Chapter - 5 Fundamental Unit of Life NCERT Solution

Page No - 59

Q1 - Who discovered cells and how ?
Ans - Cells were discovered in 1665 by Robert Hooke. He used self designed microscope to observe cells in a cork slice.

Q2 - Why is the cell called the structural and functional unit of life ?
Ans - All living organisms are made up of cells so cell is the basic building unit of a living organism and It is the smallest unit of life and capable of all living functions. This is the reason cells are referred to as the basic structural and functional unit of life.

Page No - 61

Q1 - How do substances like COand water move in and out of the cell ? Discuss.
Ans - The exchange of gas CO2 between cell takes place by diffusion process
Diffusion - It is defined as moment of a substance from a region of higher concentration to lower concentration. CO2 is formed inside cell due to respiration and it's concentration is higher in the cell as compare to the surroundings. As a result CO diffuses out from the cell.
Water move in and out of the cell by the process Osmosis
Osmosis - The movement of water from higher concentration to lower concentration through a semipermeable membrane is called Osmosis

Q2 - Why is plasma membrane called a selectively permeable membrane ?

Ans - Plasma membrane is a highly specific structure . It is made up of lipids and proteins which selectively allows the entry of substances into cell and exit of some other substances from the cell.

Page No - 63

Q1 - Fill the gaps in the following table is illustrating differences between Prokaryotic and Eukaryotic cells.





Page No - 65

Q1 - Can you name the two organelles we have studied that contain their own genetic material ?
Ans - Chloroplasts and Mitochondria

Q2 - If the organisation of a cell is destroyed due to some physical or chemical influence, what will happen ?
Ans - If the organisation of a cell is destroyed due to some physical or chemical influence then such cell would not survive any more as whole component of the cell are digested up by its lysosomes.

Q3 - Why are lysosomes known as suicide bags ?
Ans - Lysosomes are cell organelles filled with digestive enzymes. When a cell is damaged, its lysosomes may burst out and its enzymes digest up its own cell. Due to this, We can say that lysosomes are suicide bags.

Q4 - Where are proteins synthesised inside the cell ?
Ans - Ribosomes are the site of protein synthesis inside the cell.

Exercise Questions

Q1 - Make a comparison and write down ways in which plant cells are different from animal cells.
Ans -
Animal Cell
Plant Cell
Small in size
Larger than Animals cells
It do not have cell wall
It have cell wall
It do not have chloroplast
It have chloroplast
Vacuoles are small
Vacuoles are large in size

Q2 - How is Prokaryotic cell different from Eukaryotic cell ?
Ans -
Prokaryotic cell
Eukaryotic cell
Size of the cell generally small (0.5 – 5) µm
Size of the cell is generally large (50 – 100 µm)
Nuclear region is poorly defined nuclear membrane is absent
Nuclear region is well defined and surrounded by nuclear membrane
Cell division occurs by mitosis
Cell division occurs by mitosis and meiosis
Single Chromosome
More than one Chromosome

Q3 - What would happen if the plasma membrane ruptures or breaks down?
Ans - If the plasma membrane of the cell is ruptured, then the cell will die. All of it's organells leak out of the cell and the cell die.

Q4 - What would happen to the life process and if there was no Golgi apparatus?
Ans - The function of Golgi apparatus includes storage modification and Packaging of products in the vessels. If there was no Golgi apparatus for a cell then all sort of storage modification packaging and dispatch of materials with in and outside the cell would be impossible

Q5 - Which organelle is known as the powerhouse of the cell ? Why ?
Ans - Mitochondria is known as the powerhouse of the cell because it synthesis energy in the form of ATP (Andenosine Triphosphate) molecules during respiration which is vital of various life activities.

Q6 - Where do the lipids and proteins constituting the cell membrane get synthesised ?
Ans - Lipids and proteins constituting the cell membrane and synthesized in the Endoplasmic Reticulum
Endoplasmic reticulum are two types :-
(i) Smooth Endoplasmic Reticulum (SER) helps in the manufacturing of lipids
(ii)Rough Endoplasmic Reticulum (RER) has particles attached to its surface called ribosomes. These ribosomes are the site of protein synthesis.

Q7 - How does an Amoeba obtain its food ?
Ans - Amoeba obtain its food through the process of endocytosis. The flexibility of the cell membrane unable to cell to engulf the solid particle of food and another material from its external environment.

Q8 - What is osmosis ?
Ans - Osmosis is the movement of water from a region or high water concentration through a semipermeable membrane to a region of low concentration of water. It can take place only in liquid medium and not in solid or gas It's example is absorption of water from soil by plant roots.

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