The specific relationship between a legume and its mutualistic Rhizobium strain probably depends on a. each legume having a chemical dialogue with a fungus. b. each Rhizobium strain having a form of nitrogenase that works only in the appropriate legume host. c. each legume being found where the soil has only the Rhizobium specific to that legume. d. specific recognition between chemical signals and signal receptors of the Rhizobium strain and legume species.

Verified step by step guidance

1. Understand the mutualistic relationship: Mutualism is a type of symbiotic relationship where both organisms involved benefit. In this case, legumes and Rhizobium bacteria are involved.
2. Identify the role of Rhizobium: Rhizobium bacteria fix nitrogen from the atmosphere into a form that plants can use, which benefits the legume by providing essential nutrients.
3. Consider the specificity of the relationship: The relationship's specificity could be due to unique adaptations or mechanisms that ensure both organisms benefit optimally and specifically from each other.
4. Analyze the options: Look at each option and think about how it relates to the mutualistic relationship and the specificity between the legume and Rhizobium strains.
5. Choose the best option: Option 'd' mentions 'specific recognition between chemical signals and signal receptors of the Rhizobium strain and legume species,' which aligns with the idea of a highly specific mutualistic interaction necessary for optimal benefits.

Key Concepts

Mutualism

Mutualism is a type of symbiotic relationship where both species involved benefit from the interaction. In the context of legumes and Rhizobium, legumes provide carbohydrates to Rhizobium, while Rhizobium fixes atmospheric nitrogen into a form that legumes can use. This relationship is crucial for nutrient cycling in ecosystems and enhances soil fertility.

Chemical Signaling

Chemical signaling refers to the communication between organisms through chemical substances. In the legume-Rhizobium relationship, legumes release specific compounds that attract compatible Rhizobium strains. This signaling is essential for the recognition and establishment of the mutualistic relationship, ensuring that the right strain of Rhizobium associates with the appropriate legume.

Nitrogen Fixation

Nitrogen fixation is the process by which certain bacteria convert atmospheric nitrogen (N2) into ammonia (NH3), which can be utilized by plants. Rhizobium species possess the enzyme nitrogenase, which facilitates this conversion. The ability of specific Rhizobium strains to fix nitrogen effectively is often dependent on their compatibility with particular legume hosts, highlighting the importance of host specificity in this mutualistic interaction.