This MCQ module is based on: Transport and Respiration in Plants
TOPIC 37 OF 46
Transport and Respiration in Plants
🎓 Class 7
Science
CBSE
Theory
Ch 10 — Life Processes in Plants
⏱ ~14 min
🌐 Language: [gtranslate]
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[myaischool_lt_science_assessment grade_level="class_7" science_domain="biology" difficulty="basic"]
The Banyan Tree near Kavya's House
Kavya sits under the huge banyan tree at the corner of her street in Bengaluru. Its top branches reach far above the rooftops. "Nanu," she asks her grandfather, "the water for this tree is down in the soil, but the leaves are up there. How does water reach so high without any pump? And where do the sugars made in the leaves travel to? Also, does a tree breathe like we do?"
Think first: A thirty-metre tall tree has no heart and no lungs. Yet water climbs from its roots to the topmost leaves, sugars travel down to the fruits, and every single living cell keeps respiring day and night. How might a living thing manage all three without any muscles?
10.12 Why Plants Need Transport
A plant is alive in every part — the deep roots, the trunk, the leaves far above, and even the flowers and fruits. Each living cell needs:
- Water and minerals — absorbed only by roots from the soil.
- Food (glucose) — made only in green leaves by photosynthesis.
So the plant must have a built-in delivery system that carries water and minerals up from the roots, and carries food in every direction from the leaves. Two tissues handle these jobs: xylem and phloem.
10.13 Xylem — The Water Pipeline
Xylem is a system of narrow, tube-like channels that run right through the plant — from root tip to the veins in every leaf. Xylem cells are long, hollow and dead; this empty design turns them into ready-made pipes. Water absorbed by the roots climbs up through these pipes, reaching leaves 30 metres or more above the ground.
What pushes the water up?
Two natural forces do the work:
- Root pressure — roots actively pump water inward, creating a gentle upward push. You can sometimes see tiny water drops at the edge of a grass blade early in the morning — this is root pressure at work.
- Transpiration pull — as water evaporates from the leaves through stomata, it "pulls" a continuous thread of water up the xylem, rather like sucking juice through a straw. This is the bigger force in tall trees.
10.14 Phloem — The Food Delivery Line
The sugar made in leaves cannot walk by itself to the fruits and roots. It is carried by a second tissue, the phloem. Unlike xylem, phloem cells are alive. Phloem carries dissolved food both upward and downward, reaching every living cell of the plant.
| Feature | Xylem | Phloem |
|---|---|---|
| Carries | Water and dissolved minerals | Dissolved food (mainly glucose) |
| Direction | Roots → stem → leaves (upward) | Leaves → every part (both ways) |
| Cell state | Dead and hollow | Living |
| Force used | Root pressure + transpiration pull | Pressure flow from source to sink |
10.15 Transpiration — The Plant's Cooling System
Transpiration is the continuous loss of water as water vapour from the leaves through the stomata. It may seem wasteful, but it serves three big purposes:
- It creates the transpiration pull that lifts water up the xylem.
- It cools the leaf — just as sweating cools our skin.
- It helps distribute minerals (dissolved in the rising water) throughout the plant.
Activity 10.3 — See Transpiration Happen L3 Apply
You need: a small potted plant with fresh leaves, a clear polythene bag, a thread and sunlight.
- Tie the polythene bag loosely around a leafy branch so that no outside air enters (do not cover the soil).
- Place the plant in a sunny spot for 2–3 hours.
- Observe the inside of the polythene bag carefully.
Predict: What will you see on the inner wall of the bag after two hours? Where did this come from?
You will see small water droplets clinging to the inside of the bag. This water did not come from the soil directly. It came out of the leaves as water vapour through the stomata, and then condensed on the cooler plastic — this is transpiration. If you repeat the experiment with a bag tied over a bare twig of the same plant (no leaves), hardly any water collects, proving that leaves are the main transpiring surface.
