NCERT Solutions for Class 11 Biology Chapter 3 – Plant Kingdom

NCERT Solutions for class 11 Chapter 3 Plant Kingdom: The chapter on microbes In human welfare is important for students approaching the board exams. This article introduces NCERT solutions designed to help students explain the concepts of further learning and how to write to get good grades on exams. The solutions are presented in very simple language for ease of understanding.

NCERT CBSE Chapter 3 Plant Kingdom of Class 11 explains all the characteristics of plants. Different subgroups, functions, and differences between different subgroups. Importance of plant kingdom.  Revise the basic concepts of Plant Kingdom for quick revision and class notes.

Q1: What is the Basis of the Classification of Algae?

Answer: 

Algae are mostly aquatic (freshwater and marine), simple, thalloid, autotrophic organisms that consist of chlorophyll. They can also be present in moist rocks, soils, and wood, among other environments. Algae are present in environments ranging from oceans, rivers, and lakes to ponds, salt water, and even ice. Algae are often green, but they can be present in a variety of various colors. For Example, algae living in snow consist of carotenoid pigments and chlorophyll, as a result giving the surrounding snow a unique red h.

The algae are categorized into three main groups: Chlorophyceae, Phaeophyceae, and Rhodophyceae

Feature	Green Algae	Brown Algae	Red Algae
Scientific Name	Chlorophyceae	Phaeophyceae	Rhodophyceae
Location	Chlorophyceae species can also be found on the ground as well as in brackish and salt water,	Phaeophycease is present on chilly coastal seas.	Red Algae are present in freshwater and marine environments.
Pigments	They are usually green due to the presence of the pigments chlorophyll a and chlorophyll b.	They are usually Brown due to the presence of the pigments chlorophyll a and chlorophyll c.	They are usually green due to the presence of the pigments chlorophyll a and chlorophyll d.
Storage Food	They are used starch as reserved food	They used laminarin as reserved food	They are using Floridian as reserved food
Cell Wall	Cell Wall made up of cellulose	The Cell Wall is made up of cellulose and align	The Cell Wall is made up of cellulose and polysulphate esters
Flagella	Present in 9+2 Configuration	Present	Absence

Q2: When and where does Reduction Division take place in the Life cycle of a Liverwort, a Moss, a Fern, a Gymnosperm, and an Angiosperm?

Answer: 

1. Liverworts: The name Hepaticopsida comes from the word “hepatic” which means liver. Liverworts are a type included in this group of bryophytes. Contains about 900 different species are the most prevalent bryophytes. As a result of their near proximity to water, they can be mostly found in moist soil and rocks. In liverworts, meiosis occurs in the spore mother cells of the sporangium, resulting in the production of haploid spores. The sporophyte is comprised of only the capsule (in Riccia) or foot, seta, and capsule (in Marchantia). The columella is absent inside the capsule.
2. Mosses: Bryopsida is a specific class of Bryophyta and consists of approximately 1400 species. They are also referred to as Mosses. Most mosses are found in wet environments. Moss meiosis occurs in the spore mother cells of the spore sac in the sporangium capsule.
3. Fern: The sporangia are supported on the sporophyte (fertile leaves). The process of meiosis takes place in the spore mother cells of the sporangia to form haploid spores.
4. Gymnosperm: In Gymnosperm Meiosis take place in microsporangia present in microsporophylls, in microspore mother cells for the production of haploid pollen grains that provide to the male gametophyte.
5. Angiosperm: Pollen grains produced in the microspore mother cells lead to the production of the male gametophyte in the anther of the stamen. The megaspore mother cell present in the nucleus of the ovule undergoes meiosis to form the haploid megaspore, which eventually forms the female gametophyte.

Q3: Name Three Groups of Plants that bear Archegonia. Briefly describe the Life cycle of any one of them.

Answer: 

The three group of plants that bear archegonia that is Bryophytes, Pteridophytes, and Gymnosperms.

The Life Cycle Of Pteridophytes

The life span of pteridophytes consists of a maze of generations. This is referred to as metagenesis. For example, seed plants and mosses have a diploid generation which alternates with a haploid generation. The diploid generation is the sporophyte that developed spores. The haploid generation is the gametophyte that generates the gametes. Both sporophytes and gametophytes lead independent and span-independent life.

Sporophyte Generation: The most important characteristics of sporophyte generations are given below.

• Sporophyte generation is the dominant and longer stage compared to the gametophyte generation.
• The plant produces spores that are carried by the wind to distant places.
• Spores are produced by the spore mother cells by meiosis.
• Most plants produce similar spores, like Lycopodium. And furthermore, some plants are heterosporous because they produce two types of spores; Microspores and Macrospores. Like Selaginella.
• Male antheridia are produced by microspores and megaspores produce female archegonia.
• Under optimum conditions, these spores germinate into small independent gametophytes that is known as prothallus.

