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Q2 (IAS/2018) Science & Technology › Basic Science (Physics, Chemistry, Biology) › Plant anatomy physiology Official Key

Which of the following leaf modifications occur(s) in the desert areas to inhibit water loss ? 1. Hard and waxy leaves 2. Tiny leaves 3. Thorns instead of leaves Select the correct answer using the code given below :

Result
Your answer: —  ·  Correct: D
Explanation

The correct answer is option D (1, 2, and 3) because all three modifications occur in desert plants to inhibit water loss.

Desert plants have waxy-coatings and fine hairs on leaves to retard water loss[3], which confirms statement 1. Plants have few or no leaves and the foliage is either waxy, leathery, hairy or needle-shaped to reduce the loss of water through transpiration[6], supporting both statements 1 and 2. Desert plants also exhibit leafless conditions during dry periods[3], and some of them are entirely leafless, with prickles or thorns[6], which validates statement 3.

These adaptations work together: waxy coatings create a waterproof barrier, reduced leaf size (tiny leaves or needle-shaped foliage) minimizes surface area for transpiration, and thorns represent the extreme adaptation where leaves are completely replaced to eliminate water loss. Plants, whether annuals or perennials, must struggle for survival against both aridity and poor soil[6], making these multiple adaptations essential for desert survival.

Sources
  1. [1] Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 3: MAJOR BIOMES > 10. Desert Biomes > p. 15
  2. [2] Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 3: MAJOR BIOMES > 10. Desert Biomes > p. 15
  3. [3] Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 3: MAJOR BIOMES > 10. Desert Biomes > p. 15
  4. [4] Certificate Physical and Human Geography , GC Leong (Oxford University press 3rd ed.) > Chapter 18: The Hot Desert and Mid-Latitude Desert Climate > Natural Vegetation > p. 176
  5. [5] Certificate Physical and Human Geography , GC Leong (Oxford University press 3rd ed.) > Chapter 18: The Hot Desert and Mid-Latitude Desert Climate > Natural Vegetation > p. 176
  6. [6] Certificate Physical and Human Geography , GC Leong (Oxford University press 3rd ed.) > Chapter 18: The Hot Desert and Mid-Latitude Desert Climate > Natural Vegetation > p. 176
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Q. Which of the following leaf modifications occur(s) in the desert areas to inhibit water loss ? 1. Hard and waxy leaves 2. Tiny leaves …
At a glance
Origin: From standard books Fairness: High fairness Books / CA: 10/10 · 0/10

This is a classic 'reward for basics' question. It is a direct lift from G.C. Leong (Chapter 18) and NCERT Biology. If you skipped physical geography basics for high-level current affairs, you lost easy marks. It validates the strategy: Standard Textbooks > Random Web Surfing.

How this question is built

This question can be broken into the following sub-statements. Tap a statement sentence to jump into its detailed analysis.

