keshav chapter the fundamental unit of life : cell

FUNDAMENTAL UNIT OF LIFE 

CELL

Cell is the structural and functional unit of life.

Homework

Q. Why does the water come out from the cucumber when we add salt in it?

Ans- The salt cause water to be drawn out of the cucumber. Water is drawn to it because it goes from a higher concentration to the lower concentration. When there is random motion that will always happen and is called diffusion. In the cells of cucumber allows the water through but not the salt.

EXERCISE

Q.1. Make a comparison and write down ways in which plant cells are also different from animal cells?

 Ans - Plant Cell -1. Plant cells have cell wall.

2. Vacuole is large and present in centre of the cell.

3. They have plastids.

Animal cell- 1. Animal cells do not have cell wall.

2. Vacuole is small.

3. They do not contain plastids.

Q.2. How is prokaryotic cell different from a eukaryotic cell?

Ans- Prokaryotic cell is generally smaller in size , nuclear region is poorly defined , the cell organelles are not membrane bounded and has a single chromosome.

Eukaryotic cell is generally larger in size , nuclear region is well defined with nuclear membrane. Membrane bounded cell organelles are present and has more then one chromosome.

Q.3. What would happen if the plasma membrane ruptures or breaks down?

Ans- If plasma membrane ruptures or break down then the molecules of some substances will freely move in and out.

Q.4. What would happen to the life of a cell if there was no golgi apparatus?

Ans- Golgi apparatus has the function of storage , modification and packaging of the products in vesicles. If there were no golgi bodies , packaging and dispatching of materials synthesised by the cell will be stocked.

Q.5. Which organelle is known as the powerhouse of the cell? why?

Ans- Mitochondria is known as powerhouse of the cell because it releases the energy required for the different activities of life.

Q.6. Where do the lipids and the proteins consisting the cell membrane get synthesised ? 

Ans- Lipids and proteins are synthesised in ER( Endoplasmic Reticulum).

Q.7. How does amoeba obtain it's food?

Ans- Amoeba take it's food by the cell membrane which forms the food vacuole.

Q.8. What is osmosis?

Ans- Osmosis is the process of movement of water molecule from a region of higher water concentration through a semi permeable membrane to a region of lower water concentration.

MATTER IN OUR SURROUNDINGS

ACTIVITY- 
 Q. Why do we observe that the level of water does not change even after dissolving salt in it??

ANS-  When we dissolve salt in water , the particles of salt get into spaces between particles of water so this shows that the level of water does not change.