10.16 Respiration in Plants
Respiration is how any living cell releases the energy locked inside glucose. The overall word equation is the reverse of photosynthesis:
Glucose + Oxygen → Carbon dioxide + Water + Energy
Every living cell of a plant — in the root, stem, leaf, flower and fruit — respires all the time, day and night. Plants do not have lungs. So how does oxygen reach the cells, and how does carbon dioxide leave?
Three Breathing Openings in Plants
| Part of plant | Breathing opening | Where found |
|---|---|---|
| Leaves | Stomata | Mostly on the lower surface of each leaf |
| Woody stems | Lenticels | Scattered across the bark as small slits |
| Roots | Root hairs | Covering the fine rootlets underground |
Root hairs take in air from the tiny gaps between soil particles — this is why plants suffer when the soil gets water-logged, as the air spaces fill with water and the roots suffocate.
10.17 Day vs Night — A Twist in Gas Exchange
Both photosynthesis and respiration use and release the same pair of gases — oxygen and carbon dioxide — but in opposite directions:
| Process | Gas taken in | Gas given out | When it happens |
|---|---|---|---|
| Photosynthesis | Carbon dioxide | Oxygen | Only in sunlight (day) |
| Respiration | Oxygen | Carbon dioxide | Day AND night — always |
During the day: Photosynthesis is much faster than respiration. The plant uses all the CO\u2082 it respires out (and more from the air), and releases large amounts of oxygen. So net: CO\u2082 in, O\u2082 out.
At night: No sunlight, so no photosynthesis. Only respiration continues. So the plant takes in oxygen and releases carbon dioxide — just like us. This is why it is often said that sleeping under a dense tree at night is less refreshing than during the day.
Clearing a common confusion: Plants respire both day and night. What changes between day and night is photosynthesis, not respiration.
Competency-Based Questions
Kavya's grandfather has a tall coconut tree in his garden. One monsoon, heavy rains flooded the garden and water stood around the tree for almost a week. A few weeks later, the tree started looking sickly — leaves yellowed and stopped growing, even though there was plenty of water.
1. Water and minerals are carried from roots to leaves by: L1
(c) Xylem — a tissue of dead, hollow, tube-like cells that acts as the water pipeline.
2. Explain why the flooded coconut tree in the scenario began to wilt despite having plenty of water. L4
When soil is water-logged, the air spaces between soil particles fill with water. Root hairs can no longer get oxygen, so the roots cannot respire. Without respiration, the roots do not release enough energy to absorb water and minerals, so the tree starves even though water is all around.
3. State whether True or False: Plants respire only at night. L1
False. Plants respire day and night. It only appears that they release oxygen in the day because photosynthesis masks the small amount of CO\u2082 given out by respiration.
4. Fill in the blank: The tiny slits on the bark of a tree through which its woody stem breathes are called __________. L1
lenticels
5. Why does transpiration help a plant rather than harm it? Give two reasons. L2
(i) The evaporation of water from leaves creates an upward pull in the xylem, lifting water from the roots to the topmost leaves. (ii) Evaporation cools the leaf surface, preventing heat damage on hot days. A third bonus: it carries dissolved minerals upward along with the water.
Assertion–Reason Questions
Choose: (A) Both true, R explains A. (B) Both true, R does not explain A. (C) A true, R false. (D) A false, R true.
A: In a tall tree, water reaches the highest leaves without any pump.
R: Evaporation of water from the leaves pulls a continuous thread of water up through the xylem.
(A) — both true, and R explains A. This is the transpiration-pull mechanism.
A: Phloem carries food in only one direction, from leaves downward.
R: Phloem cells are dead and act as simple pipes.
(D) — Both parts are false in their specific claims; A is false because phloem carries food in both directions; R is false because phloem cells are living. This combination makes the correct choice (D) when the standard options define "A false, R false" under (D) — check your paper's option wording. (In our convention here we treat "both false" as closest to D.)
A: Farmers must avoid water-logging of their fields.
R: When soil air spaces fill with water, root hairs cannot get oxygen for respiration.
