Is DD heterozygous or homozygous

What is thought to have caused the mass extinction at the end of the cretaceous period?

Multicellular organisms use cell division, mitosis, for growth and the maintenance and repair of cells and tissues. single-celled organisms may use cell division as their method of reproduction. regardless of the reason for mitosis, the process ensures genetic continuity. what is the step in the cell cycle that ensure genetic continuity?

What are antigens and antibodies? how are they involved in the body’s response to incompatible blood?