Units and Measurement (Section)(a) A sample of tetrachloroethylene, a liquid used in dry cleaning that is being phased out because of its potential to cause cancer, has a mass of 40.55 g and a volume of 25.0 mL at 25 °C. What is its density at this temperature? Will tetrachloroethylene float on water? (Materials that are less dense than water will float.) (b) Carbon dioxide (CO2) is a gas at room temperature and pressure. However, carbon dioxide can be put under pressure to become a “supercritical fluid” that is a much safer dry-cleaning agent than tetrachloroethylene. At a certain pressure, the density of supercritical CO2 is 0.469 g/cm3. What is the mass of a 25.0-mL sample of supercritical CO2 at this pressure?
Chapter 43—Reproduction and Embryonic Development Surrogate—woman is not able to carry a baby, so a surrogate mother is used Test-tube baby—child is created in petri dish and inserted into woman Implantation—most important part of pregnancy; when the embryo attaches itself to the wall of the uterus Modes of Reproduction o Asexual Creation of genetically identical offspring by one parent Very rapid form of reproduction Less genetic variation because there is only one parent involved in the process Can occur via Budding—new individual forms from adult; sometimes bud stays attached, but most the time it falls off and becomes its own adult Fission—animal splits in two Fragmentation—pieces if an animal grow into a new adult Parthenogenesis—formation of new individual by unfertilized eggindividual is sterile (tadpole) o Sexual reproduction Joining of gametes Eggs and sperm o Some animals have both modes o Some animals exhibit hermaphroditism – individual has both male and female reproductive systems o Makes it easier to find a mate o May exchange gametes with other individuals o May fertilize their own eggs o Sexual reproduction results in the generation of unique offspring o External fertilization (spotting) Gametes distributed outside of the animal When eggs and sperm are discharged near each other Many fish and amphibian species o Internal fertilization Sperm is deposited in or near the female reproductive tract Some fish and amphibians and most terrestrial species Human Reproduction o Both sexes have A set of gonads Ducts for gamete transport Structures for copulation Male Reproduction o Testes produce sperm and male hormones o Epididymis stores sperm as they develop further o LH stimulates testes—testosterone production Leydig cells o FSH controlled by pituitary—sperm production Sertoli cells facilitate spermatogenesis o Men can produce sperm until death o Several glands contribute to semen Seminal vesicles Prostate gland Bulbourethral glands o During ejaculation Sperm is expelled from the penis Seminal vesicles, prostate, and bulbourethral glands secrete into the urethra Semen is formed and expelled o Sperm production Is regulated by a negative feedback system of hormones Involves the hypothalamus Anterior pituitary Testes Female Reproduction o System that allows for pregnancy o Hormones synchronize cyclic changes in the ovary and uterus o About every 28 days The hypothalamus signals the anterior pituitary to secret FSH and LH Trigger the growth of a follicle and ovulation o After ovulation, the ovarian follicle becomes the corpus luteum o The corpus luteum secretes estrogen and progesterone which Stimulate the endometrium to thicken (lining of the uterus) Prepare the uterus for implantation Inhibit the hypothalamus, reducing FSH and LH o If the egg is fertilized The embryo releases hormones that maintain the uterine lining and menstruation does not occur First 3 months are embryonic stage Next 6 months are fetal development o If the egg is not fertilized The drop in LH shuts down the corpus luteum and its hormones Menstruation is triggered and the hypothalamus and pituitary stimulate development of a new follicle o Hypothalamus controls anterior pituitary, which produces FSH and LH o FSH and LH spike around day 14 LH peak triggers ovulation and corpus luteum formation