【单选题】A morphogen is
A.
a cell or group of cells that signal other cells to become determined in a specific way
B.
a gene that causes a cell or group of cells to adopt a particular shape
C.
a signaling molecule that causes the differentiation of neighboring cells
D.
a signaling molecule that confers concentration-dependent positional information
【单选题】Which of the following is true about them?
A.
They didn't have 20 years of communication.
B.
They come from the same country.
C.
They are husband and wife.
D.
Their stories were turned into novels
【单选题】Activin is a protein that normally exists in a gradient within certain tissues in developing embryos. Certain undifferentiated cells cultured without activin produce epidermal cells. However, activin ...
B.
cell-surface receptor.
【简答题】听下面一段材料,回答1-3题。 1. Why didn't Jim write to the woman last month? [ ] A. Because he couldn't write. B. Because he was traveling in another country. C. Because he never wrote letters when he was on ...
【简答题】Join the two independent clauses to make a compound sentence. Use one of the coordinating conjunctions (and, but, for, or, nor, so, yet). Remember to use a comma before the connecting word. a. He enjo...
【单选题】Which of the following sentence is true?
A.
The doctor told the man to visit a beautiful city of the country for a month.
B.
The doctor didn't tell him what to do.
C.
After a month, the old man felt better.
【单选题】Some people tried to separate our country by taking illegal action, which didn't exactly ____ racial harmony. [ ]
【判断题】A morphogen is a protein that can restore totipotency to cells from an adult animal.
【简答题】完形填空。 Last January I was given a chance to work in another country. At first, I lived a 1 life, but soon I met a group of new friends and they were really nice. Then something 2 happened. One of our f...