NCERT Class 9 Science Solutions: Chapter 5 –The Fundamental Unit Of Life Part 3

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Question 2:

Q. How is a prokaryotic cell different from a eukaryotic cell?

A.

Table of Different Between Prokaryotic Cell and Eukaryotic Cell for The Fundamental Unit Of Life

Prokaryotic cell

Eukaryotic cell

Most prokaryotic cells are unicellular.

Most eukaryotic cells are multicellular.

Size of the cell is generally small.

Size of the cell is generally large

Nuclear region is poorly defined due to the absence of a nuclear membrane or the cell lacks true nucleus.

Nuclear region is well-defined and is surrounded by a nuclear membrane, or true nucleus bound by a nuclear membrane is present in the cell.

It contains a single chromosome.

It contains more than one chromosome.

Nucleolus is absent.

Nucleolus is present.

Membrane-bound cell organelles such as plastids, mitochondria, endoplasmic reticulum, Golgi apparatus, etc. are absent.

Cell organelles such as mitochondria, plastid, endoplasmic reticulum, Golgi apparatus, lysosomes, etc. are present.

Cell division occurs only by mitosis.

Cell division occurs by mitosis and meiosis.

Prokaryotic cells are found in bacteria and blue-green algae.

Eukaryotic cells are found in fungi, plants, and animal cells.

Question 3:

Q. What would happen if the plasma membrane rupture or breaks down?

A. If the plasma membrane of a cell is ruptured, then the cell is ruptured, then the cell will die. The plasma membrane regulates the movement of substances in and out of the cell by diffusion or osmosis. Thus, if the plasma membrane is ruptured, then the cell might leak out its contents.

Question 4:

Q. What would happen to the life of a cell if there was no Golgi apparatus?

Image of Golgi Apparatus for The Fundamental Unit of Life

Image of Golgi Apparatus

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A. If there was no Golgi apparatus in the cell, then most activities performed by the Golgi apparatus will not take place.

(i) Membranes of the Golgi apparatus are often connected to ER membranes. It collects simpler molecules and combines them to make more complex molecules. These are then packaged in small vesicles and are either stored in the cell or sent out as per the requirement. Thus, if the Golgi apparatus is absent in the cell, then the above process of storage, modification, and packaging of products will not be possible.

(ii) The formation of complex sugars from simple sugars will not be possible as this takes place with the help of enzymes present in Golgi bodies.

(iii) The Golgi apparatus is involved in the formation of lysosomes or peroxisomes. Thus, if the Golgi body is absent in a cell, the synthesis of lysosomes or peroxisomes will not be possible in the cell.

Question 5:

Q. Which organelle is known as the powerhouse of the cell? Why?

Image of Organelle the Powerhouse Cell for The fundamental U …

Image of Organelle

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A. Mitochondria are known as the powerhouse of cells. Mitochondria create energy for the cell, and this process of creating energy for the cell is known as cellular respiration. Most chemical reactions involved in cellular respiration occur in the mitochondria. The energy required for various chemical activities needed for life is released by the mitochondria in the form of ATP (Adenosine triphosphate) molecules. For this reason, mitochondria are known as the powerhouse of cells.

Question 6:

Q. Where do the lipids and proteins constituting the cell membrane get synthesized?

A. Lipids and proteins constituting the cell membrane are synthesized in the endoplasmic reticulum.

SER (Smooth endoplasmic reticulum) helps in the manufacturing of lipids.

RER (Rough endoplasmic reticulum) has particles attached to its surface, called ribosomes. These ribosomes are the site for protein synthesis.

Question 7:

Q. How does an Amoeba Obtain its food?

A. Amoeba obtains its food through the process of endocytosis. The flexibility of the cell membrane enables the cell to engulf the solid particles of food and other materials from its external environment.

Image of Cell Engulfing Food Particle For The Fundamental Un …

Image of Cell Engulfing Food Particle

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