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Assertion : Nitrogenase enzyme gets inac...

Assertion : Nitrogenase enzyme gets inactivated in presence of oxygen yet `N_(2)` fixation occurs in aerobic cells of legume nodules.
Reason : Laghaemoglobin allows presence of oxygen just sufficient for cellular respiration only.

A

If both assertion and reason are true and reason is the correct explanation of assertion

B

If both assertion and reason are true but reason is not the correct explanation of assertion

C

If assertion is true but reason is false

D

If both assertion and reason are false

Text Solution

AI Generated Solution

The correct Answer is:
### Step-by-Step Solution: 1. **Understanding the Assertion**: The assertion states that the nitrogenase enzyme, which is crucial for nitrogen fixation, gets inactivated in the presence of oxygen. However, nitrogen fixation still occurs in aerobic cells of legume nodules. This implies that there is a mechanism in place that allows nitrogen fixation to happen despite the presence of oxygen. 2. **Understanding the Reason**: The reason provided is that leghemoglobin allows the presence of oxygen just sufficient for cellular respiration. Leghemoglobin is a protein found in the root nodules of leguminous plants that binds oxygen. It helps to maintain an optimal level of oxygen for respiration while protecting the nitrogenase enzyme from being inactivated by excess oxygen. 3. **Analyzing the Relationship**: The assertion is correct because nitrogenase is indeed sensitive to oxygen and can be inactivated by it. However, the reason is also correct as leghemoglobin plays a vital role in regulating oxygen levels in the nodules, allowing aerobic respiration to occur without harming the nitrogenase enzyme. 4. **Conclusion**: Both the assertion and the reason are true, and the reason correctly explains the assertion. Therefore, the correct answer is that both statements are true, and the reason is the correct explanation of the assertion.
### Step-by-Step Solution: 1. **Understanding the Assertion**: The assertion states that the nitrogenase enzyme, which is crucial for nitrogen fixation, gets inactivated in the presence of oxygen. However, nitrogen fixation still occurs in aerobic cells of legume nodules. This implies that there is a mechanism in place that allows nitrogen fixation to happen despite the presence of oxygen. 2. **Understanding the Reason**: The reason provided is that leghemoglobin allows the presence of oxygen just sufficient for cellular respiration. Leghemoglobin is a protein found in the root nodules of leguminous plants that binds oxygen. It helps to maintain an optimal level of oxygen for respiration while protecting the nitrogenase enzyme from being inactivated by excess oxygen. 3. **Analyzing the Relationship**: The assertion is correct because nitrogenase is indeed sensitive to oxygen and can be inactivated by it. However, the reason is also correct as leghemoglobin plays a vital role in regulating oxygen levels in the nodules, allowing aerobic respiration to occur without harming the nitrogenase enzyme. ...
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Consider a solution of CH_3COONH_4 which is a salt weak acid and weak base. The equilibrium involved in the solutions are : CH_3COO^(-)+H_2OhArrCH_3COOH+OH^(-) " ........"(i) NH_(4)^(+)+H_(2)hArrNH_(4)OH+H^(+)" ........"(ii) H^(+)+OH^(-)hArrH_(2)O" ........"(iii) If we add these reactions, then the net reaction is : CH_(3)COO^(-)+H_(2)^(+)+H_(2)OhArrCH_(3)COOH+NH_(4)OH" ........"(iv) Both CH_(3)COO^(-) and NH_(4)^(+) get hydrolysed independently and their hydrolysis depends on : (a) their initial concentration (b) The value of K_(h) which is (K_(w))/(K_(a)) for CH_(3)COO^(-) and (K_(w))/(K_(b)) for NH_(4)^(+) . Since both of the ions were produced form the salt, their initial concertration are same. Therefore, unless and until the value of (K_(w))/(K_(a)) or K_(a) and K_(b) is same, the degree of hydrogen of ions can't be same. To explain why we assume that degree of hydrolysis of cation and anion is same, we needed to now look at the third reaction i.e.,combination of H^(+) and OH^(-) ions. It is obvious that this reaction happens only because one reaction produced H^(+) ion and the other prodcued OH^(-) ions. We can also note that this reaction causes both the hydrolysis reaction to occur more since their product ions are being consumed. Keep this in mind that the equilibrium which has smaller value of the equilibrium constant is affected more by the common ion effect. For the same reason if for any reson a reaction is made to occur to a greater extent by the consumption of any of the prodcut ion, the reaction with the smaller value of equilibrium constant tends to get affected more. Therefore, we conclude that firstly the hydroylsis of both the ions occurs more in the presence of each other (due to consumption of the product ions) than in each other's absence. Secondly,the hydroylsis of the ion which occurs to a lesser extent (due to smaller value of K_(h)) is affected more than the one whole K_(h) is greater. Hence we can see that the degree of hydroylsis of both the ions would be close to each other when they are getting hyderolysed in the presence of each other. For 0.1 M CH_3COONH_(4) salt solution given, K_(a)(CH_(3)COOH)=K_(b)(NH_(4)OH)=2xx10^(-5) . In the case : degree of hydrolysis of cation and anion are :