Statement 1
Are hard, waxy leaves a leaf modification in desert areas that inhibits water loss?
Origin: Direct from books Fairness: Straightforward Book-answerable
From standard books
Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 3: MAJOR BIOMES > 10. Desert Biomes > p. 15
Presence: 5/5
“Perennial desert plants employ other adaptive features to cope with the desert, such as long, deep tap-roots (e.g. the chaparral and maquis), succulence (i.e. thick, feshy, water-holding tissue such as that of cacti and saguaro-cactus in the desert of Arizona (USA), spreading root-systems to maximise water availability, waxy-coatings and fne hairs on leaves to retard water loss, leafess conditions during dry periods, refective surfaces to reduce leaf temperatures, and tissues that taste bad to discourage herbivores. Te deserts of the world are classifed into (i) hot-deserts, principally tropical and subtropical, and (ii) cold deserts, principally in mid-latitudes (Fig. 3.10).”
Why this source?
  • Explicitly states desert plants have waxy coatings and fine hairs on leaves to retard water loss.
  • Links these surface features to an adaptive function (reducing evaporative loss) in arid environments.
Certificate Physical and Human Geography , GC Leong (Oxford University press 3rd ed.) > Chapter 18: The Hot Desert and Mid-Latitude Desert Climate > Natural Vegetation > p. 176
Presence: 5/5
“There are plants called halophytes (salt lovers) that are adapted to survive in such saline conditions. Desert soils are deficient in humus since there is little vegetation to decay and the absence of moisture retards the rate of decomposition. Plants, whether annuals or perennials must struggle for survival against both aridity and poor soil. Most desert shrubs have long roots and are well spaced out to gather moisture, and search for ground water. Plants have few or no leaves and the foliage is either waxy, leathery, hairy or needle-shaped to reduce the loss of water through transpiration. Some of them are entirely leafless, with prickles or thorns.”
Why this source?
  • Describes desert shrub foliage as waxy, leathery, hairy or needle-shaped specifically to reduce transpiration.
  • Directly ties leaf texture/form (waxy, leathery) to the mechanism of lowering water loss.
Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 30: Climatic Regions > Desert Vegetation > p. 443
Presence: 4/5
“Plants have few or no leaves, and the foliage is either way, leathery, hairy or needle-shaped to reduce the loss of water through transpiration.• The seeds of grasses and herbs have thick, tough skins to protect them while they lie dormant for years.”
Why this source?
  • Notes desert plants have few/no leaves and that foliage is leathery, hairy or needle-shaped to reduce transpiration.
  • Reinforces the pattern of modified leaf forms in arid regions aimed at conserving water.
Statement 2
Are tiny leaves a leaf modification in desert areas that reduces water loss?
Origin: Direct from books Fairness: Straightforward Book-answerable
From standard books
Certificate Physical and Human Geography , GC Leong (Oxford University press 3rd ed.) > Chapter 18: The Hot Desert and Mid-Latitude Desert Climate > Natural Vegetation > p. 176
Presence: 5/5
“There are plants called halophytes (salt lovers) that are adapted to survive in such saline conditions. Desert soils are deficient in humus since there is little vegetation to decay and the absence of moisture retards the rate of decomposition. Plants, whether annuals or perennials must struggle for survival against both aridity and poor soil. Most desert shrubs have long roots and are well spaced out to gather moisture, and search for ground water. Plants have few or no leaves and the foliage is either waxy, leathery, hairy or needle-shaped to reduce the loss of water through transpiration. Some of them are entirely leafless, with prickles or thorns.”
Why this source?
  • Explicitly states desert plants have few or no leaves and that foliage may be needle-shaped to reduce water loss.
  • Directly links reduced/modified foliage (waxy, leathery, hairy, needle-shaped) to decreased transpiration.
Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 30: Climatic Regions > Desert Vegetation > p. 443
Presence: 5/5
“Plants have few or no leaves, and the foliage is either way, leathery, hairy or needle-shaped to reduce the loss of water through transpiration.• The seeds of grasses and herbs have thick, tough skins to protect them while they lie dormant for years.”
Why this source?
  • Notes that plants have few or no leaves and that foliage may be needle-shaped to reduce transpiration.
  • Reinforces the point that reduced leaf area/shape is an adaptation to aridity.
Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 3: MAJOR BIOMES > 10. Desert Biomes > p. 15
Presence: 4/5
