Answer:
pulmonary vein
Explanation:
The pulmonary veins
transfer oxygenated blood from the lungs to the heart.
It helps complete the pulmonary circuit, by receiving oxygenated blood in the alveoli and returning it to the left atrium.
→ Darwin believed that the need to adapt, in similar words, the changes occruing in the environment caused evolution.
The main cause of evolution, according to Darwin, was natural selection. Natural selection is a process in which a group of organisms with certain characteristics survive and thrive, in comparison to other organisms with different characteristics. This idea basically means that having some characteristics makes you suited for an environment.
And how would that ↑ explain Evolution?
Well, evolution is the change in species that occurs during time. But for you to change, there must be a cause for that change, which is none other than the need to survive, reproduce, etc.
→ As mentioned before, not all characteristics are enough to surive, and hopefully the image pasted below will help you.
Hope it helped,
BioTeacher101
Answer:
there is the answer to your question
The number of phenotypes produced for a given trait depends on how many genes control the trait. Anyhow, The distribution of phenotypes for a typical polygenic trait can often be expressed as a bell-shaped curve.
Many traits are controlled by two or more genes and are, therefore, called polygenic traits<span>. Each gene of a polygenic trait often has two or more alleles. As a result, one polygenic trait can have many possible genotypes and phenotypes.</span>