By what age does a child's gender identity develop?

Which of the following principles of genetics got its foundation in the work of Gregor Mendel?

a. The idea that a human zygote has 23 pairs of chromosomes. b. The existence of dominant and recessive genes. c. The fact that mitosis and meiosis explain how chromosomes replicate themselves. d. The concept that monozygotic twins share more of their genetic code than dizygotic twins.

Each month, one week prior to the onset of her menstrual cycle, Melissa experiences mood swings, sudden tearfulness, feelings of hopelessness, irritability and negative thoughts about herself

These symptoms cause significant impairment in her functioning and lessen in severity within a few days following the onset of menses. Melissa is likely to be diagnosed with _____________. a. dysthymic disorder c. cyclothymic disorder b. premenstrual dysphoric disorder d. bipolar II disorder