Which statement is true?
a. Feathers are waterproof because they secrete cellulose.
b. Trabeculae are small bones found in the wings.
c. Both beaks and feathers are composed of keratin.
d. Feathers help to radiate excess body heat.
c. Both beaks and feathers are composed of keratin.
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Because membranes usually are not permeable to polysaccharides, nucleic acids, and proteins, how are cells able to incorporate these molecules?
A) These macromolecules are only incorporated into structures outside the membrane. B) Macromolecules are broken down extracellularly, and their subunits diffuse through the membrane. C) Macromolecules are digested extracellularly, and their subunits move through transport proteins. D) Macromolecules are transported via endocytosis and are digested within the cell. E) both choices C and D
An abscess that begins as a red nodule in a hair follicle that ultimately becomes painful and full of pus is a:
a. folliculitis. b. furuncle. c. carbuncle. d. erythrasma.
Coral reefs consist of __________ polyps, which duplicate via __________ reproduction
a. identical; asexual b. identical; sexual c. unique; asexual d. unique; sexual
The main advantage of YAC (yeast artificial chromosome) over other vectors in cloning human genes
is that A. it is taken up more readily by recipient cells. B. it is larger. C. it is less likely to trigger rejection. D. it is made of human DNA. E. it has unique restriction sites.