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Assam ASSEB HSLC NSQF Agriculture and Horticulture study materials
Assam ASSEB HSLC NSQF Agriculture and Horticulture study resources

Assam ASSEB HSLC NSQF Agriculture and Horticulture practice questions

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Question 1Introduction to Agriculture and Horticulture; Scope and Importance in Assam

Agriculture and horticulture are both practised in Assam, but horticulture is best distinguished from general agriculture by which feature?

  1. It concerns only the processing of harvested produce in factories
  2. It deals only with field crops grown on large holdings
  3. It concentrates on intensively cultivated garden crops such as fruits, vegetables and flowers Correct answer.
  4. It is limited to the rearing of livestock and poultry

Explanation

Horticulture is a branch of agriculture that deals with intensively cultivated plants, mainly fruits, vegetables, flowers and ornamental crops, often on smaller and more managed plots. General agriculture has a wider scope that includes field crops, livestock and allied activities. The distinguishing feature is therefore the intensive, garden-type crop focus.

Question 2Introduction to Agriculture and Horticulture; Scope and Importance in Assam

In Assam, which combination of agro-climatic conditions most favours the cultivation of horticultural crops?

  1. Hot humid summers with heavy rainfall and alluvial soils Correct answer.
  2. Prolonged drought with saline soils
  3. Very low rainfall with rocky, shallow soils
  4. Cold dry winters with sandy desert soils

Explanation

Assam lies in a humid subtropical zone with high rainfall, warm summers and fertile alluvial soils along the Brahmaputra and Barak valleys. These conditions suit a wide range of fruits, vegetables and tuber crops. Desert, drought and rocky shallow-soil conditions do not describe the state's main cropping areas.

Question 3Introduction to Agriculture and Horticulture; Scope and Importance in Assam

Which horticultural crop is commonly associated with the hill districts and the Karbi Anglong region of Assam as a major commercial fruit?

  1. Mustard
  2. Wheat
  3. Pineapple Correct answer.
  4. Jute

Explanation

Pineapple is a well-known commercial horticultural crop of Assam's hill and plateau districts, including Karbi Anglong and Dima Hasao, where the climate and slopes suit it. Wheat, mustard and jute are field or oilseed/fibre crops, not horticultural fruits. The question therefore tests the link between a fruit crop and a specific production zone.

Question 4Introduction to Agriculture and Horticulture; Scope and Importance in Assam

Which statement best explains why horticulture can raise farm income in Assam compared with sole cropping of paddy?

  1. Horticultural crops always need less labour than paddy
  2. Horticultural produce cannot be sold in local markets
  3. Horticultural crops never require irrigation or plant protection
  4. Horticultural produce often gives higher returns per unit area and can be grown between main field crops Correct answer.

Explanation

Fruits, vegetables and flowers generally give higher value per unit area and allow intercropping or multiple cropping, which raises income from small holdings. They do, however, need labour, water and plant protection, so claims of zero inputs are false. Local markets and nearby urban demand make the produce saleable.

Question 5Introduction to Agriculture and Horticulture; Scope and Importance in Assam

The branch of horticulture that deals with the cultivation of fruits is known as which of the following?

  1. Floriculture
  2. Pomology Correct answer.
  3. Agronomy
  4. Olericulture

Explanation

Pomology is the study of fruit cultivation, covering fruit trees and perennial fruit crops. Olericulture deals with vegetables, floriculture with flowers, and agronomy with field crops. Each term therefore names a distinct sub-discipline within agriculture and horticulture.

Question 6Introduction to Agriculture and Horticulture; Scope and Importance in Assam

A farmer near Guwahati wants a quick-return horticultural enterprise on a small plot with assured irrigation. Which choice best matches a short-duration, high-value vegetable crop suited to the region?

