Answer
Verified
327.1k+ views
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.
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.
Recently Updated Pages
How do you arrange NH4 + BF3 H2O C2H2 in increasing class 11 chemistry CBSE
Is H mCT and q mCT the same thing If so which is more class 11 chemistry CBSE
What are the possible quantum number for the last outermost class 11 chemistry CBSE
Is C2 paramagnetic or diamagnetic class 11 chemistry CBSE
What happens when entropy reaches maximum class 11 chemistry JEE_Main
Calculate the volume occupied by 88 gram of CO2 at class 11 chemistry CBSE
Trending doubts
Difference Between Plant Cell and Animal Cell
Difference between Prokaryotic cell and Eukaryotic class 11 biology CBSE
Fill the blanks with the suitable prepositions 1 The class 9 english CBSE
Change the following sentences into negative and interrogative class 10 english CBSE
Summary of the poem Where the Mind is Without Fear class 8 english CBSE
Give 10 examples for herbs , shrubs , climbers , creepers
Write an application to the principal requesting five class 10 english CBSE
What organs are located on the left side of your body class 11 biology CBSE
What is the z value for a 90 95 and 99 percent confidence class 11 maths CBSE