“Perennial desert plants employ other adaptive features to cope with the desert, such as long, deep tap-roots (e.g. the chaparral and maquis), succulence (i.e. thick, feshy, water-holding tissue such as that of cacti and saguaro-cactus in the desert of Arizona (USA), spreading root-systems to maximise water availability, waxy-coatings and fne hairs on leaves to retard water loss, leafess conditions during dry periods, refective surfaces to reduce leaf temperatures, and tissues that taste bad to discourage herbivores. Te deserts of the world are classifed into (i) hot-deserts, principally tropical and subtropical, and (ii) cold deserts, principally in mid-latitudes (Fig. 3.10).”
Why this source?
  • Lists leaf-related adaptations in desert plants (waxy coatings, fine hairs, leafless conditions) that retard water loss.
  • Places leaf reduction/alteration among other desert adaptations (succulence, reflective surfaces) aimed at conserving water.
Statement 3
Do plants in desert areas have thorns instead of leaves as a leaf modification to inhibit water loss?
Origin: Direct from books Fairness: Straightforward Book-answerable
From standard books
Certificate Physical and Human Geography , GC Leong (Oxford University press 3rd ed.) > Chapter 18: The Hot Desert and Mid-Latitude Desert Climate > Natural Vegetation > p. 176
Presence: 5/5
“There are plants called halophytes (salt lovers) that are adapted to survive in such saline conditions. Desert soils are deficient in humus since there is little vegetation to decay and the absence of moisture retards the rate of decomposition. Plants, whether annuals or perennials must struggle for survival against both aridity and poor soil. Most desert shrubs have long roots and are well spaced out to gather moisture, and search for ground water. Plants have few or no leaves and the foliage is either waxy, leathery, hairy or needle-shaped to reduce the loss of water through transpiration. Some of them are entirely leafless, with prickles or thorns.”
Why this source?
  • Explicitly states many desert plants have few or no leaves and some are entirely leafless with prickles or thorns.
  • Links leaf reduction/absence and thorny structures to the general theme of reducing water loss (foliage adaptations listed to reduce transpiration).
Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 3: MAJOR BIOMES > 10. Desert Biomes > p. 15
Presence: 4/5
“Perennial desert plants employ other adaptive features to cope with the desert, such as long, deep tap-roots (e.g. the chaparral and maquis), succulence (i.e. thick, feshy, water-holding tissue such as that of cacti and saguaro-cactus in the desert of Arizona (USA), spreading root-systems to maximise water availability, waxy-coatings and fne hairs on leaves to retard water loss, leafess conditions during dry periods, refective surfaces to reduce leaf temperatures, and tissues that taste bad to discourage herbivores. Te deserts of the world are classifed into (i) hot-deserts, principally tropical and subtropical, and (ii) cold deserts, principally in mid-latitudes (Fig. 3.10).”
Why this source?
  • Describes leafless conditions during dry periods as a common desert adaptation.
  • Lists multiple leaf-related adaptations (waxy coatings, hairs, succulence) that serve the same function of reducing transpiration, supporting the idea that leaf modification is a water-conservation strategy.
Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 30: Climatic Regions > Desert Vegetation > p. 443
Presence: 4/5
“Plants have few or no leaves, and the foliage is either way, leathery, hairy or needle-shaped to reduce the loss of water through transpiration.• The seeds of grasses and herbs have thick, tough skins to protect them while they lie dormant for years.”
Why this source?
  • States plants have few or no leaves and foliage may be needle-shaped to reduce transpiration.
  • Supports the general pattern of leaf reduction/alteration in deserts as a water-loss inhibition strategy (even if not naming thorns specifically).
Pattern takeaway: UPSC loves 'Functional Morphology' in Environment/Geography. They move beyond 'What grows where?' to 'Why does it look like that?'. The pattern is consistent: link physical features (leaves, roots, bark) to specific environmental stresses (aridity, salinity, fire, cold).
How you should have studied
  1. [THE VERDICT]: Sitter. Directly solvable from G.C. Leong, Chapter 18 (Hot Desert Climate) or Class 11 NCERT Geography.
  2. [THE CONCEPTUAL TRIGGER]: Biome Adaptations (Xerophytes). The link between climatic stress (aridity) and biological morphology.
  3. [THE HORIZONTAL EXPANSION]: Memorize adaptations for other biomes: Mangroves (Pneumatophores/Vivipary for salinity), Rainforests (Drip-tips/Buttress roots for high rainfall), Savanna (Thick corky bark for fire resistance), and Tundra (Cushion habit to avoid wind chill).
  4. [THE STRATEGIC METACOGNITION]: Adopt the 'Form follows Function' framework. Don't just memorize 'cactus has thorns'. Ask 'Why?' (Surface area reduction). Apply this logic to every biome: How does a plant in the Tundra survive freezing? How does a plant in the Rainforest survive waterlogging?
Concept hooks from this question
📌 Adjacent topic to master
S1
👉 Waxy/leathery leaf surfaces reduce transpiration
💡 The insight