  1. Raising seasonal vegetables such as tomato, brinjal and leafy greens for the nearby urban market Correct answer.
  2. Establishing a permanent pasture for grazing cattle
  3. Planting a long-gestation timber tree for sale after twenty years
  4. Growing jute for fibre in a single long season

Explanation

Short-duration vegetables give quick returns and benefit from proximity to Guwahati's urban market, where demand is steady. Timber trees, jute and pasture are either long-gestation or non-horticultural options. The choice should match quick returns, small area and assured irrigation.

Question 7Introduction to Agriculture and Horticulture; Scope and Importance in Assam

Assam's horticultural wealth is often linked to its genetic diversity of citrus. Which group of citrus fruits is traditionally grown in the state's hill and foothill areas?

  1. Apple, pear and plum
  2. Khasi mandarin, Assam lemon and rough lemon Correct answer.
  3. Coffee, cocoa and rubber only
  4. Date palm, coconut and arecanut only

Explanation

Assam and the adjoining northeastern hills are known for citrus diversity, including Khasi mandarin, Assam lemon (kaji nemu) and rough lemon types. Apple and pear are temperate fruits of higher altitudes, while plantation crops such as arecanut and rubber are not citrus. The correct grouping is therefore the one made up of citrus types.

Question 8Introduction to Agriculture and Horticulture; Scope and Importance in Assam

Which of the following best describes the role of horticulture in generating employment in Assam?

  1. It provides work exclusively during the winter months
  2. It employs workers only in government offices
  3. It creates on-farm and off-farm jobs in nursery raising, harvesting, grading and marketing Correct answer.
  4. It eliminates the need for rural labour altogether

Explanation

Horticulture generates employment along the whole chain: nursery production, planting, harvesting, grading, packing, transport and marketing. It is labour-intensive and supports rural livelihoods in both farm and non-farm activities. It does not remove labour needs or confine work to a single season.

Question 9Introduction to Agriculture and Horticulture; Scope and Importance in Assam

A farmer in the Brahmaputra valley grows paddy in the kharif season and wants to use the same land for a vegetable crop. Which practice best describes this approach?

  1. Monoculture of paddy throughout the year
  2. Plantation cropping
  3. Multiple cropping with a horticultural crop in sequence Correct answer.
  4. Shifting cultivation

Explanation

Growing a vegetable after or alongside paddy on the same land is multiple cropping, which raises land-use intensity and income. Monoculture keeps one crop all year, shifting cultivation involves clearing forest patches, and plantation cropping refers to long-term tree crops. The described sequence is therefore multiple cropping.

Question 10Introduction to Agriculture and Horticulture; Scope and Importance in Assam

Which statement correctly pairs a horticultural sub-discipline with its subject matter?

  1. Agronomy with nursery management of orchids
  2. Olericulture with vegetable cultivation Correct answer.
  3. Pomology with flower cultivation
  4. Floriculture with fruit cultivation

Explanation

Olericulture is the science of vegetable growing, so it pairs correctly with vegetable cultivation. Pomology concerns fruits, floriculture concerns flowers, and agronomy concerns field crops. Each pairing other than the first mixes up the defined subject matter.

Question 11Introduction to Agriculture and Horticulture; Scope and Importance in Assam

Why is post-harvest management especially important for horticultural produce in Assam?

  1. Horticultural produce is never transported outside the village
  2. Storage has no effect on the price received by farmers
  3. Horticultural produce has an unlimited shelf life
  4. Fruits and vegetables are perishable and lose value quickly without proper handling and storage Correct answer.

Explanation

Horticultural produce is highly perishable, so delays in harvesting, grading, packing, cooling and transport cause spoilage and price loss. Proper post-harvest handling reduces waste and improves marketability, particularly where produce moves from hill areas to urban markets. Shelf life is limited, and storage strongly affects price.

Question 12Introduction to Agriculture and Horticulture; Scope and Importance in Assam

Which of these is an example of a horticultural crop grown for its edible underground portion in Assam?

  1. Rice
  2. Tea
  3. Banana
  4. Sweet potato Correct answer.

Explanation

Sweet potato is a tuberous root crop grown for its edible underground portion and falls within horticultural crops. Banana is grown for its fruit, tea is a plantation beverage crop, and rice is a cereal field crop. Only sweet potato matches the edible underground description.

