Contraction of the respiratory muscles causes the thoracic cavity to in volume

Where do homologous chromosomes exchange genetic material through crossing over?               a.  chlorophyll    b.  centrosomes    c.  centromeres    d.  chiasma

What are the types of mutations, and how does each alter the encoded protein? college level answer

The circles, or orbits, for electrons are called energy levels. each level can hold only a certain number of electrons. add electrons to each level until you can't add any more. how many electrons can each level hold?