Answer:
Since sickle cell disease is a disorder with an autosomal dominant inheritance pattern, and in light of the lack of data, it could be said that the only way for Pat and Tracy to have a child with sickle cell disease is for both of them to be healthy carriers of the gene, with a 25% probability.
Explanation:
Considering that both Pat and Tracy each have a sibling with a sickle cell trait and that both they and their parents are healthy, it must be assumed that some of their parents are healthy carriers:
- Pat and Tracy do not have sickle cell trait. In this case, there is no chance that they will have a child with sickle cell disease.
- Either Pat or Tracy has the trait, but the other does not. It is possible that at least one of their children is a healthy carrier.
- If both Tracy and Pat have sickle cell trait, the chances of having a child with sickle cell disease are:
Alelles R r
R RR Rr
r Rr rr
RR: healthy (25%).
Rr: healthy carrier (50%).
rr: sickle cell disease (25%).
<em>If Pat and Tracy are healthy carriers of the gene that determines sickle cell disease, the chance of having a child with the disease is 25%</em>.
Learn more:
Autosomal recesive inheritance brainly.com/question/10605612
The correct answer is D. Animals not adapted to cold migrate to warmer regions, because suppose that the cold temperatures kill most of the plants, so if they can die why they select that place to live? The option B is not logical because this require long time to evolve this characteristic and the option C has more logic but it still not enough, because if the temperatures are colder more animals can die. I hope this help.
Answer:
Humans have 23 pairs of chromosomes--22 pairs of numbered chromosomes, called autosomes, and one pair of sex chromosomes, X and Y. Each parent contributes one chromosome to each pair so that offspring get half of their chromosomes from their mother and half from their father.
Explanation:
(Sorry, I'm not sure)
Descending tracts are the pathways by which motor
signals are pass through from the brain to lower motor neurones. Thus, all
the neurones within the descending motor system are classed as upper motor
neurones. The lower motor neurones then directly innervate muscles to produce
movement. Their cell bodies are found in the cerebral cortex or the brain stem,
with their axons remaining within the CNS.
