What ecological role were the nitrogen-fixing Bradyrhizobium japonicum bacteria in soybean root nodules effectively playing when the experimenters cut off gaseous nitrogen?
a. parasite c. commensal
b. predator d. symbiont
A
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Fluid that collects in tissues is returned to the bloodstream by the
A. excretory system. B. digestive system. C. lymphatic system. D. vascular system. E. endocrine system.
“Double fertilization” produces nutrient tissue by the
union of a. two egg nuclei and one sperm nucleus. b. two sperm nuclei and one egg nucleus. c. two sperm nuclei and two egg nuclei. d. one sperm nucleus and endosperm mother cell nuclei. e. two sperm nuclei and one endosperm mother cell nucleus.
Adaptations that evolved in the group of animals called the _____ have allowed them to complete their life cycles entirely on land
Fill in the blank(s) with the appropriate word(s).
A differentiated cell ____
a. has only the genes required for that cell type b. is found in the zygote c. is not found after gastrulation d. has all the genes that came from fertilization e. has 23 chromosomes