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12. Describe the important characteristics of gymnosperms.

Important characteristics of gymnosperms 1. Gymnosperms are seed plants in which the seeds remain exposed over the surface of megasporophylls.  2. Gymnosperms are represented by 900 living species. 3. Gymnosperms are perennial and woody plants (either trees or bushes). The xylem of gymnosperms does not possess vessels except in Gnetum. Phloem is without companion cells and sieve tubes.  4. Two...

11. Match the following (column I with column II)


                 Column I                             Column II
            (a) Chlamydomonas                 (i) Moss
            (b) Cycas                                 (ii) Pteridophyte
            (c) Selaginella                         (iii) Algae
            (d) Sphagnum                         (iv) Gymnosperm

Correct matching is (a)-(iii), (b)-(iv), (c)-(ii), (d)-(i)   Column I                             Column II  (a) Chlamydomonas           (iii) Algae  (b) Cycas                            (iv) Gymnosperm  (c) Selaginella                     (ii) Pteridophyte  (d) Sphagnum                      (i) Moss

10. How would you distinguish monocots from dicots?

Differences between monocots and dicots are as follows: Monocots Dicots      Monocots possess seeds with a single cotyledon Dicots bear seeds with two cotyledons Monocots possess isobilateral leaves Dicots possess dorsiventral leaves The flowers of monocots are generally trimerous i.e. the number of sepals, petals, stamens and pistil is in the multiples of three in these plants The...

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

 

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

9. Differentiate between the following:-

            (iv) syngamy and triple fusion

The differences between syngamy and triple fusion are as follows:  Syngamy    Triple fusion It refers to the fusion of male gamete with female gamete i.e egg cell in angiosperms is called syngamy                                                                           It refers to the fusion of second male gamete with the 2 polar nuclei of the central cell. Since, in this fusion, 2 polar...

9. Differentiate between the following:-

            (iii) homosporous and heterosporous pteridophyte

 

Homosporous pteridophytes Heterosporous pteridophytes These pteridophytes produce only a single type of spores, hence are called homosporous pteridophytes These pteridophytes produce two types of spores i.e. microspores and megaspores. Hence, they are called heterosporous pteridophytes The produce only a single gametophyte which is bisexual.  They further form two types of gametophytes...

9. Differentiate between the following:-

            (ii) liverworts and moss

Differences between liverworts and mosses are as follows Liverworts Mosses     Sporophyte has very little photosynthetic tissue, so it is completely parasitic on the gametophyte Sporophyte contains more photosynthetic tissue                                    Scales often present Scales are mostly absent Gemma cups are present for vegetative reproduction in some liverworts Gemma cups...

9. Differentiate between the following:-

                (i) red algae and brown algae

Differences between red algae and brown algae are as follows: Red algae     Brown algae Red algae possess chlorophyll a, d and phycoerythrin  Brown algae consist of chlorophyll a, c and fucoxanthin They contain floridean starch as reserve food material Brown algae contain laminarin and mannitol as reserve food material Cell walls are composed of cellulose, pectin and phycocolloids The...

8. Explain briefly the following terms with suitable examples

                (6) isogamy

Isogamy- It refers to the process of fertilisation of two gametes which are exactly similar to each other in morphology, physiology, anatomy etc. Such gametes are called isogametes. 

8. Explain briefly the following terms with suitable examples

                (5) sporophyll

Sporophylls- These refer to leaf-like appendages bearing sporangia in pteridophytes, gymnosperms etc. Sporophylls can be either microsporophylls or megasporophylls and respectively they can form either microsporangia or megasporangia.

8. Explain briefly the following terms with suitable examples

                (4) diplontic

Diplontic- This is a term utilised for depicting the life cycle of angiosperms and gymnosperms. In this type of life cycle, the plant body is represented by a diploid plant i.e. sporophyte.  It bears sex organs that produce male and female gamete. The gametophyte is of reduced type and it is dependent on the sporophyte. The male and female gametes fuse and form zygote which develops on the...

8. Explain briefly the following terms with suitable examples

                (3) archegonium

Archegonium- It is female sex organ found in bryophytes, pteridophytes and gymnosperms. Based on the presence of archegonium, these three groups are referred to as archegoniate. It generally possesses a swollen venter and a tubular neck. The venter possesses ventral canal cells and neck contains neck canal cells. Archegonium also contains the female gamete which is called egg. 

8. Explain briefly the following terms with suitable examples

                (2) antheridium

Antheridium- It is the male sex organ found in bryophytes, pteridophytes and some algae. Antheridium encloses a mass of cells that give rise to male gametes. Generally, antheridium, remain enclosed by a jacket of sterile cells. 

8. Explain briefly the following terms with suitable examples:-

                (1) protonema

Protonema- It refers to the creeping, green, branched, often filamentous structure which is formed directly after the germination of moss spore. It represents the first stage in the life cycle of moss. Protonema is short-lived and it grows prostrate on the surface. Protonema bears rhizoids for the absorption of materials. 

7. What is heterospory? Briefly comment on its significance. Give two examples.

Heterospory- It refers to the existence of two types of meiospores i.e. microspores and megaspores in a single plant. These microspores and megaspores are formed respectively within microsporangia and megasporangia which in turn are borne on two distinct sporophylls called microsporophylls and megasporophylls respectively. The microspores and megaspores upon germination give rise to male and...

6. Both gymnosperms and angiosperms bear seeds, then why are they classified separately?

Both gymnosperms and angiosperms come under the group spermatophyta or seed-bearing plants. However, angiosperms and gymnosperms are classified separately in spermatophyta because gymnosperms possess naked seeds i.e. their seeds are not enclosed in ovary whereas angiosperms possess seeds that are enclosed in the ovary. 

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

Economic importance of algae  1. Green algae such as Ulva, Caulerpa, Enteromorpha, Chlorella etc are used as food rich in lipid, protein, vitamins, minerals etc. 2. Chlorella and Caulerpa are used to obtain antibiotics also.  3. A number of green algae such as Chlamydomonas, Chlorella, Scenedesmus etc are used in sewage oxidation tanks.  Economic importance of Gymnosperms 1. The seeds of Pinus...

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?

 

In the life cycle of a liverwort reduction division take place in the capsule for the formation of haploid spores that will grow into gametophytic thallus after germination. In mosses, the gametes fertilise and a zygote is formed. The zygote develops into the sporophyte. In the capsule of the sporophyte, reduction division takes place and haploid spores are formed which on germination give rise...

1. What is the basis of classification of algae?

Algae are chlorophyll-containing thallus-bearing plants characterised by the absence of embryo stage. A variety of algae are found in a variety of habitats. The various types of algae are classified on the basis of their pigments, flagellation and the reserve food material. Based on these criteria, algae are of three types i.e. red algae, brown algae and green...
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