Plants Are Everywhere — But Do We Really Know Them?
Walk out of your house and you’ll see plants. In your garden, on the roadside, in the park, in your food. We grow up surrounded by plants, yet most of us know surprisingly little about how they work and why they look the way they do.
Class 6 Biology starts here — with plants — and it’s one of the best starting points in science. Why? Because you can verify everything you learn by just stepping outside. No lab needed.
This chapter covers what makes a plant a plant: its parts, their functions, and how different plants have adapted these parts in clever ways. Once you understand the logic behind each part, you stop memorising and start seeing plants differently.
One thing that trips up many students early on: plants are not passive. They actively make their food, transport water and minerals across their entire body, and reproduce. Every part of a plant has a specific job, and understanding that job is the key to every question — whether it’s a 1-mark fill-in-the-blank or a 5-mark explanation question in your board exam.
Key Terms and Definitions
Root: The underground part of most plants. Roots anchor the plant in soil and absorb water and dissolved minerals.
Shoot: Everything above the ground — the stem, leaves, flowers, and fruits. The shoot system is responsible for food-making and reproduction.
Stem: The main stalk connecting roots to leaves. It conducts water upward and food downward, and gives the plant its shape.
Leaf: The food factory of the plant. Leaves carry out photosynthesis — making glucose using sunlight, water, and carbon dioxide.
Stomata (singular: stoma): Tiny pores on the surface of leaves (usually the underside) through which gases enter and exit. Water vapour also escapes through stomata — this is called transpiration.
Chlorophyll: The green pigment in leaves that captures sunlight for photosynthesis. This is why most leaves are green.
Photosynthesis: The process by which a plant makes its own food.
Taproot: A single thick main root with smaller lateral roots branching off it. Example: carrot, radish, mustard.
Fibrous root: A cluster of thin roots of similar thickness, with no main root. Example: wheat, grass, onion.
Petiole: The stalk that attaches a leaf to the stem.
Lamina: The flat, broad part of the leaf (the blade). This is where photosynthesis mainly happens.
Venation: The pattern of veins on a leaf. Two types: reticulate (net-like, like in mango) and parallel (straight parallel lines, like in grass).
Transpiration: Loss of water vapour from leaves through stomata. This creates a “pull” that helps draw water up from the roots.
The Parts of a Plant and Their Functions
Roots
Roots do two main jobs: anchorage and absorption.
The root tip has millions of tiny root hair cells. Each root hair is a thin extension of a single cell, and together they dramatically increase the surface area available for absorbing water. This is smart engineering — more surface area means more absorption without the plant needing to grow a much larger root.
Types of roots:
| Feature | Taproot | Fibrous Root |
|---|---|---|
| Main root | One thick main root | No single main root |
| Appearance | Carrot-like | Thread-like cluster |
| Found in | Dicots (bean, mustard) | Monocots (rice, wheat) |
| Examples | Carrot, radish, rose | Grass, wheat, maize |
Some roots also store food — carrot and radish are actually swollen taproots packed with stored nutrients.
A quick trick to remember: plants with parallel venation (monocots) have fibrous roots. Plants with reticulate venation (dicots) have taproots. Venation and root type always match — this makes for great 1-mark questions.
Stem
The stem is the plant’s transport highway. Water and minerals move upward through tube-like structures called xylem, while food (glucose) made in the leaves moves downward through phloem. You’ll study xylem and phloem in much more detail in higher classes.
Stems also:
- Support leaves, flowers, and fruits
- Store food in some plants (sugarcane stores sugar in its stem)
- Carry out photosynthesis in green stems (like cactus, where there are no proper leaves)
Modifications of stem: Some plants have modified stems for specific functions. The potato we eat is an underground modified stem called a tuber (not a root!). The “eyes” of a potato are actually buds that sprout into new plants.
Leaves
The leaf is where the real action happens. Its flat, broad shape maximises the surface area exposed to sunlight.
Parts of a leaf:
- Petiole — connects leaf to stem
- Lamina — the flat blade
- Midrib — the main central vein
- Veins — carry water in and food out
Venation patterns:
- Reticulate venation: Veins branch out and form a network. Found in dicot plants like mango, rose, tulsi, peepal.
- Parallel venation: Veins run parallel to each other. Found in monocot plants like banana, grass, bamboo.
In CBSE Class 6 exams, a very common question shows you two leaf diagrams and asks you to identify the venation type and give one example. Always pair your answer: “Reticulate venation — example: mango leaf.”