Question 13Introduction to Agriculture and Horticulture; Scope and Importance in Assam

A village wants to add value to its surplus pineapple and citrus instead of selling fresh fruit at low prices. Which approach best reflects horticultural value addition?

  1. Selling the fruit only to a single distant buyer without grading
  2. Leaving the fruit unharvested in the field
  3. Processing the fruit into juice, squash, jam or dried products Correct answer.
  4. Burning the surplus to avoid price fall

Explanation

Value addition through processing into juice, squash, jam or dried products extends shelf life and raises returns, and it creates local employment. Destroying or abandoning produce wastes the crop, while ungraded single-buyer sales weaken bargaining power. Processing is the recognised horticultural value-addition route.

Question 14Introduction to Agriculture and Horticulture; Scope and Importance in Assam

Which statement most accurately describes the relationship between agriculture and horticulture in the Assam HSLC agriculture syllabus?

  1. Horticulture excludes all fruit and vegetable crops
  2. Horticulture is completely unrelated to agriculture
  3. Horticulture is a specialised branch within the broader field of agriculture Correct answer.
  4. Agriculture is a branch of horticulture

Explanation

Agriculture is the broad discipline covering crop production, livestock and allied activities, and horticulture is one specialised branch of it. Horticulture is therefore related to, not separate from, agriculture. The reverse relationship and the exclusion of fruits and vegetables are both incorrect.

Question 15Introduction to Agriculture and Horticulture; Scope and Importance in Assam

Assam's horticultural planning must balance high rainfall with which risk that most affects fruit and vegetable production?

  1. Absence of any local market for produce
  2. Chronic shortage of rainfall in all districts
  3. Flood and waterlogging damage in the flood-prone plains Correct answer.
  4. Permanent frost throughout the year

Explanation

The Brahmaputra and Barak plains are flood-prone, and excess water damages orchards, vegetable beds and harvested produce. Assam does not experience year-round frost, and it receives abundant rainfall rather than a chronic shortage. Local markets for horticultural produce also exist. Flood and waterlogging risk is therefore the key concern.

Question 16Introduction to Agriculture and Horticulture; Scope and Importance in Assam

A student argues that horticulture should be promoted in Assam because it supports nutritional security as well as income. Which evidence best supports this argument?

  1. Horticulture replaces the need for all other foods
  2. Fruits and vegetables supply vitamins and minerals that cereal-heavy diets often lack Correct answer.
  3. Fruits and vegetables contain no vitamins or minerals
  4. Horticultural crops cannot be grown on small holdings

Explanation

Fruits and vegetables are rich sources of vitamins, minerals and dietary fibre, which complement cereal-based diets and improve nutritional security. They do not replace all other foods, and they are well suited to small holdings. The nutritional argument therefore rests on their micronutrient contribution.

Question 17Soil Science: Soil Formation, Types, Properties, and Fertility Management

In the context of ASSEB HSLC Agriculture, which soil-forming process is mainly responsible for the red colour of soils found in parts of Assam and the adjoining hill regions?

  1. Deposition of silica-rich alluvium by rivers
  2. Accumulation of calcium carbonate in the subsoil
  3. Oxidation of iron compounds under well-drained conditions Correct answer.
  4. Reduction of iron compounds under waterlogged conditions

Explanation

Red soils owe their colour to ferric (oxidised) iron minerals such as haematite that form when iron-bearing parent rock weathers in well-drained, aerated conditions. Waterlogging produces the opposite effect, giving greyish reduced soils. Calcium carbonate accumulation produces pale calcareous horizons, not red colour.

Question 18Soil Science: Soil Formation, Types, Properties, and Fertility Management

Which of the following best describes the role of 'parent material' among the five soil-forming factors?

