प्रश्न 1.बादलों के आने पर प्रकृति में जिन गतिशील क्रियाओं को कवि ने चित्रित किया है, उन्हें लिखिए। उत्तर- बादलों के आने पर प्रकृति में निम्न गतिशील क्रियाएँ हुई
बयार नाचती-गाती चलने लगी।
पेड़ झुकने लगे, मानो वे गरदन उचकाकर बादलों को निहार रहे हों।
आँधी चलने लगी। धूल उठने लगी।
नदी मानो बाँकी नज़र उठाकर ठिठक गई। पीपल का पेड़ झुकने लगा।
लताएँ पेड़ों की शाखाओं में छिप गईं।
तालाब जल से भर गए।
क्षितिज पर बिजली चमकने लगी।
धारासार जल बरसने लगा जिसके कारण जगह-जगह से बाँध टूट गए।
प्रश्न 2.निम्नलिखित किसके प्रतीक हैं?
धूल
पेड़
नदी
लता
ताल
उत्तर-नीचे दिए गए शब्द और उनके प्रतीक इस प्रकार हैं-
धूल- मेघ रूपी मेहमान के आगमन से उत्साहित अल्हड़ बालिका का प्रतीक है।
पेड़- गाँव के आम व्यक्ति का प्रतीक है जो मेहमान को देखने के लिए उत्सुक है।
नदी- गाँव की नवविवाहिता का प्रतीक है जो पूँघट की ओर से तिरछी नज़र से मेघ को देखती है।
लता- नवविवाहिता मानिनी नायिका का प्रतीक है जो अपने मायके में रहकर मेघ का इंतजार कर रही है।
ताल- घर के नवयुवक का प्रतीक है जो मेहमान के पैर धोने के लिए पानी लाता है।
प्रश्न 3.लता ने बादल रूपी मेहमान को किस तरह देखा और क्यों? उत्तर-लता ने बादल रूपी मेहमान को किवाड़ की ओट में छिपकर देखा। क्यों—वह मानिनी है। वह अपने प्रियतम के कई दिनों के बाद आने पर उनसे रूठी हुई भी है और उन्हें देखे बिना भी नहीं रह पाती।
प्रश्न 4.भाव स्पष्ट कीजिए
क्षमा करो गाँठ खुल गई अब भरम की
बाँकी चितवन उठा, नदी ठिठकी, पूँघट सरके।
उत्तर-
भाव यह है कि एक साल बीतने को हो रहे थे पर नवविवाहिता लता का पति मेघ उससे मिलने नहीं आया था। इससे लता के मन में जो भ्रम बन गया था वह मेघ के आने से टूट गया और वह क्षमा माँगने लगी।
मेघ रूपी मेहमान को देखने के लिए नदी रूपी नवविवाहिता ठिठक गई और उसने पूँघट उठाकर मेहमान को देखा।
प्रश्न 5.मेध रूपी मेहमान के आने से वातावरण में क्या परिवर्तन हुए? उत्तर- मेघ के आने से बयार चलने लगी। पेड़ झुकने लगे। आँधी और धूल चलने लगी, नदी बाँकी होकर बहने लगी। बूढे पीपल झुकने लगे। लताएँ पेड़ की ओट में छिपने लगीं। तालाब जल से भर उठे। आकाश में मेघ छा गए। अंत में धारासार वर्षा हुई। मेहमान (दामाद) के आने पर गाँव की कन्याएँ और युवतियाँ प्रसन्न हो उठीं। लोग अपने खिड़की-दरवाजे खोलखोलकर उन्हें निहारने लगे। आते-जाते लोग उन्हें गरदन उठाकर देखने लगे। नवयुवतियों ने पूँघट सरकाकर उन्हें निहारा। बूढी स्त्रियाँ विनम्रतापूर्वक उनका स्वागत करने लगीं। अतिथि की प्रिया मान करने लगी। फिर अचानक वह क्षमा माँगने लगी। दोनों की आँखों से प्रेमाश्रु बह चले।
प्रश्न 6.मेघों के लिए ‘बन-ठने के, सँवर के आने की बात क्यों कही गई है? उत्तर- मेघों के लिए ‘बन-ठन के, सँवर के आने की बात इसलिए कही गई है क्योंकि वर्षा के बादल काले-भूरे रंग के होते हैं। नीले आकाश में उनका रंग मनोहारी लगता है। इसके अलावा गाँवों में बादलों का बहुत महत्त्व है तथा उनका इंतजार किया जाता है।
प्रश्न 7.कविता में आए मानवीकरण तथा रूपक अलंकार के उदाहरण खोजकर लिखिए। उत्तर- मानवीकरण-
मेघ आए बड़े बन-ठन के सँवर के
आगे-आगे नाचती-गाती बयार चली
पेड़ झुक झाँकने लगे, गरदन उचकाए
धूल भागी घाघरा उठाए
बाँकी चितवन उठा, नदी ठिटकी
रूपक – क्षितिज-अटारी गहराई।
प्रश्न 8.कविता में जिन रीति-रिवाजों का मार्मिक चित्रण हुआ है, उनका वर्णन कीजिए। उत्तर- कविता में अनेक रीति-रिवाजों का मार्मिक चित्रण हुआ है; जैसे-
