Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Plant ecology wikipedia , lookup
Plant physiology wikipedia , lookup
Plant secondary metabolism wikipedia , lookup
Plant evolutionary developmental biology wikipedia , lookup
Plant morphology wikipedia , lookup
Perovskia atriplicifolia wikipedia , lookup
Plant reproduction wikipedia , lookup
BOARD OF INTERMEDIATE EDUCATION Botany – Paper – 1 Model Question Paper (English Medium) Time: 3 hrs Max marks: 60 SECTION – A Answer all the questions (Very short answer type) (10 x 2 = 20) 1. What is growth? What is the difference between the growth in living organisms and growth in non-living objects? 2. What is the principle underlying the use of cyanobacteria in agriculture fields for crop improvement? 3. Mention the Ploidy of the following a) Leaf cell of a moss b) PEN in a dicotyledon c) Meristem cell of monocot d) Gemma cell in Marchantia 4. Why certain fruits are called false fruits? Name two examples of plants having false fruits? 5. What is the morphology of cup like structure in cyathium? In which family it is found? 6. Explain the scope and significance of ‘Numerical Taxonomy’? 7. What are micro bodies? What do they contain? 8. Glycine and Alanine are different with respect to one substituent on the α – carbon. What are the other common substituent groups? 9. Assume that the average duplication time of E.coli is 20 minutes. How much time will two E.coli cells take to become 32 cells? 10. Climax stage is achieved quickly in secondary succession as compared to primary succession. Why? SECTION – B Answer any six questions (Short answer type) (4 x 6 = 24) 11. Explain in brief the scope of Botany in relation to agriculture, horticulture and medicine. 12. Give the salient features and importance of chrysophytes? 13. Give a brief account on the phases of the life cycle of an angiosperm plant? 14. Describe essential floral parts of plants belonging to Liliaceae? 15. Describe centrosome? 16. Though redundantly described as a resting phase, interphase does not really involve rest. Comment. 17. A transverse section of the trunk of a tree shows concentric rings which are known as annual rings. How are these rings formed? What is the significance of these rings? 18. Define plant succession. Differentiate primary and secondary successions? SECTION – C Answer any two questions (Long answer type) (2 x 8 = 16) 19. Explain how stem is modified variously to perform different functions. 20. Describe the process of fertilization in angiosperms. 21. Describe the internal structure of dorsiventral leaf with the help of a labeled diagram. KEY TO THE MODEL QUESTION PAPER SECTION – A Answer all the questions (Very short answer type) (10 x 2 = 20) 1. What is growth? What is the difference between the growth in living organisms and growth in non-living objects? Increase in mass and size of an organism by means of cell division and differentiation is called growth. Growth in living organisms is from inside (internal). Whereas growth in non-living objects is external that is by accumulation of material on the surface. 2. What is the principle underlying the use of cyanobacteria in agriculture fields for crop improvement? Cyanobacteria like Nostoc and Anabaena can fix atmospheric Nitrogen by means of special cells called heterocysts. Hence they are used in agriculture fields for crop improvement. 3. Mention the Ploidy of the following a) Leaf cell of a moss b) PEN in a dicotyledon c) Meristem cell of monocot d) Gemma cell in Marchantia a) b) c) d) Leaf cell of a moss PEN in a dicotyledon Meristem cell of monocot Gemma cell in Marchantia - haploid (n) - triploid (3n) - diploid (2n) - haploid (n) 4. Why certain fruits are called false fruits? Name two examples of plants having false fruits? Some fruits are formed from floral parts like thalamus and pedicel along with the ovary. Such fruits are called false fruits. Ex: Pyrus malus (apple – thalamus) Anacardium occidentalis ( cashew nut – pedicel) 5. What is the morphology of cup like structure in cyathium? In which family it is found? Involucre of bracts forms the cup like structure in cyathium. It is seen in Euphorbiaceae. 6. Explain the scope and significance of ‘Numerical Taxonomy’? Scope of Numerical taxonomy: • It evaluates differences and similarities between taxonomic groups using mathematical methods. • It uses computers and processes data by assigning numbers and codes to all the characters. Significance of Numerical taxonomy: • All characters are given equal importance. • Hundreds of characters are considered at the same time. 7. What are micro bodies? What do they contain? Micro bodies are peroxisomes and glyoxysomes. Peroxisomes contain enzymes of fattly acid catabolism, peroxidation, and photo respiration. Glyoxisomes contain enzymes of glyoxylate cycle. 8. Glycine and Alanine are different with respect to one substituent on the α – carbon. What are the other common substituent groups? Substituent groups of amino acid are: H - Hydrogen COOH - Carboxyl group NH2 - Amino group R - Variable group like Hydrogen, methyl group or hydroxymethyl group 9. Assume that the average duplication time of E.coli is 20 minutes. How much time will two E.coli cells take to become 32 cells? 80 minutes. (Explanation) 2 cells - 20 minutes = 4 cells 4 cells - 20 minutes = 8 cells 8 cells - 20 minutes = 16 cells 16 cells – 20 minutes = 32 cells. 