The hyphae of arbuscular mycorrhizal fungi (AMF) form bushy structures after making contact with the plasma membrane of a root cell. What is the function of these structures?
a. They anchor the fungus inside the root, so the association is more permanent.
b. They increase the surface area available for the transfer of nutrients.
c. They produce toxins that protect the plant cells against herbivores.
d. They break down cellulose and lignin in the plant cell wall.

Verified step by step guidance

1. Understand the role of arbuscular mycorrhizal fungi (AMF) in plant roots. AMF are symbiotic fungi that form mutualistic relationships with plant roots, aiding in nutrient exchange.
2. Recognize the structure formed by AMF hyphae. These bushy structures are known as arbuscules, which are specialized for nutrient exchange between the fungus and the plant.
3. Consider the function of increased surface area. Arbuscules increase the surface area within the root cells, facilitating efficient transfer of nutrients such as phosphorus from the fungus to the plant.
4. Evaluate the options given in the problem. Option b, which states that these structures increase the surface area available for the transfer of nutrients, aligns with the known function of arbuscules.
5. Conclude that the primary function of the bushy structures formed by AMF hyphae is to enhance nutrient exchange, particularly increasing the surface area for nutrient transfer.

Key Concepts

Arbuscular Mycorrhizal Fungi (AMF)

Arbuscular mycorrhizal fungi are a type of fungi that form symbiotic relationships with the roots of most plant species. They penetrate the root cells and create structures called arbuscules, which facilitate nutrient exchange between the plant and the fungus. This mutualistic relationship enhances the plant's nutrient uptake, particularly phosphorus, and improves its growth and resilience.

Arbuscules

Arbuscules are highly branched, bushy structures formed by arbuscular mycorrhizal fungi within the root cells of plants. These structures significantly increase the surface area for nutrient exchange, allowing efficient transfer of nutrients like phosphorus from the fungus to the plant and carbohydrates from the plant to the fungus. Arbuscules are crucial for the symbiotic relationship, optimizing nutrient absorption and plant health.

Nutrient Exchange in Symbiosis

In the symbiotic relationship between plants and arbuscular mycorrhizal fungi, nutrient exchange is a key process. The fungi enhance the plant's ability to absorb essential nutrients, such as phosphorus and nitrogen, from the soil, while the plant provides the fungi with carbohydrates produced through photosynthesis. This exchange is vital for plant growth and development, making the symbiosis beneficial for both organisms.