  1. It controls only the temperature and rainfall received at a site
  2. It determines the mineral reserve from which soil develops and influences texture and nutrient content Correct answer.
  3. It decides the kind of crops grown by farmers in a season
  4. It fixes the slope and drainage pattern of the landscape

Explanation

Parent material is the weathered rock or transported deposit from which the soil profile develops, and it supplies most of the mineral matter, influencing texture and nutrient reserves. Climate, relief and organisms are separate factors, and cropping choice is a management decision rather than a soil-forming factor.

Question 19Soil Science: Soil Formation, Types, Properties, and Fertility Management

Alluvial soils of the Brahmaputra valley are generally considered fertile mainly because they

  1. are rich in undecomposed organic matter throughout the profile
  2. are regularly renewed by fresh silt and sand deposited by floods Correct answer.
  3. contain very high amounts of exchangeable sodium
  4. have a very deep, strongly leached B horizon

Explanation

Alluvial soils are young, transported soils that receive periodic additions of fresh sediment from river floods, which renews nutrients and keeps the soil productive. Strong leaching and high sodium are characteristics of degraded soils, not of fertile alluvium.

Question 20Soil Science: Soil Formation, Types, Properties, and Fertility Management

A soil sample from a field has a pH of 5.2. Which lime recommendation approach is most appropriate for correcting this acidity?

  1. Apply gypsum at a high rate to lower the pH further
  2. Apply muriate of potash to raise the pH
  3. Apply agricultural lime based on a lime requirement test to raise pH towards the target for the crop Correct answer.
  4. Apply elemental sulphur to neutralise the acidity

Explanation

Acidic soils are corrected by applying agricultural lime, and the dose should be based on a lime requirement test rather than a fixed blanket rate. Gypsum and elemental sulphur both acidify or do not neutralise acidity, and potash fertiliser has little liming effect.

Question 21Soil Science: Soil Formation, Types, Properties, and Fertility Management

Which of the following is a primary macronutrient that leguminous crops obtain largely through biological nitrogen fixation?

  1. Zinc
  2. Molybdenum
  3. Boron
  4. Nitrogen Correct answer.

Explanation

Nitrogen is a primary macronutrient, and legumes obtain much of their requirement through symbiotic fixation by Rhizobium bacteria in root nodules. Zinc, boron and molybdenum are micronutrients required only in small amounts and are not fixed biologically in this way.

Question 22Soil Science: Soil Formation, Types, Properties, and Fertility Management

Which soil texture class generally holds the greatest amount of plant-available water per unit depth?

  1. Loam Correct answer.
  2. Coarse sand
  3. Silt
  4. Gravel

Explanation

Loam combines sand, silt and clay in proportions that give good pore-size distribution, so it retains useful water while still draining and aerating well, making it the most favourable texture for available water. Coarse sand and gravel drain too fast, while pure silt has poor structure and low available water.

Question 23Soil Science: Soil Formation, Types, Properties, and Fertility Management

A farmer in a hilly area of Assam wants to reduce soil erosion on a sloping field. Which practice is most directly effective for this purpose?

  1. Contour bunding with vegetative cover along the contour Correct answer.
  2. Ploughing up and down the slope before sowing
  3. Leaving the field bare during heavy rainfall
  4. Burning crop residues before the monsoon

Explanation

Contour bunding with vegetative cover slows runoff and traps soil along the contour, directly reducing erosion on slopes. Ploughing up and down the slope, burning residues and leaving the soil bare all accelerate detachment and loss of topsoil.

Question 24Soil Science: Soil Formation, Types, Properties, and Fertility Management

In a soil profile, the layer where most organic matter accumulates and biological activity is highest is generally the

  1. A horizon Correct answer.
  2. R horizon
  3. C horizon
  4. B horizon

Explanation

The A horizon is the surface mineral layer where organic matter accumulates and where roots, microbes and soil fauna are most active. The B horizon is a subsoil zone of accumulation, the C horizon is weathered parent material, and the R horizon is unweathered bedrock.

Question 25Soil Science: Soil Formation, Types, Properties, and Fertility Management

A soil has a cation exchange capacity of 25 cmol(+)/kg and is dominated by calcium and magnesium on the exchange complex. What does this indicate about the soil?

