<span>All cells have the same DNA. They are different because different genes have been locked up and only some of them are expressed. The process began in the embryonic stage, when stem cells are turned into different types of cells by turning off some of the genes. Scientists have been looking for ways to reverse the process, meaning turning specialized cells back into stem cells. Some success has been reported using different methods. The latest one uses a weak acid to stress the cells.</span>
Answer:
backcrossing
Explanation:
when you cross the offspring (inttermediate size) to one of the parental strains, (the small strain for example) you should get 1/2 intermediate size and 1/2 parental size (small) if body size is due to single gene. On the other hand if the trait "size" is polygenic you should get mice around half way between small and intermediate sizes.
<span>the undigested lactose in the intestine draws water into the large intestine and is broken down by bacteria.
Lactose intolerance is due to the body no longer producing the enzyme required to break down the disaccharide sugar called lactose into the monosaccharide sugars glucose and galactose. Those undigested sugars provide food for bacteria that in turn generate gas. With that in mind, let's look at the available options to see which one is correct.
the lactose is an irritant to the stomach.
- I hope not. Because babies world wide need lactose for their growth. So this is a wrong answer.
the lactose in the small intestine neutralizes enzyme action.
- There's a lot of different enzymes used in the digestive process. And it's the lack of the enzyme lactase that causes lactose intolerance. But lactose doesn't neutralize any enzymes, so this is a wrong answer.
the undigested lactose in the intestine draws water into the large intestine and is broken down by bacteria.
- This looks reasonable. This is the correct answer.
the presence of lactose in the small intestine causes the gall bladder to contract more forcefully?
- This one is just plain silly. Wrong answer.</span>
