Answer:
The positive charge of the histone proteins get reduced due to the process of histone acetylation, thus making the wrapping of DNA around the histones less tightened. The loose connected DNA afterward associates with the transcription factors for the articulation of the genes situated in that area.
Generally, when there is no requirement of gene anymore, the acetyl groups from the histones get withdrawn by the activity of histone deacetylase enzyme (HDAC9) that makes the DNA tightly wrapped and inaccessible again. In case, when less expression of histone deacetylase enzyme occurs, the process of deacetylation fails to take place. This indicates that within an immune cell, at the time of infection, the inflammatory gene, which was made available does not get re-wrapped firmly around the histones.
Answer:
B. Birds allow their temperature drop in order to increase their production efficiency.
Explanation:
Most birds can drop the temperature a few centigrade degrees, while there are torpid birds capable of lowering much more. Birds can drop body temperature in response to environmental conditions. Bird species including, among others, swifts, hummingbirds and chickadees are capable of regulating body temperature during torpor state. There are different morphological and behavioral adaptative traits that enable birds to minimize the cost of thermoregulation. In the first place, epidermis surface allows heat loss to the environment, while arteries and veins in the legs help to retain heat in cold conditions.
