Chapter 11, Problem 4A

Summary Introduction

Introduction :

Cystic fibrosis is the common recessive genetic disorderthat affects the glands producing mucus, sweat glands, and digestive enzymes. In this condition, chloride ions are not absorbed into the cells of a person. Instead, their chloride ions are excreted in the sweat. With insufficient chloride ions in cells, water can not diffuse from cells. This results insecretion of thick mucus. The thick mucus blocks organs of digestive and respiratory system.

Answer to Problem 4A

Correct answer :

The correct answer is option (C) lack of skin pigments.

Explanation of Solution

Explanation/justification for the correct answer :

Option (C) is lack of skin pigments. Skin pigment depends on the amount of production and distribution of melanin pigment. So, lack of skin pigment is not a characteristic of a person with cystic fibrosis. Thus, the correct answer is option (C).

The explanation for the incorrect answer :

Option (A) is chloride channel defect. It is a characteristic of a person with cystic fibrosis. Thus, this is an incorrect option.

Option (B)is digestive problems. The thick mucus due to cystic fibrosis clogs the ducts in the pancreas and interrupts digestion. The digestive problem is a characteristic of a person with cystic fibrosis. Thus, this is an incorrect option.

Option (D) is recurrent lung infection. Patients with cystic fibrosis are at a higher risk of infection in their lungs. So, recurrent lung infection is a characteristic of a person with cystic fibrosis. Thus, this is an incorrect option.