मेहमान के आने की सूचना पाकर सारा गाँव उल्लसित हो जाना।
उत्साहित एवं जिज्ञासु होकर मेहमान को देखना।
घर के बुजुर्ग द्वारा मेहमान का आदर-सत्कार करना।
प्रश्न 9.कविता में कवि ने आकाश में बादल और गाँव में मेहमान (दामाद) के आने का जो रोचक वर्णन किया है, उसे लिखिए। उत्तर- मेघ रूपी शहरी पाहुन के आते ही पूरा गाँव उल्लास से भर उठा। शीतल बयार नाचती-गाती हुई पाहुन के आगे-आगे चलने लगी। सभी ग्रामवासियों ने अपने दरवाजे और खिड़कियाँ खोल लिए, ताकि वे पाहुन के दर्शन कर सकें। पेड़ उचक-उचककर पाहुन को देखने लगे। आँधी अपना घाघरा उठाए दौड़ चली। नदी बंकिम नयनों से मेघ की सज-धज को देखकर हैरान हो गई। गाँव के पुराने पीपल ने भी मानो झुककर नमस्ते की। आँगन की लता संकोच के मारे दरवाजे की ओट में सिकुड़ गई और बोली-तुमने तो बरसों बाद हमारी सुध ली है। गाँव का तालाब पाहुन के स्वागत में पानी की परात भर लाया। क्षितिज रूपी अटारी लोगों से लद गई। बिजली भी चमकने लगी। इस प्रकार पूरा गाँव उल्लास से तरंगित हो उठा।
प्रश्न 10.काव्य-सौंदर्य लिखिए- पाहन ज्यों आए हों गाँव में शहर के। मेघ आए बड़े बन-ठन के सँवर के। उत्तर- भाव सौंदर्य- इन पंक्तियों में शहर में रहने वाले दामाद का गाँव में सज-सँवरकर आने का सुंदर चित्रण है। शिल्प-सौंदर्य
पाहुन ज्यों आए हों गाँव में शहर के’ में उत्प्रेक्षा अलंकार, ‘बड़े बन-ठनके’ में अनुप्रास तथा ‘मेघ आए बड़े बन-ठन के सँवर के’ में मानवीकरण अलंकार है।
1. Define growth, differentiation, development, dedifferentiation, redifferentiation, determinate growth, meristem and growth rate. Solution: Growth is defined as a vital process which brings about an irreversible and permanent change in the shape, size, form, weight and volume of a cell, organ or whole organism, accompanied with increase in dry matter. Differentiation is a localised qualitative change in size, biochemistry, structure and function of cells, tissues or organs, e.g., fibre, vessel, tracheid, sieve tube, mesophyll, leaf etc. Thus it is a change in form and physiological activity. It results in specialisation for particular functions. Development may be defined as a process which includes growth, differentiation and maturation in a regular sequence in the life history of a cell, organ or organism viz., seed germination, growth, differentiation, flowering, seed formation and senescence. Dedifferentiation is the process by which the differentiated cells which have lost the ability to divide under certain circumstances, become meristematic and regain the divisibility. Redifferentiation is defined as maturation or differentiation of dedifferentiated cells to form cells which are unable to divide e.g., secondary xylem elements, cork cells etc., are formed by redifferentiation of secondary cambial cells. Determinate growth is the ability of a cell, tissue or the organism to grow for a limited period of time. Meristem is a tissue consisting of unspecialised immature cells, possessing the power of continuous cell division and adding new cells to the body. Growth rate is defined as the increased growth per unit time.
