Class 8 Science


Extra Questions

Very Short Answer Type Questions

Question 1: Cell organelles are present in which part of the cell?

Answer: Cytoplasm

Question 2: How will you define a cell?

Answer: Cell is the structural unit of a living being.

Question 3: How will you define a unicellular organism?

Answer: An organism which is composed of a single cell is called unicellular organism.

Question 4: How will you define a multicellular organism?

Answer: An organism which is composed of more than one cell is called multicellular organism.

Question 5: What is tissue?

Answer: A group of specialized cells made for a specific task is called a tissue.

Question 6: What is an organ?

Answer: A group of tissues made to perform a specific set of functions is called an organ.

Question 7: What are pseudopodia?

Answer: Finger like projections outside the cell of amoeba are called pseudopodia.

Question 8: What is cytoplasm?

Answer: The jelly-like substance present between the cell and nucleus is called cytoplasm.

Question 9: Define prokaryotic organisms?

Answer: Organisms in which nucleus is absent are called prokaryotic organisms.

Question 10: Define eukaryotic organisms?

Answer: Organisms in which nucleus is present are called eukaryotic organisms.

Short Answer Type Questions

Question 1: Write a short note on plasma membrane.

Answer: Cell membrane is also called plasma membrane. It makes the boundary of a cell. It is composed of protein and lipid. It is porous and allows various materials to pass through it. Cell membrane is semi-permeable in nature which means it allows selected materials to pass through it.

Question 2: Write a short note on cell wall.

Answer: Cell wall is present in plant cells and in bacteria. Cell wall in plants is made up of cellulose. Cell wall gives additional strength and protection to plant cells.

Question 3: What are the functions of nucleus?

Answer: Functions of nucleus are as follows:

  • Nucleus controls the function of a cell.
  • Nucleus controls inheritance of characters, i.e. transfer of characters from one generation to the next generation.

Question 4: What are functions of pseudopodia?

Answer: Functions of pseudopodia are as follows:

  • Movement and locomotion
  • Catching food

Question 5: Why do we resemble our parents?

Answer: We know that genes transfer characters from parents to offsprings. It is because of inheritance that we get characters from our parents. Due to this, we resemble our parents.

Question 6: Comment on shape of cells.

Answer: Cells show wide variety in terms of shape.

  • Amoeba is a unicellular organism. It is of irregular shape. The shape of amoeba keeps on changing because of formation of pseudopodia. Similarly, white blood cells (WBCs) in our body are of irregular shape.
  • Cells are generally round, spherical or elongated.
  • Smooth muscle cells are spindle-shaped. They are swollen in the middle and pointed at both ends.
  • Red Blood Cells are concave and round. RBCs can easily pass through narrow capillaries because of concave shape.
  • Cells of striated muscle are cylindrical in shape and are very long.
  • Nerve cells (neurons) appear like a star with long tail.