Question

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Explanation:

Analyze root branching function

Roots absorb water and essential nutrients from the soil.
More branches increase the root system's surface area.

Connect absorption to photosynthesis

Water is a key reactant for photosynthesis.
Nutrients like nitrogen and phosphorus support cellular growth.

Link photosynthesis to biomass

Photosynthesis produces glucose, the building block for plant tissues.
Increased glucose production directly increases the plant's overall mass.

Synthesize the complete pathway

Fewer root branches limit water and nutrient uptake.
This restricts photosynthesis, reducing the plant's total biomass.

Answer:

The protein coded by gene X determines the number of root branches, which directly dictates the surface area of the root system. A more branched root system increases the plant's capacity to absorb water and essential nutrients from the soil. Since water and nutrients are critical inputs for photosynthesis and cellular growth, enhanced absorption allows the plant to produce more glucose and biomass, thereby increasing the plant's overall mass. Conversely, fewer branches limit resource uptake, restricting growth and resulting in a lower plant mass.