Asbestos and Lung Function Sample Cluster

Base your answers to questions 1 through 5 on the information below and on your knowledge of biology.

Source 1: The Hidden Danger of Asbestos

Asbestos is a group of naturally occurring minerals composed of microscopic, durable fibers. Because of its resistance to heat and fire, it was once commonly used in construction materials like insulation and roofing. However, when these materials are damaged, the microscopic fibers become airborne and can be inhaled.

Unlike dust, which the body can often cough up, asbestos fibers are sharp and needle-like. They can bypass the upper respiratory system and lodge deep within the lungs, specifically irritating the alveoli. Over time, the body’s immune system attempts to destroy these foreign fibers but fails, leading to chronic inflammation and scarring. This scarring thickens the tissue, making the lungs stiff and reducing the surface area available for gas exchange.

In severe cases, this chronic irritation leads to a rare and aggressive cancer called mesothelioma. As the tumor grows and lung tissue thickens, the diffusion of oxygen from the alveoli into the capillaries is blocked. Consequently, blood oxygen saturation levels drop, depriving cells throughout the body of the oxygen needed to function efficiently.

Source 2: Asbestos Exposure and Blood Oxygen Levels

Scientists conducted a study monitoring the respiratory health of factory workers exposed to high levels of asbestos over several decades. They measured the average resting Blood Oxygen Saturation ($SpO_2$) of workers at different stages of employment. Normal oxygen saturation is typically between 95-100%.

Table 1: Average Resting Blood Oxygen Saturation in Asbestos-Exposed Workers

1. Based on the information provided, which specific life function is directly disrupted by the thickening of the alveolar walls due to asbestos scarring?

(1) The digestion of large molecules into simple sugars 

(2) The diffusion of gases between the lungs and the blood 

(3) The synthesis of antibodies by white blood cells 

(4) The active transport of ions across the cell membrane

2. According to Source 2, what is the general trend regarding the effect of long-term asbestos exposure on homeostasis?

(1) As years of exposure increase, the body maintains stable oxygen levels more efficiently. 

(2) As years of exposure decrease, the reported symptoms of fatigue increase significantly. 

(3) As years of exposure increase, the blood oxygen saturation levels decrease, disrupting homeostasis. 

(4) As years of exposure increase, the rate of cellular respiration increases to compensate for lung damage.

3. Workers with 30 or more years of exposure reported "Severe fatigue" and "Exhaustion." Which statement best explains the biological cause of this fatigue?

(1) The cells lack sufficient glucose to assemble proteins. 

(2) The mitochondria cannot produce enough ATP because oxygen levels are too low. 

(3) The ribosomes are blocked by asbestos fibers, stopping enzyme production. 

(4) The carbon dioxide levels in the blood are too low to stimulate muscle contraction.

4. Explain how the change in the structure of the lung tissue, as described in Source 1, affects the rate of diffusion. [1]

5. A patient with advanced mesothelioma has difficulty walking for long distances without stopping to rest. Using your knowledge of cellular respiration, explain why low blood oxygen saturation limits the patient’s ability to exercise. [1]