Peter and Luke Are Identical Twins Who Are Juniors at the Same

question 426

Multiple Choice

Peter and Luke are identical twins who are juniors at the same college. Throughout their college years, both have been treated for major depressive disorder. Based on what researchers have found from twin studies, we know that it is probable that Peter and Luke:

• A) have abnormal brain structures, such as smaller frontal lobe and enlarged ventricles.
• B) have a deficiency in the neurotransmitters norepinephrine and serotonin.
• C) had a viral infection during prenatal development or shortly after birth.
• D) have inherited a genetic predisposition for major depressive disorder.

---

Definitions:

Hemoglobin

An iron-containing protein in red blood cells that transports oxygen from the lungs to the tissues of the body.

Oxygen Gas

A diatomic molecule consisting of two oxygen atoms, essential for respiration in most living organisms and used in various industrial processes.

Carbon Monoxide

A colorless, odorless gas produced by the incomplete burning of carbon-containing materials, toxic to humans and animals when inhaled.