Question

Which of the following is true about mycorrhizae? (a) Association between roots and fungus. (b) Fungal hyphae have very large surface area that absorb water and mineral from the soil. (c) Roots provide sugar and \(\mathrm{N}\) -containing compound to the fungus. (d) All the above

Short answer

Choice (d) 'All the above' is the correct answer for this exercise.

Step-by-step solution

Understanding Mycorrhizae

Mycorrhizae is a symbiotic relationship formed between roots of plants and a type of fungi. It's crucial to know this as it sets the basis for understanding the given answers.

Validating Answer (a)

Given answer (a) says, 'Association between roots and fungus.' which is correct. As mentioned, Mycorrhizae is an association between plant roots and fungi, so this answer is valid.

Validating Answer (b)

Answer (b) says that fungal hyphae have a large surface area to absorb water and minerals from the soil. This is indeed true. The fungi's network of hyphae helps increase the root's absorption capacity. So, answer (b) is also valid.

Validating Answer (c)

According to answer (c), roots provide sugar and \(\mathrm{N}\) -containing compound to the fungus. This is indeed correct. Photosynthetic plants produce sugars and other organic compounds that are provided to the fungus.

Final Decision

Given that all options (a, b, c) are correct, the final answer tends towards 'all of the above', thus, the correct answer to this question is choice (d).

Key concepts

Symbiotic Relationships

Understanding the natural world often means looking at the partnerships between living organisms, known as symbiotic relationships. These relationships can be described as long-term interactions between two or more different biological species.

There are several types of symbiotic relationships: mutualism, where both species benefit; commensalism, where one species benefits without affecting the other; and parasitism, where one species benefits at the expense of the other. Mycorrhizae fall into the category of mutualism, as both the fungus and the plant roots derive significant advantages from the association.

The plant benefits from the fungus's extensive hyphal network that greatly enhances water and nutrient uptake, while the fungus receives essential sugars and compounds produced by the plant through photosynthesis. This symbiotic relationship is fundamental to the health and sustainability of many ecosystems, showcasing the intricate ways in which species rely on one another for survival.

Plant Root-Fungi Association

Delving into the specifics, the mycorrhizal association is a fascinating example of plant root-fungi cooperation. There are primarily two types of mycorrhizae: ectomycorrhizae and endomycorrhizae. Ectomycorrhizae envelop the outer layer of roots, forming a sheath, while endomycorrhizae penetrate the root cells, creating a more intimate bond.

How Mycorrhizae Work

Fungal hyphae extend much farther into the soil than plant roots alone, effectively increasing the root system's reach. This allows the plant access to nutrients that were otherwise out of reach, such as phosphorus and nitrogen, enabling better growth and stress resistance.

In return, the fungi receive carbohydrates such as glucose and sucrose from the plant. This exchange is so crucial that some plants, especially those in nutrient-poor soils, may not survive without their fungal partners. Research into these associations helps us understand how to enhance plant growth and maintain healthy ecosystems.

Nutrient Absorption in Plants

Photosynthesis allows plants to produce their own food in the form of carbohydrates. However, plants also require a multitude of other nutrients and minerals absorbed from the soil through their roots.

Nutrient uptake is not just a matter of 'sucking in' what's needed; it's affected by many factors including soil composition, pH levels, and the presence of symbiotic partners like mycorrhizal fungi. The vast network of fungal hyphae acts as a sort of extension of the plant's root system, providing a greater surface area for absorption.

Key Nutrients and Their Uptake

Nitrogen, phosphorus, and potassium are vital nutrients for plant growth, and they are absorbed from the soil with the aid of mycorrhizae. Fungi are particularly adept at breaking down organic matter, releasing nutrients in a form that plants can use. This collaboration not only nourishes the plants but also improves soil structure and fertility, demonstrating the foundational role of mycorrhizae in plant nutrition and soil ecology.