Video Transcript
How could governments prevent the
transmission of diseases from parents to newborn babies as much as possible? (A) By raising the awareness of
families so that newborn babies undergo medical screenings. (B) By raising the awareness of
couples so that they undergo medical screenings before marriage. (C) By raising the awareness of
couples so that they would not get married at the age of 30. (D) All of the answers are
correct.
When we think of diseases, we often
think about pathogens infecting us. However, there are also diseases
that have a genetic basis and can be inherited from our parents. Let’s go over how this works.
Let’s say there is a gene that is
represented by the letter T, and it has two alleles: uppercase T and lowercase
t. The uppercase T allele is the
functional version of this gene, and the lowercase t is the nonfunctional
version. There are three possible genotypes
as shown here. If a person has two copies of
lowercase t, then they’re affected by a disease. But if they have at least one
functional copy, then they’re unaffected.
People who are heterozygous, with
both a copy of the uppercase T and lowercase t alleles, are said to be carriers. They carry the disease-causing
allele but don’t have the disease themselves. If two carriers of the disease have
children, then they could pass on either the uppercase T allele or the lowercase t
allele in the ratios shown here. 25 percent of the time, they will
have an unaffected child. 50 percent of the time, they will
have an unaffected child who is a carrier. And 25 percent of the time, they
will have an affected child with two copies of the disease-causing allele.
By being screened before marriage,
the parents will learn if they are a carrier of this disease. With this knowledge, they can
decide if they’re willing to take the risk or not. So answer choice (B) seems to be
correct. But since answer choice (D) states
that all answers are correct, let’s make sure that this isn’t the case before
deciding on our final answer.
Answer choice (A) proposes that
newborns are tested. This is incorrect, because this
wouldn’t prevent transmission to the newborn, because the disease would have already
been inherited when the baby was conceived. Answer choice (C) is also
incorrect, since the transmission of a disease isn’t affected by the age of the
parents. Therefore, a way that governments
could prevent the transmission of diseases from parents to newborns is given by
answer choice (B), by raising the awareness of couples so that they undergo medical
screenings before marriage.
