Tag: number and shape of cells

Questions Related to number and shape of cells

The term cytoskeleton was given by

biology organization of life the cell structure cytoplasm number and shape of cells

  1. Koltzoff

  2. Rhodin

  3. Menke

  4. Park

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Correct Option: A
Explanation:
  • Cytoskeleton refers to the complex network of interlinking filaments and tubules which extend throughout the cytoplasm of the cell from the nucleus to the plasma membrane.
  • They are composed of microtubules, actin filaments and intermediate filaments. 
  • They give shape and support to the cell and also facilitates movement within the cell (cytoplasmic streaming or cyclosis).
  • It was discovered by Nikolai K. Koltsov in the year 1903.
  • So, the correct answer is 'Koltzoff'.

Cytokinesis is a division of:

biology organization of life the cell structure cytoplasm number and shape of cells

  1. Cytoplasm

  2. Nucleus

  3. chromosomes

  4. Nucleolus

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Correct Option: A
Explanation:

Cytokinesis is the process of division of Cytoplasm. "Kinesis" means division and "cyto" refers to cytoplasm. it occurs during cell division. It is variable from plant cells to animal cells.

So, the correct option is 'Cytoplasm'.

 Select the correct statement _________________________.

biology organization of life the cell structure cytoplasm number and shape of cells

  1. Histone protein is present in all prokaryotes but absent in animal cell

  2. ER is absent in eukaryotes but presents in prokaryotes

  3. Nuclear membrane is absent in prokaryotes but nuclear membrane is present in eukaryotes

  4. Ribosome is present in eukaryotic cells but absent in prokaryotic cells

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Correct Option: C
Explanation:
Nucleus is well defined in eukaryotes and nuclear membrane is present.
Histone proteins and endoplasmic reticulum (ER) are present in eukaryotes. Ribosomes are present in both eukaryotes and prokaryotes.
Hence, the correct answer is 'Nuclear membrane is absent in prokaryotes but nuclear membrane is present in eukaryotes'.

Which of the following is correct?

biology organization of life the cell structure cytoplasm number and shape of cells

  1. Cells of all living organisms have a nucleus

  2. Both animal and plant cells have a well defined cell wall

  3. In prokaryotes, there are no membrane bound organelles

  4. Cells are formed de novo from abiotic materials

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Correct Option: A

End of prophase is marked by?

biology organization of life the cell structure cytoplasm number and shape of cells

  1. Initiation of condensation of chromosomal material

  2. Complete disintegration of nuclear membrane

  3. Reappearance of ER, Golgi body, nucleolus and nuclear envelop

  4. Alignment of chromosomes at the equator

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Correct Option: A

Cells capable of division are

biology organization of life the cell structure cytoplasm number and shape of cells

  1. Stem cells.

  2. Meristematic cells.

  3. Undifferentiated cells.

  4. All of the above.

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Correct Option: D
Explanation:

Stem cells are totipotent cells that can able to differentiate and divide into any type of cells of the body. meristematic cells are undifferentiated cells of the plants that can able to divide and form tissues, organs of the plant. so cells capable of division are all the cells including stem cells, meristematic cells and undifferentiated cells. Hence option D is correct.

A nucleated differentiated cell that has lost the power to dedifferentiate is ____________.

biology organization of life the cell structure cytoplasm number and shape of cells

  1. Nerve cells.

  2. Kidney cells.

  3. Liver cells.

  4. All of the above.

Show answer
Correct Option: A
Explanation:
A nucleated differentiated cell that has lost the power to division are nerve cells. These are the cells of nervous system and carry electrical messages and signals throughout the body. They have lost their power to division because the existing ones can grow new connections by loosing the old ones and also these cells needs oxygen and nutrients and if it divides rapidly and get packed, it will become difficult to supply and hence will starve.
So, the correct answer is option A.

RBCs are

biology organization of life the cell structure cytoplasm number and shape of cells

  1. Differentiated cells.

  2. Undifferentiated cells.

  3. Dedifferentiated cells.

  4. Dead cells.

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Correct Option: A
Explanation:

Mammalian erythrocytes also called as red blood cells are formed in bone marrow from multipotential hemocytoblast and further converted to erythroblast (normoblast). The nucleus and mitochondria of erythroblast disappear and it is converted to mature erythrocyte with haemoglobin. So RBC's are differentiated cells which lack a nucleus.

Which one of the following is anucleate?

biology organization of life the cell structure cytoplasm number and shape of cells

  1. Sieve tube

  2. Companion cell

  3. Medullary ray

  4. All of the above

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Correct Option: A

Formation of meristems cork cambium from fully differentiated parenchyma cells is an example of :

biology organization of life the cell structure cytoplasm number and shape of cells

  1. Differentiation

  2. Redifferentiation

  3. Dedifferentiation

  4. Regenration

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Correct Option: C
Explanation:
Cambium is the layer which forms Cork and acts as a secondary meristem from a layer of collenchyma or parenchyma immediately beneath the epidermis. The cells which produce from cork cambium will differentiate and will get mature to perform a specialized function. The living cells which lost the capacity to divide can regain the capacity of the division under certain conditions is called as 'Dedifferentiation.'
So the correct option is 'Dedifferentiation.'