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12. RESPIRATION IN PLANTS

The chapter discusses the process of respiration in plants, detailing how energy is obtained from food through cellular respiration, including glycolysis, fermentation, and aerobic respiration. It highlights the differences between anaerobic and aerobic pathways, the role of respiration in plants, and the importance of ATP in energy transfer. Additionally, the respiratory pathway is described as an amphibolic pathway that supports both catabolism and anabolism, with the respiratory quotient (RQ) illustrating the type of substrates used.

Sections

RESPIRATION IN PLANTS

This section discusses how plants respire, the processes involved in cellular respiration, including glycolysis, fermentation, and aerobic respiration.

12 Section Overview

Start current section content and materials

12.1 Do Plants Breathe?

Plants breathe using stomata for gas exchange, allowing them to inhale oxygen and exhale carbon dioxide.

12.2 Glycolysis

Glycolysis is the metabolic pathway where glucose is oxidized to produce energy in the form of ATP in cells.

12.3 Fermentation

Fermentation is the anaerobic process by which pyruvic acid is converted into either lactic acid or ethanol and carbon dioxide, releasing a small amount of energy.

12.4 Aerobic Respiration

Aerobic respiration is a metabolic process where pyruvate is completely oxidized in the mitochondria, resulting in the production of ATP, water, and carbon dioxide.

12.4.1 Tricarboxylic Acid Cycle

The Tricarboxylic Acid (TCA) cycle, also known as the Krebs cycle, is a critical metabolic pathway that processes acetyl CoA to produce energy and metabolic intermediates.

12.4.2 Electron Transport System (ETS) and Oxidative Phosphorylation

The Electron Transport System (ETS) enables the oxidation of NADH and FADH₂, producing ATP through oxidative phosphorylation.

12.5 The Respiratory Balance Sheet

The respiratory balance sheet outlines the theoretical net ATP gain from the complete aerobic respiration of glucose.

12.6 Amphibolic Pathway

The amphibolic pathway is a metabolic link that integrates both catabolic and anabolic processes, illustrating how various substrates can be utilized for energy production and synthesis within the respiratory pathway.

12.7 Respiratory Quotient

The respiratory quotient (RQ) quantifies the relationship between carbon dioxide produced and oxygen consumed during respiration, varying by the type of substrate used.

12.8 SUMMARY

The section summarizes the key aspects of plant respiration, highlighting processes like glycolysis, fermentation, and aerobic respiration.

12.9 EXERCISES

The exercises section tests the reader's understanding of respiration in plants, focusing on key processes like glycolysis, fermentation, aerobic respiration, and respiratory pathways.

Learning Objectives

  • Plants respire and exchange gases through stomata and lenticels, unlike animals that have specialized organs.

  • The breakdown of glucose through respiration is essential for energy release, which is often captured in the form of ATP.

  • Respiration can occur aerobically, utilizing oxygen, or anaerobically, without oxygen, each leading to different end products and energy yields.

Key Concepts

Respiration

The process by which organisms convert food into energy, involving the breakdown of glucose and the release of CO2 and energy.

Glycolysis

The first step in the breakdown of glucose that occurs in the cytoplasm, converting glucose into two molecules of pyruvic acid and generating a small amount of ATP.

Krebs Cycle

A series of reactions in aerobic respiration occurring in the mitochondria that fully oxidizes pyruvic acid to CO2, producing high energy molecules like NADH and FADH2.

Electron Transport System (ETS)

A series of complexes located in the inner mitochondrial membrane that transfer electrons from NADH and FADH2 to oxygen, generating a proton gradient used for ATP synthesis.

Oxidative Phosphorylation

The process of producing ATP using the energy released from electrons transferred through the ETS, coupled with the reduction of oxygen to water.

Respiratory Quotient (RQ)

The ratio of carbon dioxide produced to oxygen consumed during respiration, indicative of the type of substrate being oxidized.

Amphibolic Pathway

A metabolic pathway that serves both anabolic (synthesis) and catabolic (breakdown) functions, as seen in respiration.

Practice Exercises

Total Questions

4

Estimated Time

8 min

Passing Score

70%

Instructions

  • Read each question carefully
  • You can use hints if you need help
  • Complete all questions before submitting