Tag: unit of living - cell

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Questions Related to unit of living - cell

Multiple choice bio-chemistry unit of living - cell eukaryotic cell kinds of cell introduction to eukaryotic cell

Which of the following is not true for a eukaryotic cell?

  1. Cell wall is made up of peptidoglycans

  2. It has 80S type of ribosome present in the cytoplasm

  3. Mitochondria contain circular DNA

  4. Membrane bound organelles are present
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
  • Inside the cell wall, if present, do not contain muramic acid (therefore, no peptidoglycan). 
  • A eukaryotic cell has 80S ribosomes present in the cytoplasm. 
  • Membrane-bound organelles are present, like, mitochondria, ER, Golgi apparatus, chloroplasts, etc. 
  • Mitochondria are semi-autonomous organelles, which are double membrane-bound and have their own ribosomes (70S) and DNA (circular).
  • So, (A) statement is not true for the eukaryotic cells.
Multiple choice bio-chemistry unit of living - cell eukaryotic cell kinds of cell introduction to eukaryotic cell

Choose the incorrect statement 

  1. RNAi silencing takes place in all eukaryotic cells for cellular defence

  2. RNAi involves binding of dsRNA molecules with mRNA for silencing to occur.

  3. Complementary nucleic acid could be from mobile genetic elements (transposons).

  4. Ti plasmid with nematode specific genes have been used in RNAi
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Gene silencing by dsRNA makes use of the naturally occurring cell machinery that is involved in the processing of miRNA in eukaryotic cells. It does not provide any defense mechanism. So the correct answer is ' RNAi silencing takes place in all eukaryotic cells for cellular defense'.

Multiple choice bio-chemistry unit of living - cell eukaryotic cell kinds of cell introduction to eukaryotic cell

Which of the following statements is correct?

  1. Prokaryotic cells are surrounded by a cell membrane.

  2. Prokaryotic cells have a nucleus.

  3. Eukaryotic cells have genetic information.

  4. Eukaryotic cells have membrane bound organelles.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
Organelles are the specialised and organised structures in a living cell. These may be bound by a single or double membrane (Exception is ribosomes which are non-membranous cell organelles present in both prokaryotes and eukaryotes). Membrane-bound cell organelles include nucleus, vacuole, endoplasmic reticulum, chloroplasts, mitochondria, lysosomes, Golgi apparatus and are present only in eukaryotes.
Hence D is the correct option.

Multiple choice bio-chemistry unit of living - cell eukaryotic cell kinds of cell introduction to eukaryotic cell

Select the correct sequence of molecules in cell on the basis of molecular size from the smallest to the largest.

  1. Carbon dioxide$-$phospholipid$-$DNA polymerase$-$ribosome
  2. Phospholipid$-$DNA polymerase$-$ribosome$-$carbon dioxide
  3. Phospholipid$-$carbon dioxide$-$ribosome$-$DNA polymerase
  4. Carbon dioxide$-$DNA polymerase$-$phospholipid$-$ribosome
  5. DNA polymerase$-$ribosome$-$carbon dioxide$-$phospholipid
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Carbon dioxide, has two atoms of oxygen and one atom of carbon, making it the smallest one among the given options. Phospholipids are amphipathic molecules, having phosphate head group and fatty acid tails. DNA polymerase is polypeptide enzyme while ribosomes are the assemblage of rRNA and proteins. 
The correct answer is option A.

Multiple choice bio-chemistry unit of living - cell eukaryotic cell kinds of cell introduction to eukaryotic cell

Cell organelles are embedded in

  1. Cytoplasmic membrane

  2. Protoplasm

  3. Cytoplasm

  4. None of the above
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
  • Cytoplasm is a semifluid matrix present within a cell surrounding the nucleus (i.e without the nucleoplasm) which is enclosed by a cell membrane.
  • They are the nonnuclear content of protoplasm in which all of the cell organelles are embedded.
  • A cytoplasmic membrane or cell membrane is a phospholipid bilayer that separates the cell from the external environment.
  • Protoplasm is the living substance of a cell that is enclosed by a plasma membrane and includes the nucleoplasm.
  • So, the correct answer is 'Cytoplasm'.
Multiple choice bio-chemistry unit of living - cell eukaryotic cell kinds of cell introduction to eukaryotic cell


Which of the following is not characteristic of a eukaryotic plant cell?

