QCAA Agricultural Science Plant production B

This describes plant tissue culture or micropropagation, where plant cells are grown in a sterile, nutrient-rich medium.

This refers to propagation by cuttings, where a severed plant part is planted to regenerate roots, rather than fusing two plants together.

This describes hybridization or sexual breeding, whereas grafting is an asexual technique that physically combines existing plant parts.

Grafting is the horticultural technique of joining tissues from two different plants (the scion and rootstock) so they unite and grow as a single organism.

Grain fill is the phase where seeds accumulate starch and proteins; while nitrogen is essential for this, the direct function of root nodules is acquiring that nitrogen, not the filling process itself.

Legumes form symbiotic relationships with bacteria (such as Rhizobium) in root nodules to perform nitrogen fixation, converting atmospheric nitrogen ($N_2$) into ammonia ($NH_3$) that the plant can use for growth.

While nitrogen supports overall plant growth, the specific biological purpose of the microorganisms within the nodules is to fix nitrogen, not to directly drive the physical development of the root system.

Carbon sequestration is primarily achieved through photosynthesis and biomass accumulation, whereas the specialized function of root nodules is the fixation of atmospheric nitrogen.