Answer: The environment changed suddenly from a shallow ocean setting to a river system.
Explanation: Changes seen in rock layers represent changes in Earth's local history. The rock layer stack overall shows a shallow ocean setting. But the youngest layer at the top was deposited by a river. This shows the geologist that the local environment changed suddenly from an ocean setting to a river system.
The TYR, TRP2, and TRP1 genes are located next to each other on a single chromosome and are organized into an operon is most likely to be accurate.
The option a is correct.
Explanation:
The genes for the Tyrosinase, TRP2 and TRP1 are located on the same chromosome and are operons. These are operons because they are controlled by same transcription factors on mRNA.
Tyrosinase enzyme is important for the synthesis of melanin, eye pigments and hair colour. The synthesis of all these is completed in three distinct reactions catalysed by TRP1, TRP2 and Tyr genes. These work as operon and the protein product is almost 40% similar of the three genes.
The amount of melanin production depends on tyrosinase enzyme activity of all the three genes.
The genetic regulation is done by operons.
Answer:
RBCs' production is controlled by erythropoietin.
Mature RBCs are released into the bloodstream after approximately seven days RBCs are produced in the bone marrow
Explanation:
The hormone erythropoietin is produced and released in the bloodstream by peritubular interstitial cells of kidneys. The function of erythropoietin is to increase the number of the precursors of red blood cells and thereby to stimulate the production of red blood cells in the bone marrow. When the oxygen supply to body cells is reduced, the hormone erythropoietin stimulates the development of proerythroblasts into reticulocytes and thereby increases the RBC production.
RBCs are produced by the process of erythropoiesis and take about seven days to become mature and to be released in circulation to serve the function of oxygen delivery. The maturation of RBCs also includes the loss of most of the organelles such as the nucleus and mitochondria to accommodate hemoglobin protein. The life span of circulating RBCs is about 100-120 days.
Cells are the smallest unit of life. This is true.
Cells are important to the structure and function of living things. This is true.
All organisms are made of multiple cells. This is false, because there are many single celled organisms like bacteria.
Cells come in different shapes and sizes. This is true, as there are cells with a variety of shape and size (round shaped cocci and the elongated and flat bacillus). There are cells from squid's nervous system, called the neurons, that are comparatively very large in size than the vast majority of the other cells.