Review the key concepts, formulae, and examples before starting your quiz.
🔑Concepts
Plants do not have specialized respiratory organs like lungs or gills; instead, each plant part (root, stem, leaf) takes care of its own gas-exchange needs.
Gaseous exchange in plants occurs through (primarily in leaves) and (in woody stems).
The distance that gases must diffuse even in a large, bulky plant is not great, as living cells are organized in thin layers beneath the bark or near the surface, and are interconnected by a system of intercellular spaces.
During the day, released during photosynthesis is used for respiration, and the produced during respiration is utilized for photosynthesis. Thus, there is a net release of and a net uptake of .
At night, since photosynthesis is absent, plants take in from the environment and release .
The complete combustion of glucose, which yields energy, , and , is represented by the chemical equation: .
The availability of oxygen is critical; in waterlogged soils, roots may suffer from lack of because gas diffusion in water is much slower than in air.
📐Formulae
💡Examples
Problem 1:
Calculate the Respiratory Quotient () for the aerobic respiration of Glucose ().
Solution:
Explanation:
In aerobic respiration of carbohydrates like glucose, the number of molecules of evolved is equal to the number of molecules of consumed, resulting in an of .
Problem 2:
Why do plants not require highly specialized respiratory systems like animals?
Solution:
- Each part of the plant takes care of its own gas exchange needs. 2. Plants do not have great demands for gas exchange (low metabolic rate compared to animals). 3. The distance for diffusion is short due to the thin layers of living cells and large intercellular spaces filled with air.
Explanation:
These factors allow plants to rely on simple diffusion through and rather than a centralized circulatory/respiratory system.