  1. It has a high nutrient-holding capacity and can retain applied cations against leaching Correct answer.
  2. It is sodic and unsuitable for most crops
  3. It has a low nutrient-holding capacity and will leach bases quickly
  4. It is a sandy soil with very low clay and organic matter content

Explanation

Cation exchange capacity measures the soil's ability to hold exchangeable cations, so a value of 25 cmol(+)/kg indicates a good nutrient-holding capacity, especially when calcium and magnesium dominate. Low CEC is typical of sandy soils, and sodic soils are dominated by sodium rather than calcium and magnesium.

Question 26Soil Science: Soil Formation, Types, Properties, and Fertility Management

Which practice best improves soil organic matter and long-term fertility in a rice-based cropping system?

  1. Removing all crop residues after harvest
  2. Incorporating green manure crops such as dhaincha before transplanting Correct answer.
  3. Applying only urea at every crop stage
  4. Continuous puddling without any organic input

Explanation

Green manure legumes such as dhaincha add both organic matter and biologically fixed nitrogen when incorporated, improving long-term fertility. Residue removal and exclusive reliance on urea deplete organic matter, and continuous puddling degrades soil structure.

Question 27Soil Science: Soil Formation, Types, Properties, and Fertility Management

Waterlogging in a poorly drained field is likely to cause which set of changes in the soil?

  1. Complete disappearance of clay minerals within one season
  2. Increase in oxygen supply and rapid oxidation of organic matter
  3. Formation of reduced iron and manganese compounds and loss of nitrogen through denitrification Correct answer.
  4. Rapid rise in soil pH to strongly alkaline levels

Explanation

When pores fill with water, oxygen is depleted and anaerobic conditions develop, causing iron and manganese to be reduced and nitrate to be lost as nitrogen gas through denitrification. Oxygen does not increase, and clay minerals do not disappear within a season.

Question 28Soil Science: Soil Formation, Types, Properties, and Fertility Management

Which soil type is most characteristic of the char and floodplain areas of the Brahmaputra, where fresh sandy and silty deposits are laid down each year?

  1. Laterite soil
  2. Peaty soil
  3. Alluvial soil Correct answer.
  4. Saline-alkaline soil

Explanation

The char and floodplain lands of the Brahmaputra are dominated by alluvial soils formed from fresh sandy and silty deposits brought by floods. Laterite soils develop on well-drained uplands under heavy leaching, and peaty and saline-alkaline soils form under very different conditions.

Question 29Soil Science: Soil Formation, Types, Properties, and Fertility Management

A soil test report shows a soil with 45% sand, 40% silt and 15% clay. Which texture class does this sample most closely match?

  1. Loam Correct answer.
  2. Sandy clay
  3. Silty clay
  4. Clay

Explanation

A sample with roughly equal proportions of sand and silt and a modest clay fraction falls in the loam class, which is intermediate in texture. Clay and silty clay classes require much higher clay contents, and sandy clay requires a high sand plus high clay combination.

Question 30Soil Science: Soil Formation, Types, Properties, and Fertility Management

Which statement correctly distinguishes soil structure from soil texture?

  1. Texture is determined by organic matter, while structure is determined by parent rock
  2. Texture varies with cultivation, while structure remains fixed for a given soil
  3. Texture is the proportion of sand, silt and clay, while structure is the arrangement of these particles into aggregates Correct answer.
  4. Texture refers to the arrangement of aggregates, while structure refers to the proportion of sand, silt and clay

Explanation

Texture is the relative proportion of sand, silt and clay particles, whereas structure describes how those particles are bound into aggregates or peds. Texture is largely fixed by the mineral fraction, while structure can be altered by cultivation, organic matter and management.

Question 31Soil Science: Soil Formation, Types, Properties, and Fertility Management

A field shows patchy yellowing of younger leaves and poor crop vigour, and soil testing shows adequate nitrogen. Which nutrient deficiency is most likely to be involved in this alkaline soil?

