It is energetically cheaper to produce a male gamete than a female gamete. Menarche Menstruation Follicular phase Ovulation Luteal phase. Informed Health Links.
Evolution of sexual reproduction Anisogamy Isogamy Germ cell Meiosis Gametogenesis Spermatogenesis Oogenesis Gamete spermatozoon ovum Fertilization External fertilization Internal fertilization Sexual selection Plant reproduction Fungal reproduction Sexual reproduction in animals Sexual intercourse Copulation Human reproduction Lordosis behavior Pelvic thrust.
Menarche Menstruation Follicular phase Ovulation Produces male and female sex cells in Or phase. The spermatozoon has a flagellum, which is a tail-shaped structure that allows the cell to propel and move. When the male and female gametes fuse, they become a zygote containing the full 46 chromosomes, half of which came from the father and half from the mother.
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If the zygote has two Produces male and female sex cells in Or chromosomes it will develop into a female, if it has an X and a Y chromosome, it will develop into a male. While arguably adequate for defining the sexes in humans, these traits are largely inadequate for use in a broader definition of what is male and what is female across the animal kingdom.
The urethra is also part of the urinary system because it is also the channel through which pee passes as it leaves the bladder and exits the body. The zygote divides to form two new cells, which then continue to divide many times. Think of pregnancy and lactation in a typical female mammal — again, heavily maternally-biased investments.
The inside of the penis is made of a spongy tissue that can expand and contract.
Support Center Support Center. Edition: Available editions United Kingdom. Humans, like other organisms, pass some characteristics of themselves to the next generation.