exposed seeds on the pteridophyte sporophyte
Show answer

(b) The two spore types form sex-specific gametophytes, and retention of the female gametophyte permits embryo development on the parent

Microspores and megaspores develop into male and female gametophytes respectively. Retention of the female gametophyte on the parent sporophyte and development of the zygote into an embryo within it are described as precursors to seed habit; pteridophytes are not said to produce seeds.

Seed plants: gymnosperms and angiosperms

Question 10

Which comparison of reproductive structures in Pinus and Cycas is correct?

  1. (a)Both Pinus and Cycas always bear their male and female reproductive structures on different trees.
  2. (b)Pinus bears the two kinds on different trees, whereas every Cycas tree bears both kinds.
  3. (c)Pinus bears male and female strobili on the same tree, whereas Cycas bears male cones and megasporophylls on different trees.
  4. (d)Both Pinus and Cycas always bear male and female reproductive structures on the same tree.
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(c) Pinus bears male and female strobili on the same tree, whereas Cycas bears male cones and megasporophylls on different trees.

Pinus can bear male and female strobili on the same tree. In Cycas, male cones and megasporophylls occur on different trees, so the Pinus pattern cannot be generalised to all gymnosperms.

Question 11

Which comparison correctly pairs reproductive structures with seed enclosure in the two seed-plant groups?

  1. (a)Both groups bear flowers, and both groups leave their mature seeds exposed.
  2. (b)Gymnosperms bear strobili with enclosed seeds, while angiosperms bear flowers with exposed seeds.
  3. (c)Gymnosperms bear strobili or cones with exposed ovules; angiosperms bear flowers and enclose seeds in fruits.
  4. (d)Gymnosperm cones are flowers, while angiosperms bear a different kind of cone.
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(c) Gymnosperms bear strobili or cones with exposed ovules; angiosperms bear flowers and enclose seeds in fruits.

Gymnosperms arrange sporophylls in strobili or cones and retain exposed ovules and seeds. Angiosperms form pollen and ovules in flowers, and their seeds are enclosed in fruits.

Comparative life-cycle reasoning across plant groups

Question 12

A moss has a conspicuous gamete-producing plant body and an attached sporophyte. A fern has a conspicuous vascular sporophyte and a small free-living prothallus. Which conclusion is correct?

  1. (a)The moss sporophyte must be dominant because the dominant generation is always diploid.
  2. (b)The dominant moss generation is haploid, while the dominant fern generation is diploid.
  3. (c)The fern prothallus is dominant because every free-living generation is dominant.
  4. (d)Both plants have a haploid sporophyte as their dominant generation.
Show answer

(b) The dominant moss generation is haploid, while the dominant fern generation is diploid.

The haploid gametophyte is dominant in the moss, whereas the diploid sporophyte is dominant in the fern. Dominance describes which phase is the main plant body; it is not another word for diploidy.

Question 13

A student reasons: ‘The bryophyte sporophyte must be the dominant phase because dominance always means diploid. Also, the zygote becomes diploid by meiosis during fertilisation.’ Which diagnosis is correct?

  1. (a)Only the first claim is correct because a dominant generation must always be diploid.
  2. (b)Only the second claim is correct because meiosis takes place as gametes fuse during fertilisation.
  3. (c)Both errors must be corrected: bryophyte dominance is gametophytic, and fertilisation forms the diploid zygote.
  4. (d)Both claims are correct because ploidy alone determines dominance and reproduction.
Show answer

(c) Both errors must be corrected: bryophyte dominance is gametophytic, and fertilisation forms the diploid zygote.

Both ideas are wrong. The dominant bryophyte body is the haploid gametophyte, and fertilisation—not meiosis—forms the diploid zygote; meiosis later produces haploid spores.

Algal diversity, reproduction, and classes

Question 14

In Spirogyra, two non-motile gametes that are similar in size fuse. What type of reproduction is this?

  1. (a)Isogamy
  2. (b)Anisogamy
  3. (c)Zoospore formation
  4. (d)Sexual reproduction other than isogamy
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(a) Isogamy

Fusion of gametes similar in size is called isogamy. The gametes may be motile or non-motile. Spirogyra has non-motile gametes, so their lack of motility does not exclude isogamy.

Question 15

Which evidence supports identifying a red-looking alga as Rhodophyceae?

  1. (a)Fucoxanthin and floridean starch
  2. (b)r-Phycoerythrin and floridean starch
  3. (c)r-Phycoerythrin and laminarin
  4. (d)Red colour alone
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(b) r-Phycoerythrin and floridean starch

Rhodophyceae contain the red pigment r-phycoerythrin and store floridean starch. Red appearance alone is insufficient for classification. Laminarin and fucoxanthin are characteristic of Phaeophyceae.

Common misconception in Plant Kingdom

Open full misconception guide →

Do seed plants need flowers to make seeds?

Wrong

A pine produces spores only because it has no flowers.

Why it feels right. Seeds are associated with fruits and flowers.

Right

Gymnosperms produce seeds without enclosing them in fruits.

Worked example

Fern
Spores→No seeds
Pine
Seeds→On cone scales
Pea
Seeds→Enclosed in fruit
The three plants differ in what they produce and how they enclose it.
  1. A fern disperses spores and makes no seeds.
  2. A pine can carry seeds on cone scales.
  3. A pea plant makes seeds enclosed in a fruit that develops from the ovary.