Ancestors of giraffes with shorter necks could not reach branches high up in trees for food. This led to selection for longer-necked giraffes.

A. disruptive
B. sexual
C. artificial
D. directional
E. stabilizing


D. directional

Biology & Microbiology

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The earliest photosynthesizers likely used ____ as electron donors

a. chloride gas b. hydrogen peroxide c. hydrogen sulfide d. magnesium sulfide e. ammonia

Biology & Microbiology

Introduction of alien or exotic species into new ecosystems can occur through

A. accidental transport by ship or plane without anyone's knowledge. B. agricultural and horticultural activities. C. colonization when new settlers arrive in an area. D. All of the choices are correct.

Biology & Microbiology

Viral replication can involve the copying of RNA in an RNA virus.

Answer the following statement true (T) or false (F)

Biology & Microbiology

Angiosperms are different from all other plants because only they have ___________.

A. a life cycle that involves alternation of generations B. seeds C. flowers D. vascular tissue

Biology & Microbiology