2. Why is not any one parameter good enough to demonstrate growth throughout the life of a flowering plant? Solution: A flowering plant consists of a number of organs viz., roots, stem, leaves, flowers, fruits etc. growing differently under different stages of life cycle. These plant organs require different parameters to demonstrate their growth. In plant organs like fruits, bulbs, corms etc. fresh weight is used for measuring their growth. In case of fruits, increase in volume, diameter etc., are also used as other parameters for the measurement of their growth. For flat organs like leaves, increase in surface area is used as the parameter. Stem and roots primarily grow in length and then in girth, thus increase in length and diameter are used for measuring their growth. Consequently, the flowering plants exhibit several parameters to demonstrate growth.
3. Describe briefly (a) Arithmetic growth (b) Geometric growth (c) Sigmoid growth curve (d) Absolute and relative growth rates Solution: (a) Arithmetic growth: If the length of a plant organ is plotted against time it shows a linear curve, the growth is called arithmetic growth. In this growth, the rate of growth is constant and increase in growth occurs in arithmetic progression e.g., length of a plant is measured as 2,4, 6, 8,10,12 cms at a definite interval of 24 hrs. It is found in root or shoot elongating at constant rate. Arithmetic growth is expressed as Lt = L0 + rt Here, Lt = length after time t. L0 = length at the beginning, r = growth rate. (b) Geometric growth: Geometric growth is the growth where both the progeny cells following mitosis retain the ability to divide and continue to do so. It occurs in many higher plants and in unicellular organisms when grown in nutrient rich medium. Number of cells is initially small so that initial growth is slow which is called lag phase. Later on, there is rapid growth at exponential rate. It is called log or exponential phase. (c) Sigmoid growth curve: Geometric growth cannot be sustained for long. Some cells die. Limited nutrient availability causes slowing down of growth. It leads to stationary phase. There may be actually a decline. Plotting the growth against time will give a typical sigmoid or S-curve. S-curve of growth is typical of most living organisms in their natural environment. It also occurs in cells, tissues and organs of plants. (d) Absolute growth rate is the measurement of total growth per unit time. Relative growth rate is growth per unit time per unit initial growth. Growth in given time period/ Measurement at start of time period Suppose two leaves have grown by 5 cm2 in one day. Initial size of leaf A was 5 cm2 while that of leaf B was 50 cm2. Though their absolute growth is the same (5 cm2/day), relative rate of growth is faster in leaf A(5/5) because of initial small size than in leaf B(5/50).
4. List five main groups of natural plant growth regulators. Write a note on discovery, physiological functions and agricultural/ horticultural applications of any one of them. Solution: There are five main groups of natural plant growth regulators which are very much recognised as natural hormones in plants. These are:
Auxins
Gibberellins
Cytokinins
Abscisic acid
Ethylene
Discovery of auxin: In 1880, Charles Darwin and Francis Darwin worked with the coleoptile of canary grass (Phalaris sp.) and found the existence of a substance in coleoptile tip, which was able to recognise the light stimulus and leads to the bending of tip towards light. Boysen and Jensen (1910-1913) worked on Avena seedling and explained that the substances secreted in the tip are soluble in water (gelatin). Paal (1919) reported that the substances secreted in the tip are translocated downwards and caused cell elongation in half portion which was on the dark side and hence bending was observed in opposite direction. F.W. Went (1928) further refined this experiment and supported the observations of Paal. He was the first person to isolate and name these substances of tip as auxins (Greek Auxein – means ‘to grow’). In 1931, Kogl and Haagen-Smith isolated crystalline compounds from human urine. These were named as auxin-a, auxin-b and heteroauxin.
Physiological functions of auxins:
Auxins induce cambial cell divisions, shoot cell elongation and early differentiation of xylem and phloem in tissue culture experiments.
In general, auxins initiate rooting but inhibit the growth of roots. IBA is the most potent root initiator.
Auxins inhibit the growth of axillary buds (apical dominance) but enhance the size of carpel and hence earlier fruit formation.
Application of auxins retards the process of senescence (last degradative phase), the abscission of leaves, fruits, branches, etc.
Auxins induce feminisation, i.e., on male plant, female flowers are produced.
Agricultural/horticultural application of auxins:
Application of auxins like IAA, IBA, NAA induce rooting in stem cuttings of many plants. This method is widely used to multiply several economically useful plants.