Stomata — the breathing pores:
Stomata are microscopic pores, mostly on the lower surface of the leaf. Each stoma is surrounded by two guard cells that control whether it’s open or closed.
When the plant needs CO₂ for photosynthesis (during daylight), stomata open. At night, they close. When the plant is short of water, they also close to reduce water loss — the plant is protecting itself.
Flowers
The flower is the reproductive organ of a plant. Its parts:
- Petals: Colourful parts that attract pollinators (bees, butterflies)
- Sepals: Green leaf-like structures at the base that protect the bud
- Stamens: Male reproductive parts (produce pollen)
- Pistil: Female reproductive part (receives pollen, produces seeds)
Not all flowers have all four parts. A complete flower has petals, sepals, stamens, and pistil. Many flowers we eat — like bottle gourd flowers — are either male or female, not both.
Fruits and Seeds
After pollination, the pistil develops into a fruit. The fruit protects the seed and helps in its dispersal — spreading seeds to new locations so new plants can grow without competing with the parent.
Seeds contain a baby plant (embryo) and stored food. When conditions are right — right temperature, moisture, air — the seed germinates and the embryo starts growing.
Photosynthesis — The Most Important Process in Biology
Every animal on Earth, including us, depends directly or indirectly on photosynthesis. Plants capture sunlight and use that energy to combine CO₂ from air and water from soil to make glucose. Oxygen is released as a byproduct — the oxygen we breathe.
Simple version: Carbon dioxide + Water → Glucose + Oxygen
Three things are needed for photosynthesis:
- Sunlight (energy source)
- Water (absorbed by roots)
- Carbon dioxide (enters through stomata)
And one ingredient must already be present in the leaf: 4. Chlorophyll (the pigment that captures sunlight)
A plant kept in a dark room will stop making food and eventually die — even if it has water and CO₂ — because there’s no sunlight for photosynthesis. This is why plants grow towards light.
Solved Examples
Example 1 — Easy (CBSE Board)
Q: Identify the type of root system shown in the figure of a wheat plant. Give two characteristics.
Solution:
Wheat has a fibrous root system.
Characteristics:
- No single main root — instead, many thin roots of similar thickness arise from the base of the stem.
- The roots form a dense cluster near the soil surface.
Other examples: grass, rice, maize, onion.
Example 2 — Medium (CBSE Board)
Q: Why do leaves appear green? If a plant is kept in darkness for a few days, what will happen to its leaves and why?
Solution:
Leaves appear green because they contain chlorophyll, a green pigment present in chloroplasts. Chlorophyll reflects green light (which we see) and absorbs red and blue light for photosynthesis.
If kept in darkness for several days:
- The plant cannot carry out photosynthesis (no sunlight = no energy)
- Chlorophyll breaks down and is not replaced
- Leaves turn yellow — a condition called etiolation
- Eventually the plant will wilt and die
This shows that chlorophyll production depends on light.
Example 3 — Medium (CBSE Board)
Q: A student performed an experiment to show that stomata are present on the lower surface of a leaf. Describe the experiment and expected result.
Solution:
Experiment (Cobalt chloride paper test):
- Take two strips of dry cobalt chloride paper (blue when dry, turns pink when wet).
- Attach one strip to the upper surface of a leaf and another to the lower surface.
- Cover both with glass slides held in place with rubber bands.
- Observe after 15–20 minutes.
Expected result: The strip on the lower surface turns pink first (and more intensely) because more stomata are present on the lower surface, allowing more water vapour to escape.
Conclusion: Stomata are more numerous on the lower surface of the leaf.
Example 4 — Higher Order (CBSE Class 6, Activity-Based)
Q: Radha soaked some seeds overnight and then pressed a bean seed open. Draw and label what she would see inside.
Solution:
Inside a soaked bean seed, Radha would see:
- Seed coat (testa): Outer protective covering
- Two cotyledons: Two thick fleshy halves — these store food for the germinating seedling
- Embryo: The tiny baby plant nestled between the cotyledons, consisting of:
- Plumule — the baby shoot (grows upward)
- Radicle — the baby root (grows downward)
Soaking helps because the seed coat softens and swells, making it easier to open and observe the internal structure.
The cotyledons provide nutrition until the seedling grows its first true leaves and can photosynthesize on its own. This is why seeds are so nutrient-dense — we eat them!