Gametophyte Generation: The most important characteristics of gametophyte generations are given below.

• Prothallus (gametophyte) can develop only in a moist and cool shady place. Their development is limited to only a few places.
• Gametophytes are multicellular and photosynthetic.
• They have a male sex organ known as antheridia and female sex organ archegonia is present.
• In antheridia, the sperm merges with the egg in the archegonia resulting in the formation of the zygote.
• The zygote later produces a multicellular sporophyte.
• Therefore the life cycle of Pteridophyte gets completed.

Q4: Mention the Ploidy of the following: Protonemal cell of a Moss; Primary Endosperm nucleus in dicot, leaf cell of a Moss; prothallus cell of a ferm; gemma cell in Marchantia; meristem cell of monocot, ovum of a Liverwort, and zygote of a fern.

Answer: 

Cell	Type of Ploidy
Protonemal cell of a moss	Haploid
Primary endosperm nucleus in dicot	Triploid
leaf cell of a moss	Haploid
Prothallus cell of a ferm	Haploid
Gemma cell in Marchantia	Haploid
Meristem cell of monocot	Diploid
Ovum of a liverwort	Haploid
Zygote of a fern	Diploid

Q5: Write a note on the Economic Importance of Algae and Gymnosperms.

Answer: 

Economic Importance of Algae

1. Algae are mostly aquatic (freshwater and marine), simple, thalloid, autotrophic organisms that consist of chlorophyll.
2. Algae fix carbon dioxide with the use of photosynthesis
3. It enhances the level of dissolved oxygen in the area around them.
4. They produce abundant substances that provide food for aquatic animals.
5. Seaweed is consumed as food. For Example Laminaria with Sargassum,
6. Some algae are utilized to create hydrocolloids.
7. Agar is used to prepare jellies and to culture microorganisms.
8. Chlorella is used as food by astronauts.
9. The algae may reproduce through sexual, asexual, and vegetative methods. Vegetative reproduction is by fragmentation.
10. Algae are helpful to the pharmaceutical industry. Chlorella is the source of the antibiotic chlorella.

Economic Importance of Gymnosperms:

1. Gymnosperms are utilized in the form of ornamental plants. Some are bonsai plants that are used as ornaments in formal gardens
2. Their fibers are used to make paper pulp
3. Turpentine and resins are achieved from conifer resin.
4. Some useful oils are extracted from gymnosperms including junipers, pines, hemlocks, firs, spruce, and arborvitae.
5. Gymnosperm seeds are included in foods like baked products.
6. occasionally used for the production of silk and other textiles
7. Many gymnosperms have medicinal uses. The fresh juice extracted from the leaves of Cycas sarcinalis is used as a medicine for stomach disorders.
8. Some species of Pinus are the best sources of turpentine, wood gas, and wood alcohol.

Q6: Both Gymnosperms and Angiosperms bear seeds, then why are they classified separately?

Answer: 

Both gymnosperms and angiosperms are seed-bearing plants, but gymnosperms are differentiated from angiosperms by the presence of open megasporophylls to which the ovules are freely exposed. In angiosperms, ovules are enclosed in ovaries, which eventually develop into fruits. Gymnosperms have haploid endospores that form before fertilization, whereas angiosperms have triploid endosperms that develop following double fertilization. Gymnosperms do not undergo double fertilization, but double fertilization occurs in angiosperms.

Q7: What is Heterospory? Briefly comment on its significance. Give two examples.

Answer: 

Heterospory is the presence of two different types of spores in the same plant. The smaller of these spores are referred to as microspores, and the larger ones are known as megaspores. Pteridophytes were the first to develop heterospores. Homosporous bryophytes are monosporangiate, or their sporophytes have only one form of capsule, and the gametophyte is dominant.

Significance of Heterospory:

• Seed development is induced by heterospory.
• Heterospory helps to distinguish between male and female gametophytes.
• As the spores in homosporous pteridophytes must germinate on soil, they are more sensitive to environmental issues.
• Heterospory causes the development of seeds in gymnosperms and angiosperms.
• Examples: Salvinia, Selaginella

Q8: Explain briefly the following terms with suitable examples:-

1. Protonema
2. Antheridium
3. Archegonium
4. Diplontic
5. Sporophyll
6. Isogamy

Answer: 

