Problem 3 - Campbell Biology

Question

Mycorrhizae enhance plant nutrition mainly by (A) absorbing water and minerals through the fungal hyphae. (B) providing sugar to root cells, which have no chloroplasts. (C) converting atmospheric nitrogen to ammonia. (D) enabling the roots to parasitize neighboring plants.

Step-by-Step Solution

Answer

A

Step 1 - Understand Mycorrhizae

Mycorrhizae are symbiotic associations between fungi and plant roots. They play a crucial role in plant nutrition.

Step 2 - Identify the Function

Determine what mycorrhizae do for plants. The main benefit of mycorrhizae is to enhance the plant's ability to absorb water and nutrients from the soil.

Step 3 - Evaluate Option A

Option (A): Mycorrhizae absorb water and minerals through the fungal hyphae, which is a correct statement.

Step 4 - Evaluate Option B

Option (B): Mycorrhizae providing sugar to root cells is incorrect, as plant roots typically get their sugars from photosynthesis.

Step 5 - Evaluate Option C

Option (C): Converting atmospheric nitrogen to ammonia is a function of certain bacteria, not mycorrhizae.

Step 6 - Evaluate Option D

Option (D): Enabling the roots to parasitize neighboring plants is not a function of mycorrhizae. This statement is incorrect.

Step 7 - Select the Correct Answer

Based on the evaluations, (A) absorbing water and minerals through the fungal hyphae is the correct answer.

Key Concepts

symbiotic associations

Symbiotic associations are relationships between two different organisms where both benefit from the relationship. Mycorrhizae are a perfect example of this kind of relationship. They form a bond with plant roots, where fungi and plants support each other. The fungi colonize the plant roots and extend their hyphae into the soil.
This benefits the plant by improving water and nutrient uptake. In return, the fungi receive organic compounds like sugars from the plant. This mutual exchange enhances the growth and health of plants.
Symbiotic associations like this are crucial in natural ecosystems and agricultural settings.

plant roots

Plant roots are vital for a plant's overall health and nutrition. They anchor the plant in the soil and are essential for absorbing water and nutrients. Roots have a surface area that interacts with soil particles, but with the help of mycorrhizae, this surface area increases.
The fungal hyphae extend beyond the root zone, reaching more soil areas. This extension allows plants to access more water and nutrients.
Roots play a pivotal role in storing carbohydrates and other nutrients, ensuring that the plant can survive and thrive even in less favorable conditions.

water and mineral absorption

Water and mineral absorption are critical functions for plant growth. Plants need water for photosynthesis, nutrient transport, and maintaining cell turgor. Minerals like phosphorus, nitrogen, and potassium are essential for various metabolic processes.
Mycorrhizae enhance the plant's ability to absorb these essential elements. The fungal hyphae penetrate the soil more deeply and extensively than plant roots alone. This deeper reach allows plants to access water and minerals from a broader area.
This increased absorption capacity is especially important in nutrient-poor soils, where mycorrhizae can make a significant difference in plant health and productivity.

fungal hyphae

Fungal hyphae are the thread-like structures that make up the body of a fungus. In the context of mycorrhizae, these hyphae form an extensive network in the soil. This network helps plants in several ways. Firstly, the hyphae increase the root surface area, allowing for more efficient water and nutrient absorption.
Secondly, the hyphae can break down organic matter in the soil. This process releases essential nutrients that plants can use.
The hyphae also help in protecting plant roots from pathogens by outcompeting harmful organisms in the soil.
Overall, fungal hyphae are a key component of the mycorrhizal symbiosis, enhancing plant nutrition and health.