  1. Molybdenum
  2. Sulphur
  3. Chlorine
  4. Iron Correct answer.

Explanation

Iron deficiency commonly appears as interveinal yellowing of young leaves in alkaline soils, where iron becomes less available even though total soil iron may be adequate. Molybdenum availability generally increases with pH, and sulphur deficiency usually affects older leaves first.

Question 32Soil Science: Soil Formation, Types, Properties, and Fertility Management

Which of the following is the most appropriate method for determining the lime requirement of an acidic soil before recommending a dose to a farmer?

  1. Measuring only the soil colour and texture in the field
  2. Counting the earthworms present in a spade of soil
  3. Estimating the crop yield from the previous season
  4. Measuring exchangeable aluminium and base saturation in a laboratory test Correct answer.

Explanation

Lime requirement is assessed from laboratory measurements of exchangeable aluminium and base saturation, combined with the target pH for the crop. Field colour, previous yield and earthworm counts do not quantify the acidity that lime must neutralise.

Question 33Soil Science: Soil Formation, Types, Properties, and Fertility Management

In the context of soil formation, 'weathering' of rocks is best described as

  1. the transport of eroded material by rivers and wind
  2. the accumulation of organic matter on the surface
  3. the compaction of soil by farm machinery
  4. the breakdown and alteration of rock minerals by physical, chemical and biological processes Correct answer.

Explanation

Weathering is the in-situ breakdown and chemical alteration of rock minerals through physical, chemical and biological processes, providing the mineral basis for soil formation. Transport by rivers and wind is erosion and deposition, and compaction is a management-induced physical change.

Question 34Soil Science: Soil Formation, Types, Properties, and Fertility Management

A soil in a tea garden shows a pH of 4.5, and the grower wants to maintain the acid-loving crop. Which management approach is most consistent with this situation?

  1. Avoid heavy liming and manage acidity within the range suited to the crop Correct answer.
  2. Apply gypsum to raise pH to neutral
  3. Apply heavy lime to raise pH above 7.0
  4. Apply sodium chloride to raise pH

Explanation

Tea is an acid-tolerant crop that performs well in moderately acidic soils, so heavy liming to neutral or alkaline pH is unnecessary and can reduce nutrient availability. Gypsum, sodium chloride and lime do not provide the desired acidic range and may harm the crop.

Question 35Soil Science: Soil Formation, Types, Properties, and Fertility Management

Which combination of practices is most likely to maintain soil organic carbon and aggregate stability in an intensive annual cropping system?

  1. Continuous clean cultivation with residue removal and no organic additions
  2. Monoculture with repeated deep ploughing and burning of stubble
  3. Regular addition of compost or farmyard manure combined with reduced tillage and residue retention Correct answer.
  4. Annual application of only soluble nitrogen fertiliser

Explanation

Organic carbon and aggregate stability are maintained when organic inputs such as compost or farmyard manure are combined with reduced tillage and residue retention, which protect soil structure and slow decomposition. Clean cultivation, residue burning and fertiliser-only strategies all deplete carbon and weaken aggregates.

Question 36Soil Science: Soil Formation, Types, Properties, and Fertility Management

A soil has a high bulk density, low porosity and a hard plough pan just below the plough layer. Which management sequence is most appropriate to correct this condition?

  1. Apply more nitrogen fertiliser to compensate for the poor root growth
  2. Increase the number of shallow ploughings at the same depth every season
  3. Subsoil or chisel plough to break the pan, then add organic matter and avoid working the soil when wet Correct answer.
  4. Flood the field continuously to soften the pan

Explanation

A plough pan restricts rooting and water movement, so mechanical loosening by subsoiling or chisel ploughing, followed by organic matter addition and avoidance of tillage at high moisture, restores porosity. Repeated shallow ploughing, extra nitrogen and continuous flooding do not break the compacted layer and can worsen the problem.

Question 37Plant Science: Anatomy, Physiology, Growth, and Development of Crop Plants

In a typical dicot root, which tissue layer lies immediately inside the epidermis and controls the movement of water and dissolved minerals into the root cortex?

