In some cells, there are many ion electrochemical gradients across the plasma membrane even though there are usually only one or two proton pumps present in the membrane. The gradients of the other ions are most likely accounted for by _____
A) cotransport proteins
B) ion channels
C) pores in the plasma membrane
D) passive diffusion across the plasma membrane
E) cellular metabolic reactions that create or destroy ions
Answer: A
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Mendel selected pea plants for his experiments because ____
a. the offspring are infertile b. others were also using pea plants for their experiments and this would allow data sharing c. male and female flowers are on separate plants d. they can be self-fertilized or artificially fertilized by hand e. he was told by his superior that only pea plants were suitable for experimentation
The root apical meristem is surrounded and protected by a structure called the
a. endodermis. b. root cap. c. quiescent center. d. pericycle. e. root hairs.
In adaptive immunity, the ______ are the cells that poke holes in foreign cells.
Fill in the blank(s) with the appropriate word(s).
Which bacterial structures are important for adherence to surfaces?
A. endospores B. cell walls C. fimbriae D. capsules E. flagella