A dwarf is a recessive trait. In order for the plant to be shorter, it would have to have 2 recessive alleles. The plant is also purebread so it wont contain the tall allele. The gametes that are possible are tt.
The deep sea vent organisms or benthic organisms normally live in dark conditions because of no penetration of sunlight. These organisms in order to colonize ocean surface must develop photo sensory receptors and should adapt to the light conditions along with variation in temperatures and pressure in ocean currents.