Biomass is the total mass of a specific organism in the area. If there is a negative value of change in shoot biomass, that mean the mass of the shoot in this period are less than before. This indicate increases in predation/death which reduce the population of the shoot more than its growing rate. The cause could be an increases in predator population or decreases in food/resource.
Answer: The blank can be filled correctly by "if the seeds contain the gene or allele responsible for large size of the tomatoes"
Explanation:
In plants also, characters or traits of characters are defined by genes. Different alleles produce different traits of the same character.
For example, in classic Mendelian genetics, T was the allele responsible for tall plant trait while t was the responsible for dwarf trait.
Similarly, there would be a gene(s) responsible for size of the tomatoes. In addition, seeds are the products of sexual reproduction of plants. So, they may carry genetic combination different from parent plants (due to meiosis, crossing over, independent assortment, et cetera).
So, if the seed contains the gene or allele responsible for large size of tomatoes then only they will produce same kind of tomatoes.
The "Receptor site" is the answer.
