A couple comes into the clinic for genetic counseling. Both parents are heterozygous for sickle cell trait. What is the chance each of their children will have sickle cell anemia?
50%
25%
75%
100%
The Correct Answer is B
The correct answer is b. 25%.
Choice A: 50%
If both parents are heterozygous for the sickle cell trait (carriers), each child has a 50% chance of inheriting one sickle cell gene from one parent and a normal gene from the other parent. This would make the child a carrier of the sickle cell trait, not someone with sickle cell anemia. Therefore, the chance of having sickle cell anemia is not 50%.
Choice B: 25%
When both parents are carriers of the sickle cell trait (heterozygous), there is a 25% chance that their child will inherit two sickle cell genes (one from each parent), resulting in sickle cell anemia. This is because each parent has one normal hemoglobin gene (A) and one sickle cell gene (S). The possible combinations for their children are AA (normal), AS (carrier), SA (carrier), and SS (sickle cell anemia). The probability of the SS combination is 25%.
Choice C: 75%
A 75% chance is not accurate in this scenario. The 75% figure might be mistakenly considered if one were to add the probabilities of being a carrier (50%) and having sickle cell anemia (25%). However, these probabilities are distinct and should not be combined in this manner.
Choice D: 100%
A 100% chance would imply that every child of the couple would have sickle cell anemia, which is not the case. Since each parent is a carrier, there is only a 25% chance for each child to have sickle cell anemia. The remaining 75% of the time, the child will either be a carrier or have normal hemoglobin.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is ["3600"]
Explanation
Step-by-Step Calculation:
Step 1: Determine the amount of ORS needed per kg for moderate dehydration.
- Moderate dehydration requires 100 mL of ORS per kg.
Step 2: Calculate the total amount of ORS needed.
- Child’s weight = 36 kg
- Amount of ORS per kg = 100 mL
Step 3: Multiply the child’s weight by the amount of ORS per kg.
- 36 kg × 100 mL/kg = 3600 mL
Step 4: Convert the total amount of ORS from mL to cups.
- 1 cup = 240 mL
- Total ORS needed = 3600 mL
Step 5: Divide the total ORS needed by the amount of mL in one cup.
- 3600 mL ÷ 240 mL/cup = 15 cups
Summary:
The child will need 3600 mL (or 15 cups) of ORS within 4 hours.
Correct Answer is D
Explanation
The correct answer is d) Central nervous system.
Choice A reason:
The musculoskeletal system is not primarily affected by abnormal phenylalanine levels. Phenylketonuria (PKU) is a metabolic disorder that primarily impacts the brain and cognitive functions. While muscle weakness can occur due to overall health deterioration, it is not the primary system affected by phenylalanine toxicity.
Choice B reason:
The renal system is not the main target of phenylalanine toxicity. Although the kidneys play a role in filtering blood and excreting waste, the toxic effects of phenylalanine accumulation are more pronounced in the brain. Therefore, the renal system is not the primary system affected by abnormal phenylalanine levels.
Choice C reason:
The GI system, or gastrointestinal system, is not the primary system affected by abnormal phenylalanine levels. While dietary management is crucial for individuals with PKU to control phenylalanine intake, the toxic effects are primarily seen in the brain. The GI system is involved in the absorption and digestion of nutrients, but it is not the main system impacted by phenylalanine toxicity.
Choice D reason:
The central nervous system (CNS) is the primary system affected by abnormal phenylalanine levels. Phenylketonuria (PKU) leads to the accumulation of phenylalanine in the brain, causing severe brain damage and cognitive impairments. High levels of phenylalanine can disrupt neurotransmitter synthesis and brain development, leading to intellectual disabilities and other neurological issues. Therefore, the CNS is the main system impacted by phenylalanine toxicity.
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