Question

Tay-Sachs, which is a recessive lethal disease, results only when individuals possess two copies of the disease-causing allele. Which of the following statements is true about this disease?a. Heterozygous individuals may pass on their copy of the disease-causing allele to offspring.
b. Heterozygous individuals only pass on the dominant copy of the allele to offspring.
c. Heterozygous individuals are more fit than homozygous dominant individuals, so eventually, there will only be heterozygotes in the population.
d. All cases of this disease must be caused by new mutations.
e. None of the above.

Answer 1

Answer:

a. Heterozygous individuals may pass on their copy of the disease-causing allele to offspring.

Explanation:

Tay-Sachs, which is a recessive lethal disease  ---- Let say the recessive lethal diseases is s

∴ it only results when an individual posses two copies of the diseases-causing allele i.e two copies of the disease will be ss.

Now, when two hetrozygous individuals crossed , it is obvious that each can pass on their copy of the disease-causing allele to the offspring.

Let show an illustration for the above statement.

Let the heterozygous individual be Ts, if Ts cross with another Ts;

we will have:

Ts × Ts

         T          s

T        TT        Ts

s        Ts          ss

the offspring are TT,Ts,Ts,ss

We can now see how the Heterozygous individuals pass on their copy of the disease-causing allele to the offspring (Ts).