How does carbon dioxide enter a leaf?
A) CO2 diffuses through the epidermis into the mesophyll.
B) CO2 passes through openings called stomata on the leaf surface.
C) Dissolved CO2 is transported from roots to leaves in the xylem.
D) Atmospheric pressure forces CO2 through pits on the leaf surface.
E) CO2 is moved by active transport into the leaf by special cells called guard cells.
B
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Microbes are sometimes used in secondary treatment of wastewater to
A) convert heavy metals into carbon dioxide. B) remove organic matter. C) remove large particles. D) convert heavy metals into carbon dioxide, remove organic matter, and remove large particles.
In some cases the DNA lesion is bypassed by the DNA polymerase, leaving a gap that is single-stranded and contains the lesion. Since the gap is single-stranded the lesion cannot be repaired
Which of the following is not a feature of the repair of such gaps? A. The 3' single-strand overhang invades the intact portion of the chromosome, pairs with its complementary strand, and displaces the other. B. Strand invasion occurs by the intact, lesion-containing strand. C. Branch migration generates two Holliday junctions. D. The displaced, undamaged strand is replicated. E. Holliday intermediates are cleaved by resolvases.
The "mosaic" part of the fluid mosaic model refers to the membrane ____
a. proteins b. phospholipids c. cholesterol d. functions e. layers
Which cardiovascular structures in the fetus shunt blood away from the fetal lungs?
A) foramen ovale and ductus arteriosus B) foramen magnum and ductus venosus C) foramen ovale and ductus venosus D) umbilical artery and umbilical vein E) umbilical artery and ductus venosus