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Plant Kingdom NCERT PDF

 Plant Kingdom NCERT PDF

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Plant Kingdom NCERT PDF

Plant Kingdom NCERT PDF Summary 

Dear readers, here we are offering Plant Kingdom NCERT PDF to all of you. American taxonomist Whitaker classified living beings into five kingdoms in 1969. The plant world is also commonly called the vegetable world. According to time, there have been many changes in the subject of this world, as initially it was considered in the plant world due to the cell wall in Fungi, Monera, and Protista. But now they are considered separate worlds.

Initially, cyanobacteria were considered as blue-green algae but now they are considered as prokaryotes. Multicellular, eukaryotic, photosynthetic organisms come under the plant kingdom. In the traditional system of classification (Ischler, 1883), the plant kingdom is divided into two suborders, the non-flowering plants (Cryptogamae) and the flowering plants (Phanerogamae).

Plant Kingdom NCERT PDF

Q.1- What is the basis of the classification of algae? 

Ans. The main basis of the classification of algae is the presence or absence of pigments. The classification is as follows:

        Chlorophyceae: In-class Chlorophyceae chlorophyll a and b both are present and impart a green color. Chlorophyceae are also called ‘blue-green algae. 

        Phaeophyceae: In-class Phaeophyceae chlorophyll a and c and fucoxanthin are present. Fucoxanthin imparts brown color. Phaeophyceae are also called ‘brown algae’. 

        Rhodophyceae: In-class Rhodophyceae chlorophyll a and d and phycoerythrin are present. Phycoerythrin imparts red color. Rhodophyceae is also called ‘red algae’.

Q.2- When and where does reduction division take place in the life cycle of a liverwort, a moss, a fern, a gymnosperm, and an angiosperm? 

Ans. In liverwort, moss, and fern, during sexual reproduction, the sporophytic phase of the plant produces haploid spores after meiosis which happens in the spore mother cells. While in gymnosperm and angiosperm, meiosis takes place in the anthers and ovary during the formation of pollen grains and ovules. 

Q.3- Name three groups of plants that bear archegonia. Briefly describe the life cycle of any one of them.

Ans. Bryophytes, Pteridophytes, and Gymnosperms are the three groups of plants that bear archegonia. The life cycle of  gymnosperms involves:

Reproduction: The gymnosperms are heterosporous and produce haploid microspores and megaspores. The micro and megaspores are produced within sporangia that are borne on sporophylls. The spores are arranged spirally along an axis to form lax or compact strobila or cones.

v The microsporangia or male strobili are strobili-bearing microsporophylls and microsporangia. The microspores develop into a male gametophytic generation which is highly reduced and is confined to a limited number of cells. This reduced gametophyte is called a pollen grain which develops within the microsporangia.

Female Gamete: The microsporangia or female strobili are the cones bearing megasporophylls with ovules or megasporangia. The male or female cones or strobili can be borne on the same tree as in Pinus or, of needle-like on the different trees as in Cycas. From one of the cells of the nucellus, the megaspore mother cell is differentiated. The nucellus is protected by envelopes and the composite structure that is called an ovule. The ovules are borne on megasporophylls which may get clustered to form the female cones. To form four megaspores the megaspore mother cell divides meiotically. Within the megasporangium or nucellus, one of the megaspores is enclosed and develops into a multicellular female gametophyte that bears two or more archegonia or female sex organs. Within the megasporangium, the multicellular female gametophyte is also retained.

Fertilization: The pollen grain is released from the microsporangium, is carried through air currents, and comes in contact with the opening of the ovules that develop on megasporophylls. In the ovules, the pollen tube carrying the male gametes grows towards the archegonia, and near the mouth of the archegonia, they discharge their contents. The zygote develops into an embryo and the ovules into seeds after completing fertilization.

Q.4- 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 fern; gemma cell in Marchantia; meristem cell of monocot, ovum of a liverwort, and zygote of a fern. 

Ans. The related ploidy is as follows:

Protonemal cell of a moss  Haploid
Primary endosperm nucleus in a dicot  Triploid
Leaf cell of a moss  Haploid
Prothallus of a fern  Haploid
Gemma cell in Marchantia  Haploid
Meristem cell of a monocot  Diploid
Ovum of a liverwort  Haploid
Zygote of a fern  Diploid

Q.5- Write a note on the economic importance of algae and gymnosperms. 

Ans. The note is as follows: 

Economic Importance of Algae: In a variety of ways the algae is useful to mankind. They perform half of the total carbon dioxide fixation on earth by photosynthesis, acting as the primary producers in aquatic habitats. Chlorella and Spirulina are rich in proteins. They are used as food supplements as many species of marine algae such as Porphyra, Sargassum, and Laminaria are edible. In the preparation of jellies and ice cream agar is used. It is obtained from Gelidium and Gracilaria. In chocolates, paints, and toothpaste carrageenan is used as an emulsifier. It is obtained from the red algae. Many red algae are used in treating worm infections eg. Corallina. 

Economic Importance of Gymnosperms: Gymnospermous plants are widely used as ornamentals. Many conifers such as pine, cedar, etc., are sources of softwood used in construction and packing. It has medicinal uses also as an anticancer drug Taxol is obtained from Taxus. For the treatment of asthma and bronchitis, many species of Ephedra are used which produce ephedrine. The seeds of Pinus gerardiana are edible. For manufacturing sealing waxes and water-proof paints, the resins are used commercially. Turpentine a type of resin is obtained from various species of Pinus.

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