I believe the biggest space mission of the twenty-first century will be a manned mission to Mars, and the colonization that follows. This is the stated goal of several nations, companies, and individuals, all with considerably deep pockets. This mission will not only be a huge leap forward in space exploration, it will usher in a new era in human history in which the human race is an interplanetary civilization, a natural milestone as humanity continues to progress and advance.
Significant challenges are many and overwhelming. In terms of getting to mars, we need efficient, powerful propulsion systems and a spaceship that can not only accommodate a full crew for a mission that would likely last years, but withstand the various hazards that a long trip through space and entrance into the Martian atmosphere will entail. In terms of colonization, significant challenges will include establishing efficient and frequent travel/transport between the planets, and in the longer term, the necessity to terraform the planet (make it more like Earth) so that humans can more easily live there.
Answer:
The correct answer is A. autosomal recessive
Explanation:
In an autosomal disease, the mutation occurs in the autosomal chromosome, not in the sex chromosome. In autosomal recessive disease if both the defected allele from parent comes in the child then only the child would be affected by the disease. If the offspring have single defected allele than he is said to be a carrier.
So as the defect is not in sex chromosome the disease will occur in the same frequency in both the sexes and if parents are carriers which means they are not affected by disease than 25% offspring can have the disease because out of four offspring one can get both the defected allele, one from each parent. So the correct answer is A.
Lower esophageal sphincter! <span />
