Question

An animal cell without a nucleus does not have
A. Chromosomes
B. Ribosomes
C. Lysosomes
D. Mitochondria

Answer 1

Hint : The Nucleus is the brain of the cell. It encloses the genetic material. It comprises Nuclear envelope or Karyotheca (which has two nuclear membranes and nuclear pores), Nucleoplasm and Nucleoid. It is known as the 'Brain of the cell'.

Complete answer : Cell is the fundamental unit of the living organisms. Depending on the absence and presence of nuclear membrane the cells are Prokaryotic and Eukaryotic. Animal cells contain well-defined nuclei and thus these are Eukaryotic cells.

There are certain Animal cells that do not have a nucleus. These are Erythrocytes (RBC) and Platelets. These are blood cells. Mature erythrocytes lack a nucleus and thus it does not show the presence of chromosomes also and hence cannot divide. The Nucleus is absent so that RBCs can accommodate more hemoglobin which is a respiratory pigment. Erythrocytes also lack organelles like mitochondria.

Platelets are also blood cells. The precursor of these cells are Megakaryocytes which undergo fragmentation to form platelets. These cells also lack a nucleus and thus chromosomes also. However, Mitochondria is present. Thus if the nucleus is absent, the chromosomes are absent but mitochondria may or may not be absent.

Thus the correct Option is A.

Note :If we observe a cell under the microscope, we can easily recognize whether the Eukaryotic cell is ready to undergo division or has already divided. This is due to the presence of genetic material in the nucleus. If the nucleus contains chromatin thread, such a cell is getting ready to divide. If the nucleus contains chromosomes, this means the cell has already divided.