30. Sex cells are always haploid, meaning they have half the number of chromosomes.
This would be a recessive disease.
Father is dd
Mother is Dd (has to be because one child has the disease)
Parents cross is dd x Dd which gives rise to Dd (0.5) and dd (0.5). Each time they have a child they have a 50% chance of the child having the disease. In their case, only one of their 3 children is dd. The others though are carriers!
The correct answer would be Fluoride was not used to help protect teeth then
Cavity is not a genetic disease and thus there is no relevance of gene transfer in this case. Thus option A, B and D gets ruled out.
However, flouride in a limited amount is very useful for removing the cavities. Flouride in the foood and water enters the blood stream and make the teeth strong from inside. While the Flouride in Saliva make the teeths stronger and cavity free from outside. It reduces reminization that causes the loss of minerals.
Thus lack of flouride makes the teeth more cavity prone.
Correct answer: D). Damage to nerves that control the stomach
Gastroparesis is a medical condition in which the stomach is unable to empty its food. it is mainly caused due to damage caused to the vagus nerve, it is a nerve that regulates the digestive system.
Due to the damaged of vagus nerve the muscles of the stomach are not able to contract, which prevent the movement of food by the digestive system and results in gastroparesis.
The major cause of gastroparesis includes uncontrolled diabetes, multiple sclerosis, gastric surgery that cause injury to the vagus nerve and use of antidepressants etc.
