Chapter 42

The end product of cleavage is a ______. a. gamete b. blastula c. gastrula d. zygote

The outermost germ layer in a vertebrate gastrula is the ______. a. endoderm b. ectoderm c. mesoderm d. dermis

A morphogen ______. a. diffuses through an embryo b. has different effects at different concentrations c. influences gene expression d. all of the al

Match each term with the most suitable description. _____ apoptosis _____ embryonic induction _____ cleavage _____ gastrulation _____ implantation a. blastomeres form b. cellular rearrangements form primary tissues c. cells die on cue d. cells influence neighbors e. blastocyst burrows into the uterus

In humans, fertilization typically occurs in the ______. a. vagina b. uterus c. cervix d. oviduct

The _____, a fluid-filled sac, surrounds and protects a human embryo and keeps it from drying out. a. amnion b. allantois c. yolk sac d. chorion

The placenta consists of ______. a. embryonic tissue b. maternal tissue c. paternal tissue d. a combination of a and b

During the fetal period, _______. a. gastrulation ends b. somites form c. a tail forms d. limb movements begin

Human milk contains ______. a. sugars b. lysozyme c. antibodies d. all of the above

Match each hormone with its action(s). _____ prolactin _____ oxytocin _____ human chorionic gonadotropin a. milk protein production b. sustains corpus luteum c. causes contraction of uterus, milk ducts

Pharyngeal arches of a human embryo will later develop into _____. a. gills b. lungs c. structures of the head and neck

______ removes webs between developing digits. a. Gastrulation b. Lactation c. Apoptosis d. Implantation

Most miscarriages ______. a. occur in the first trimester c. are caused by exposure to a pathogen b. can be prevented by a cesarean section d. threaten the life of the mother

A pregnancy test detects ______ in the urine. a. lysozyme b. prolactin c. oxytocin d. human chorionic gonadotropin

Number these events in human development in the correct order. _____ gastrulation is completed _____ blastocyst forms _____ tail is reabsorbed _____ implantation occurs _____ zygote forms _____ neural tube forms _____ maternal cervix softens