  1. Ribosomes associated with endoplasmic reticulum

  2. Dictyosomes associated with Golgi bodies

  3. Cristae inside of mitochondria

  4. Thylakoids inside of chloroplasts
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The characteristics of a eukaryotic plant cell are

1. A membrane-bound nucleus.
2. Ribosomes associated with the endoplasmic reticulum.
3.Thylakoids inside of chloroplasts.
4. Dictyosomes are not associated with Golgi bodies. These are discrete tubules of the Golgi Apparatus.
Hence, the correct answer is 'Dictyosomes associated with Golgi bodies'.

Multiple choice bio-chemistry unit of living - cell eukaryotic cell kinds of cell introduction to eukaryotic cell


Organelles 

  1. Are typical of eukaryotic cells, not prokaryotic cells

  2. Separate chemical reactions in time and space

  3. Are membrane bound compartments

  4. All of the above are features of the organelles
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Organelles are small, specialised structures which perform a specific function within the cell. Organelles are enclosed by their own membrane.  They are found in eukaryotic cells. Their function is from generating energy to the cell to controlling of cell's growth and reproduction.

Hence, the correct answer is 'All of the above are features of the organelles'.

Multiple choice bio-chemistry unit of living - cell eukaryotic cell kinds of cell introduction to eukaryotic cell

Which cellular organelle would be concentrated at the top of the centrifuged mixture after centrifugation of cells containing solution?

  1. Nuclei

  2. Endoplasmic reticulum

  3. Mitochondria

  4. Ribosomes

  5. Membrane-bound proteins
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Centrifugation of cells is a sedimentation process used to separate certain organelles for analysis of specific parts of cells. a sample of tissue is lysed to break the cell membranes and mix up the contents of the cell. However, while the procedures may break many of the membranes of the cell including the plasma membrane and endoplasmic reticulum, it leaves certain  organelles such as mitochondria, nuclei, Golgi apparatus, peroxisomes and lysosomes intact in a homogeneous extract. During the process, particles of different densities or size sediment at different rates. The largest and most dense particle sediments first followed by less dense and smaller particles. Hence the cellular organelle concentrated on the top of the centrifuged mixture will be the mitochondria due to its less density and small size. Thus, the correct answer is option C.

Multiple choice bio-chemistry unit of living - cell eukaryotic cell kinds of cell introduction to eukaryotic cell

Mesokaryotic condition was distinguished by

  1. Whittaker

  2. Dodge

  3. Copeland

  4. Haeckel
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
  • A mesokaryotic (meso= in between, karyon= nucleus) cell shows intermediate resemblance to both eukaryotic and prokaryotic cell.
  • It contains well-developed nucleus but it undergoes cell division by amitosis (because the mitotic spindle is not formed).
  • This condition in a cell was first distinguished by Dodge in the year 1966.
  • So, the correct answer is 'Dodge'.
Multiple choice bio-chemistry unit of living - cell eukaryotic cell kinds of cell introduction to eukaryotic cell

The structure of the nuclear membrane facilitates

  1. Organization of spindle

  2. Nucleo-cytoplasmic exchange of materials

  3. Anaphasic separation of daughter chromosomes

  4. Synapsis of chromosomes
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

In eukaryotic cells, the nucleus is bound by a double membrane or nuclear envelope. It possesses openings at certain intervals called as 'nuclear pore'. Nuclear pores are large protein complexes regulates the exchange of material between nucleus and cytoplasm, i.e., nucleo-cytoplasmic exchange of materials.