10. Climax stage is achieved quickly in secondary succession as compared to primary succession. Why? In primary succession formation of fertile soil takes several hundreds to thousands of years. Hence it will take very long time for establishment of biotic communities and climax stage is achieved at a slow pace. Whereas secondary succession starts in an area where soil or sediment is already present. Hence establishment of biotic communities is faster and climax stage is achieved quickly. SECTION – B Answer any six questions (Short answer type) (4 x 6 = 24) 11. Explain in brief the scope of Botany in relation to agriculture, horticulture and medicine. • • • • • • • • Knowledge of botany lead to experiments in hybridization and genetic engineering. Knowledge of plant breeding helps to develop hybrid varieties of rice, wheat, sugarcane etc. Mineral nutrition, plant hormones, seed dormancy, plant pathology etc are studied in botany and help in improving crops, and crop yields. A knowledge of plant pathology helps in identification, prevention and eradication of plant diseases. Increasing the shelf-life of vegetables and leafy vegetables, artificial ripening of fruits is possible with plant growth hormones. Botany helps in development of industries like cotton, paper, pharmacy, sugar etc. Medicinal plants are used in human and animal healthcare. Plant science is the basis for ayurvedic pharmacies. 12. Give the salient features and importance of chrysophytes? Chrysophytes belong to the kingdom protista. This group includes diatoms and golden algae (desmids). They may be freshwater or marine, microscopic and photosynthetic. The cell wall forms a shell with a epitheca and hypotheca made up of silica. ¾ Based on symmetry the diatoms may belong to centrales and pennales. ¾ They reproduce asexually by binary fission and sexually by production of auxospores. Importance of chrysophytes: ¾ They form diatomaceous earth (kiselguhr) used for polishing and filtration of oils and syrups. ¾ The diatoms are the chief producers in the seas and oceans. ¾ ¾ ¾ ¾ 13. Give a brief account on the phases of the life cycle of an angiosperm plant? Angiosperm lifecycle includes a dominant diploid sporophytic phase and a haploid gametophytic phase. Sporophytic phase: It is the diploid dominant phase in the life cycle. This plant body bears flowers which produce the male sex organs, stamens and female sex organs carpels or pistil. Microspores (pollen grains) are produced by meiosis in the anthers of androecium and Megaspores are produced in the ovule of the gynoecium. Gametophytic phase: The microspore develops into a male gametophyte which produces two male gametes. Megaspore develops into female gametophyte and produces egg cell (female gamete). During fertilization the male gamete and female gamete fuse to form a diploid zygote which develops into a embryo in the seed. Zygote is the first cell of sporophyte. During seed germination the embryo develops into a sporophytic plant. 14. Describe essential floral parts of plants belonging to Liliaceae? Androecium and gynoecium are considered as the essential parts of a flower. The essential floral parts of Liliaceae show the following characters: Androecium: There are six stamens in two whorls of 3 each. (3 + 3). They may be free or epiphyllous (attached to tepals). Anthers are dithecous, basifixed, introrse with longitudinal dehiscence. Gynoecium: Tricarpellary syncarpous gynoecium with trilocular superior ovary. Many ovules on axile placentation. Terminal style, stigma trifid or capitate. 15. Describe centrosome? ¾ Centrosome is the cell organelles usually found in animal cells. ¾ It contains two cylindricial structures called centrioles. ¾ Each centriole has a cartwheel like organization with nine fibrils made of tubulin. ¾ Each peripheral fibril is a triplet. The central part of the centriole is called hub and connected to peripheral triplets by radial spokes. ¾ The centrioles form the basal body of cilia, flagella and spindle fibres that give rise to spindle apparatus during cell division in animal cells. (figure on page 166 of Jr. botany text book) 16. Though redundantly described as a resting phase, interphase does not really involve rest. Comment. Interphase is not a resting phase but a preparatory phase for cell division because: ¾ During this phase the cell prepares for division by undergoing both cell growth and DNA replication. ¾ It includes three phases: G1 Phase (Gap 1) S phase (Synthesis) G2 Phase (Gap 2 ) ¾ During G1 phase the cell grows continuously. ¾ During S phase DNA synthesis or replication takes place (2C becomes 4C) ¾ During G2 phase proteins are synthesized and cell growth continues. ¾ The cell enters divisional phase only when it has completed all these phases of interphase. Hence interphase is not a resting phase but a preparatory phase. 