  1. Endodermis Correct answer.
  2. Xylem parenchyma
  3. Epidermis
  4. Pericycle

Explanation

The endodermis is the innermost layer of the cortex, and its Casparian strips force water and ions to pass through living cells rather than the cell walls. This selective barrier regulates what reaches the stele. The pericycle lies inside the endodermis and gives rise to lateral roots.

Question 38Plant Science: Anatomy, Physiology, Growth, and Development of Crop Plants

A rice seedling is grown in waterlogged soil and its roots show reduced oxygen uptake. Which anatomical feature of rice roots helps it tolerate this condition?

  1. Casparian strips
  2. Periderm
  3. Root hairs
  4. Aerenchyma tissue Correct answer.

Explanation

Rice forms aerenchyma, a spongy tissue with large air spaces that conducts oxygen from the shoot down to the roots. This adaptation allows respiration to continue in flooded, oxygen-poor soils. Root hairs and Casparian strips do not transport oxygen.

Question 39Plant Science: Anatomy, Physiology, Growth, and Development of Crop Plants

Water rises in the xylem of a tall tree mainly because of which mechanism?

  1. Active pumping by living xylem vessels
  2. Root pressure pushing water up the entire height
  3. Transpiration pull generated by evaporation at the leaves Correct answer.
  4. Capillary action alone in the vessel elements

Explanation

Evaporation of water from leaves creates a tension that pulls a continuous water column up the xylem, a process called transpiration pull. Cohesion between water molecules and adhesion to vessel walls keep the column intact. Root pressure and capillarity contribute only minor lifting over short distances.

Question 40Plant Science: Anatomy, Physiology, Growth, and Development of Crop Plants

Which pigment mainly absorbs light energy and transfers it to the reaction centre during the light reactions of photosynthesis?

  1. Anthocyanin
  2. Carotene
  3. Chlorophyll a Correct answer.
  4. Chlorophyll b

Explanation

Chlorophyll a is the primary photosynthetic pigment whose molecules in the reaction centre convert absorbed light energy into chemical energy. Accessory pigments such as chlorophyll b and carotenes absorb additional wavelengths and pass energy to chlorophyll a. Anthocyanins are not involved in photosynthesis.

Question 41Plant Science: Anatomy, Physiology, Growth, and Development of Crop Plants

A farmer notices that a crop plant becomes limp under midday sun but recovers by evening. Which process best explains this temporary loss of rigidity?

  1. Death of the vascular cambium
  2. Complete closure of stomata
  3. Loss of turgor pressure in cells Correct answer.
  4. Breakdown of chlorophyll

Explanation

When transpiration exceeds water uptake, cells lose water and turgor pressure falls, so the plant wilts temporarily. Restoring water supply re-establishes turgidity and the plant recovers. Cambium death, stomatal closure and chlorophyll breakdown do not produce reversible wilting.

Question 42Plant Science: Anatomy, Physiology, Growth, and Development of Crop Plants

Which plant hormone is chiefly responsible for promoting cell elongation and causing apical dominance?

  1. Ethylene
  2. Abscisic acid
  3. Cytokinin
  4. Auxin Correct answer.

Explanation

Auxin, produced mainly in shoot apices, promotes cell elongation and suppresses lateral bud growth, producing apical dominance. Cytokinins promote cell division and lateral bud growth, opposing auxin. Abscisic acid and ethylene are mainly inhibitory hormones.

Question 43Plant Science: Anatomy, Physiology, Growth, and Development of Crop Plants

A gardener applies a synthetic auxin to a field to control broadleaf weeds. What is the basis of this herbicidal action?

  1. Blocking of photosynthesis in the chloroplast
  2. Hardening of the seed coat
  3. Uncontrolled growth that disrupts normal plant development Correct answer.
  4. Prevention of water uptake by the roots

Explanation

Synthetic auxins at high concentration cause abnormal, uncontrolled growth in broadleaf plants, distorting stems and leaves until the plant dies. This selective action makes them useful as herbicides. They do not act by blocking photosynthesis or water uptake.

