Class 9 Science - ICSE-BIOLOGY
Respiration in Plants
The chapter 'Respiration in Plants' explores how plants break down glucose to release energy needed for their survival, growth, and development. Unlike animals, plants do not have a specialized respiratory system; instead, they exchange gases through stomata in leaves and lenticels in stems. You will learn about the two main types of respiration—aerobic (requiring oxygen) and anaerobic (in the absence of oxygen)—and the key differences between photosynthesis and respiration. This topic is crucial for ICSE Class 9 Biology board exams, frequently featuring in structural diagrams, process comparisons, and direct short-answer questions.
Start Learning FreeKey Concepts
Cellular Respiration
The biochemical process in which cells break down glucose molecules in the presence or absence of oxygen to release usable energy in the form of ATP.
Aerobic Respiration
Respiration that takes place in the presence of oxygen, completely breaking down glucose into carbon dioxide, water, and a large amount of energy.
Anaerobic Respiration
Respiration that occurs without oxygen, producing ethyl alcohol, carbon dioxide, and a very small amount of energy in plants and yeast.
Stomata and Lenticels
Stomata are tiny pores on leaves primarily used for gas exchange, while lenticels are small raised openings on woody stems that allow oxygen to enter plant tissues.
Compensation Point
The specific light intensity at which the rate of photosynthesis exactly matches the rate of respiration in plants, resulting in no net gas exchange with the environment.
Important Formulas
Board Exam Info
In ICSE Biology Class 9, this chapter typically carries around 4 to 7 marks in the final exams. Common question types include distinguishing between aerobic and anaerobic respiration, defining compensation point, labeling diagrams of plant gas exchange structures, and writing word or chemical equations for cellular processes.
Frequently Asked Questions
Do plants respire all day or only at night?
Plants respire 24 hours a day, constantly taking in oxygen and releasing carbon dioxide, unlike photosynthesis which only occurs in the presence of sunlight.
Why is it dangerous to sleep under a tree at night?
At night, plants only respire and consume oxygen while releasing carbon dioxide, which can slightly lower the oxygen concentration in a closed, poorly ventilated room.
What is the main difference between breathing and respiration?
Breathing is a physical process of inhaling oxygen and exhaling carbon dioxide, whereas respiration is a chemical process that occurs inside cells to release energy.
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