Microbiology

To solve this problem, we need to analyze the assertion and reason provided and determine whether they are correct and if the reason correctly explains the assertion.

1. Understanding the Assertion [A]:
The assertion states that Nitrosomonas is a chemoautotrophic bacteria. This is true. Nitrosomonas is a type of bacteria that derives energy through the process of chemoautotrophy, which involves oxidizing inorganic substances like ammonia to obtain energy. It uses carbon dioxide (CO₂) as its carbon source, making it an autotroph.

2. Understanding the Reason [R]:
The reason provided is that chemoautotrophs derive energy from sunlight and carbon from CO₂. This is partly true but incomplete. Chemoautotrophs derive energy not from sunlight but from the oxidation of inorganic compounds, such as ammonia, nitrites, or sulfur compounds. They use CO₂ as their carbon source. The statement incorrectly mentions sunlight, which is characteristic of photoautotrophs, not chemoautotrophs.

3. Conclusion:
While the assertion is correct, the reason is only partially correct, as it incorrectly associates sunlight with chemoautotrophs instead of the correct source of energy (inorganic compounds). Therefore, the reason does not correctly explain the assertion.

Final Answer:
The correct answer is Option C: A is correct but R is incorrect.

To solve the problem, we need to identify the correct pair of genetic combinations based on Mendelian inheritance patterns.

1. Analyzing the Genetic Crosses:
We are given four genetic combinations with their corresponding probabilities:

• I. RrYy with a probability of 4/16
• II. Rryy with a probability of 1/16
• III. RrYY with a probability of 2/16
• IV. rrYy with a probability of 1/16

2. Understanding the Inheritance:
In this case, we are dealing with a dihybrid cross involving two traits. The allele combinations for each trait will follow the standard Mendelian inheritance ratios. The correct pairings of genetic combinations are:

• I. RrYy (4/16): This represents a heterozygous condition for both traits.
• III. RrYY (2/16): This represents a heterozygous condition for the first trait and homozygous dominant for the second trait.

3. Identifying the Correct Pair:
The correct genetic pair that matches the given probabilities is:
I = RrYy (4/16)
III = RrYY (2/16)

Final Answer:
The correct option is (A) I, III.