Plant Structure and Function — REET Notes
This page covers the main parts of a plant for REET Level 2 (Maths-Science), the types of roots and their special adaptations (such as pneumatophores), and the classification of crops. REET 2024 asked questions from this topic based on plant adaptation and crop classification, so every concept here is explained in simple language with examples, making it easy to teach to Class 6-8 students too.
- 2 questions in REET 2024
- Class 6-8 level
- 9 min read
How REET asks this topic
REET 2024 carried two kinds of questions from this topic — one was based on special root adaptations in plants (pneumatophores, halophytes), and the other was based on the classification of crops (identifying a pulse/leguminous crop), which was later dropped (treated as a bonus) because of flawed answer options. In other words, alongside plant structure, REET also asks direct questions on everyday agricultural knowledge (types of crops). Since Rajasthan is an agriculture-heavy state, practical examples drawn from crops often show up among the options, so being able to identify local crops is useful too.
The main parts of a plant and their functions
A fully grown plant's main parts are the root, stem, leaf, flower and fruit, which together ensure the plant's nutrition, growth and reproduction. The root absorbs water and mineral salts from the soil and holds the plant firmly in place in the soil.
The stem carries the water and minerals absorbed by the root up to the leaves, and carries the food made in the leaves to the rest of the plant, while also supporting the leaves, flowers and fruits. The leaf is the plant's main food-making organ — through photosynthesis, it uses sunlight, carbon dioxide and water, in the presence of chlorophyll, to make food (glucose) and oxygen. Tiny pores on the leaf called stomata assist in gas exchange and in transpiration, and are found mostly on the lower surface of most leaves.
Types of roots
| Type | Feature | Example |
|---|---|---|
| Tap root | One main, thick root with thinner branches growing out of it; found in dicot plants | Mango, hibiscus, mustard, chickpea |
| Fibrous root | Many thin roots of roughly equal thickness growing in a bunch; found in monocot plants | Wheat, rice, grass, maize |
The first root to emerge when a seed germinates is called the radicle, which later develops into either a tap root or a fibrous root system.
Special root adaptations
| Adaptation | Found in which group of plants | Function |
|---|---|---|
| Pneumatophores (breathing roots) | Halophytes, such as mangroves | Grow upward in waterlogged, oxygen-poor saline soil to take in oxygen from the atmosphere |
| Prop roots | Large trees such as banyan | Provide extra support and stability to the trunk |
| Adventitious roots | Plants with a fibrous root system | Arise from the stem or the base of a leaf, rather than from the plant's original root |
Types of plants based on soil and water availability
Xerophytes are plants that grow in dry regions such as deserts; their roots go deep in search of water, the stem is thick and stores water, and the leaves are small or spine-like, cutting down water loss through transpiration — the cactus is a good example.
Hydrophytes are plants that grow in or near water; their stem is light and filled with air spaces (aerenchyma) that let them float in water, as seen in the lotus and water hyacinth. Halophytes grow in coastal, waterlogged, saline land, and are known for special roots like pneumatophores along with salt tolerance, as seen in mangroves (sundari forests).
Parts of a plant sometimes transform away from their usual function to serve a special purpose. The edible part of a potato is not actually a root but an underground stem (a stem tuber) that stores food, on which 'eyes' (buds) are found. Similarly, in the pea plant, part of a leaf changes into a thin, coiled tendril that helps it cling to a support, while in a cactus the leaves change into spines to reduce water loss.
Classification of crops
| Type | Examples |
|---|---|
| Cereals | Wheat, rice, maize, sorghum (jowar), pearl millet (bajra) |
| Pulses / leguminous crops | Chickpea (chana), green gram (moong), pigeon pea (arhar), lentil (masoor), black gram (urad) |
| Oilseeds | Groundnut, mustard, soybean, sesame |
| Cash crops | Sugarcane, cotton |
Crops such as bajra, mustard and chickpea are widely grown in Rajasthan, so understanding their classification well is useful from a REET perspective.
Features of pulse (leguminous) crops
- Nodules on roots
- small nodules (root nodules) form on the roots of leguminous plants
- Rhizobium bacteria
- these nodules host Rhizobium bacteria, which fix atmospheric nitrogen
- Benefit to soil
- this raises the nitrogen content of the soil and improves its fertility
- Use in crop rotation
- this is exactly why farmers include leguminous crops in crop rotation, to maintain the fertility of the field
How to teach this to children
Classroom activity
Have students collect samples of tap-rooted and fibrous-rooted plants from the school premises, identify the difference between the two themselves, sort them into a table, and paste it into their notebook.
Teaching aids
Show photos or short videos of plants growing in different conditions — cactus, lotus and mangrove — and have students compare the root-leaf structure of each, so they can work out the relationship between environment and structure for themselves.
Common misconception
Students often think the root's only job is to anchor the plant in the soil, or mistake the potato for a root. Make clear that absorbing water and mineral salts is just as much a main function of the root, and that the presence of buds ('eyes') on the potato proves it is a stem.
Assessment idea
Show plant samples brought to class and have students identify the type of root and any special adaptation present, ask them for the reason, and have them write it in their own words.
Memory trick
'Deep in the desert, up in the swamp' — a xerophyte's (desert plant's) roots go deep searching for water, while a halophyte's (mangrove's) roots rise upward searching for oxygen — these upward-growing roots are exactly what are called pneumatophores.
