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Arbuscular mycorrhiza fungi (AMF) are fungi which grow on, and into, the roots of plants - AQA - A-Level Biology - Question 5 - 2017 - Paper 1
Question 5
Arbuscular mycorrhiza fungi (AMF) are fungi which grow on, and into, the roots of plants. AMF can increase the uptake of inorganic ions such as phosphate. 1. Sugges... show full transcript
Worked Solution & Example Answer:Arbuscular mycorrhiza fungi (AMF) are fungi which grow on, and into, the roots of plants - AQA - A-Level Biology - Question 5 - 2017 - Paper 1
Step 1
Suggest one way in which an increase in the uptake of phosphate could increase plant growth.
Answer
An increase in the uptake of phosphate by plants can enhance their growth by promoting the synthesis of essential compounds such as ATP, which is critical for energy transfer during photosynthesis and cellular respiration. This boosts overall metabolic activities, enabling better nutrient absorption and higher rates of growth.
Step 2
Suggest one way in which AMF may benefit from their association with plants.
Answer
AMF may benefit from their association with plants by accessing carbohydrates produced through photosynthesis. In exchange for enhancing nutrient uptake, plants provide carbon sources that the AMF utilize for their metabolism and growth.
Step 3
Explain why an increase in shoot biomass can be taken as a measurement of net primary productivity.
Answer
An increase in shoot biomass indicates a rise in net primary productivity (NPP) because it reflects higher rates of photosynthesis compared to respiration. NPP represents the energy available to the next trophic level, and increased biomass signifies that more organic matter is being produced and stored in the plant community.
Step 4
Using the data from Figure 5, evaluate the effect on plant productivity of adding AMF species and adding phosphate to the soil.
Answer
The data in Figure 5 illustrates that adding AMF species generally correlates with increased shoot biomass, particularly under high phosphate conditions. For instance, the Entrophospora species showed a significant growth increase due to phosphate supplementation. In contrast, Scutellospora exhibited reduced growth, perhaps due to competitive interactions affecting nutrient availability. Overall, AMF species contribute positively to plant productivity when optimized with adequate phosphate levels.
Step 5
Using the e^x button on your calculator, determine the rate of shoot biomass production in grams per day for the control plot in soil with normal phosphate concentration.
Answer
Using the e^x function, if the shoot biomass is recorded as 1.0 g per 20 weeks, converting this to a daily production rate involves first converting weeks to days: 20 weeks = 140 days. The average daily production rate is then calculated as follows:
Thus, the rate of shoot biomass production for the control plot with normal phosphate concentration is approximately 0.0071 g day⁻¹.