Note: To use this page as intended your browser must be JavaScript enabled.

Click on the question buttons (left) to navigate to the questions, type your answer in the text area provided below each question and then click the submit button (your answer will then appear below the text area). After answering a question, click on the answer button to view a sample answer. Compare your answer to the sample answer. If your answer is significantly different, I suggest you examine how you arrived at your answer. Instructions for saving this page with your responses.

AM Fungi in Plants and Soil Questions

Question 1

Submit Answer 1

Answer 1

Four features indicate that the host controls colonisation. Total colonisation of the root system is prevented; the fungus never enters the stele. The initiation of colonisation is reduced to a single penetration point from multiple appressoria. Thirdly, the fungus must pass through passage cells of the hypodermis. Finally, different types of AM are associated with specific hosts.


Question 2

Submit Answer 2

Answer 2

Arum types have extensive intercellular spaces, and more regular cell arrays in the cortex. Paris type colonies appear to have tighter junctions between cells. Thus physical barriers are likely to prevent intercellular spread in Paris-type hosts. However, oxygen availability might also be important.


Question 3

Submit Answer 3

Answer 3

AM fungi are heterotrophic. They rely utterly on their host for organic carbon. Penetration of the root probably requires an expenditure of energy by the fungus. Thus it seems likely that the fungus must gain energy from the root before commencing lateral spread.


Question 4

Submit Answer 4

Answer 4

Except for passage cells, the outer layer of the hypodermis is suberised soon after formation. The loss of exudates from the root is thus limited to a proportion of the surface. This limited area of nutrient loss may attract hyphae of AM fungi. Secondly, the cell becomes suberised soon after penetration, thus further limiting penetration by all fungi, yet maintaining control over the mineral uptake provided by the AM fungi. This is likely to reduce attack by pathogens, and enable longer periods where the cortex is used for nutrient exchange.


Question 5

Submit Answer 5

Answer 5



Question 6

Submit Answer 6

Answer 6



Question 7

Submit Answer 7

Answer 7