Question 44Plant Science: Anatomy, Physiology, Growth, and Development of Crop Plants

Which type of seed germination is shown when the cotyledons remain below the soil surface while the epicotyl elongates?

  1. Hypogeal germination Correct answer.
  2. Epigeal germination
  3. Apomictic germination
  4. Viviparous germination

Explanation

In hypogeal germination the cotyledons stay underground and the epicotyl pushes the plumule upward, as in pea and maize. Epigeal germination instead lifts the cotyledons above the soil. Vivipary and apomixis describe different reproductive phenomena.

Question 45Plant Science: Anatomy, Physiology, Growth, and Development of Crop Plants

Which part of the seed provides the main stored food for the developing embryo in a cereal grain such as wheat?

  1. Plumule
  2. Seed coat
  3. Endosperm Correct answer.
  4. Radicle

Explanation

The endosperm is the triploid tissue that stores starch and other nutrients used by the embryo during germination in cereals. The radicle and plumule are embryonic root and shoot parts. The seed coat is protective only.

Question 46Plant Science: Anatomy, Physiology, Growth, and Development of Crop Plants

During which stage of plant development does the transition from vegetative to reproductive growth occur in a typical annual crop?

  1. Fruit ripening
  2. Senescence
  3. Seed germination
  4. Flowering initiation after the juvenile phase Correct answer.

Explanation

After the juvenile phase, plants become competent to flower and respond to signals such as photoperiod and temperature, marking the shift to reproductive growth. Germination, ripening and senescence are separate stages. Flowering initiation is the transition point.

Question 47Plant Science: Anatomy, Physiology, Growth, and Development of Crop Plants

A short-day crop planted in Assam flowers when the night length exceeds a critical value. What is the most accurate modern description of this response?

  1. Response to red light intensity only
  2. Long-night requirement for floral induction Correct answer.
  3. Dependence on soil nitrogen level
  4. Requirement for high daytime temperature

Explanation

Plants classically called short-day plants actually respond to a long, uninterrupted dark period exceeding a critical night length. Interrupting the night with light prevents flowering. Day length and temperature alone do not define this response.

Question 48Plant Science: Anatomy, Physiology, Growth, and Development of Crop Plants

Which tissue is responsible for secondary growth in thickness of a dicot stem?

  1. Epidermis
  2. Pith
  3. Vascular cambium Correct answer.
  4. Collenchyma

Explanation

The vascular cambium is a lateral meristem that divides to produce secondary xylem inward and secondary phloem outward, increasing stem girth. The epidermis, pith and collenchyma do not produce secondary thickening.

Question 49Plant Science: Anatomy, Physiology, Growth, and Development of Crop Plants

A section of a monocot stem is examined and shows scattered vascular bundles. Which statement best explains this arrangement?

  1. Vascular bundles are scattered in ground tissue without a distinct cambial ring Correct answer.
  2. Bundles are embedded in the epidermis
  3. Bundles are arranged only in the cortex
  4. Bundles form a single ring around the pith

Explanation

Monocot stems have vascular bundles scattered through the ground tissue and lack a continuous cambial ring, which limits secondary thickening. Dicot stems instead arrange bundles in a ring. This scattered arrangement is a key diagnostic feature.

Question 50Plant Science: Anatomy, Physiology, Growth, and Development of Crop Plants

Which process converts atmospheric nitrogen into ammonia in the root nodules of leguminous crops?

  1. Denitrification by Pseudomonas
  2. Ammonification by fungi
  3. Nitrification by Nitrosomonas
  4. Biological nitrogen fixation by Rhizobium Correct answer.

Explanation

Rhizobium bacteria in root nodules use the enzyme nitrogenase to reduce atmospheric nitrogen to ammonia, which the plant can use. Nitrification and denitrification are soil processes involving different bacteria. Ammonification releases ammonia from organic matter.