1. Protonema: A protonema is a thread-like chain of cells that form the initial stages of the gametophyte produced during the life cycle of the moss. It is typically a branched, green, and fibrous structure produced by a germinating moss or fern spore. The protonema is a branching network of multicellular filaments excellent source of chlorophyll that is produced directly from the germinating spore in most mosses. For Instance: Funaria
2. Antheridium: The male sex organ referred to as the antheridium, is a sac-like structure composed of a jacket of sterile cells one cell is thick; It encloses a number of cells, each of which when they are completely produces a single sperm. The antheridium is often connected to the gametophyte by a slender stalk. For Instance, Antheridia are present in many fungi and algae throughout the reproductive stages,
3. Archegonium: Archegonia is the female reproductive organ that is non-flowering including mosses, ferns, hornworts, some algae, and some conifers. The archegonium consists of an egg that will be fertilized and developed into a sporophyte. They are jacketed and multicellular and have a neck and swollen venter. Archegonia are usually present on the surface of the plant thallus, and they are embedded in hornworts. For instance-cycads and conifers
4. Diplontic: The zygote divides mitotically to form a multicellular diploid individual or an assembly of multiple unicellular diploid cells during gametic meiosis. Diploid cells then go through meiosis to develop haploid cells or gametes. Haploid cells can divide once more (through mitosis) to produce new haploid cells. Individuals or cells formed as a result of mitosis are referred to as haploids, and this life cycle is referred to as the Diplontic life cycle. For Instance, Sargassum.
5. Sporophyll: A sporophyll is a spore-producing leaf. Sporophylls are a type of diploid sporophyte, and meiosis produces spores, which germinate to form haploid gametophytes. In a plant, if the sporophyll bears female sporangia, they are referred to as megasporophyll. If the sporophyll bears male sporangia, they are referred to as microsporophyll. Sporophylls promote the development of male and female seed plant gametophytes. These structures combine together to produce strobili (cones). For instance, Pinus
6. Isogamy: Isogamous reproduction is a type of sexual reproduction in which the morphology of both gametes participating in fertilization is comparable. They are not differentiated as male or female. The algae Ulothrix and Spirogyra are examples of isogamous reproduction. These species produce a large number of gametes.

Q9: Differentiate between the following:-

1. Red algae and brown algae
2. Liverworts and moss
3. Homosporous and heterosporous pteridophyte

Answer: 

• Red algae and brown algae

Red Algae	Brown Algae
They are usually green due to the presence of the pigments chlorophyll a and chlorophyll d.	They are usually Brown due to the presence of the pigments chlorophyll a and chlorophyll c.
Centrioles and flagella are absense in Red Algae.	Flagella are present.
It is reserved food as Floridian starch	It reserved food as laminarin  starch
Red algae can reproduce vegetatively, commonly by fragmentation.	They can reproduce both sexually or asexually.

• Liverworts and moss

Liverworts	Moss
It is generally dichotomously branched and could be thalloid, i.e., flat or spiral in shape.	The plant body of a gametophyte is divided into prostrate, branched filamentous, thalloid protonema, and leafy erect gametophore.
There is no protonema phase in the life cycle of liverworts.	Moss starts with the protonema phase.
The plant body is dorsoventral.	The plant body is separated into a stem axis
Elater are present but some liverworts are absent for example Riccia	There is no elater.

• Homosporous and heterosporous pteridophyte

Homosporous	Heterosporous
It consists of only one type of spores	It consists of different types of Spores
These spores are equal in size	The smaller of these spores are referred to as microspores, and the larger ones are known as megaspores.
This is produced by only one type of gametophyte	The Microspores are produced by male gametophytes and megaspores are produced by female gametophytes.
For Example Lycopodium	For Example Salvinia

Q10: Match the following (column I with column II)

Column I	Column II
Chlamydomonas	Moss
Cycas	Pteridophyte
Selaginella	Algae
Sphagnum	Gymnosperm

Answer:

Column I	Column II
Chlamydomonas	Algae
Cycas	Gymnosperm
Selaginella	Pteridophyte
Sphagnum	Moss

Q11: Describe the Important Characteristics of Gymnosperms.

Answer: 

The term  “Gymnosperm” originated  from the Greek words “gymnos”( meaning naked) and “Sperma”( meaning seed), therefore is referred to as “Naked seeds.” The plants that produce seeds are known as gymnosperms, but unlike angiosperms, they developed seeds devoids of fruits. These plants are produced on the surface of scales or leaves, or at the tip of stalks forming a cone-like structure.

Gymnosperms are part of the kingdom ‘Plantae‘ and sub-kingdom ‘Embryophyta’. According to the fossil evidence that they originated through the Paleozoic era, around 390 million years ago.

In contrast to angiosperms, gymnosperms are plants in which the ovules are not encased within the ovary wall. It continues to be exposed both before and after fertilization as well as before becoming a seed. Gymnosperm stems can have branches or be unbranched. The rate of water loss in these plants is slowed down by their thick cuticle, needle-like leaves, and recessed stomata.

The family of gymnosperms contains conifers, cycads, gnetophytes, and the species of Gynkgophyta category and Ginkgo biloba.

Characteristics of Gymnosperms

• Some important characteristics of gymnosperms:
• Flowers are not produced by them.
• Fruits do not develop seeds inside of them. They are unclothed.
• They are present in colder areas where snowfall occurs.
• They produced needle-like leaves.