Chapter 3: Plant Kingdom Assertion-Reason Questions | biology Class 11 CBSE

Assertion-Reason

Easy difficulty • Check the statement and reason

Easy

Question 1

Logic Check

Assertion (A): Algae are called primary producers in aquatic ecosystems. Reason (R): Algae are autotrophic, photosynthetic organisms that produce energy-rich organic compounds forming the basis of aquatic food chains.

Reasoning Options

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Assertion-Reason

Medium difficulty • Check the statement and reason

Medium

Question 2

Logic Check

Assertion (A): Cyanobacteria are classified as algae in modern classification systems. Reason (R): Cyanobacteria are photosynthetic organisms with blue-green pigmentation and were historically called blue-green algae.

Reasoning Options

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Assertion-Reason

Easy difficulty • Check the statement and reason

Easy

Question 3

Logic Check

Assertion (A): Red algae (Rhodophyceae) can survive at great depths in the ocean. Reason (R): Red algae contain r-phycoerythrin, which absorbs blue-green light wavelengths that penetrate deepest into ocean water.

Reasoning Options

ByteNotes

Assertion-Reason

Medium difficulty • Check the statement and reason

Medium

Question 4

Logic Check

Assertion (A): Bryophytes are called the amphibians of the plant kingdom. Reason (R): Bryophytes can live both in deep water and on land, alternating between aquatic and terrestrial phases of their life cycle.

Reasoning Options

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Assertion-Reason

Easy difficulty • Check the statement and reason

Easy

Question 5

Logic Check

Assertion (A): The sporophyte of bryophytes is not free-living. Reason (R): The bryophyte sporophyte is attached to and derives its nourishment from the photosynthetic gametophyte.

Reasoning Options

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Assertion-Reason

Medium difficulty • Check the statement and reason

Medium

Question 6

Logic Check

Assertion (A): Pyrenoids are found in the chloroplasts of green algae and are associated with starch synthesis. Reason (R): Pyrenoids contain protein besides starch and serve as centres of carbon dioxide fixation and starch production.

Reasoning Options

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Assertion-Reason

Easy difficulty • Check the statement and reason

Easy

Question 7

Logic Check

Assertion (A): Pteridophytes are considered evolutionarily more advanced than bryophytes. Reason (R): Pteridophytes possess well-differentiated vascular tissues (xylem and phloem) and have the diploid sporophyte as the dominant phase.

Reasoning Options

ByteNotes

Assertion-Reason

Medium difficulty • Check the statement and reason

Medium

Question 8

Logic Check

Assertion (A): In heterosporous pteridophytes, the female gametophyte is retained on the parent sporophyte. Reason (R): This retention of the female gametophyte on the sporophyte is considered a precursor to the seed habit seen in gymnosperms.

Reasoning Options

ByteNotes

Assertion-Reason

Medium difficulty • Check the statement and reason

Medium

Question 9

Logic Check

Assertion (A): In gymnosperms, the male and female gametophytes have an independent free-living existence. Reason (R): Gymnosperm gametophytes are highly reduced and are retained within sporangia on the sporophyte plant.

Reasoning Options

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Assertion-Reason

Easy difficulty • Check the statement and reason

Easy

Question 10

Logic Check

Assertion (A): Seeds of gymnosperms are naked. Reason (R): In gymnosperms, ovules are not enclosed by any ovary wall, and after fertilisation, seeds develop without being covered by a fruit wall.

Reasoning Options

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Assertion-Reason

Hard difficulty • Check the statement and reason

Hard

Question 11

Logic Check

Assertion (A): Pinus bears both male and female cones on the same tree. Reason (R): In Cycas, male cones and megasporophylls bearing ovules are also found on the same individual plant.

Reasoning Options

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Assertion-Reason

Easy difficulty • Check the statement and reason

Easy

Question 12

Logic Check

Assertion (A): Mosses play an important role in preventing soil erosion. Reason (R): Dense moss mats on soil reduce the impact of falling rain and bind soil particles, preventing them from being washed away.

Reasoning Options

ByteNotes

Assertion-Reason

Easy difficulty • Check the statement and reason

Easy

Question 13

Logic Check

Assertion (A): Water is essential for sexual reproduction in pteridophytes. Reason (R): Antherozoids (male gametes) in pteridophytes are flagellated and require a film of water to swim from antheridia to the archegonium for fertilisation.

Reasoning Options

ByteNotes

Assertion-Reason

Medium difficulty • Check the statement and reason

Medium

Question 14

Logic Check

Assertion (A): Floridean starch found in red algae is structurally unique and has no similarity to any other known polysaccharide. Reason (R): Floridean starch is very similar in structure to amylopectin and glycogen.

Reasoning Options

ByteNotes

Assertion-Reason

Easy difficulty • Check the statement and reason

Easy

Question 15

Logic Check

Assertion (A): Phylogenetic classification systems are currently the most accepted systems for classifying plants. Reason (R): Phylogenetic classification is based on evolutionary relationships between organisms and assumes that organisms belonging to the same taxa have a common ancestor.

Reasoning Options

ByteNotes

Assertion-Reason

Medium difficulty • Check the statement and reason

Medium

Question 16

Logic Check

Assertion (A): The gametophyte of pteridophytes (prothallus) requires cool, damp, and shady places to grow. Reason (R): This specific restricted requirement, along with the need for water for fertilisation, limits the geographical spread of living pteridophytes to narrow regions.

