What developmental landmark occurs at day 25 in humans?
a. primitive streak
b. neural tube
c. yolk sac
d. pharyngeal arches
e. somites
ANSWER: d
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Which of the following molecules coordinates the expression of nonadjacent genes?
A) leucine zippers B) response elements C) transcription factors D) coactivators E) control elements
A special capsule or chamber where a plant will make the first cells of the gametophyte generation is called a ____
a. vascular system b. protonema c. sporangium d. rhizome e. shoot system
Which feature is found in both nonvascular and vascular plants?
a. xylem b. cuticle c. apical meristem d. lignin
Which one of the following insect organ systems has placed the greatest limitation on their body size?
A. excretory system B. nervous system C. digestive system D. reproductive system E. respiratory system