What type of membrane proteins have an exposed site on the outer cell surface that can attach to a ligand?
A. marker molecules
B. receptor proteins
C. channel protein
D. carrier proteins
E. enzymes
B
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Which do not belong to the respiratory portion of the respiratory system?
A. Pulmonary alveoli B. Alveolar ducts C. Respiratory bronchioles D. Terminal bronchioles E. Alveolar sacs
The ____ is the largest and heaviest bone of the body
a. humerus b. tibia c. femur d. ulna
Describe the orientation of smooth muscle fibers in the muscular layer of the digestive tract
A) The cells align parallel to each other and form an inner circular layer and an outer longitudinal layer. B) The cells align parallel to each other and form an inner longitudinal layer and an outer circular layer. C) The cells align perpendicular to each other and form an inner circular layer and an outer longitudinal layer. D) The cells align perpendicular to each other and form spiraling bands. E) The cells align obliquely to each other and form three interwoven layers.
Puberty in a female is characterized by
A. adipose tissue deposition in the breasts and around the hips. B. increased muscle mass, especially in the hips. C. growth of facial hair. D. closure of the uterine tubes. E. growth of chest hair.