Final answer:
It is false that sex-influenced traits are expressed in only one sex with no expression in the other. These traits can appear in both sexes but may be different due to hormones. The presence and expression of sex-limited genes contribute largely to sexual dimorphism.
Step-by-step explanation:
For a given species, it is false that sex-influenced traits are expressed in only one sex and have zero penetration in the other sex. Sex-influenced traits are indeed present in both sexes but may be expressed differently due to hormonal differences between the sexes. Sex-limited genes, on the other hand, are genes that are present in both sexes but are predominantly or exclusively expressed in one sex, leading to significant differences in traits, known as sexual dimorphism.
The determination of sex in certain organisms is based on their sex chromosomes. For instance, in mammals, sex is determined by XX chromosomes in females and XY chromosomes in males, while in birds, it is determined by ZW chromosomes in females and ZZ chromosomes in males.