Life Processes in Plants
Discover how plants prepare food, exchange gases, respire, transport water and nutrients, and coordinate essential life processes without moving from place to place.
Chapter Snapshot
- Plants perform essential life processes just as animals do.
- Green plants prepare their own food through photosynthesis.
- Photosynthesis requires carbon dioxide, water, sunlight and chlorophyll.
- Leaves contain stomata, which allow exchange of gases.
- Roots absorb water and dissolved minerals from the soil.
- Xylem transports water and minerals from roots to other plant parts.
- Phloem transports prepared food from leaves to growing and storage regions.
- Plants lose water vapour mainly through stomata by transpiration.
- Transpiration can contribute to upward movement of water through a plant.
- Plants perform respiration continuously, during both day and night.
- Photosynthesis stores energy in food, while respiration releases usable energy from food.
- Different plant structures work together to maintain growth, repair and survival.
What You Will Learn
- Explain why plants need life processes for survival and growth
- Describe how green plants prepare their own food
- Identify the raw materials and conditions required for photosynthesis
- Explain the roles of chlorophyll, sunlight, carbon dioxide and water
- Describe the structure and function of stomata
- Explain how roots absorb water and minerals from the soil
- Describe the role of xylem in transporting water and minerals
- Describe the role of phloem in transporting prepared food
- Define transpiration and explain its importance
- Differentiate between photosynthesis and respiration
- Explain why plants respire during both day and night
- Connect photosynthesis, transport and respiration as coordinated plant life processes
Chapter Overview
Plants may appear quiet and inactive, but a great deal of biological activity is taking place inside them.
A plant:
- absorbs water from soil;
- takes carbon dioxide from air;
- captures sunlight;
- prepares food;
- transports water and nutrients;
- exchanges gases;
- releases energy from food;
- grows;
- repairs damaged tissues.
Unlike animals, green plants can prepare their own food.
This ability makes them extremely important because most food chains ultimately depend on plants.
Plants may not move from place to place like many animals, but they perform all essential activities required for life.
They:
- grow;
- respire;
- respond to surroundings;
- transport substances;
- reproduce;
- remove or store wastes.
Movement from one location to another is therefore not the only sign of life.
Detailed Explanation
1. Life Processes in Plants
Important plant life processes include:
- nutrition;
- respiration;
- transport;
- excretion;
- growth;
- reproduction.
In this chapter, we focus mainly on:
- how plants obtain food;
- how materials move inside plants;
- how plants release energy.
2. How Do Plants Obtain Food?
Animals usually obtain ready-made food from plants or other animals.
Green plants are different.
They can manufacture food from simple substances present in their surroundings.
Green plants are autotrophs because they make food using:
- carbon dioxide;
- water;
- sunlight.
This process is called photosynthesis.
Photosynthesis
This is a simplified word equation showing the main materials involved.
Show answer
3. Where Does Photosynthesis Occur?
Photosynthesis mainly takes place in green parts of plants.
Leaves are especially suited for photosynthesis.
Most leaves are:
- broad;
- thin;
- exposed to sunlight;
- rich in chlorophyll;
- supplied with water through veins;
- able to exchange gases through stomata.
Chlorophyll is found inside specialised cell structures in green plant tissues.
At Class 7 level, the important idea is:
chlorophyll captures light energy that enables photosynthesis.
Do not write:
"Chlorophyll is food."
Correct idea:
Chlorophyll is a green pigment that helps capture light energy for photosynthesis.
4. How Does Carbon Dioxide Enter a Leaf?
Leaves contain many tiny pores on their surfaces.
These openings are called stomata.
Through stomata:
- carbon dioxide can enter the leaf;
- oxygen can leave or enter depending on the plant's activity;
- water vapour can escape.
Each stoma is associated with specialised cells called guard cells that help regulate its opening.
5. How Does Water Reach the Leaves?
Photosynthesis also requires water.
But leaves are often far above the ground.
Water must therefore travel from the soil to the leaves.
The process begins at the roots.
6. Roots Absorb Water and Minerals
Roots anchor a plant in the soil, but anchorage is not their only function.
Roots also absorb:
- water;
- dissolved mineral nutrients.
Many roots possess very thin extensions called root hairs.
Root hairs:
- are numerous;
- are very thin;
- come into close contact with soil particles;
- increase the absorptive surface of roots.