REET 2024 questions (solved)
Question 145Bonus — dropped in the final key
Example of pulses crop is
- Aगेहूँ
- Bगन्ना
- Cज्वार
- Dमूँगफली
Explanation
BSER ने अंतिम उत्तर कुंजी में इस प्रश्न को BONUS (निरस्त) कर दिया है। दिए गए विकल्पों में कोई भी दलहनी (pulse) फसल नहीं है: गेहूँ अनाज (cereal), गन्ना नकदी/शर्करा फसल, ज्वार मोटा अनाज (millet) और मूँगफली तिलहन (oilseed) फसल है। दलहनी फसलों के उदाहरण चना, मूँग, अरहर, मसूर आदि हैं; इसलिए कोई सही विकल्प न होने से प्रश्न निरस्त हुआ प्रतीत होता है।
Question 133
Presence of pneumatophore in root is an adaptation of
- Aमरुद्भिद
- Bलवणमृदोद्भिद
- Cजलोद्भिद
- Dसमेद्भिद
Explanation
न्यूमेटोफोर (श्वसन मूल) ऊपर की ओर बढ़ने वाली जड़ें हैं जो मैंग्रोव जैसे लवणीय, दलदली स्थानों के पौधों (लवणमृदोद्भिद / halophytes) में पाई जाती हैं। दलदली मिट्टी में ऑक्सीजन की कमी होती है, इसलिए ये जड़ें वायु से गैसीय विनिमय में सहायता करती हैं। मरुद्भिदों में गहरी जड़ें व मोटी पत्तियाँ जैसे अनुकूलन होते हैं।
Practice questions
Question 1
Absorption of water and mineral salts in a plant mainly happens through —
- Aतना
- Bजड़
- Cपत्ती
- Dफूल
Explanation
The root absorbs water and mineral salts from the soil and also anchors the plant firmly in the soil.
Question 2
Dicot plants generally have which type of root?
- Aझकड़ा जड़
- Bमूसला जड़
- Cअपस्थानिक जड़
- Dस्तंभ जड़
Explanation
In dicot plants (such as mango, chickpea), branches grow out of one main thick root, which is called a tap root.
Question 3
The breathing roots found in saline swampy plants like mangroves are called —
- Aस्तंभ मूल
- Bन्यूमेटॉफोर
- Cपरजीवी मूल
- Dसंचयी मूल
Explanation
Pneumatophores are upward-growing special roots that assist with gas exchange with the air in oxygen-poor waterlogged soil.
Question 4
A common adaptation in desert plants (xerophytes) to reduce water loss is —
- Aबड़ी चौड़ी पत्तियाँ
- Bमोटी छल्ली एवं कांटेनुमा पत्तियाँ
- Cजड़ों का पूर्ण अभाव
- Dअत्यंत पतली छाल
Explanation
In xerophytes, a thick cuticle along with spine-like leaves reduces water loss through transpiration.
Question 5
The structure present in the leaf for gas exchange and transpiration is —
- Aरंध्र (स्टोमेटा)
- Bजाइलम
- Cफ्लोएम
- Dक्लोरोफिल कण
Explanation
Stomata, present on the surface of the leaf, assist in both gas exchange and transpiration.
Question 6
The nitrogen-fixing bacteria found in the root nodules of leguminous crops is —
- Aएस्केरिशिया कोलाई
- Bराइजोबियम
- Cलैक्टोबैसिलस
- Dसाल्मोनेला
Explanation
Rhizobium bacteria live in the root nodules of leguminous plants and fix atmospheric nitrogen, making the soil fertile.
Question 7
Which of the following crops belongs to the oilseed category?
- Aचना
- Bगेहूँ
- Cसरसों
- Dगन्ना
Explanation
Mustard is an oilseed crop because oil is extracted from its seeds; chickpea is a pulse, wheat is a cereal, and sugarcane is a cash crop.
Question 8
The most effective activity for teaching types of roots in Class 7 is —
- Aकेवल पाठ्यपुस्तक का चित्र दिखाना
- Bविद्यार्थियों से वास्तविक पौधों की जड़ें लाकर तुलना करवाना
- Cकेवल परिभाषा रटवाना
- Dविषय पर कोई गतिविधि न करना
Explanation
Direct observation of real samples helps students understand the difference between tap roots and fibrous roots in a lasting way.
Question 9
A common misconception among students is that the only function of a root is to hold the plant in the soil. The suitable way to clear this is —
- Aभ्रांति को नज़रअंदाज़ करना
- Bजड़ द्वारा जल व खनिज अवशोषण को उदाहरण सहित समझाना
- Cकेवल परीक्षा में पूछना
- Dजड़ का विषय हटा देना
Explanation
Explaining with examples helps students understand that the root's main function also includes absorption, not just providing stability.
Question 10
The special structure in aquatic plants (hydrophytes) like the lotus that helps them float on water is called —
- Aकांटे
- Bवायु कोष्ठ (एरेनकाइमा)
- Cमोटी छाल
- Dगहरी जड़ें
Explanation
Aquatic plants (hydrophytes) have air-filled spaces (aerenchyma) in their stem and leaves, which give them buoyancy and help them float in water.
Frequently asked questions
How many questions come from Plant Structure in REET?+
REET 2024 carried 2 questions from this topic, one based on root adaptation and one based on crop classification.
What are pneumatophores?+
Pneumatophores are breathing roots that grow upward in halophytes such as mangroves, taking in oxygen from the atmosphere.
Why are pulse crops beneficial for soil?+
Rhizobium bacteria in the root nodules of pulse crops fix atmospheric nitrogen, which increases the fertility of the soil.
What is the difference between a tap root and a fibrous root?+
A tap root has one main thick root (dicot plants), while a fibrous root has many thin roots of similar thickness growing in a bunch (monocot plants).
Is a potato a root?+
No, a potato is not actually a root but an underground stem (a stem tuber), on which buds ('eyes') are found — something roots never have.
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Change Log
- 17 September 2026 — English page published — mirrors the fact-checked Hindi page, independently bilingual-accuracy checked