Normally, auxins inhibit flowering however in litchi and pineapple, application of auxin promotes flowering thus used in orchards.
Auxin induces parthenocarpy in some plants including tomato, pepper, cucumber and Citrus, thus, produces seedless fruits of more economic value.
Auxins like 2, 4-D and 2, 4, 5-T are commercially used as weedicides, due to their low cost and greater chemical stability. They are selective herbicides (killing broad-leaved plants, but not grasses).
For checking premature fruit drop, auxins are applied which prevent the formation of abscission zone in the petiole or just below the fruit. Auxin regulates maturing fruit on the trees of apples, oranges and grape fruit. High doses of auxins can cause fruit drop. Thus, heavy applications of synthetic auxins are used commercially to promote a coordinated abscission of various fruits to facilitate harvesting.
Auxin, produced in the apical bud, suppresses the development of lateral buds, i.e., apical dominance. Thus practically used in prolonging the dormancy period of potato tubers.
Naphthalene acetamide is used to prevent the lodging (excessive elongation and development of weak plants, specially in gramineae) or falling of crops.
Auxin (2,4-D) promotes callus formation in tissue culture. Complete plantlets are regenerated from callus tissue, using auxins and cytokinin which are then transplanted into the soil. Now-a-days, this is a widely practised method of propagation in the field of agriculture and horticulture.
5. What do you understand by photoperiodism and vernalisation? Describe their significance. Solution: The physiological mechanism for flower-ing is controlled by two factors: photoperiod or light period, i.e., photoperiodism and low temperature, i.e., vernalisation. Photoperiodism is defined as the flowering response of a plant to relative lengths of light/ dark period. Significance of photoperiodism is as follows:
Photoperiodism determines the season in which a particular plant shall flower. For example, short day plants develop flowers in autumn-spring period (e.g., Dahlia, Xanthium) while long day plants produce flowers in summer (e.g., Amaranthus).
Knowledge of photoperiodic effect is useful in keeping some plants in vegetative growth (many vegetables) to obtain higher yield of tubers, rhizomes etc. or keep the plant in reproductive stage to yield more flowers and fruits.
A plant can be made to flower throughout the year by providing favourable photoperiod.
Helps the plant breeders in effective cross-breeding in plants.
Enable a plant to flower in different seasons. Vernalisation is promotion or induction of flowering by exposing a plant to low temperature for some time. Significance of vernalisation is as follows : (i) Crops can be grown earlier. (ii)Plants can be grown in such regions where normally they do not grow. (iii)Yield of the plant is increased. (iv)Resistance to cold and frost is increased. (v) Resistance to fungal diseases is increased.
6. Why is abscisic acid also known as stress hormone? Solution: A fairly high concentration of abscisic acid (ABA) is found in leaves of plants growing under stress conditions, such as drought, flooding, injury, mineral deficiency etc. It is accompanied by loss of turgor and closure of stomata. When such plants are transferred to normal conditions, they regain normal turgor and ABA concentration decreases. Since the synthesis of ABA is accelerated under stress condition and the same is destroyed or inactivated when stress is relieved, it is also known as stress hormone.
7. ‘Both growth and differentiation in higher plants are open’. Comment. Solution: Plant growth is generally indeterminate. Higher plants possess specific areas called meristems which take part in the formation of new cells. The body of plants is built on a modular fashion where structure is never complete because the tips (with apical meristem) “are open ended – always growing and forming new organs to replace the older or senescent ones. Growth is invariably associated with differentiation. The exact trigger for differentiation is also not known. Not only the growth of plants are open- ended, their differentiation is also open. The same apical meristem cells give rise to different types of cells at maturity, e.g., xylem, phloem, parenchyma, sclerenchyma fibres, collenchyma, etc. Thus, both the processes are indeterminate, unlimited and develop into different structures at maturity i.e., both are open.
8. ‘Both a short day plant and a long day plant can produce flower simultaneously in a given place’. Explain. Solution: A short day plant (SDP) flowers only when it receives a long dark period and short photoperiod, e.g., Xanthium, Dahlia etc. On the other hand, a long day plant (LDP) will flower only when it receives a long photoperiod and short dark period, e.g., wheat, oat etc. Thus critical photoperiod is that continuous duration of light which must not be exceeded in SDP and should always be exceeded in LDP in order to bring them to flower. Xanthium requires light for less than 15.6 hrs and Henbane requires light for more than 11 hrs. Xanthium (a SDP) and Henbane (DP) will flower simultaneously in light period between 11 to 15.6 hrs.
