Please refer to the The Fundamental Unit Of Life Notes Class 9 Science given below. These revision notes have been designed as per the latest NCERT, CBSE, and KVS books issued for the current academic year. Students will be able to understand the entire chapter in your class 9th Science book. We have provided chapter-wise Notes for Class 9 Science as per the latest examination pattern.
Revision Notes Chapter 5 The Fundamental Unit Of Life Class 9 Science
Students of Class 9 Science will be able to revise the entire chapter and also learn all important concepts based on the topic-wise notes given below. Our best teachers for Grade 9 have prepared these to help you get better marks in upcoming examinations. These revision notes cover all important topics given in this chapter.
Question. Why is the cell called the structural and functional unit of life?
Answer. There are various components in the animal and plant cell known as cell organelles. Each kind of cell organelle performs a specific function, such as making new materials in the cells, release of waste, transportation, etc. Thus, a cell can perform all its functions with the help of these organelles. That is why the cells are called structural and functional unit of life.
Question. How do substances like CO2 and water move in and out of the cell? Discuss.
Answer. Substances like CO2 accumulate in high concentration inside the cell. There is CO2 concentration difference in the internal and external environment of a cell. CO2moves out of the cell, from a region of high concentration to a region of low concentration outside the cell by the process of diffusion.
Question. Why is the plasma membrane called a selectively permeable membrane?
Answer. The plasma membrane selectively allows the entry and exit of some materials in and out of the cell. It also prevents movement of some other materials. Therefore, it is called a selectively permeable membrane.
Question. Why are lysosomes known as suicide bags?
Answer. The Iysosomes contain very powerful hydrolytic enzymes which are capable of breaking down organic matter. For example, when a cell gets damaged, then Iysosomes burst and enzymes digest their own cell. Hence, the Iysosomes are known as ‘suicide bags’ of cells.
Question. Where are proteins synthesised inside the cell?
Answer. Ribosomes are the site of protein is synthesis. Exercises
Question. Make a comparison and write down ways in which plant cells are different from animal cells.
Answer. Comparison of plant cell and animal cell
Plant Cell
Cell wall is present outside the plasma membrane.
Generally regular in shape.
Larger in size than animal cells
Plastids are present.
A permanent and large vacuole is present.
Animal Cell
Cell wall is absent.
Generally irregular in shape.
Smaller in size than animal cells.
Plastids are absent except in Euglena.
Vacuoles are many, small and temporary.
Question. What would happen to the life of a cell if there was no Golgi apparatus?
Answer. Effect of absence of Golgi apparatus on life of a cell
(i) The packaging and dispatching of different types of proteins to various targets inside and outside the cell will be influenced.
(ii) The products of cell cannot be stored and modified later.
(iii) There will be effect on Iysosomes formation. This will cause accumulation of worn out and dead cell organelles within the cell which may cause cell death.