Exam-Specific Tips
For CBSE Class 6
- 1-mark questions often ask: root type of a given plant, venation type, function of stomata, or the equation for photosynthesis. Memorise all examples alongside their category.
- 3-mark questions usually ask you to compare two things (taproot vs. fibrous root, reticulate vs. parallel venation). Always use a table format — examiners love it.
- 5-mark questions often involve experiments (showing stomata, showing that leaves need light for photosynthesis). Learn the steps, materials, and conclusion format for each standard experiment.
- Diagrams carry marks. Practice the labelled diagram of a leaf (with veins, midrib, petiole, lamina) and parts of a flower (petals, sepals, stamen, pistil).
The photosynthesis equation is a guaranteed 1-mark question in most CBSE schools. Write it in words AND symbols — some papers accept either, some want both.
Common Mistakes to Avoid
Mistake 1: Calling potato a root. Potato is a modified stem (tuber), not a root. It grows underground but has nodes, buds (“eyes”), and is part of the shoot system. In contrast, radish and carrot are modified roots. This single mistake costs marks in virtually every school exam.
Mistake 2: Thinking all plants have flowers. Not true. Ferns, mosses, and fungi (not really a plant, but often confused) reproduce without flowers. At Class 6 level, you’re mainly studying flowering plants, but don’t make a blanket statement that “all plants have flowers.”
Mistake 3: Reversing venation and root type. Parallel venation → fibrous roots (monocots). Reticulate venation → taproot (dicots). Students often flip these. Trick: “Parallel = Palm trees = Fibrous.” Visualise a palm tree’s fibrous roots.
Mistake 4: Saying stomata are only for breathing. Stomata serve multiple functions: gas exchange (CO₂ in, O₂ out during photosynthesis; O₂ in, CO₂ out during respiration) AND transpiration (water vapour out). Students who only write “for breathing” lose the transpiration mark.
Mistake 5: Confusing petals and sepals in diagrams. Sepals are the green, leaf-like parts at the base of the flower that protect the bud. Petals are the colourful parts that attract pollinators. In a diagram, if you label them the wrong way round, you lose the mark completely.
Practice Questions
Q1. Name the part of the plant that absorbs water from the soil. How does its structure help it do this job efficiently?
Answer: Roots absorb water from the soil. The root tip is covered with millions of root hair cells — each root hair is an extension of a single cell. This greatly increases the total surface area in contact with soil water, allowing much faster and more efficient absorption.
Q2. Classify the following plants into taproot and fibrous root systems: Mango, Wheat, Mustard, Grass, Carrot, Onion, Rose, Rice.
Taproot: Mango, Mustard, Carrot, Rose
Fibrous root: Wheat, Grass, Onion, Rice
Q3. A leaf from a mango tree and a leaf from a banana tree are placed side by side. How would you tell them apart by looking at their venation? Draw and label the venation pattern for each.
Mango leaf: Shows reticulate venation — veins branch out from the midrib and form an irregular net-like pattern across the lamina.
Banana leaf: Shows parallel venation — veins run parallel to each other from the midrib to the leaf margin, without forming a network.
(Your diagram should show: midrib in the centre, branching network for mango vs. parallel lines for banana.)
Q4. What are stomata? Why are there more stomata on the lower surface of a leaf than the upper surface?
Stomata are tiny pores on the leaf surface surrounded by guard cells. They allow CO₂ to enter and O₂ to exit during photosynthesis, and also allow water vapour to escape (transpiration).
More stomata on the lower surface because:
- The upper surface is exposed to direct sunlight, which would cause excessive water loss if stomata were present there
- Keeping stomata on the shaded lower surface reduces unnecessary water loss while still allowing gas exchange
- This is an adaptation to conserve water
Q5. Why do plants need both roots and leaves to survive? Can a plant survive with only one of these?
Plants need both because they perform different but equally essential functions:
- Roots absorb water and dissolved minerals from soil — without these raw materials, photosynthesis cannot happen.
- Leaves carry out photosynthesis to make food — without food, the plant starves and cannot grow.
A plant with only roots but no leaves cannot make food and will die. A plant with only leaves but no roots cannot get water and minerals — it will wilt and die quickly. Both systems are interdependent.
Q6. Riya noticed that a plant left without water for days had drooping, wilted leaves, but after she watered it, the leaves became firm again within hours. Explain why this happens.
Plant cells have a large central vacuole that fills with water. When cells are well-watered, the vacuole pushes against the cell wall creating turgor pressure — this makes cells firm, which makes leaves and stems rigid.
