The fundamental unit of life
11) When placed in hypertonic solution, a living plant cell shows
plasmolysis 12) Cell wall provides mechanical strength to the cell. It permits
the cell to withstand huge changes in the surrounding medium.
13) Nucleus is an important, spherical, usually centrally located
constituent of the cell and is bounded by double layered nuclear envelope.
14) The nucleus of a dividing cell shows rod-shaped chromosomes, made up
of DNA and proteins. In a non-dividing cell, the chromosomes elongate and take
the form of thread-like chromatin.
15) DNA molecules are responsible for transmitting hereditary information
from one generation to the next.
16) Nucleus controls all metabolic activities of the cell.
17) Depending on the presence or absence of nucleus, cells may be
prokaryotic or eukaryotic.
i) Prokaryotic cells lack a well-defined nucleus and instead show nucleoid,
an undefined nuclear region containing the genetic material. ii) Eukaryotic
cells possess a proper nucleus with nuclear membrane.
18) Cytoplasm is the fluid content of the cell, occurring between nucleus
and plasma membrane. It stores several vital chemicals and is the site of
certain important metabolic pathways.
19) Several specialized cell organelles are present in the cytoplasm.
These organelles perform different kinds of metabolic activities and are kept
separate from each other.
20) The various cell organelles include endoplasmic reticulum, Golgi
apparatus, lysosomes, mitochondria, plastids, vacuoles and centrosome.
21) Endoplasmic reticulum (ER) is an extensive, interconnected,
membranebound network of tubes and sheets.
22) Ribosomes are attached to the surface of Rough Endoplasmic Reticulum
(RER) and are absent in Smooth Endoplasmic Reticulum (SER)
