Answer:
2%
Explanation:
The scientist believe that around 2% of the species that existed on Earth have been preserved in the fossil records. It is still a hot debate about it though, as there are only around 250,000 species identified in the fossil records so far, which is less than a quarter from the species that live in the present.
The reason why scientists believe that the majority of the species have not been preserved are very logical though. One of the reasons is that lot of species existed very long time ago, so their remains just didn't lasted so long. Other reason is the movement of the plates, where we have situation where plates that existed in the past have been totally suducted and melted in the mantle, while others are at the verge of it, so every fossil with them is melted and destroyed too. Another reason is that lot of species do not have hard parts, solid bone structure, so their preservation has been pretty much impossible,
Answer:
The correct answer is a inducer(lactose) = acts by stepping on the gas pedal.
Explanation:
In lac operon lactose act as an inducer.Lactose exerts its action by binding with the repressor and inducing a conformation al change in the repressor molecule and prevent the later from binding to the operator region.
This ultimately result in the expression of the structural genes such as Lac Z ,Lac Y and Lac A.
According to the given question if the lac operon is described using a car analogy then the inducer lactose will act by stepping on the the gas pedal and this is the positive regulation of Lac operon.
Answer:
The correct option is <em>B) Some wolves may have had variants in their digestion that allowed them to eat wheat, rice, barley, corn, and potatoes and so were able to survive with humans.</em>
Explanation:
Organism of a population might have genetic variations in them due to many reasons. The species of a population which are better adapted to live in a particular area are able to survive and produce more offsprings. As a result, that particular area increases in that genetic variant.
In the above scenario, some of the wolves had variants in their digestion which made them better adapted to live with the humans as they could eat wheat, rice etc. The wolves which did not have variants in their digestion couldn't survive in the human areas.
Answer:
why do you think that 100 sperm cells are released during ejaculation if only one sperm is needed to fertilize an egg?
Millions of sperm cells are produced as a result of ejaculation but during swimming to the egg only few make it to the egg while just one is being fertilized.
The reason is not far-fetched because the higher the population produced the higher the competition which led to one that survives it.
If few were produced and during the cause of swimming to the egg, they die along the line. There would not be any sperm cell to be fertilized
Explanation:
