Afaq New Sun Series Science 4 - Unit 1 Building Unit of Life

Science 4 - Unit 1 Building Unit of Life

Important Definitions:

• A cell is the basic structural and functional unit of life.
• Cell some in different types, sizes, and shapes, each with its own functions or job
• The smaller parts within a cell are called organelles, each with its own function.
• Organisms which are made up of only one cell are called unicellular organisms; organisms are made up of millions of cells are called multicellular organisms.
• Plant cell and animal cell are different from one another in many aspects. For example, a plant cell has a cell wall, chloroplast, single large vacuole, etc. but an animal cell does not have a cell wall and chloroplast. It has numerous small vacuoles.

EXERCISE (SOLVED)

A. Answer the following questions.

1. Why is the cell called the basic unit of life?
   Ans: Cell is the basic unit of life because all the living organisms are made up of cells and these cells control all the activities necessary.
   
   
2. Define unicellular and multicellular organisms.
   Ans: Unicellular Organisms: Organisms that are made up of only one cell are called unicellular organisms. A single cell carries out all the life activities.
   Multicellular Organisms: Living things such as animals and plants are made up of millions of cells. They are called multicellular organisms in which different cells are specialized to perform different duties.
   
   
3. Match Column a with Column B to make an analogy between cell's organelles and a school's segments. Also write an appropriate function of each cell organelle in Column C.
   Ans:
   

   Column-A	Column-B	Column-C
   Cell membrane	Power generating room in a school	The outer covering of the cell.
   Cytoplasm	Main Gate	Jelly Like liquid filled in the cell.
   Mitochondria	Playground	Generate Energy for Cell.
   Nucleus	Mian Office	control all activities in Cell

B. Choose and write the correct option.

• Cells similar in structure and function combine together to form tissues. (tissue, organs, organelles)
• Cell repairing is a function of the nucleus. (the nucleus, vacuoles, Cytoplasm.)
• Chloroplasts are disk-like structures which contain a green pigment called chlorophyll (Chloroplasts, Vacuoles, Mitochondria)
• An organelle that allows certain materials to pass through and also gives shape to the cell is called a cell membrane. (cytoplasm, a cell membrane, a cell wall)

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