Why are some genes sometimes turned on and other times turned off? ()
A: Because
sometimes cells are hungry.
B: Because
cells need to rest.
C: Because only
when the products are needed by cells.
D: Because
cells want to use up some products.
A: Because
sometimes cells are hungry.
B: Because
cells need to rest.
C: Because only
when the products are needed by cells.
D: Because
cells want to use up some products.
举一反三
- Mammals cannot use acetyl-CoA as a precursor of glucose, because the ________________________ is irreversible and cells have no other pathway to convert acetyl-CoA to pyruvate.
- When tourists travel abroad, they are sometimes ________ by the local people because the tourists don’t know the real value of products. A: turned in B: given chase C: ripped off D: wrapped up
- Compared with normal mice, mice immunized with antigens for many times have the larger and heavier spleens because of ( ). A: proliferation of antigen specific T cells B: proliferation of antigen specific B cells C: proliferation of antigen specific T and B cells D: proliferation of antigen non-specific T and B cells
- In peripheral nerve fibers, sheath cells are () A: Astrocytes B: Oligodendrocytes C: Satellite cells D: Ependymal cells E: Schwann<br/>cells
- Why do people in some countries not react negatively to<br/>corruption?___ A: because they feel it cannot be avoided B: because they want reform C: because almost everyone in the government is corrupt D: because they have paid money to gain influence