The appropriate answer is doing. decreased atmospheric water vapor leads to an increased greenhouse effect. This is not true because water vapor is a green house gas and increasing the levels of it in the atmosphere will lead to more warming. All the other answers represent appropriate feedback mechanisms associated with global warming.
Answer:
The correct answer is a) It brings a transport liquid into close contact with all cells in the body.
Explanation:
The circulatory system helps in bringing the blood which is a transport liquid in close contact with the cells present in our body. This helps in gas exchange between cells and blood. The circulation of blood in the body occurs by the pumping of blood by the heart into arteries, veins, and capillaries.
This circulation of blood plays many other vital functions like transport of nutrients to the cells, transport of waste products from the cell to outside the body, transport of hormones, maintenance of body temperature, etc.
So all these processes become possible when transport liquid comes in contact with the cells. Therefore the right answer is a.
Answer:
False
Explanation:
The histones that are more positively charged, tight hardly to negatively charged DNA. So, enzymes, such as acetyltransferases, that reduce the positive charge of histones promote transcription.
Chromatin structure and its modifications can change the package of the DNA and consequently, alter the gene expression. The most common modifications of the chromatin are covalent modifications such as acetylation/deacetylation (by acetyltransferases and eacetylases), methylation (by methyltransferases), and phosphorylation (by kinases). This is the way of gene expression regulation.
The effects of modifications are different, for example methylation promotes condensation of the chromatin and as a consequence, prevents binding of transcription factors to the DNA (transcription is repressed).
Acetylation loosens the association between nucleosomes and DNA (because it neutralizes the positive charge of histones) and consequently promotes transcription. Deacetylation is a process opposite to acetylation.