7. Transport of Water and Minerals
After water and minerals enter the roots, they need to reach:
- stem;
- branches;
- leaves;
- flowers;
- fruits.
Plants contain specialised conducting tissues.
One of them is xylem.
Xylem forms a continuous transport pathway through much of the plant.
A simplified route is:
Soil → Root hairs → Roots → Xylem → Stem → Leaves
8. Food Prepared by Leaves
Photosynthesis produces glucose.
Plants use glucose in several ways.
It may be:
- used during respiration;
- converted into other substances;
- transported to growing tissues;
- stored for later use.
Some glucose is converted into starch for storage.
This is why the iodine test is useful when investigating photosynthesis.
Iodine produces a blue-black colour in the presence of starch.
9. Testing a Leaf for Starch
If a leaf has carried out photosynthesis and accumulated stored carbohydrate, starch may be detected.
10. Is Sunlight Necessary for Photosynthesis?
We can investigate this scientifically.
11. Is Chlorophyll Necessary for Photosynthesis?
A variegated leaf contains:
- green regions;
- non-green regions.
Only the green regions contain sufficient chlorophyll.
If such a leaf is exposed to sunlight and then tested for starch, the green regions usually show starch formation much more clearly.
Show answer
12. Transport of Prepared Food
Food is mainly prepared in leaves, but every part of the plant needs nutrients.
Growing roots need food.
Young buds need food.
Flowers, fruits and seeds need food.
Storage organs also receive food.
The tissue responsible for transporting prepared food is called phloem.
Food may move towards:
- roots;
- growing shoots;
- flowers;
- fruits;
- seeds;
- storage organs.
Xylem vs Phloem
| Feature | Xylem | Phloem |
|---|---|---|
| Main material transported | Water and dissolved minerals | Prepared food, mainly sugars |
| Main source | Roots | Leaves and other food-producing regions |
| Main destination | Stem, leaves and other parts | Growing and storage parts throughout the plant |
| Importance | Supplies water and mineral nutrients | Distributes prepared food |
The difference between xylem and phloem is one of the most important exam areas in this chapter.
Always mention what each tissue transports.
13. Transpiration
Plants absorb a large amount of water, but not all of it remains inside the plant.
Some water is lost as water vapour from aerial parts, especially through stomata.
This process is called transpiration.
Transpiration can:
- contribute to movement of water through the plant;
- help cool leaf surfaces;
- form part of the water cycle.
14. Observing Transpiration
15. Factors Affecting Transpiration
The rate of water loss can change with environmental conditions.
Temperature
Warmer conditions can increase evaporation.
Wind
Moving air can carry away water vapour near the leaf surface.
Humidity
When the surrounding air already contains a large amount of water vapour, transpiration may be slower.
Stomatal Opening
More open stomata generally allow more water vapour to escape.
16. Do Plants Respire?
Yes.
Plants perform respiration just as animals do.
The simplified overall relationship is:
Respiration
The released energy is used for:
- growth;
- repair;
- transport;
- cell activities;
- formation of new tissues.
17. When Do Plants Respire?
Plants respire:
- during the day;
- during the night.
Respiration occurs continuously in living plant cells.
Photosynthesis, however, requires light.
Therefore:
During Daylight
Both:
- photosynthesis;
- respiration
can occur.
During Darkness
Photosynthesis stops because sufficient light is unavailable.
Respiration continues.
A very common mistake is to write:
"Plants photosynthesise in daytime and respire only at night."
This is incorrect.
Correct idea:
Photosynthesis requires light.
Respiration occurs continuously in living cells.
18. Gas Exchange During Photosynthesis and Respiration
Plants exchange gases mainly through stomata.
Photosynthesis
The overall process:
- uses carbon dioxide;
- releases oxygen.
Respiration
The overall process studied at this level:
- uses oxygen;
- releases carbon dioxide.
Photosynthesis vs Respiration
| Feature | Photosynthesis | Respiration |
|---|---|---|
| Main function | Preparation of food | Release of usable energy from food |
| Light | Requires light | Does not depend directly on light |
| Carbon dioxide | Used | Produced in the process studied here |
| Oxygen | Produced | Used in the process studied here |
| Glucose | Produced | Broken down |
| Time | Occurs when suitable light is available | Occurs continuously in living cells |
Show answer
19. Net Gas Exchange in Daylight
During bright daylight, photosynthesis can occur at a high rate.
