Could your lifestyle or the food you eat influence evolution? How?
What will be an ideal response?
Such influence can occur through epigenetics, which involves a stable alteration in gene expression without changes in DNA sequence. DNA methylation and histone acetylation alter gene expression by affecting how tightly packaged the DNA molecule is. DNA methylation (adding a methyl group to the cytosine bases in DNA) turns off the activity of a gene by bringing in proteins that act to compact DNA into a tighter form. Histone acetylation, in contrast, makes the DNA less tightly coiled and gene expression easier. DNA methylation patterns can be affected by environmental factors, cause disease, be transmitted through generations, and potentially influence evolution.
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Barringer Crater in Arizona was formed when a
300,000-ton asteroid slammed into Earth 50,000 years ago. Which of the following is true about this event? a. It hit so early that it had little influence on the history of life. b. This one produced about 150 times the energy of the bomb that hit Hiroshima. c. Its impact produced a minor crater. d. Scientists recently disproved that an asteroid impacted our planet just prior to the mass extinctions at the K-T boundary. e. An asteroid impact releases only minor amounts of energy.
The letter “A” in the above figure represents the
a. style. b. ovary. c. stigma. d. anther. e. filament.
It has been observed that when the sugar source changes in a growth medium, the growth rate of yeast vary widely in response. Some strains of yeast are slow to induce catabolic operons while other strains quickly synthesize proteins to process the new sugar. What might be one explanation for this difference in the growth rate of the strains?
A. Operons for anabolic pathways are controlled by many global regulatory mechanisms, and different sugars can favor initiation of different pathways depending on the strain of yeast. B. Catabolic repression strategies of operons for using different sugars may vary among strains, thereby favoring initiation of transcription in one strain over another depending on the sugar. C. All of the choices are correct. D. Different sugars can act as effector or repressor molecules in various strains, promoting or inhibiting transcription of genes depending on the type of sugar present.
Recent theories on the biological need for IgE as an:
A. Apoptosis causing agent B. Antiviral agent C. Antibacterial agent D. Antifungal agent E. Anti-helminthic