9. Which one of the plant growth regulators would you use if you are asked to (a) induce rooting in a twig (b) quickly ripen a fruit (c) delay leaf senescence (d) induce growth in axillary buds (e) ‘bolt’ a rosette plant (f) induce immediate stomatal closure in leaves. Solution: (a) Auxins like IBA, NAA. (b) Ethylene (c) Cytokinins (d) Cytokinins (e) Gibberellins (f) Abscisic acid (ABA)
10. Would a defoliated plant respond to photo- periodic cycle? Why? Solution: No, a defoliated plant would not respond to photoperiodic cycle because photoperiodic stimulus is picked up by the leaves only. Even one leaf or a part of it is sufficient for this purpose. For perception of photoperiodic cycle, there must be the presence of leaves under inductive photoperiod, so that, the hormone responsible for flowering can be produced.
11. What would be expected to happen if: (a) GA3 is applied to rice seedlings (b) dividing cells stop differentiating (c) a rotten fruit gets mixed with unripe fruits (d) you forget to add cytokinin to the culture medium. Solution: (a) The coleoptile will elongate rapidly, as GA3 helps in cell growth. (b) The development of callus (mass of undifferentiated cells) will take place. (c) The unripe fruits will ripe quickly because of the increased rate of respiration due to emission of ethylene from rotten fruit. (d) Cell division will retard and shoot will not initiate from the callus.
Page 204 Question 1. What do we get from cereals, pulses, fruits and vegetables? Answer: Cereals give carbohydrates which provide energy. Pulses give proteins which build our body. Vegetables and fruits provide vitamins and minerals.
Page 205 Question 1. How do biotic and abiotic factors affect crop production? Answer: Factors responsible for loss of grains, during storage and production are: (a) Biotic factors like rodents, pests, insects, etc. (b) Abiotic factors like temperature, humidity, moisture, etc. Combination of both biotic and abiotic factors causes :
infestation of insects
weight loss
poor germination ability
degradation in quality
discolouration
poor market price
Question 2. What are the desirable agronomic characteristics for crop improvements? Answer: Desirable agronomic characteristics for crop improvements are: (a) Tallness and profuse branching are desirable characters for fodder crops. (b) Dwarfness is desired in cereals, so that less nutrients are consumed by these crops.
Page 206
Question 1. What are macro-nutrients and why are they called macro-nutrients? Answer: Macro-nutrients are the essential elements which are utilised by plants in large quantities. Many macro-nutrients are required by the plants for the following functions:
As the constituent of protoplasm
N, P, S are present in proteins
Ca is present in cell wall
Mg is important constituent of chlorophyll
Question 2. How do plants get nutrients? Answer: Plants get nutrients from air, water and soil. There are, sixteen nutrients essential for the growth of plants. Carbon and Oxygen are supplied by water. The remaining thirteen nutrients are supplied by soil.
Page 207 Question 1. Compare the use of manure and fertilizers in maintaining soil fertility. Answer: Effects of using manures on soil quality:
The manures enrich the soil with nutrients.
They provide a lot of organic matter (humus) to the soil and thus restores water retention capacity of sandy soils and drainage in clayey soil.
The addition of manures reduces soil erosion.
They provide food for soil organisms, like soil friendly bacteria.
Effects of using fertilizers on soil quality:
By the continuous use of fertilizers, the soil becomes powdery, dry and rate of soil erosion increases.
By the use of fertilizers, the organic matter decreases which further decreases the porosity of soil and the plant roots do not get oxygen properly,
The nature of soil changes to acidic or basic.
Page 208 Question 1. Which of the following conditions will give the most benefits? Why? (a) Farmers use high-quality seeds, do not adopt irrigation or use fertilizers. (b) Farmers use ordinary seeds, adopt irrigation and use fertilizer. (c) Farmers use quality seeds, adopt irrigation, use fertilizer and use crop protection measures. Answer: In this, (c) Farmers use quality seeds, adopt irrigation, use fertilizer and use crop protection measures. Use of any quality seeds is not sufficient until they are properly irrigated, enriched with fertilizers and protected from biotic factors. Hence, option (c) will give the most benefits.
