Select all that apply. chromosomes are rod shaped structures that contain dna are located in the nucleus occur in numbers that are the same for all members of a certain species occur in numbers that are the same for all organisms are organized into karyotypes for scientists to analyze

the corpus luteum secretes estrogens and progesterone. the latter hormone causes changes in the uterus that make it more suitable for implantation of the fertilized ovum and the nourishment of the embryo. if the egg is not fertilized, the corpus luteum becomes inactive after 10–14 days, and menstruation occurs.

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