Question

Use the paragraph to answer the question.

Phenylalanine is an amino acid found in all protein-rich foods and even some artificial sweeteners. Phenylalanine build up in the blood affects nerve and brain development. The condition phenylketonuria, or PKU, is caused by the toxic buildup of the amino acid phenylalanine. PKU is caused by a mutation in a gene that affects the breakdown of phenylalanine. The effects of PKU can be reduced by removing foods containing phenylalanine from the diet.

Which statement is true about expressed traits of PKU and environmental factors?

(1 point)
Responses

PKU leads to blood circulation problems in patients, and is caused by the environmental factor of eating phenylalanine foods.
PKU leads to blood circulation problems in patients, and is caused by the environmental factor of eating phenylalanine foods.

PKU leads to blood circulation problems because environmental factors cause phenylalanine to build up in the red blood cells.
PKU leads to blood circulation problems because environmental factors cause phenylalanine to build up in the red blood cells.

PKU leads to nerve and mental problems regardless of environmental factors.
PKU leads to nerve and mental problems regardless of environmental factors.

PKU leads to nerve and mental problems, and is caused by the environmental factor of eating food that has phenylalanine in it.

Answer 1

Answer: "PKU leads to nerve and mental problems, and is caused by the environmental factor of eating food that has phenylalanine in it."

Explanation: PKU causes nerve and brain/mental problems when phenylalanine builds up. The buildup depends on diet (foods containing phenylalanine), so environmental factors affect the expressed traits — though the underlying cause of PKU is a genetic mutation that prevents proper breakdown of phenylalanine.