Why is the plasma membrane called a selectively permeable membrane ?
Why is the plasma membrane called a selectively permeable membrane ?
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.
Similar Questions
Full in the gaps in the following table illustrating differences between prokaryotic and eukaryotic cells.
Prokaryotic Cell
Eukaryotic Cell
$1.$ Size : generally small $(1-10 \,\mu \,m )$
$1 \,\mu \,m =10^{-6} \,m$
$1.$ Size : generally large $(5-100 \,\mu \,m )$
$2.$ Nuclear region : ................... and ...............
$2.$ Nuclear region: well defined and surrounded by a nuclear membrane
$3.$ Chromosome : single
$3.$ More than one chromosome
$4.$ Membrane-bound cell organelles absent
$4.$ .........................
Full in the gaps in the following table illustrating differences between prokaryotic and eukaryotic cells.
| Prokaryotic Cell | Eukaryotic Cell |
| $1.$ Size : generally small $(1-10 \,\mu \,m )$ $1 \,\mu \,m =10^{-6} \,m$ |
$1.$ Size : generally large $(5-100 \,\mu \,m )$ |
| $2.$ Nuclear region : ................... and ............... | $2.$ Nuclear region: well defined and surrounded by a nuclear membrane |
| $3.$ Chromosome : single | $3.$ More than one chromosome |
| $4.$ Membrane-bound cell organelles absent | $4.$ ......................... |
If the organisation of a cell is destroyed due to some physical or chemical influence, what will happen ?
If the organisation of a cell is destroyed due to some physical or chemical influence, what will happen ?
Why are lysosomes known as suicide bags ?
Why are lysosomes known as suicide bags ?
Which organelle is known as the powerhouse of the cell? Why ?
Which organelle is known as the powerhouse of the cell? Why ?
Carry out the following osmosis experiment :
Take four peeled potato halves and scoos each one out to make potato cups. One of these potato cups should be made from a boiled potato. Put each potato cup in a trough containing water. Now,
$(a)$ Keep cup $A$ empty
$(b)$ Put one teaspoon sugar in cup $B$
$(c)$ Put one teaspoon salt in cup $C$
$(d)$ Put one teaspoon sugar in the boiled potato cup $D$.
Keep these for two hours. Then observe the four potato cups and answer the following :
$(i)$ Explain why water gathers in the hollowed portion of $B$ and $C$.
$(ii)$ Why is potato $A$ necessary for this experiment ?
$(iii)$ Explain why water does not gather in the hollowed out portions of $A$ and $D$.
Carry out the following osmosis experiment :
Take four peeled potato halves and scoos each one out to make potato cups. One of these potato cups should be made from a boiled potato. Put each potato cup in a trough containing water. Now,
$(a)$ Keep cup $A$ empty
$(b)$ Put one teaspoon sugar in cup $B$
$(c)$ Put one teaspoon salt in cup $C$
$(d)$ Put one teaspoon sugar in the boiled potato cup $D$.
Keep these for two hours. Then observe the four potato cups and answer the following :
$(i)$ Explain why water gathers in the hollowed portion of $B$ and $C$.
$(ii)$ Why is potato $A$ necessary for this experiment ?
$(iii)$ Explain why water does not gather in the hollowed out portions of $A$ and $D$.