Subject Experts Solutions for Chapter: Cell Structure and Functions, Exercise 3: TOUGH NUT

The size or the number of cells does not determine the size of an organism. However, do you think the shape of the nerve cells of an organism is related to its function?

Why is the cell wall present only in a plant cells?

Why is spinal or head injury a matter of great concern?

Do you think it is right to say that living beings are made up of cells, while non-living things are made up of atoms and molecules? Support your answer.

Friends Monica and Geeta were discussing about values, their sources, and their transfer through generations.

Monica: In the human world how are values transferred from one generation to the next?

Geeta: There are many ways of transferring values. The major ones include books in the library, informal teachings from parents and elders, formal teaching in schools and colleges, and teachings received from religions.

Monica: I remember reading about something similar in chapter 8 (Cell - Structure and function) of my science textbook.

Geeta: But that was different. Here we have multiple sources of information. There we read about only one source which contained all the information.

Monica: Yes, we should also have one source for transferring values.

Geeta: No, don't think so. In chapter 8 we learnt that characters are passed on only from parents to children through special units called genes. In human beings, values are transferred from previous generations to the next and between the present generations also. We can learn things from anyone.

(i) Which topic in chapter 8 (Cell - Structure and function) of the science book, are Monica and Geeta referring to?
(ii) Geeta is saying that the human system of transferring values is better than the genetic system. Do you agree? Give reasons.

Rakesh has a good knowledge about the human body and its complex organ systems. He shares his knowledge with Ranbir.

Rakesh: The human body comprises complex systems. Every system works on the basis of specialisation and unity.

Ranbir: How?

Rakesh: Different organs in the human body perform different functions. They do not interfere with each other. Each organ performs its own function.

Ranbir: Ok.

Rakesh: Each organ is made up of tissues. Tissues have different functions and the functions are performed accordingly. Though they work together, yet different tissues perform different functions.

Ranbir: Now I understand. Each tissue is made up of different cells and each cell performs its functions without interfering with any other cell. Cells performing the similar type of work unite to form tissues, tissues working in unity form organs, and organs working together form the human body!

(i) Does this example hold true for all living organisms? Give exceptions, if any.

(ii) Name two different cells found in human body.

The terms related to 'Cell-biology' are hidden in the alphabet grid given below. Try to find out all of these terms by going up, down, or even diagonally forward as well as backward.