LIFE SCIENCE

Detailed explanation-1: -Nucleus. Red blood cells in mammals are anucleate when mature, meaning that they lack a cell nucleus.

Detailed explanation-2: -Unlike most other eukaryotic cells, mature red blood cells don’t have nuclei. When they enter the bloodstream for the first time, they eject their nuclei and organelles, so they can carry more hemoglobin, and thus, more oxygen. Each red blood cell has a life span of around 100–120 days.

Detailed explanation-3: -Red Blood Cells are produced in the bone marrow and they have a nucleus when they are initially produced. Later, they lose nucleus in order to accommodate more haemoglobin so that they can transport more amount of oxygen. Therefore they are still considered as cells.

Detailed explanation-4: -Platelets are fragments of special cell and help in the clotting of blood. Mature mammalian red blood cells and platelets lack a nucleus whereas white blood cells contain a nucleus.