Q.23 Select the plant or ecosystem known to have highest energy conversion efficiency:
- Tropical forest plantation
- Sugar cane
- Cornfield
- Open sea
Sugar cane has the highest energy conversion efficiency among the given options due to its C4 photosynthetic pathway.
Option Analysis
Tropical Forest Plantation
Tropical forests boast high primary productivity from diverse C3 plants and ample sunlight, but their average photosynthetic efficiency stays low at 1-3% because of photorespiration in hot conditions. They excel in total biomass over vast areas yet lag in per-unit energy capture compared to optimized crops.Sugar Cane
As a C4 plant, sugar cane achieves 7-8% photosynthetic efficiency by minimizing photorespiration and efficiently fixing CO2 even under high light and temperature. This makes it the top biomass producer per hectare, outperforming others in solar-to-chemical energy conversion.Cornfield
Corn, another C4 crop, reaches 4-6% efficiency, strong but below sugar cane due to slightly less optimized CO2 concentration mechanisms. It yields high biomass yet falls short in peak energy conversion rates under tropical conditions.Open Sea
Ocean ecosystems have low primary productivity per area (around 1-2% efficiency) because phytoplankton face nutrient limits, light penetration issues, and vast dilution. They contribute globally in volume but rank lowest here for concentrated energy conversion.Introduction to Highest Energy Conversion Efficiency
In plant biology and ecosystem studies, highest energy conversion efficiency measures how well solar radiation turns into stored chemical energy via photosynthesis. For competitive exams like GATE Life Sciences, understanding why sugar cane outshines tropical forest plantation, cornfield, and open sea is key. This C4 crop’s superior mechanism drives top biomass yields.
Why Sugar Cane Dominates Energy Conversion
Sugar cane’s C4 pathway bundles CO2 in bundle sheath cells, slashing photorespiration losses common in C3 plants. This yields 7-8% efficiency—double most crops—making it the highest energy conversion efficiency option. Tropical climates boost its performance, with net productivity up to 4 kg/m².
Comparing Ecosystem Efficiencies
Option Pathway/Type Efficiency (%) Key Limitation Sugar Cane C4 crop 7-8 None standout Tropical Forest Plantation Mostly C3 forest 1-3 Photorespiration in heat Cornfield C4 crop 4-6 Less optimized than cane Open Sea Phytoplankton 1-2 Nutrient/light limits Tropical forests impress with total output but average lower per plant efficiency. Corn trails due to subtle C4 differences, while seas prioritize volume over density.
Implications for Agriculture and GATE Prep
Sugar cane’s edge supports bioenergy and high-yield farming, vital for sustainability questions in exams. Students: Focus on C3 vs C4 for highest energy conversion efficiency MCQs.
