Question

Student to attempt either option (A) or (B):
(A) How is the interaction between Ophrys and its specific bee pollinator one of the best examples of co-evolution? Explain. 
OR 
(B) Arrange the given important steps of decomposition in their correct order of occurrence in the breakdown of complex organic matter and explain the fourth step in the process.

Hint:

Ophrys-bee pollination is a classic example of species-specific co-evolution. In decomposition, humification forms stable humus essential for fertile soil.

Answer 1

(A) Step 1: Co-evolution describes the reciprocal evolutionary influence between two or more species.
Step 2: The *Ophrys* orchid flower visually and olfactorily imitates a female bee.
Step 3: This mimicry entices male bees to attempt mating, facilitating pollination.  
Step 4: The specific bee species and *Ophrys* have evolved together to sustain this specialized pollination system.  
Conclusion: This exact and exclusive relationship exemplifies co-evolution.  
OR  
(B) Step 1: Correct sequence of decomposition stages:

1. Fragmentation
2. Leaching
3. Catabolism
4. Humification
5. Mineralisation

Step 2: Elaboration on Humification (the fourth stage):

• Humification results in the creation of humus, a dark, amorphous material.
• Humus is highly resistant to microbial degradation and thus remains in the soil for extended periods.
• It significantly contributes to soil fertility by enhancing its structure and water retention.