Reasoning Options

ByteNotes

Assertion-Reason

Medium difficulty • Check the statement and reason

Medium

Question 17

Logic Check

Assertion (A): Angiosperms are divided into dicotyledons and monocotyledons. Reason (R): This division is based on whether the seeds are enclosed within fruits or are naked.

Reasoning Options

ByteNotes

Assertion-Reason

Hard difficulty • Check the statement and reason

Hard

Question 18

Logic Check

Assertion (A): Algae belonging to Rhodophyceae are completely aflagellate. Reason (R): Rhodophyceae reproduce sexually by non-motile gametes, and their sexual reproduction is oogamous and accompanied by complex post-fertilisation developments.

Reasoning Options

ByteNotes

Assertion-Reason

Medium difficulty • Check the statement and reason

Medium

Question 19

Logic Check

Assertion (A): The liverwort plant body is dorsiventral and closely appressed to the substrate. Reason (R): Liverworts possess multicellular and branched rhizoids that enable them to stand upright away from the substrate surface.

Reasoning Options

ByteNotes

Assertion-Reason

Medium difficulty • Check the statement and reason

Medium

Question 20

Logic Check

Assertion (A): Artificial classification systems are considered inadequate because vegetative characters are more easily affected by the environment. Reason (R): Artificial systems gave equal weightage to vegetative and sexual characteristics, which is not acceptable since vegetative characters are less reliable indicators of true relationships.

Reasoning Options

ByteNotes

Chapter sections

Chapter 3: Plant Kingdom | Assertion-Reason

Assertion (A): Algae are called primary producers in aquatic ecosystems. Reason (R): Algae are autotrophic, photosynthetic organisms that produce energy-rich organic compounds forming the basis of aquatic food chains.

Assertion (A): Cyanobacteria are classified as algae in modern classification systems. Reason (R): Cyanobacteria are photosynthetic organisms with blue-green pigmentation and were historically called blue-green algae.

Assertion (A): Red algae (Rhodophyceae) can survive at great depths in the ocean. Reason (R): Red algae contain r-phycoerythrin, which absorbs blue-green light wavelengths that penetrate deepest into ocean water.

Assertion (A): Bryophytes are called the amphibians of the plant kingdom. Reason (R): Bryophytes can live both in deep water and on land, alternating between aquatic and terrestrial phases of their life cycle.

Assertion (A): The sporophyte of bryophytes is not free-living. Reason (R): The bryophyte sporophyte is attached to and derives its nourishment from the photosynthetic gametophyte.

Assertion (A): Pyrenoids are found in the chloroplasts of green algae and are associated with starch synthesis. Reason (R): Pyrenoids contain protein besides starch and serve as centres of carbon dioxide fixation and starch production.

Assertion (A): Pteridophytes are considered evolutionarily more advanced than bryophytes. Reason (R): Pteridophytes possess well-differentiated vascular tissues (xylem and phloem) and have the diploid sporophyte as the dominant phase.

Assertion (A): In heterosporous pteridophytes, the female gametophyte is retained on the parent sporophyte. Reason (R): This retention of the female gametophyte on the sporophyte is considered a precursor to the seed habit seen in gymnosperms.

Assertion (A): In gymnosperms, the male and female gametophytes have an independent free-living existence. Reason (R): Gymnosperm gametophytes are highly reduced and are retained within sporangia on the sporophyte plant.

Assertion (A): Seeds of gymnosperms are naked. Reason (R): In gymnosperms, ovules are not enclosed by any ovary wall, and after fertilisation, seeds develop without being covered by a fruit wall.

Assertion (A): Pinus bears both male and female cones on the same tree. Reason (R): In Cycas, male cones and megasporophylls bearing ovules are also found on the same individual plant.

Assertion (A): Mosses play an important role in preventing soil erosion. Reason (R): Dense moss mats on soil reduce the impact of falling rain and bind soil particles, preventing them from being washed away.

Assertion (A): Water is essential for sexual reproduction in pteridophytes. Reason (R): Antherozoids (male gametes) in pteridophytes are flagellated and require a film of water to swim from antheridia to the archegonium for fertilisation.

Assertion (A): Floridean starch found in red algae is structurally unique and has no similarity to any other known polysaccharide. Reason (R): Floridean starch is very similar in structure to amylopectin and glycogen.

Assertion (A): Phylogenetic classification systems are currently the most accepted systems for classifying plants. Reason (R): Phylogenetic classification is based on evolutionary relationships between organisms and assumes that organisms belonging to the same taxa have a common ancestor.

Assertion (A): The gametophyte of pteridophytes (prothallus) requires cool, damp, and shady places to grow. Reason (R): This specific restricted requirement, along with the need for water for fertilisation, limits the geographical spread of living pteridophytes to narrow regions.

Assertion (A): Angiosperms are divided into dicotyledons and monocotyledons. Reason (R): This division is based on whether the seeds are enclosed within fruits or are naked.

Assertion (A): Algae belonging to Rhodophyceae are completely aflagellate. Reason (R): Rhodophyceae reproduce sexually by non-motile gametes, and their sexual reproduction is oogamous and accompanied by complex post-fertilisation developments.

Assertion (A): The liverwort plant body is dorsiventral and closely appressed to the substrate. Reason (R): Liverworts possess multicellular and branched rhizoids that enable them to stand upright away from the substrate surface.

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