Penetrance In a certain breed of plants, thorns are determined by the dominant allele T and thornless is determined by the recessive allele t. T is 60% penetrant in the heterozygote; 40% of heterozygotes will appear thornless. If you make the parental cross TT x tt; what would be the expected number of progeny for each phenotype in a population of 400 F2 plants?

Ascientist is investigating the effects of salinity on fish development. he places fertilized fish eggs in an aquarium that contains low salinity and observes their development. what factor would improve experimental design the most? place the fish eggs in the open ocean because that is the natural habitat include another aquarium that has normal salinity to compare to the low salinity aquarium include an aquarium that replaces salt with sugar to confirm that the effects are specific to salt grow algae with the fish eggs in order to provide adequate nutrients to the developing embryos