Page 209 Question.1. Why should preventive measures and biological control methods be preferred for protecting crops? Answer. Diseases in plants are caused by pathogens. To get rid of pathogens, some preventive measures and biological control methods are used as they are simple, economic and minimise pollution without affecting the soil quality.
Question 2. What factors may be responsible for losses of grains during storage? Answer: The factors responsible for losses of grains during storage are:
Abiotic factors like moisture (present in food grains), humidity (of air) and temperature.
Biotic factors like insects, rodents, birds, mites, bacteria and fungi.
Page 210 Question 1. Which method is commonly used for improving cattle breeds and why ? Answer: Cross breeding is a process in which indigenous varities of cattle are crossed by exotic breeds to get a breed which is high yielding. During cross breeding, the desired characters are taken into consideration. The offspring should be high yielding, should have early maturity and should be resistant to climatic conditions.
Page 211 Question 1. Discuss the implications of the following statement: “It is interesting to note that poultry is India’s most efficient converter of low fibre food stuff (which is unfit for human consumption) into highly nutritious animal protein food”. Answer: The basic aim of poultry farming is to raise domestic fowl for egg production and chicken meat. These poultry birds are not only the efficient converters of agricultural by-products, particularly cheaper fibrous wastes (which is unfit for human consumption but can be formulated into cheaper diets for poultry birds) into high quality meat and also help in providing egg, feathers and nutrient rich manure. For this reasons, it is said that, “poultry is India’s most efficient converter of low fibre food stuff into highly nutritious animal protein food”.
Page 211 Question 1. What management practices are common in dairy and poultry farming? Answer:
Shelter: Dairy animals and poultry birds require proper shelter, i.e., well designed dairy and hygienic shelter.
Feeding: To get good yield of food product, proper feed is provided to dairy animals and poultry birds.
Caring for animal health: Animal and birds must be protected from diseases caused by virus, bacteria or fungi.
Question 2. What are the differences between broilers and layers and in their management? Answer: The poultry bird groomed for obtaining meat is called broiler. The egg laying poultry bird is called layer. The housing, nutritional and environmental requirements of broilers are somewhat different from those of egg layers. The ration (daily food requirement) for broilers is protein rich with adequate fat. The level of vitamins A and K is kept high in the poultry feeds while layers require enough space and proper lightning.
Page 213 Question 1. How are fish obtained? Answer: There are two ways of obtaining fish. One is from natural resources, which is called capture fishing. The other way is by fish farming, which is called culture fishery.
Question 2. What are the advantages of composite fish culture? Answer: In composite fish culture, a combination of five or six fish species is used in a single fish pond. These species are selected so that they do not compete for food among them and are having different types of food habits. As a result, the food available in all the parts of the pond is used. For example, Catlas are surface feeders, Rohus feed in the middle-zone of the pond, Mrigals and Common Carps are bottom feeders and Grass Carps feed on the weeds, together these species can use all the food in the pond without competing with each other. This increases the fish yield from pond.
– Page 213 Question 1. What are the desirable characters of bee varieties suitable for honey production? Answer:
The variety of bee should be able to collect a large amount of honey.
The bees should stay in a given beehive for a longer period.
The bees should have capacity of breeding well.
The variety of bee should be disease resistant.
Question 2. What is pasturage and how is it related to honey production? Answer: The pasturage means the flowers available to the bees for nectar and pollen collection. In addition to adequate quantities of pasturage, the kind of flowers available will determine the taste of the honey.
Question 1. Explain any one method of crop production which ensures high yield. Answer: One method used for crop production which ensures high yield is plant breeding. It is the science involved in improving the varieties of crops by breeding plants. The plants from different areas/places is picked up with desired traits and then hybridisation or cross-breeding of these varieties is done to obtain a plant/crop of desired characteristic. The high yielding crop variety shows the following characteristics: High yield, early maturation, less water for irrigation, better quality seeds are produced, less fertilizers required, adapts itself to the environmental conditions.
Question 2. Why are manure and fertilizers used in fields? Answer: They are used to ensure good vegetative growth (leaves, branches and flowers), giving rise to healthy plants, that results in high crop production.
Question 3. What are the advantages of inter-cropping and crop rotation? Answer: Advantages of using inter-cropping:
It helps to maintain soil fertility.
It increases productivity per unit area.
Save labour and time.
Both crops can be easily harvested and processed separately.
