Cell differentiation of a pre-embryo begins
A) immediately upon the first division of the fertilized egg.
B) after the 32-cell stage.
C) after the 4-cell stage.
D) after the 8-cell stage.
E) after the 2-cell stage.
D
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Postranscriptional modification to remove introns is needed for the bacterial RNA that has codon, rather than anticodon, sequences.
Answer the following statement true (T) or false (F)
What would happen to the gas exchange rate within an insect if the circulatory system was compromised?
A. The gas exchange rate would increase slightly. B. The gas exchange rate would increase significantly. C. The gas exchange rate would be unaffected. D. The gas exchange rate would decrease significantly. E. The gas exchange rate would decrease slightly.
Prior to 500 million years ago, organisms were
unable to venture onto land because a. the earth’s crust was too hot. b. the land was too dry. c. there was not enough oxygen in the atmosphere for respiration. d. the land was not shielded from the sun’s ultraviolet radiation. e. there was no organic matter on land for food
Which of the following defines Hardy-Weinberg equilibrium?
A. generation-to-generation change in a population's frequencies of alleles B. the smallest scale of evolution C. a nonevolving population in genetic equilibrium D. 2pq