Q1 of 18 Page 61

Why is plasma membrane called a selectively permeable membrane?

Plasma membrane is called selectively permeable membrane because it allows or permits the entry and exit of some selected substances across it and not all of them.


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1

Why is the cell called the structural and functional unit of life?

 1

How do substances like CO2 and water move in and out of the cell?

 1

Fill in the gaps in the following table illustrating differences between prokaryotic and eukaryotic cells.











Prokaryotic cell



Eukaryotic cell



1. Size : generally small (1-10 μm); 1μm = 10-6 m


2. Nuclear region :


................................


...............................


And known as ..............


3. Chromosome : single


4. Membrane – bound organelles : absent



1. Size generally large (5-100 Mm)


2. Nuclear region : well defined and surrounded by a nuclear membrane


3. Chromosome : more than one


4. .......................


...........................


 1

Can you name the two organelles we have studied that contain theor own genetic material?