There are three major forms of fossil fuels and these are coal, oil and natural gas. All three were formed many millions of years ago before the time of dinosaurs.
Plants and trees died and sank to the bottom of swamps which filled the land. The dead matter formed layers of a spongy material called peat. Over time the peat was covered by sand, clay and other minerals which turned into sedimentary rock.
As the layers of rock piled up, their weight squeezed the peat until water came out of it and it eventually turned into coal, oil and natural gas.
Eutrophication of water bodies like lake, pond, shallow stretches of river, etc. is the phenomenon where excess growth of vegetation on the surface of the water takes place. This excess growth results in the clouding of the water, depletion of dissolved oxygen in water, and the death of aquatic organisms. The primary reason for the cause of eutrophication is the presence of nutrients in excess amounts in the water. The nutrients B. come from fertilizer and sewage runoff.
Answer:
C) Through genomic imprinting, methylation regulates expression of the paternal copy of the gene in the brain.
Explanation:
The pattern of gene expression wherein either paternal or maternal gene is expressed in specific cells while the other one is prevented from expression is known as genomic imprinting.
In the given example, the maternal copy of the gene on chromosome 15 is expressed in brain cells while its paternal copy is not expressed in these cells. Hence, the pattern of expression of this gene is regulated through genome imprinting. One of the mechanism is methylation of cytidine residues of CpG islands of the DNA that are more frequently present within promoters of the genes.
When the cytidine residues of these sequences are methylated into 5-methylcytidine, the transcription factors do not bind to these promoters preventing the expression of these genes.
Hence, methylation of cytidine residue in CpG islands of the promoters of the gene present on chromosome 15 could have silenced its expression in brain cells.
Answer:
B. Because weather is a complex interaction among many different variables that are constantly changing
Explanation:
Answer:
It’s A
Explanation:
Itw a because it does contain a nucleus