Advantages of using crop rotation:
It improves the soil fertility.
It avoids depletion of a particular nutrient from soil.
It minimise pest infestation and diseases.
It helps in weed control.
It prevents change in the chemical nature of the soil.
Question 4. What is genetic manipulation? How is it useful in agricultural practices? Answer: Genetic manipulation is a process of incorporating desirable (genes) characters into crop varieties by hybridisation. Hybridisation involves crossing between genetically dissimilar plants. This is done for production of varieties with desirable characteristics like profuse branching in fodder crops, high yielding varieties in maize, wheat, etc. Genetic manipulation is useful in developing varieties which shows:
Increased yield
Better quality
Shorter and early maturity period
Better adaptability to adverse environmental conditions
Desirable characteristics
Question 5. How do storage grain losses occur? Answer: The factors responsible for loss of grains during storage are:
Abiotic factors like moisture (present in foodgrains), humidity (of air) and temperature.
Biotic factors like insects, rodents, birds, mites and bacteria.
Question 6. How do good animal husbandry practices benefit farmers? Answer: Good animal husbandry practices are beneficial to the farmers in the following ways:
Improvement of breeds of the domesticated animals.
Increasing the yield of foodstuffs such as milk, eggs and meat.
Proper management of domestic animals in terms of shelter, feeding, care and protection against diseases. Which ultimately helps the farmers to improve their economic condition.
Question 7. What are the benefits of cattle farming? Answer: Cattle farming is beneficial in the following ways:
Milk production is increased by high yielding animals.
Good quality of meat, fibre and skin can be obtained.
Good breed of draught animals can be obtained.
Question 8. For increasing production, what is common in poultry, fisheries and bee-keeping? Answer: Through cross breeding, the production of poultry, fisheries and bee-keeping can be increased.
Question 9. How do you differentiate between capture fishing, mariculture, and aquaculture? Answer: Capture fishing: It is the fishing in which fishes are captured from natural resources like pond, sea water and estuaries. Mariculture: It is the culture of fish in marine water. Varieties like prawns, oysters, bhetki and mullets are cultured for fishing. Aquaculture: It is done both in fresh water and in marine water.
Q.1.Fill in the blanks: (a) An image that cannot be obtained on a screen is called ___________ . (b) Image formed by a convex is __________ always virtual and smaller in size. (c) An image formed by a __________ mirror is always of the same size as that of the object. (d) An image which can be obtained on a screen is called a __________ image. (e) An image formed by a concave __________ cannot be obtained on a screen. Ans.(a) virtual image (b) mirror (c) plane (d) real (e) lens
Q.2.Mark ‘T’ if the statement is true and ‘F’ if it is false: (a) We can obtain an enlarged and erect image by a convex mirror. (T/F) (b) A concave lens always form a virtual image. (T/F) (c) We can obtain a real, enlarged and inverted image by a concave mirror. (T/F) (d) A real image cannot be obtained on a screen. (T/F) (e) A concave mirror always form a real image. (T/F) Ans. a) F (b) T (c) T (d) F (e) F
Q.3. Match the items given in Column I with one or more items of Column II Ans.
Q.4.State the characteristics of the image formed by a plane mirror. Ans.(i) Plane mirror forms an erect image. (ii) It forms a virtual image. (iii) Size of the image is same as that of the object. (iv)Image is formed at the same distance behind the mirror as the object stands in front of it. (v) Image formed is a laterally inverted image i.e., right hand side of the object seems to be the left hand side and vice-versa.
Q.5.Find out the letters of English alphabet or any other language known to you in which the image formed in a plane mirror appears exactly like the letter itself. Discuss your findings. Ans.Letters like A, H, I, M, O, T, U ,V, W etc. appear same when seen through a plane mirror
Q.6.What is a virtual image? Give one situation where a virtual image is formed. Ans.The image which cannot be taken on a screen is called virtual image. When some object is placed very close to the concave mirror we don’t get any image on the white screen placed behind the mirror. Such image is called virtual image.
Q.7. State two differences between a convex and a concave lens.
Q.8. Give one use each of a concave and a convex mirror. Ans. Use of concave mirror: Concave mirror is used by dentists to examine the teeth. Use of convex mirror: Convex mirror is used as side view mirror in vehicles
Q.9. Which type of mirror can form a real image? Ans. Concave mirror can form a real image.