Because photosynthesis uses carbon dioxide and releases oxygen, a green plant may show an overall:
- intake of carbon dioxide;
- release of oxygen.
But respiration is still happening at the same time.
At night:
- photosynthesis stops;
- respiration continues;
- oxygen is used;
- carbon dioxide is released.
20. Do Roots Respire?
Yes.
Roots are made of living cells and need energy.
Air is present in spaces between soil particles.
Oxygen from these spaces can reach root cells.
This is one reason excessive waterlogging can be harmful to many land plants.
When soil spaces become filled with water for too long:
- less air remains available;
- root respiration may be affected.
21. How Are Photosynthesis and Respiration Connected?
These two processes are closely related but perform different functions.
Photosynthesis:
- captures light energy;
- prepares glucose.
Respiration:
- breaks down glucose;
- releases usable energy.
A simplified comparison can be represented as:
Photosynthesis
Respiration
22. How Plant Life Processes Work Together
Consider a growing mango fruit.
To grow, the fruit needs:
- water;
- minerals;
- sugars;
- energy.
Where do these come from?
Water and Minerals
Roots absorb them.
Xylem transports them.
Food
Leaves prepare sugars through photosynthesis.
Phloem carries food towards the developing fruit.
Energy
Cells in the fruit perform respiration and release usable energy.
Thus:
Roots + Stem + Leaves + Transport Tissues + Respiration
all work together.
Concept Map
23. Importance of Plants in the Environment
Photosynthesis affects much more than the individual plant.
Green plants are important because they:
- produce food;
- release oxygen during photosynthesis;
- form the base of many food chains;
- remove carbon dioxide from air during photosynthesis;
- provide habitats;
- contribute water vapour through transpiration.
Green plants convert simple substances into energy-rich food.
This makes them producers in ecosystems.
Animals depend directly or indirectly on this food-making ability.
24. Common Plant Life-Process Connections
Plant Structures and Their Major Functions
| Structure | Major Function | Life Process |
|---|---|---|
| Root hairs | Absorb water and minerals | Absorption |
| Xylem | Transports water and minerals | Transport |
| Leaves | Major site of photosynthesis | Nutrition |
| Stomata | Gas exchange and water-vapour loss | Photosynthesis, respiration and transpiration |
| Phloem | Transports prepared food | Transport |
| Living plant cells | Release energy from food | Respiration |
Foundation Extension
Exam Focus
Important Exam Areas
- definition of life processes;
- autotrophic nutrition;
- definition and requirements of photosynthesis;
- photosynthesis word equation;
- role of chlorophyll;
- role of sunlight;
- entry of carbon dioxide through stomata;
- absorption of water and minerals by roots;
- root hairs and surface area;
- xylem and transport of water and minerals;
- formation and storage of starch;
- iodine test for starch;
- experiment showing sunlight is necessary for photosynthesis;
- meaning of destarching;
- variegated-leaf experiment and role of chlorophyll;
- phloem and transport of food;
- difference between xylem and phloem;
- definition and importance of transpiration;
- stomata and transpiration;
- respiration in plants;
- comparison of photosynthesis and respiration;
- respiration during day and night;
- root respiration;
- coordination among photosynthesis, transport and respiration.
Key Terms
Key Terms
Formula Revision
Formula / Key Relations
Photosynthesis
Photosynthesis stores solar energy in energy-rich food.
Respiration
Respiration releases usable energy from food.
Quick Revision
Quick Revision
- Plants perform essential life processes required for survival.
- Green plants prepare their own food and are called autotrophs.
- Photosynthesis mainly takes place in green plant parts.
- Photosynthesis requires carbon dioxide, water, sunlight and chlorophyll.
- Chlorophyll is the green pigment that captures light energy.
- Stomata are tiny pores involved in gas exchange.
- Carbon dioxide enters leaves mainly through stomata.
- Roots absorb water and dissolved minerals from soil.
- Root hairs increase the absorptive surface area of roots.
- Xylem transports water and minerals mainly from roots towards other plant parts.
- Glucose formed during photosynthesis may be converted into starch for storage.
- Iodine gives a blue-black colour in the presence of starch.
- Destarching removes much of the previously stored starch before a photosynthesis investigation.
- Experiments with covered leaves show that sunlight is necessary for starch formation.
- Variegated leaves provide evidence that chlorophyll is necessary for photosynthesis.
- Phloem transports prepared food to growing and storage parts.
- Xylem carries water and minerals; phloem carries food.
- Transpiration is the loss of water vapour mainly through stomata.
- Transpiration contributes to water movement through plants and can cool leaves.
- Plants perform respiration continuously.
- Respiration releases usable energy from glucose.
- Photosynthesis requires light, but respiration occurs during day and night.
- During daylight, photosynthesis and respiration can occur simultaneously.
- Roots also respire and require oxygen from air spaces in soil.
- Excessive waterlogging can reduce air available to roots.
- Photosynthesis stores energy in food; respiration releases usable energy.
- Plant organs and tissues work together as a coordinated biological system.
Practice Questions
A. Multiple Choice Questions
Which process allows green plants to prepare food?
A. Respiration B. Photosynthesis C. Transpiration D. Germination
View Solution
Correct Answer: B. Photosynthesis
Green plants prepare food from carbon dioxide and water using sunlight in the presence of chlorophyll.
Which pigment captures light energy for photosynthesis?
A. Haemoglobin B. Chlorophyll C. Starch D. Cellulose
View Solution
Correct Answer: B. Chlorophyll
Chlorophyll is the green pigment that absorbs light energy required for photosynthesis.
Carbon dioxide mainly enters a leaf through:
A. root hairs B. xylem C. stomata D. phloem
View Solution
Correct Answer: C. Stomata
Stomata are tiny pores on leaf surfaces that allow gas exchange.
Which tissue transports water and minerals in plants?
A. Phloem B. Xylem C. Stomata D. Chlorophyll
View Solution
Correct Answer: B. Xylem
Xylem transports water and dissolved minerals mainly from the roots towards other parts of the plant.
Prepared food is mainly transported through:
A. xylem B. phloem C. root hairs D. stomata
View Solution
Correct Answer: B. Phloem
Phloem carries food prepared in leaves to growing, storage and other plant parts.
Iodine solution gives a blue-black colour in the presence of:
A. glucose B. protein C. starch D. oxygen
View Solution
Correct Answer: C. Starch
The iodine test is used to detect starch.
Transpiration is:
A. preparation of food B. movement of food through phloem C. loss of water vapour from aerial plant parts D. absorption of mineral salts by roots
View Solution
Correct Answer: C. loss of water vapour from aerial plant parts
Most transpiration from leaves occurs through stomata.
Which statement about respiration in plants is correct?
A. It occurs only at night. B. It occurs only during daylight. C. It occurs continuously in living cells. D. It occurs only in leaves.
View Solution
Correct Answer: C. It occurs continuously in living cells.
Plants respire during both day and night.
B. Very Short Answer Questions
-
What is photosynthesis?
-
Name the green pigment required for photosynthesis.
-
What are stomata?
-
What is the function of root hairs?
-
What does xylem transport?
-
What does phloem transport?
-
What is transpiration?
-
What colour does iodine produce in the presence of starch?
-
What is destarching?
-
Do plants respire during daytime?
Answers
-
Photosynthesis is the process by which green plants prepare food from carbon dioxide and water using sunlight in the presence of chlorophyll.
-
Chlorophyll.
-
Stomata are tiny pores on leaf surfaces involved in gas exchange and water-vapour loss.
-
Root hairs increase the surface area for absorption of water and minerals from soil.
-
Xylem transports water and dissolved minerals.
-
Phloem transports prepared food.
-
Transpiration is the loss of water vapour from aerial plant parts, mainly through stomata.
-
Blue-black.
-
Destarching is the process of keeping a plant in darkness for a suitable time so that much of the previously stored starch is used.
-
Yes. Respiration occurs during both day and night.
C. Short Answer Questions
Why are leaves well suited for photosynthesis?
View Solution
Leaves are well suited for photosynthesis because they:
- are usually broad and receive light;
- contain chlorophyll;
- receive water through xylem;
- contain stomata for carbon dioxide entry;
- have a large surface exposed to the surroundings.
These features support efficient photosynthesis.
Explain the role of root hairs.
View Solution
Root hairs are fine extensions of root cells.
They increase the surface area of the root that is in contact with soil.
This helps the plant absorb more:
- water;
- dissolved mineral nutrients.
Differentiate between xylem and phloem.
View Solution
Xylem
Xylem transports:
- water;
- dissolved minerals
mainly from roots towards stems and leaves.
Phloem
Phloem transports:
- prepared food, mainly sugars
from leaves and other food-producing regions to growing and storage parts.
Why is a plant destarched before an experiment testing whether sunlight is necessary for photosynthesis?
View Solution
A leaf may already contain starch produced during earlier photosynthesis.
If this old starch remains, the experiment may give a misleading result.
Keeping the plant in darkness allows much of this stored starch to be used.
Therefore, starch detected after the experiment is more likely to have formed during the experimental period.
Explain why stomata are important to a plant.
View Solution
Stomata are important because they allow:
- carbon dioxide to enter for photosynthesis;
- oxygen and carbon dioxide to exchange during respiration;
- water vapour to leave during transpiration.
Thus, stomata participate in several life processes.
Why can excessive waterlogging harm the roots of many land plants?
View Solution
Root cells require oxygen for respiration.
In normal soil, some air is present in spaces between soil particles.
If these spaces remain filled with excessive water, less oxygen may be available to the roots.
This can interfere with normal root respiration.
D. Long Answer Questions
Explain the process of photosynthesis and describe the role of each major requirement.
View Solution
Photosynthesis is the process by which green plants prepare food from carbon dioxide and water using sunlight in the presence of chlorophyll.
The simplified relationship is:
Carbon Dioxide
Carbon dioxide comes from air and enters leaves mainly through stomata.
Water
Roots absorb water from soil.
Xylem transports it to leaves.
Sunlight
Sunlight supplies the energy required for photosynthesis.
Chlorophyll
Chlorophyll absorbs light energy.
Products
Glucose is produced as food.
Oxygen is released as a product.
Some glucose can be converted into starch for storage.
Describe an experiment to show that sunlight is necessary for photosynthesis.
View Solution
Preparation
Keep a healthy potted plant in darkness for a suitable period to destarch its leaves.
Procedure
- Cover part of a leaf on both sides with opaque black paper.
- Place the plant in sunlight for several hours.
- Remove the selected leaf.
- Perform the starch test under teacher supervision.
- Compare the covered and uncovered regions.
Observation
The region exposed to sunlight develops a blue-black colour with iodine.
The covered region does not show the same result.
Conclusion
The uncovered region received light and formed starch.
Therefore, the experiment provides evidence that sunlight is necessary for photosynthesis.
Explain how water, minerals and food are transported through a plant.
View Solution
Water and Minerals
Roots absorb water and dissolved mineral nutrients from soil.
Root hairs increase the absorptive surface area.
Water and minerals enter the xylem.
Xylem transports them mainly upward through the root and stem towards leaves and other plant parts.
Food
Leaves prepare glucose during photosynthesis.
Food is transported through phloem.
Phloem carries sugars towards:
- roots;
- growing shoots;
- flowers;
- fruits;
- seeds;
- storage organs.
Therefore:
Xylem → water and minerals
Phloem → food
Compare photosynthesis and respiration in plants.
View Solution
Photosynthesis
- prepares food;
- requires light;
- uses carbon dioxide;
- uses water;
- produces glucose;
- releases oxygen;
- stores energy in food.
Respiration
- breaks down food;
- occurs continuously;
- uses oxygen in the process studied at this level;
- releases carbon dioxide;
- releases usable energy.
Plants therefore perform both processes.
Photosynthesis and respiration have different functions and should not be treated as the same process.
E. Application and HOTS Questions
A healthy green plant receives water, carbon dioxide and chlorophyll but is kept permanently in darkness. Can it continue making food by photosynthesis? Explain.
View Solution
No.
Sunlight provides the energy required for photosynthesis.
Even if water, carbon dioxide and chlorophyll are present, the plant cannot continue normal photosynthesis without a suitable light source.
Therefore, all major requirements must be available.
A plant has damaged xylem but healthy leaves. Predict one major problem that may occur.
View Solution
Xylem transports water and dissolved minerals from the roots towards leaves and other plant parts.
If xylem is severely damaged:
- water transport may decrease;
- leaves may receive insufficient water;
- photosynthesis may be affected;
- the plant may wilt.
Therefore, healthy leaves alone are not enough if transport tissues cannot supply them properly.
A student says, "Leaves prepare food, so roots do not need food." Explain why this is incorrect.
View Solution
Root cells are living cells.
They need energy for:
- growth;
- absorption;
- maintenance;
- other cellular activities.
Food prepared in leaves is transported through phloem to roots and other non-photosynthetic regions.
Roots use this food during respiration to release energy.
Why might a plant wilt faster on a hot, dry and windy day?
View Solution
Hot and windy conditions can increase water loss through transpiration.
Dry air can also favour faster loss of water vapour from leaves.
If water is lost faster than roots can replace it:
- plant cells lose water;
- leaves may droop;
- the plant may wilt.
Why does covering all stomata of a leaf interfere with more than one life process?
View Solution
Stomata participate in several processes.
They allow:
- carbon dioxide entry for photosynthesis;
- gas exchange during respiration;
- water-vapour loss during transpiration.
Blocking stomata can therefore interfere with:
- photosynthesis;
- respiration-related gas exchange;
- transpiration.
Assertion–Reason
Assertion: Root hairs help plants absorb water efficiently.
Reason: Root hairs increase the surface area in contact with soil.
Choose the correct option:
A. Both Assertion and Reason are true, and Reason correctly explains Assertion. B. Both are true, but Reason does not explain Assertion. C. Assertion is true, but Reason is false. D. Both are false.
View Solution
Correct Answer: A
A larger contact surface improves the root's ability to absorb water and dissolved minerals from soil.
Assertion: Plants respire only during the night.
Reason: Respiration releases energy from food.
Choose the correct option:
A. Both statements are true. B. Assertion is true, but Reason is false. C. Assertion is false, but Reason is true. D. Both statements are false.
View Solution
Correct Answer: C
The assertion is false because plants respire during both day and night.
The reason is true because respiration releases usable energy from food.
Assertion: Xylem and phloem perform different transport functions.
Reason: Xylem mainly carries water and minerals, while phloem carries prepared food.
Choose the correct option:
A. Both Assertion and Reason are true, and Reason correctly explains Assertion. B. Both are true, but Reason does not explain Assertion. C. Assertion is true, but Reason is false. D. Both are false.
View Solution
Correct Answer: A
The two tissues transport different materials and therefore perform different major roles.
Apply Your Learning
Choose a healthy plant around your school or home.
Without damaging the plant, identify or infer:
- where water enters the plant;
- where photosynthesis mainly occurs;
- where carbon dioxide enters;
- how water reaches the leaves;
- how food reaches the roots;
- where transpiration occurs;
- which parts need respiration.
Then create this flow:
Soil → Root hairs → Xylem → Leaves → Photosynthesis → Phloem → Other plant parts
Add the gas exchange:
Carbon dioxide → Stomata → Leaf
and:
Water vapour → Stomata → Atmosphere
Finally, connect respiration:
Food + Oxygen → Usable Energy
Common Mistakes to Avoid
Final Chapter Summary
Chapter Summary
- Plants are living organisms and perform essential life processes.
- Green plants are autotrophs because they manufacture their own food.
- Photosynthesis uses carbon dioxide and water in the presence of sunlight and chlorophyll.
- Glucose is produced during photosynthesis and oxygen is released.
- Chlorophyll captures the light energy required for photosynthesis.
- Stomata are tiny pores involved in gas exchange and transpiration.
- Carbon dioxide enters leaves mainly through stomata.
- Root hairs increase the surface area for absorption of water and dissolved minerals.
- Xylem transports water and minerals mainly from roots towards other plant parts.
- Some glucose produced by photosynthesis can be converted into starch for storage.
- Iodine produces a blue-black colour when starch is present.
- Destarching helps remove previously stored starch before photosynthesis experiments.
- Covered-leaf experiments show that sunlight is necessary for starch formation.
- Variegated-leaf experiments provide evidence that chlorophyll is necessary for photosynthesis.
- Phloem transports prepared food from food-producing regions to growing and storage regions.
- Xylem and phloem form specialised transport systems in plants.
- Transpiration is the loss of water vapour mainly through stomata.
- Transpiration contributes to water movement and can help cool the plant.
- Plant cells respire continuously during day and night.
- Respiration releases usable energy from food.
- Photosynthesis stores energy in food, while respiration releases usable energy.
- Roots also need oxygen for respiration.
- Waterlogging can reduce air available to roots.
- Plant life depends on coordination among absorption, transport, photosynthesis, transpiration and respiration.
- Green plants support ecosystems by producing food and releasing oxygen during photosynthesis.