Does the expected rate of return on the portfolio depend on the percentage of the portfolio invested

Question:

Does the expected rate of return on the portfolio depend on the percentage of the portfolio invested in each stock? What about the riskiness of the portfolio?

Portfolio
A portfolio is a grouping of financial assets such as stocks, bonds, commodities, currencies and cash equivalents, as well as their fund counterparts, including mutual, exchange-traded and closed funds. A portfolio can also consist of non-publicly...