NCERT Exemplar Class 11 Biology Solutions Chapter 3 Plant Kingdom

Multiple Choice Questions:

Question:1

What are Cyanobacteria are classified under?
(a) Plantae
(b) Protista
(c) Algae
(d) Monera

Answer:

Question:2

What is the term for the fusion of two motile gametes which are dissimilar in size?
(a) Anisogamy
(b) Isogamy
(c) Oogamy
(d) Zoogamy

Answer:

Question:3

Holdfast, stipe and frond constitutes the plant body in case of
(a) Phaeophyceae
(b) All of the above
(c) Rhodophyceae
(d) Chlorophyceae

Answer:

Question:4

A plant shows thallus level of organisation. It shows rhizoids and is haploid. It needs water to complete its life cycle because the male gametes are motile. Identify the group to which it belongs to
(a) Pteridophytes
(b) Bryophytes
(c) Monocots
(d) Gymnosperms

Answer:

Question:5

A Prothallus is
(a) A structure in pteridophytes formed before the thallus develops
(b) A sporophytic free living structure formed in pteridophytes
(c) A primitive structure formed after fertilisation in pteridophytes
(d) A gametophyte free living structure formed in pteridophytes

Answer:

Question:6

Plants of this group are diploid and well adapted to extreme conditions. They grow bearing sporophylls in compact structures called cones. The group in reference is
(a) Monocots
(b) Gymnosperms
(c) Pteridophytes
(d) Dicots

Answer:

Question:7

The embryo sac of an Angiosperm is made up of
(a) 8 cells
(b) 7 cells and 7 nuclei
(c) 8 nuclei
(d) 7 cells and 8 nuclei

Answer:

Question:8

If the diploid number of a flowering plant is 36. What would be the chromosome number in its endosperm?
(a) 36
(b) 54
(c) 18
(d) 72

Answer:

Question:9

Protonema is
(a) Haploid and is found in mosses
(b) Haploid and is found in pteridophytes
(c) Diploid and is found in pteridophytes
(d) Diploid and is found in liverworts

Answer:

Question:10

The giant Redwood tree (Sequoia sempervirens) is a/an
(a) Gymnosperm
(b) Free fern
(c) Pteridophyte
(d) Angiosperm

Answer:

Very Short Answer Type Questions:

Question:1

Food is stored as Floridean starch in Rhodophyceae. Mannitol is the reserve food material of which group of algae?

Answer:

Question:2

Give an example of plants with
(a) Haplontic life cycle
(b) Diplontic life cycle
(c) Haplo- diplontic life cycle

Answer:

Question:3

The plant body in higher plants is well-differentiated and well developed. Roots are the organs used for the purpose of absorption. What is the equivalent of roots in the less developed lower plants?

Answer:

Question:4

Most algal genera show haplontic lifestyle. Name an alga which is

(a) Haplo-diplontic, (b) Diplontic.

Answer:

Question:5

In Bryophytes, male and female sex organs are called ____ and ____.

Answer:

Short Answer Type Questions:

Question:1

Why are bryophytes called the amphibians of the plant kingdom?

Answer:

Question:2

Heterospory, i.e., the formation of two types of spores – microspores and megaspores are a characteristic feature in the life cycle of a few members of pteridophytes and all spermatophytes. Do you think heterospory has some evolutionary significance in the plant kingdom?

Answer:

Yes, heterospory has evolutionary significance in plant kingdom because heterospory is the formation of two types of spores differentiating in the size and the sex, microspores, and megaspores. Microspores are the male who is smaller in size, and megaspores are the female who is larger in size. In Pteridophytes, the microspores and megaspore sprout together to give rise to male and female gametophytes. In the end, the zygote matures in the female gametophyte. Seeds make it possible for gymnosperms and angiosperms to survive long periods of hostile conditions. Seeds have also made it possible for them to spread to a different geographical area by seed dispersal.

Question:3

How far does Selaginella, one of the few living members of lycopodiales (pteridophytes) fall short of seed habit?

Answer:

Ans. In Selaginella, the development of the zygote into the embryo takes place inside of the female gametophyte. The female gametophyte holds on to the parent plant for fluctuating periods. This is considered as a precursor, or the parent of seed habit as an improved version of this occurrence is observed in higher plants. Although, unlike seeds in higher plants; the embryo in Selaginella requires it to mature quickly to start the new generation.

