Unlike arteries, veins contain valves that ensure blood flows in only one direction. (Arteries don't require valves because pressure from the heart is so strong that blood is only able to flow in one direction.) Valves also help blood travel back to the heart against the force of gravity.
Guessing it’s D. Hope this was helpful!
For an individual to have the behavioral expression of the disorder pku, the individual must inherit a recessive combination of alleles and be exposed to phenylalanine in the diet.
What is pku?
A rare genetic condition known as phenylketonuria, or PKU, causes the body to accumulate phenylalanine, an amino acid. The phenylalanine hydroxylase (PAH) gene is altered in PKU. The enzyme required to degrade phenylalanine is produced in part because to this gene.
When a person with PKU consumes protein-containing foods or aspartame, an artificial sweetener, a dangerous buildup of phenylalanine can occur because this person lacks the enzyme required to break down phenylalanine. This may ultimately result in severe health issues.
To learn more about phenylketonuria click on the link below:
brainly.com/question/3711599
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Answer:
It is covered in spots
The fin on its back is very close to the tail.
It has a long, narrow body.