When water is scarce, the vacuole shrinks, cells lose turgor pressure, and leaves droop (wilt). When water is available again, roots absorb it rapidly, water moves up the stem into leaves, vacuoles fill back up, and leaves become firm again.
This also explains why stomata close when water is scarce — the guard cells lose turgor and the pore shuts, reducing further water loss.
Q7. The following are examples of plants: sugarcane, cactus, onion, rose, banana, peepal, grass, mustard. Categorise them by: (a) root type, (b) venation type.
| Plant | Root Type | Venation |
|---|---|---|
| Sugarcane | Fibrous | Parallel |
| Cactus | Taproot | Reticulate |
| Onion | Fibrous | Parallel |
| Rose | Taproot | Reticulate |
| Banana | Fibrous | Parallel |
| Peepal | Taproot | Reticulate |
| Grass | Fibrous | Parallel |
| Mustard | Taproot | Reticulate |
Notice how root type and venation always correspond — fibrous with parallel, taproot with reticulate.
Q8. Explain with reasons why a green plant kept in a sealed transparent container with soil and water can survive for weeks without opening the container.
The plant creates a self-sustaining closed system:
- During the day: The plant photosynthesises — absorbs CO₂ and releases O₂. It also uses some O₂ for its own respiration and releases CO₂.
- Water cycle: Water absorbed by roots moves to leaves, evaporates through stomata (transpiration), condenses on the container walls, and drips back into the soil.
- Gas cycle: Photosynthesis and respiration together cycle CO₂ and O₂ within the container.
The sealed transparent container allows light in (needed for photosynthesis) while recycling water and gases internally. This is essentially a miniature ecosystem.
FAQs
Q: Why do leaves change colour in autumn?
As days get shorter and colder, trees prepare to shed their leaves. Chlorophyll (green) breaks down first, revealing other pigments that were always present — yellow xanthophylls and orange carotenoids. Some trees also produce red anthocyanins as chlorophyll breaks down. This is not covered deeply in Class 6 but is great context for understanding chlorophyll’s role.
Q: Is a mushroom a plant?
No. Mushrooms are fungi, not plants. The key difference: plants make their own food through photosynthesis (autotrophs). Fungi cannot — they absorb nutrients from dead or living organic material (heterotrophs). Fungi have no chlorophyll and no cell walls made of cellulose (they use chitin instead). At Class 6 level, remember: if it can’t make its own food, it’s not a plant.
Q: Do plants breathe?
Yes, but differently from animals. Plants respire continuously (taking in O₂, releasing CO₂) using the food they’ve made. But during daylight, they also photosynthesize, which uses CO₂ and releases O₂. The rate of photosynthesis is much higher than respiration during the day, so the net effect during the day is CO₂ in and O₂ out. At night, only respiration happens: O₂ in and CO₂ out.
Q: Why do some plants have colourful flowers while others have dull ones?
Colourful flowers attract animal pollinators — bees, butterflies, birds, bats. These animals transfer pollen from one flower to another. Plants that are pollinated by wind (like grasses) don’t need to attract animals, so their flowers are small, dull, and produce large amounts of lightweight pollen. The flower’s appearance is a direct result of how it gets pollinated.
Q: Can a plant survive without roots?
Some aquatic plants (like hydrilla, lotus) have roots but they float or are anchored in mud differently. A few plants like some mosses get water directly through their surfaces and have no true roots. But for land plants with stems and leaves, roots are essential for both anchorage and water absorption. Remove the roots of a land plant and it dies.
Q: What is the difference between a fruit and a vegetable?
Botanically: a fruit is the ripened ovary of a flower containing seeds. A vegetable is any other edible part of a plant — root (carrot), stem (potato), leaf (spinach), or flower (broccoli). By this definition, tomato, cucumber, capsicum, and brinjal are all fruits! But in everyday cooking, we call them vegetables. Botanists and cooks disagree — and that’s actually a wonderful example of how scientific definitions differ from everyday usage.
Q: Why is photosynthesis called the basis of all life on Earth?
All food ultimately comes from plants (or other photosynthesisers like algae). Herbivores eat plants. Carnivores eat herbivores. Even decomposers break down dead organisms that were once part of this food chain. Remove photosynthesis and the entire food chain collapses. Additionally, the oxygen in Earth’s atmosphere is almost entirely produced by photosynthesis — by plants, algae, and cyanobacteria — over billions of years. Every breath we take is a gift from photosynthesis.