Question:4

Each plant or group of plants has some phylogenetic significance in relation to evolution: Cycas, one of the few living members of gymnosperms, is called the ‘relic of past’. Can you establish a phylogenetic relationship of Cycas with any other group of plants that justifies the above statement?

Answer:

• In Cycas, the seeds are shed when the embryo is still developing or mature. In gymnosperms, seeds are shed solely when the embryo is mature.
• The megasporophylls look like a leaf.
• Even though the pollen tubes are present, the male gametes are flagellate.
• Leaf base is persistent in nature.
• Circinate ptyxis; which is similar as in Pteridophytes.

Question:7

Comment on the lifecycle and nature of a fern prothallus.

Answer:

Fern, which is a type of pteridophytes; reveals a haplo-diplontic state. In this situation, both the stages of gametophytic and sporophytic are multicellular. The diploid sporophyte is represented by a prepotent and independent, photosynthetic, vascular plant body. The haploid gametophyte, which is also independent in nature, but the duration of its life is shorter than that of the sporophytes.

Question:8

How are the male and female gametophytes of pteridophytes and gymnosperms different from each other

Answer:

Question:9

In which plant will you look for mycorrhiza and coralloid roots? Also, explain what these terms mean.

Answer:

Mycorrhiza, which is also known as ‘fungus-root’, is basically a mutually beneficial relationship between that of plant root and a fungus. In most cases, the fungus grows within the roots of the plants and helps the plant to absorb water and nutrients, and in return, the plant provides the fungus with food. E.g., Pinus. In some cases, the fungus could be harmful to the plants.

Coralloid Roots: These roots are associated with nitrogen-fixing cyanobacteria. In coralloid roots, the nodules are formed in large numbers, in the roots giving them coralloid appearance. E.g. Cycas and plants of Leguminosae.

Long Answer Type Questions:

Question:1

Gametophyte is a dominant phase in the life cycle of a bryophyte. Explain.

Answer:

The dominant phase in bryophytes is represented by gametophytic plants. The gametophyte is self-reliant, photosynthetic, and erect. Antheridia and archegonia are developed and found on the gametophyte. These male and female organs are multicellular in nature. The Antheridia and Archegonia carry the male and female gametes. The antheridium produces biflagellate antherozoids, while the archegonium produces a single egg. Water helps to carry the antherozoids to the archegonium. The antherozoids flagellate, which gives them the feature to be motile. After the process of fertilisation, the zygote is formed. The zygote develops into a multicellular figure called a sporophyte.

The sporophyte in bryophytes is smaller comparably and is not self-reliant. The sporophyte is attached to the gametophyte and gets it nutrition from the gametophyte. The gametophyte has control over the life cycle of a bryophyte in every phase. The gametophyte is self-independent and photosynthetic. The size of the gametophyte is larger in size as compared to the sporophyte. Also, the sporophyte is not independent and holds on to the gametophyte for nutrition.

Question:2

With the help of a schematic diagram, describe the haplo-diplontic life cycle pattern of a plant group.

Answer:

Ans. Pteridophyte and Bryophyte both reveal a haplo-diplontic life cycle. The diploid phase is not independent in bryophytes; however, it is independent in the case of pteridophytes. Furthermore, the sporophyte is more clearly visible in the case of pteridophytes than in bryophytes.

Question:3

Lichen is usually cited as an example of ‘symbiosis’ in plants where an algal and a fungal species live together for their mutual benefit. Which of the following will happen if algal and fungal partners are separated from each other?
(a) Both will survive and grow normally and independent of each other.
(b) Algal components will survive while the fungal component will die.
(c) Both will die
(d) The Fungal component will survive while the algal partner will die.
Based on the answer, how do you justify this association as symbiosis?

Answer:

Question:4

Explain why sexual reproduction in angiosperms is said to take place through double fertilisation and triple fusion. Also, draw a labelled diagram of embryo sac to explain the phenomena.

Answer:

In the process of double fertilisation in case of angiosperms; one male gamete fuses with the female gamete, and the second male gamete fuses with the secondary nucleus. This fusion of the male and female gametes results in the outcome of the zygote. And the fusion between the second male gamete and the secondary nucleus results in the outcome of the primary endosperm nucleus. Since two occurrences of fusion of nuclei take place, thus it is called double fertilisation. These following figures show double fertilisation:

Question:5

Draw labelled diagrams of the following:
(a) Female and male thallus of a liverwort.
(b) Gametophyte and sporophyte of Funaria.
(c) Alternation of generation in Angiosperm.

Answer: