Respiration and Excretion in Plants

Respiration and Excretion in Plants

Table of Contents


Cellular respiration: This is the process by which cells break down glucose (sugar) for energy (ATP) in the presence of oxygen. Even though plants make their own food through photosynthesis, they still require respiration to function.

Cellular respiration: aerobic and anaerobic

Cellular Respiration in Plants

  • Just like in animals, respiration in plants occurs in tiny structures called mitochondria, present in all plant cells.
  • The basic equation for cellular respiration can be summarized as:

Glucose (C₆H₁₂O₆) + Oxygen (O₂) → Carbon Dioxide (CO₂) + Water Vapor (H₂O) + Adenosine Triphosphate (ATP)

Cellular respiration equation isolated on white background.  Vector illustration.

  • It’s crucial to remember that respiration is essential for plants, even during photosynthesis. The energy (ATP) produced by respiration is used for various vital functions like growth, nutrient uptake, and protein synthesis.

Gaseous Exchange in Plants

  • Plants don’t have lungs, but they exchange gases through tiny pores on their leaves called stomata. These pores act like valves, opening and closing to regulate the flow of gases.
How does gas exchange in plants work? - Quora
  • When stomata are open, plants can take in carbon dioxide (CO₂), which is a key ingredient for photosynthesis. At the same time, oxygen (O₂), a byproduct of respiration, is released back into the environment.
  • The opening and closing of stomata are influenced by factors like light availability and water content in the plant.

Excretion in Plants

  • Excretion refers to the removal of waste products from an organism. Compared to animals, plants have a more limited amount of waste to expel.
FOUNDATION Course For Class 10 Biology Excretion in Plants - TopperLearning
  • The main excretory products in plants include:
    • Carbon dioxide (CO₂): Released as a byproduct of respiration through stomata.
    • Excess water vapor: Released through two main processes:
      • Transpiration: The loss of water vapor through stomata, which helps regulate plant temperature.
      • Guttation: The formation of water droplets that exit from leaf margins, often seen early in the morning.
    • Some organic waste products: These may be stored in various plant parts like leaves, bark, or fruits. While less emphasized in exams, it’s a good bonus point to know.

Between Respiration and Photosynthesis

  • Respiration and photosynthesis are two crucial but opposite processes in plants:
    • Photosynthesis: Consumes carbon dioxide (CO₂) and releases oxygen (O₂) into the environment, using light energy to create glucose (sugar).

What Is Photosynthesis: How Plants Make Food - EuroSchool

    • Respiration: Consumes oxygen (O₂) and releases carbon dioxide (CO₂), using glucose (sugar) to generate energy (ATP).
Plants release during respiration.
  • It’s important to understand that these processes are interconnected but not entirely independent. Plants require both for survival. Photosynthesis provides the fuel (glucose) for respiration, and respiration provides the energy for various functions, including supporting photosynthesis itself.


  • Cellular respiration allows plants to generate energy needed for various functions, while excretion helps them eliminate waste products.
  • Plants have efficient gas exchange mechanisms through stomata, enabling them to balance respiration with photosynthesis for optimal growth and survival.


  • Excretion: Excretion is the biological process by which waste products, toxic substances, and excess materials are removed from an organism. In plants, excretion involves the elimination of substances such as salts, excess water, and metabolic byproducts.

  • Respiration: Respiration is a vital biological process in which cells break down organic molecules, usually glucose, to release energy for cellular activities. In plants, respiration occurs in organelles called mitochondria, and it involves the consumption of oxygen and the production of carbon dioxide.

  • In plants, excretion primarily occurs through processes like transpiration and the elimination of excess salts. Transpiration, the loss of water vapor through stomata in leaves, helps regulate water balance and eliminates excess water. Additionally, some plants excrete excess salts through specialized structures like salt glands.

During respiration, plants primarily excrete carbon dioxide (CO2). As part of cellular respiration, plants take in oxygen and release carbon dioxide as a byproduct. This exchange of gases occurs mainly through stomata on the surface of leaves.

Excretion in plants is crucial for maintaining proper physiological balance. It helps eliminate excess water, salts, and other metabolic byproducts. This process ensures that plants maintain optimal conditions for growth, reproduction, and overall health.

  1. Waste Elimination: Excretion removes metabolic waste products, preventing the accumulation of harmful substances that could interfere with cellular functions.

  2. Osmoregulation: Plants excrete excess salts to regulate osmotic pressure, ensuring proper water balance in cells.

  3. Water Balance: Transpiration aids in regulating water balance by eliminating excess water absorbed by the roots, preventing waterlogged conditions.

  4. Nutrient Homeostasis: Excretion helps maintain optimal levels of essential nutrients in plant tissues, preventing toxic buildup.

  5. Environmental Adaptation: Excretion allows plants to adapt to changing environmental conditions by regulating water and solute concentrations.

  • In plants, excretion occurs through various modes:

    • Transpiration: The release of water vapor from stomata on leaves.
    • Salt Glands: Specialized structures that excrete excess salts.
    • Cellular Processes: Metabolic processes within cells contribute to the elimination of waste products.


  1. Which process involves the release of energy from glucose in plants?

    • a) Respiration
    • b) Photosynthesis
    • c) Transpiration
    • d) Germination
  2. What is the primary waste product of plant respiration?

    • a) Carbon dioxide
    • b) Oxygen
    • c) Water
    • d) Glucose
  3. Where does respiration mainly occur in plants?

    • a) Leaves
    • b) Mitochondria
    • c) Chloroplasts
    • d) Stems
  4. What is the process by which plants eliminate excess water through small openings in their leaves?

    • a) Photosynthesis
    • b) Transpiration
    • c) Excretion
    • d) Respiration
  5. Which structure in plants regulates the exchange of gases during respiration and photosynthesis?

    • a) Stomata
    • b) Xylem
    • c) Guard cells
    • d) Phloem
  6. Which of the following is NOT a waste product of plant respiration?

    • a) Carbon dioxide
    • b) Water
    • c) Glucose
    • d) Heat
  7. During respiration, which molecule is broken down to release energy in plants?

    • a) Glucose
    • b) Oxygen
    • c) Carbon dioxide
    • d) Water
  8. What is the primary function of stomata in plants?

    • a) Absorbing sunlight
    • b) Facilitating gas exchange
    • c) Transporting water
    • d) Storing nutrients
  9. Which of the following is an example of excretion in plants?

    • a) Production of oxygen
    • b) Elimination of excess salts
    • c) Absorption of water
    • d) Photosynthesis
  10. Which organelle is primarily responsible for cellular respiration in plants?

    • a) Chloroplasts
    • b) Mitochondria
    • c) Endoplasmic reticulum
    • d) Golgi apparatus
  11. What is the main purpose of plant respiration?

    • a) Produce glucose
    • b) Release energy
    • c) Absorb carbon dioxide
    • d) Generate oxygen
  12. Which process occurs during both day and night in plants?

    • a) Photosynthesis
    • b) Respiration
    • c) Transpiration
    • d) Germination
  13. Which of the following structures control the opening and closing of stomata?

    • a) Xylem
    • b) Guard cells
    • c) Phloem
    • d) Root hairs
  14. What happens to the excess water absorbed by plant roots?

    • a) It is converted into glucose
    • b) It is eliminated through transpiration
    • c) It is stored in vacuoles
    • d) It is used for photosynthesis
  15. Which process involves the breakdown of glucose molecules to release energy for cellular activities in plants?

    • a) Photosynthesis
    • b) Respiration
    • c) Transpiration
    • d) Germination
  16. Which gas is released as a byproduct of plant respiration?

    • a) Oxygen
    • b) Carbon dioxide
    • c) Nitrogen
    • d) Hydrogen
  17. Which part of the plant is responsible for the absorption of water and minerals from the soil?

    • a) Leaves
    • b) Roots
    • c) Stems
    • d) Flowers
  18. Which process involves the movement of water vapor from the leaves to the atmosphere in plants?

    • a) Photosynthesis
    • b) Transpiration
    • c) Respiration
    • d) Excretion
  19. Which of the following is a waste product produced during photosynthesis?

    • a) Oxygen
    • b) Oxygen
    • c) Glucose
    • d) Carbon dioxide
  20. What is the primary purpose of respiration in plants?

    • a) Produce oxygen
    • b) Release energy for cellular activities
    • c) Absorb carbon dioxide
    • d) Generate water
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