An extra copy of chromosome 21 in humans causes
down syndrome
cystic fibrosis
hiv
none of the above

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?

Astudent constructs a venom diagram to compare the organelle last in plant and animal cells which organelle should be listed under “both” in the diagram?

Which of the following statements is true regarding a basic amino acid? a.) the hydrophilic r group of a basic amino acid will be located on the interior of a protein b.) the positively charged r group of a basic amino acid could bind dna c.) the r group of a basic amino acid would only be able to form covalent bonds with other molecules d.) a basic amino acid would be considered both polar and hydrophobic e.) all of the above