which of the following is not one of the four nitrogenous bases found in DNA ? A: Adenine B: Guanine C: Uracil D: cytosine

Which best describes meiosis? a. it produces cells that are identical to the original cell b. it is responsible for the replacement of damaged skin cells c. it is responsible for growth of the organism d. it produces male and female sex cells

Which of the following statements is accurate about evolution? question 10 options: natural selection only eliminates odd individuals. evolution means that a population never has changes in its genetic frequencies. mutations are always harmful. evolution means that a population undergoes changes in its gene frequencies over time.

Once an egg cell is fertilized by sperm, the cell then, as the embryo develops, it receives nourishment and eliminates wastes by transferring substances from its blood to its mother's blood. a. becomes a fetus immediately and exits the womb b. begins to divide and implants itself in the wall of the uterus c. remains in the uterus without dividing for several months d. travels back to the ovaries until the fetus is developed