Answer:
A feedback loop is a biological occurrence where the output of a system amplifies the system (positive feedback) or inhibits the system (negative feedback).
Explanation:
Example, during blood clotting, a cascade of enzymic proteins acitvates each other, leading to the formation of fibrin clot that prevents further blood loss.
Answer:
B. Epithelial
Explanation:
The respiratory segment comprises most of each nasal cavity, and is lined with ciliated pseudostratified columnar epithelium (also called respiratory epithelium).
Answer:
- New seedlings: histone acetylation
- After cold exposure: histone methylation
Explanation:
Vernalization is an adaptive mechanism whose objective is to ensure that flowering occurs only after winter (i.e., after cold conditions). In certain plants, this process (vernalization) suppresses the expression of genes that encode repressors of flowering. In <em>Arabidopsis</em>, vernalization is associated with histone modifications at <em>FLC</em> chromatin. The <em>FLOWERING LOCUS C </em>(<em>FLC</em>) is a MADS-box gene that acts as a repressor of flowering in <em>Arabidopsis</em>. Epigenetic modifications control the expression of the <em>FLC</em> gene. The <em>FLC</em> gene is expressed at low temperatures due to histone acetylation at <em>FLC</em> chromatin, and thereby the expression of <em>FLC</em> mRNA transcripts ensures that the <em>Arabidopsis</em> plant cannot flower. Subsequently, as the <em>Arabidopsis</em> plant is exposed to cold, <em>FLC</em> is repressed by the accumulation of trimethylation on lysine 27 of histone 3 (H3K27me3), thereby allowing it to flower when temperatures become warmer.
Answer:
Please attach the photo of the organism.
Explanation:
