Question:
Given below are two statements, one is labelled as Assertion (A) and other one labelled as Reason (R).
Assertion (A): Physiological zero is the temperature at which the embryo is under suspended animation condition.
Reason (R): Physiological zero for chicken egg is 75 \(^{\circ}\text{F}\).
In light of the above statements, choose the correct answer from the options given below.
Given below are two statements, one is labelled as Assertion (A) and other one labelled as Reason (R).
Assertion (A): Physiological zero is the temperature at which the embryo is under suspended animation condition.
Reason (R): Physiological zero for chicken egg is 75 \(^{\circ}\text{F}\).
In light of the above statements, choose the correct answer from the options given below.
Assertion (A): Physiological zero is the temperature at which the embryo is under suspended animation condition.
Reason (R): Physiological zero for chicken egg is 75 \(^{\circ}\text{F}\).
In light of the above statements, choose the correct answer from the options given below.
Show Hint
Physiological Zero for chicken eggs = 20--21 \(^{\circ}\text{C}\) (68--70 \(^{\circ}\text{F}\)).
Storing eggs above this temperature triggers slow, abnormal cell division, while storing them below 10 \(^{\circ}\text{C}\) (50 \(^{\circ}\text{F}\)) damages embryonic tissues, both of which reduce hatchability.
Storing eggs above this temperature triggers slow, abnormal cell division, while storing them below 10 \(^{\circ}\text{C}\) (50 \(^{\circ}\text{F}\)) damages embryonic tissues, both of which reduce hatchability.
Updated On: Jul 24, 2026
- Both (A) and (R) are true and (R) is the correct explanation of (A).
- Both (A) and (R) are true but (R) is NOT the correct explanation of (A).
- (A) is true but (R) is false.
- (A) is false but (R) is true.
Show Solution
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The Correct Option is C
Solution and Explanation
Step 1: Understanding the Concept:
Physiological zero is a critical temperature threshold used during the storage of fertile eggs before incubation.
It is the temperature below which cellular division and embryonic development are completely halted, allowing the embryo to remain viable in a state of suspended animation.
Step 2: Detailed Explanation:
Let us analyze both statements:
- Assertion (A): Sylvanus (and subsequent researchers) defined physiological zero as the temperature below which embryonic development ceases without damaging the embryo's viability.
Storing fertile eggs below this threshold keeps the blastoderm in a dormant state of suspended animation, preserving cell viability until they are placed in the incubator.
Therefore, Assertion (A) is correct.
- Reason (R): In poultry science, the physiological zero for chicken eggs is defined as approximately 20 \(^{\circ}\text{C}\) to 21 \(^{\circ}\text{C}\) (which corresponds to 68 \(^{\circ}\text{F}\) to 70 \(^{\circ}\text{F}\)).
If eggs are stored at 75 \(^{\circ}\text{F}\) (approx. 24 \(^{\circ}\text{C}\)), which is above physiological zero, slow, uncoordinated, and abnormal embryonic development occurs, resulting in early embryonic mortality during storage.
Therefore, the statement that physiological zero is 75 \(^{\circ}\text{F}\) is incorrect, making Reason (R) false.
Since Assertion (A) is true and Reason (R) is false, option (C) is the correct choice.
Step 3: Final Answer:
Assertion (A) is true but Reason (R) is false.
Physiological zero is a critical temperature threshold used during the storage of fertile eggs before incubation.
It is the temperature below which cellular division and embryonic development are completely halted, allowing the embryo to remain viable in a state of suspended animation.
Step 2: Detailed Explanation:
Let us analyze both statements:
- Assertion (A): Sylvanus (and subsequent researchers) defined physiological zero as the temperature below which embryonic development ceases without damaging the embryo's viability.
Storing fertile eggs below this threshold keeps the blastoderm in a dormant state of suspended animation, preserving cell viability until they are placed in the incubator.
Therefore, Assertion (A) is correct.
- Reason (R): In poultry science, the physiological zero for chicken eggs is defined as approximately 20 \(^{\circ}\text{C}\) to 21 \(^{\circ}\text{C}\) (which corresponds to 68 \(^{\circ}\text{F}\) to 70 \(^{\circ}\text{F}\)).
If eggs are stored at 75 \(^{\circ}\text{F}\) (approx. 24 \(^{\circ}\text{C}\)), which is above physiological zero, slow, uncoordinated, and abnormal embryonic development occurs, resulting in early embryonic mortality during storage.
Therefore, the statement that physiological zero is 75 \(^{\circ}\text{F}\) is incorrect, making Reason (R) false.
Since Assertion (A) is true and Reason (R) is false, option (C) is the correct choice.
Step 3: Final Answer:
Assertion (A) is true but Reason (R) is false.
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