BIOS 242 Final Exam 3

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BIOS 242 Final Exam 3

• chromosomes

–Answer autosome (22 pairs) sex chromosomes (1 pair)

• autosomes

–Answer -22 pairs -each member of a pair carries the same complement of genes

• sex chromosomes

–Answer -2 forms = X and Y -not all genes are paired -X in both male and females --> has essential genes -Y in only males --> essential genes for developing into male XX = female XY = male

• mitosis

–Answer normal cell division -DNA replicated once -cells undergo division once

• meiosis

–Answer cell division to produce gametes -DNA replicated once -cells undergo division twice 1 / 4

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• reproductive system

–Answer all organs involved in mating, gametogenesis, or other functions involved in producing offspring

• gonads

–Answer -males = testes -females = ovaries

• major functions

–Answer

-produce gametes -secrete sex hormones

• accessory reproductive organs

–Answer organs of reproductive system = transport of gametes glands = secrete fluids onto reproductive tract

• sex hormones

–Answer testes = androgens ovaries = estrogens and progesterone **both males and females have androgens and estrogens and progesterone -adrenal cortex also produces androgens

• copulation

–Answer act of mating -sperm deposited into female to fertilize ovum 2 / 4

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• pregnancy/gestation

–Answer -first 2 months = embryo -after 2 months = fetus

~ 9 months = birth/parturtionevents following fertilization –Answer -chromosomes determine whether fetus devel- ops ovaries of testes = sex determination -sex differentiation controlled by hormones

• Y chromosome

–Answer srY gene (sex-determining region of the Y chromosome) -if present = testes -if absent = ovaries

• srY gene

–Answer -codes for testes-determining factor -if present = testes-determining facto causes fetus to develop testes -if absent = ovaries develop

• embryo in first 2 weeks

–Answer sexually indifferent -wolffian ducts (precursor to male tract) -mullerian ducts (precursor to female tract) if testes present --> secrete hormones -testosterone = stimulates development of wolffian ducts -mullerian-inhibiting hormone (MIH) = degeneration of mullerian ducts no testes -hormones absent --> wolffian ducts regress, mullerian ducts develop 3 / 4

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• adolescence

–Answer prior to 10-14 years -inability to reproduce

• puberty

–Answer starts at 10-14 years -sexual maturation -reproductive organs mature (can produce gametes) -secondary sexual characteristics develop

• during sexual maturation

–Answer from late teens onward -female reproductive system cycles -female loses ability to reproduce at ~ages 45-50 -menopause = loss of female reproductive capacity -male retains ability to produce sperm until andropause

• male reproductive anatomy

–Answer -gonads = testes -reproductive tract = epididymis, vas deferens, ejaculatory duct, urethra -external genitalia = penis, scrotum

• male external genitalia

–Answer penis and scrotum -sperm ejaculated through urethra in penis -scrotum suspended beneath penis, houses testes --> sperm cannot develop at body temperature, allows a cooler environment for sperm development

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