The driving force for the movement of materials in the phloem of plants it
A. gravity
B. a difference in osmotic potential between the source and the sink
C. root pressure
D. transpiration of water through the stomates
E. adhesion of water to vessel elements
Ans: B. a difference in osmotic potential between the source and the sink
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Tubulin may assemble and disassemble simultaneously in a process known as
A) dynamic instability. B) treadmilling. C) microtubule organizing. D) MAP motoring. E) actin-regulated assembly.
Which statement about sex chromosomes is correct?
a. The Y chromosome carries a greater number of genes for nonsexual traits than does the X. b. X and Y are different in size but carry nearly equal numbers of genes. c. The X chromosome carries more genes for nonsexual traits than does the Y. d. The X chromosome carries only gender-related genes. e. The X chromosome carries the SRY gene.
Which of the following hormones helps the body avoid dehydration and water overload?
A) oxytocin B) follicle-stimulating hormone C) thyroid-stimulating hormone D) antidiuretic hormone
The pectoral girdle supports the ________.
a) arms b) legs c) skull d) thoracic cage