Ans.
Sex-linked genes are those genes that found on sex-chromosomes (X and Y chromosomes) and their phenotypic expression for a trait depends on the gender of the offspring.
Most of the sex-linked genes are present on X chromosomes as X chromosomes have more number of genes as they are made up of more DNA as compared to Y chromosome.
However, male individuals are more likely to exhibit the sex-linked traits. It is because most of the sex-linked traits are recessive and males have only one copy of X chromosome, while females have two copies of X chromosome. One mutated copy in male can exhibit the trait, while in females, both of the mutated copies are required to exhibit that trait.
Not trying to anger you or sound disrespectful, but it would be easier to answer if we could actually see the diagram :/
I think the more features two organisms share or the shared anatomical features, the closely related they are. For example; the class insecta (e.g bee, butterfly) and the class arachnida (e.g spider and tick) belong to phylum arthropoda because they have similar anatomical features such as appendages, segmented body among other features.
Because it can be a matter of our physical safety. In the wilderness a loud noise nearby is usually not a good thing. It is just natural instinct for the majority, if not all, species.
