#Question id: 1520
#Unit 4. Cell Communication and Cell Signaling
Following statements are regarding to enzymatic processing of benzo(a)pyrene to a more potent mutagen and carcinogen.
A. Liver enzymes, particularly P-450 enzymes, modify benzo(a)pyrene in a series of reactions, producing 7,8-diol-9,10-epoxide, a highly potent mutagenic species that reacts with DNA primarily at the N2 atom of a guanine base.
B. The adduct, (+)-trans-anti-B(a)P-N2-dG, causes polymerase to insert an A rather than a C opposite the modified G base. Next time the DNA is replicated, a T will be inserted opposite the A, and the mutation will be complete.
C. Potent mutagen majorly causes conversion of guanine (G) to thymine (T) bases, a transition mutation.
D. When this potent mutagen applied to cultured bronchial epithelial cells, activated benzo(a)pyrene induces many mutations, including activating mutations at codons 175, 248, and 273 of the p53 gene.
Which of the following statements are correct?
#Question id: 7265
#Unit 5. Developmental Biology
Following statement regarding to the cascade of regulated RNA splicing controls drosophila sexual differentiation.
A. The Sex-lethal (Sxl)
protein, encoded by the sex-lethal gene, is the first protein to act in the
cascade and present only in female embryos.
B. Early in development, the Sxl gene is transcribed from a
promoter that functions only in male embryos.
C. Later in development, this male-specific promoter is shut
off, and another promoter for sex-lethal becomes active in both male and female
embryos.
D. In male embryos, however, in the absence of early Sxl
protein, exon 3 of the sex-lethal pre-mRNA is spliced to exon 2 to produce an
mRNA that contains a stop codon early in the sequence.
Which of the following is correct?
#Question id: 5720
#Unit 8. Inheritance Biology
Which two of the following are the CORRECT statements ?
P. Nondisjunction in the parental meiosis is not essential to produce diploid organisms
Q. Nondisjunction in the parental meiosis is essential to produce aneuploid organisms
R. Nondisjunction in the parental meiosis is essential to produce hexaploid organism
S. Nondisjunction in the parental meiosis is essential to produce tetraploid organisms
#Question id: 23784
#Unit 7. System Physiology – Animal
#Question id: 19490
#Unit 4. Cell Communication and Cell Signaling