Practice free Botany NEET multiple-choice questions online with instant answers and detailed explanations. No login required.
If fatty acids are to be utilized as a respiratory substrate, they are first degraded to:
The NCERT text mentions: 'Fats would need to be broken down into glycerol and fatty acids first. If fatty acids were to be respired they would first be degraded to acetyl CoA and enter the pathway.'
Glycerol, when used as a respiratory substrate, enters the pathway after being converted to:
The NCERT states: 'Glycerol would enter the pathway after being converted to PGAL.'
Proteins, after degradation by proteases and deamination, can enter the respiratory pathway as:
According to the NCERT: 'The proteins would be degraded by proteases and the individual amino acids (after deamination) depending on their structure would enter the pathway at some stage within the Krebs’ cycle or even as pyruvate or acetyl CoA.'
Which of the following is an example of an anabolic process within the respiratory pathway?
Anabolism refers to synthesis. While the respiratory pathway primarily involves catabolic breakdown for energy, intermediates can be 'withdrawn from the respiratory pathway for the synthesis of the said substrates,' such as fats, which is an anabolic process.
A key characteristic that distinguishes the respiratory pathway as amphibolic is that its intermediates:
The NCERT states: 'the carbon skeleton produced during respiration is used as precursors for biosynthesis of other molecules in the cell.' This highlights the anabolic role of respiratory intermediates, making the pathway amphibolic.
Why is it inaccurate to purely label the respiratory pathway as 'catabolic'?
The NCERT explicitly questions this understanding: 'But is this understanding correct? We have discussed above, at which points in the respiratory pathway different substrates would enter if they were to be respired... What is important to recognise is that it is these very compounds that would be withdrawn from the respiratory pathway for the synthesis of the said substrates.' This demonstrates its amphibolic nature.
When carbohydrates are used as a respiratory substrate, they are typically first converted into:
The NCERT states: 'Glucose is the favoured substrate for respiration. All carbohydrates are usually first converted into glucose before they are used for respiration.'
The interrelationship among metabolic pathways showing respiration-mediated breakdown of different organic molecules to CO2 and H2O (Figure 12.6, not provided here but referred to in text) visually represents:
Given the discussion of respiration as an amphibolic pathway and the description of various substrates entering at different points, the figure would illustrate how these pathways converge and diverge, supporting both breakdown and synthesis, hence its amphibolic nature.
Which of the following processes in decomposition is primarily responsible for the conversion of detritus into simpler inorganic substances by bacterial and fungal enzymes?
According to the NCERT text, 'Bacterial and fungal enzymes degrade detritus into simpler inorganic substances. This process is called as catabolism.'
Detritus refers to the raw material for decomposition. Which of the following components would NOT be considered part of detritus?
The NCERT states, 'Dead plant remains such as leaves, bark, flowers and dead remains of animals, including fecal matter, constitute detritus'. Living phytoplankton are producers, not dead remains.
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