Answer:
Towards should be the answer.
Manipulative experiments alter levels of a predictor variable (or factor), and then measures how one or more variables respond to these alterations. ... Natural experiments-An observational study in which we take advantage of natural variation that is present in the variable of interest.
Answer:
Different species within a phylum all have the same basic characters, anatomical and functional integrity, common ancestry.
Explanation:
The animals having same phylum but different species have similar basic structural pattern. That means the anatomical features are constructed on the same ground plan. This individuals have similar functional integration. All animals of a phylum work as a functional machines with similar functional integration.
Another important feature is they have common ancestry. Evolutionary study have confirmed all members of a similar phylum have been derived directly or indirectly from a common primitive ancestry.
Sister chromatids first appear during the S phase of the cell cycle.