17. A transverse section of the trunk of a tree shows concentric rings which are known as annual rings. How are these rings formed? What is the significance of these rings? In temperate regions more leaves and flowers are formed during spring and plant requires large amount of water and mineral salts. Hence the wood (Xylem vessels) formed during spring shows morenhumber of xylem vessels with wide lumens. This is called “spring wood” or early wood. During autumn the plants are less active and do not require more water and salts. Hence the wood produced during this period shows less number of xylem vessels having narrow lumens. This is known as “autumn wood” or late wood. In this way two types of wood are produced in one year. These two kinds of wood, spring wood and autumn wood that appear as concentric rings form an annual ring or a growth ring. Significance: By counting the number of annual rings, the approximate age of trees can be estimated. This branch of science is known as dendrochronology. 18. Define plant succession. Differentiate primary and secondary successions? The gradual changes in composition of plant species of a given area is called plant succession. Plant succession occurs in response to the changing environmental conditions. In plant succession there is an increase in number of species and increase in total biomass in an area. Primary succession It occurs in a bare area like newly cooled area, bare rock, newly created pond or reservoir. The establishment of new biotic communities is slow. It takes hundreds to thousands of years to produce fertile soil, hence succession is slow. It takes very long time to establish a climax community. Secondary succession It occurs in areas where natural biotic communities are destroyed or abandoned farm lands, burned or cut forest lands, flooded lands etc. Establishment of new communities is faster. Since some soil or sediment is already present, succession is faster. Climax community is achieved at a quicker pace. SECTION – C ANSWER ANY TWO QUESTIONS (LONG ANSWER TYPE) (2 x 8 = 16) 19. Explain how stem is modified variously to perform different functions. In some plants stems are modified to perform functions like storage of good, vegetative propagation, giving mechanical support and protection. The modifications of stems may be summed up into three categories: • Underground stem modifications • Aerial stem modifications • Sub-aerial stem modifications 1) Underground stem modifications: In some plants the stem grows into the soil and undergoes modification to perform additional functions like storage of food, perennation, vegetative propagation and protection from grazing animals. Some of the underground stem modifications are: a) Stem tuber: Ex: Potato b) Rhizome: Ex: Zinziber c) Corm: Ex; Colocasia d) Bulb: Ex: Onion 2) Aerial stem modifications: In some plants the stem is above ground (aerial) and may perform additional functions like climbing, protection, photosynthesis, storage and vegetative propagation. Some of the aerial stem modifications are: a) Stem tendrils: They are slender, spirally coiled structures which help in climbing. Ex: water melon b) Thorns: They are sharp pointed structures that help in protection. Ex: Bougainvillea. c) Phylloclades: They are photosynthetic stems in some xerophytic plants. Ex: Opuntia d) Bulbils: They are vegetative buds or floral buds that store food and help in vegetative propagation. Ex: Dioscorea 3) Sub-aerial stem modifications: a) Runners: Ex: Oxalis b) Stolons: Ex: Nerium c) Offsets: Ex: Pistia d) Suckers: Ex: Chrysanthemum (note: diagrams carry marks) 20. Describe the process of fertilization in angiosperms. In angiosperms process of fertilization follows pollination. The important events during the process of fertilization are as follows: ¾ After pollination the pollen tube enters the ovule and then into the embryosac with two male gametes in it. ¾ The pollen tube bursts and releases the two male gametes into the synergids. ¾ One of the male gametes fuses with the egg cell to form a diploid zygote. This process of fusion between a male gamete and the female egg cell is called ‘syngamy’ or ‘fertilization’. ¾ The second male gamete fuses with the diploid secondary nucleus in the central cell to form a triploid primary endosperm nucleus (PEN). This fusion of three nuclei ( one male and two polar nuclei) is called ‘triple fusion’. ¾ As fertilization occurs twice, i.e syngamy and triple fusion it is called double fertilization. ¾ Later the diploid zygote develops into an embryo and PEN (primary endosperm nucleus) becomes PEC (primary endosperm cell) which gives rise to triploid tissue called endosperm. (note: diagrams carry marks) 21. Describe the internal structure of dorsiventral leaf with the help of a labeled diagram. The transverse section of a dorsiventral leaf shows three main parts: ¾ Epidermis ¾ Mesophyll and ¾ Vascular system A. Epidermis: The epidermis is differentiated into upper epidermis (adaxial) and lower epidermis (abaxial). It is protected by a cuticle. More number of stomata are found on lower epidermis. B. Mesophyll: It is the tissue between the upper and the lower epidermis. It is photosynthetic in function. It is differentiated into palisade parenchyma and spongy parenchyma. I. Palisade parenchyma: It is made up of elongated cells parallel to each other. It is present below the upper epidermis. II. Spongy parenchyma: It is present between palisade cells and lower epidermis. The cells are oval or round and loosely arranged with large air cavities. C. Vascular system: It includes vascular bundles which are seen in veins and midrib. Each vascular bundle is surrounded by a layer of thick walled bundle sheath cells. The vascular tissues xylem and phloem are present in the vascular bundle. Note: see page 214 of academy text book for diagram.