U–Z
11.1 A–D
 
11.2 E–H
 
11.3 I–L
 
 
11.4 M–P
 
11.5 Q–T
 
11.6 U–Z
 
U–Z
U
uterus
Structure in the female reproductive system in which the embryo develops.
V
vascular cambium
Tissue that produces new vascular cells; lies between the xylem and phloem in dicot stems.
vascular tissue
A conductive component (either xylem or phloem) of the vascular system that transports food and nutrients throughout the plant body.
vegetative propagation
A form of asexual reproduction in which plants produce genetically identical offshoots (clones) of themselves, which then develop into independent plants.
vein
A blood vessel that carries blood back to the heart. The blood in veins is not oxygenated, with the exception of the pulmonary vein.
vertebrate
An animal that has a skeletal rod of bone or cartilage running up its back, surrounding the nerve cord. Segments of this rod are called vertebrae. All vertebrate animals belong to subphylum Vertebrata, part of phylum Chordata.
vestigial structures
Bodily structures that developed in the past but no longer serve any function for an organism.
villi
Fingerlike projections in the small intestine that increase surface area and maximize the absorption of nutrients.
vitamins
Complex molecules that usually serve as coenzymes, assisting in physiological processes.
W
warm-blooded
Animals that have developed fat and fur, hair, or feathers in order to retain heat produced by metabolic activities. Also known as endothermic. Warm-blooded animals are able to thrive in various climates, because they are minimally affected by environmental fluctuations in temperature.
X
xylem
Vascular tissue composed of cells that are dead at maturity; transports water and dissolved minerals upward from the roots to the shoot.
Z
zygote
In sexual reproduction, the diploid product of the fusion of the father’s haploid sperm cell and the mother’s haploid ovum (egg) cell. The single-celled zygote divides billions of times to form a whole individual.
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