Answer:
C. Some marsupial mole rats had a natural immunity to the virus.
Explanation:
According to Darwin's evolutionary theory, over time some of marsupial moles may have acquired natural immunity which evolves as an adaptive trait in the population. Since these organisms have more chance to survive and reproduce (survival of the fittest), they will likely transmit the natural immunity to the next generation
.
The correct answer is: B) G1
Normal cells (unlike cancer cells), move through the cell cycle in a regulated way in order to make sure that cells don't divide under conditions that are unfavorable for them. Information about their own internal state (nutrients, signal molecules, DNA integrity) is signal to go or not to go through the cell division. Because of that there are few checkpoints in the cell cycle at which the cell examines the signals and makes a “decision”. The major checkpoints are:
• The G1- the first point at which it must choose, once it passes the G1 checkpoint the cell enters S phase
• The G2-the cell checks DNA integrity and checks if replication is done well.
• The spindle checkpoint-at the transition from metaphase to anaphase.
During the cell cycle, it skips the whole process in the cell cycle to produce a cell, which causes errors within the cells and produce more of these errors. This how cancer occurs.
Answer:
In the cholesterol biosynthetic pathway, the rate-limiting step is the reduction of HMG-CoA, which takes place in the existence of the HMG-CoA reductase enzyme. In case, when mutation takes place within the mentioned enzyme, it loses the tendency to combine with the substrate HMG-CoA, and as a consequence, the pathway fails to move forward and synthesis of cholesterol stops.
When the levels of cholesterol are high within the organism than the mutation of the enzyme HMG-CoA reductase results in less synthesis of cholesterol within the body of the organism and will eventually assist in balancing the level of cholesterol present within the body.