Multiple references state waxy or leathery coatings on leaves are used by arid-region plants to retard water loss.

High-yield for questions on plant adaptations to aridity — explains a direct morphological adaptation and the physiological aim (reduce transpiration). Connects ecology to plant physiology and biome questions; useful for comparison-type and cause-effect questions in GS and optional papers.

📚 Reading List :
  • Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 3: MAJOR BIOMES > 10. Desert Biomes > p. 15
  • Certificate Physical and Human Geography , GC Leong (Oxford University press 3rd ed.) > Chapter 18: The Hot Desert and Mid-Latitude Desert Climate > Natural Vegetation > p. 176
🔗 Anchor: "Are hard, waxy leaves a leaf modification in desert areas that inhibits water lo..."
📌 Adjacent topic to master
S1
👉 Leaf reduction and modification in arid climates
💡 The insight

Evidence shows desert plants often have few/no leaves or modified forms (needles, hairs, thorns) to minimize water loss.

Important for answering why vegetation structure changes with climate — links to desertification, biome classification and plant survival strategies. Enables pattern-recognition and explanation-based answers in geography/ecology questions.

📚 Reading List :
  • Certificate Physical and Human Geography , GC Leong (Oxford University press 3rd ed.) > Chapter 18: The Hot Desert and Mid-Latitude Desert Climate > Natural Vegetation > p. 176
  • Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 30: Climatic Regions > Desert Vegetation > p. 443
🔗 Anchor: "Are hard, waxy leaves a leaf modification in desert areas that inhibits water lo..."
📌 Adjacent topic to master
S1
👉 Succulence and internal water storage as a complementary drought strategy
💡 The insight

References mention succulence (thick, fleshy water-holding tissue) and stems/leaves storing water alongside surface modifications.

Helps build composite answers on desert plant adaptations (surface + internal strategies). Useful for balanced answers in mains and interviews explaining multiple adaptive mechanisms rather than single-factor explanations.

📚 Reading List :
  • Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 3: MAJOR BIOMES > 10. Desert Biomes > p. 15
  • Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 3: Terrestrial Ecosystems > iifffi E > p. 28
🔗 Anchor: "Are hard, waxy leaves a leaf modification in desert areas that inhibits water lo..."
📌 Adjacent topic to master
S2
👉 Leaf reduction and modification in arid climates
💡 The insight

Multiple references state desert plants have few or reduced leaves (needle-shaped or absent) as an adaptation to aridity.

High-yield for UPSC: explains a core vegetation adaptation in desert biomes and appears often in questions on plant ecology and biome characteristics. Mastering this links to topics on biomes, plant physiology and climate-vegetation interactions and helps answer 'why' and 'how' adaptation questions.

📚 Reading List :
  • Certificate Physical and Human Geography , GC Leong (Oxford University press 3rd ed.) > Chapter 18: The Hot Desert and Mid-Latitude Desert Climate > Natural Vegetation > p. 176
  • Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 30: Climatic Regions > Desert Vegetation > p. 443
  • Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 3: Terrestrial Ecosystems > i) The plants conserve water by following methods: > p. 27
🔗 Anchor: "Are tiny leaves a leaf modification in desert areas that reduces water loss?"
📌 Adjacent topic to master
S2
👉 Mechanisms to reduce transpiration (waxy coatings, hairs, small surface area)
💡 The insight

References describe waxy coatings, fine hairs and reduced leaf surface (needle-shaped) specifically to retard water loss via transpiration.

Understanding mechanisms is useful for explanatory answers in ecology and environmental geography; it connects plant structure to physiological processes (transpiration) and supports comparative questions on adaptations across climates.

📚 Reading List :
  • Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 3: MAJOR BIOMES > 10. Desert Biomes > p. 15
  • Certificate Physical and Human Geography , GC Leong (Oxford University press 3rd ed.) > Chapter 18: The Hot Desert and Mid-Latitude Desert Climate > Natural Vegetation > p. 176
🔗 Anchor: "Are tiny leaves a leaf modification in desert areas that reduces water loss?"
📌 Adjacent topic to master
S2
👉 Suite of desert plant adaptations (roots, succulence, leaf changes)
💡 The insight

Evidence groups leaf reduction with other desert adaptations such as deep roots and succulence, showing adaptations are integrated.

Useful for holistic answers on desert ecosystems, desertification and afforestation strategies; helps frame multi-part questions requiring causes, effects and management measures.

📚 Reading List :
  • Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 3: MAJOR BIOMES > 10. Desert Biomes > p. 15
  • Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 3: Terrestrial Ecosystems > iifffi E > p. 28
  • Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 3: Terrestrial Ecosystems > i) The plants conserve water by following methods: > p. 27
🔗 Anchor: "Are tiny leaves a leaf modification in desert areas that reduces water loss?"
📌 Adjacent topic to master
S3
👉 Leaf modifications in xerophytes (leaflessness, thorns, needle-shaped leaves)
💡 The insight

References directly describe desert plants having few/no leaves, some becoming entirely leafless with prickles/thorns, and needle-shaped foliage as adaptations to reduce transpiration.

High-yield for geography/botany questions on desert vegetation — explains a core xerophytic adaptation and helps answer comparisons between plant forms in arid vs. humid biomes. Mastery allows quick elimination/justification in MCQs and short-answer questions about plant form and function under water stress.

📚 Reading List :
  • Certificate Physical and Human Geography , GC Leong (Oxford University press 3rd ed.) > Chapter 18: The Hot Desert and Mid-Latitude Desert Climate > Natural Vegetation > p. 176
  • Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 3: MAJOR BIOMES > 10. Desert Biomes > p. 15
  • Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 30: Climatic Regions > Desert Vegetation > p. 443
🔗 Anchor: "Do plants in desert areas have thorns instead of leaves as a leaf modification t..."
🌑 The Hidden Trap

The physiological sibling to these morphological changes is 'CAM Photosynthesis' (Crassulacean Acid Metabolism) and 'Scotoactive Stomata' (stomata that open only at night to reduce water loss). Expect a question linking these physiological traits to desert plants soon.

⚡ Elimination Cheat Code

Use the 'Evolutionary Logic' heuristic. In a desert, water is the scarcest resource. Any option that describes a mechanism to *reduce* surface area (tiny leaves, thorns) or *seal* moisture (wax) is evolutionarily mandatory. Unless an option says 'Large broad leaves' (which increases transpiration), assume all water-saving modifications are present. 'All of the above' is the default state for adaptation questions.

🔗 Mains Connection

Link this to GS-3 Agriculture (Dryland Farming). Understanding natural xerophytic adaptations (deep roots, low water requirement) explains why Millets (C4 plants) are promoted for Climate Resilient Agriculture in drought-prone regions like Marathwada or Rayalaseema.

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SIMILAR QUESTIONS

IAS · 2013 · Q69 Relevance score: 8.03

Which of the following leaf modifications occurs/occur in desert areas to inhibit water loss? 1. Hard and waxy leaves 2. Tiny leaves or no leaves 3. Thorns instead leaves Select the correct answer using the codes given below.

CAPF · 2020 · Q44 Relevance score: -4.60

Which one of the following statements about the Acacia tree is/are correct ? 1. It has a long shallow root system which enables it to find moisture 2. It has thorny leaves to prevent water loss 3. It has wide crown so the foliage can absorb the maximum Sunlight Select the correct answer using the code given below:

CDS-I · 2009 · Q71 Relevance score: -5.71

Because of which one of the following factors, clouds do not precipitate in deserts?

CAPF · 2013 · Q26 Relevance score: -6.13

Leaves of lotus and water lily are not easily wet because the leaves

IAS · 2017 · Q71 Relevance score: -6.43

Which of the following practices can help in water conservation in agriculture ? 1. Reduced or zero tillage of the land 2. Applying gypsum before irrigating the field 3. Allowing crop residue to remain in the field Select the correct answer using the code given below :