Page 60 - Genius Kidz Prudence Learning Sc-8

4. Nucleus : It is another cell organelle present function is called tissue.
in the protoplasm of the cell. Nucleus is the A group of tissues performing specialized

brain of the cell. It is present both in plant function is called an organ.
and animal cell.
A group of organs performing specialized
The fluid present in nucleus is called function is called an organ system.
nucleoplasm. It is surrounded by a Organ systems together form an organism :
membrane called nuclear membrane,

Nuclear membrane is broken at certain Cells ¾® Tissues ¾® Organ ¾®
points forming a nuclear pore. Nucleus Organ system ¾® Organism
contains a small body called nucleolus. PROKARYOTES AND EUKARYOTES
Nucleus can be seen with a light 1. Prokaryotes : Organisms with primitive
microscope but nucleolus can be seen with nucleus i.e. a nucleus without a nuclear
electron microscope only. membrane are called prokaryotic organisms or

Most important component of a nucleus prokaryotes and the constituent cell is called a
includes chromosome that encodes the prokaryotic cell.
genetic information of an organism. 2. Eukaryotes : Organisms with a true

Functions : nucleus i.e. a nucleus surrounded by a nuclear
(i) It controls the cellular metabolic membrane are called eukaryotes or eukaryotic
activities. organisms and the constituent cell is a

(ii) It stores the hereditary information of eukaryotic cell.
the cell. Examples of prokaryotes include bacteria, blue

LEVELS OF ORGANIZATION green algae, etc. and those of eukaryotes
include plants and animals.
A group of cells that performs the same

of

life
unit
is
the
basic
Cell
! ! Cell is the basic unit of life.
! Cell is the basic unit of life. .
1665
w
in
v
ober
e
disco
Hook
t
as
in
Cell
! Cell was discovered by Robert Hooke in 1665 in cork slices.
b
y
slices
cork
ered
! ! Cell was discovered by Robert Hooke in 1665 in cork slices. .
R
! ! Cell comprises of cell membrane, cell wall and a number of cell organelles. .
membrane
,

of
umber
anelles
org
cell
all
w
cell
n
a
and
comprises
! Cell comprises of cell membrane, cell wall and a number of cell organelles.
of

cell
Cell
house
! Power house of the cell is mitochondria.
! ! Power house of the cell is mitochondria.
hondria.
er
w
P
o
is
of

the
mitoc
cell
ucleus
Brain
is
n

the
cell
! ! Brain of the cell is nucleus.
! Brain of the cell is nucleus. .
of
EXERCISE
EXERCISE
1. Multiple choice question.
(a) Mitochondria is the _____________ of the cell.
(i) Energy currency (ii) Power house (iii) Brain (iv) None of these
(b) The largest cell is :
(i) Neuron (ii) Ostrich egg cell (iii) RBC (iv) WBC
60