Damage to which structures may result in a heart murmur?

Damage to heart valves can lead to heart murmur.

Explanation:

Heart murmur refers to the sound of blood flow. The sound of flowing blood in the heart is usually not heard.

The heart murmurs can result due to two reasons that is either a damaged valve or any condition that causes the heart to beat at a faster rate.

The types of damage to the heart valve that may lead to heart murmurs are:

Mitral valve prolapse, Mitral valve or aortic stenosis and Mitral or aortic sclerosis.

Sometimes, the murmurs do not signify a serious condition but  under certain condition they may indicate the risk of heart failure.

organisms that lack symmetry are called asymmetrical and belong to phylum porifera/sponges.

organisms with specialized stinging cells belong to phylum cnidaria. stinging cells are called cnidoblast cells.

cnidarians show two morphological forms : polyp (sessile) and medusa (mobile)

filter feeding is observed in porifera members.  

alternation of generation is observed in coelenterata or cnidaria. there is alternation of asexual polyp form and sexual medusoid form. it is also referred as metagenesis.

oxygen +1 most likely