Which statement is true of deuterostomes?
a. The second opening into the embryo becomes the anus.
b. They have two tissue layers.
c. The second opening into the embryo becomes the mouth.
d. The first opening into the embryo becomes the mouth.
e. They are typically radially symmetrical.
ANSWER: c
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The Y chromosome can be used to trace ancestry because:
A. natural selection favors specific mutations in specific places. B. mutations in the Y chromosome occurred as people migrated around the globe. C. mutations in the Y chromosome are independent of mutations in mitochondria. D. mutations in the Y chromosome occur only in a few locations. E. nonmutant Y-chromosome genotypes are eliminated from human populations.
The ________ is the substrate concentration needed for an enzyme to achieve half maximal velocity.
What will be an ideal response?
A storage container in a cell is generally called a(n)
A. vacuole. B. endoplasmic reticulum. C. pinocyte. D. nucleus.
The smallest unit of life that can exist as a separate entity is a(n) ___________.
A. cell B. molecule C. organ D. population E. ecosystem