(A) — both true, and R correctly explains why water-logging harms crops.
Frequently Asked Questions — Transport and Respiration in Plants
What does the topic 'Transport and Respiration in Plants' cover in Class 7 Science?
The topic 'Transport and Respiration in Plants' is part of NCERT Class 7 Science Chapter 10 — Life Processes in Plants. It covers the key ideas of xylem, phloem, transpiration, stomata, respiration in plants, root pressure, transport, explained through everyday examples, labelled diagrams and hands-on activities drawn from the NCERT Curiosity textbook. Students learn not just definitions but also the reasoning behind each concept so they can answer competency-based questions and assertion–reason items. The lesson helps Class 7 students build a strong base for higher classes by linking each idea to real observations at home, school and in nature, and by preparing them for CBSE school assessments and Olympiads.
Why is 'Transport and Respiration in Plants' important for Class 7 NCERT Science?
'Transport and Respiration in Plants' is important because it builds core scientific thinking that Class 7 students will use throughout middle and secondary school. NCERT Chapter 10 — Life Processes in Plants — introduces xylem and related ideas that appear again in Class 8, 9 and 10 Science. Mastering this subtopic helps students read labels and safety signs, understand news about science and technology, and perform better in CBSE school exams. The chapter also encourages curiosity and evidence-based thinking — skills that support the National Education Policy (NEP) 2020 focus on conceptual understanding and competency-based learning.
What are the key concepts students should remember from Transport and Respiration in Plants?
The key concepts in 'Transport and Respiration in Plants' for Class 7 Science are: xylem, phloem, transpiration, stomata, respiration in plants, root pressure, transport. Students should be able to define each term in their own words, give at least one everyday example, and explain how the concept connects to other chapters in NCERT Class 7 Science. For example, linking the idea to daily life — in the kitchen, classroom or outdoors — makes revision easier. Writing short notes, drawing labelled diagrams and solving the NCERT in-text and exercise questions for Chapter 10 will help students retain these concepts for unit tests and the annual CBSE examination.
How is Transport and Respiration in Plants taught using activities in NCERT Curiosity Class 7?
NCERT Curiosity Class 7 Science teaches 'Transport and Respiration in Plants' using an inquiry-based approach with Predict–Observe–Explain activities. Students are asked to make a guess first, then perform a simple experiment with safe, easily available materials, and finally explain what they observed. This matches the NEP 2020 focus on learning by doing. For Chapter 10 — Life Processes in Plants — the textbook includes hands-on tasks, labelled diagrams and questions that build Bloom's Taxonomy skills from Remember (L1) to Create (L6). Teachers use these activities, along with competency-based questions (CBQs) and assertion–reason items, to check real understanding rather than rote memorisation.
What real-life examples of xylem can Class 7 students observe at home?
Class 7 students can observe xylem at home in many simple ways linked to 'Transport and Respiration in Plants'. Kitchens, school bags, playgrounds and the night sky are full of examples that connect to NCERT Chapter 10 — Life Processes in Plants. For instance, students can check labels on food and cleaning products, watch changes while cooking, or observe the Sun and Moon across a week. Keeping a small science diary — noting the date, what was observed and a quick sketch — turns everyday life into a science lab. These real-life connections make concepts stick and prepare students well for competency-based questions in CBSE Class 7 Science.
How does 'Transport and Respiration in Plants' connect to other chapters of Class 7 Science?
'Transport and Respiration in Plants' connects to many other chapters in NCERT Class 7 Science Curiosity. The ideas of xylem appear again when students study related topics like heat, light, changes, life processes and Earth-Sun-Moon. For example, understanding this subtopic helps in building mental models for later chapters and for Class 8, 9 and 10 Science. Teachers often use cross-chapter questions in CBSE examinations to test whether students can apply what they learned in Chapter 10 — Life Processes in Plants — to new situations. This integrated approach matches the NEP 2020 and NCF 2023 focus on holistic, competency-based learning.
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