The fundamental unit of life
37) The membrane-bound cell organelles are absent in prokaryotic
cells.
38) Differences between plant cell and animal cell.
Plant cell
|
Animal cell
|
|
1
|
Plant cells are
generally large in size.
|
Animal cells are
smaller than plant cells.
|
2
|
Plant cells possess
plastids.
|
Animal cells lack
plastids.
|
3
|
Cell wall is
present
|
Cell wall is absent.
|
4
|
Mature plant cells possess a large, central
and permanent vacuole.
|
Animal cells possess many small and
temporary vacuoles.
|
5
|
Centrosome and
centrioles are absent in plant cells.
|
Centrosome and
centrioles are present in animal cells.
|
39) The basic structural organization of the cell helps it to perform
important functions like respiration, nutrition, excretion and protein
synthesis.
1)
Cell - An autonomous self-replicating
structure that forms the structural, functional and biological unit of all
living organisms.
2)
Prokaryotic cell – A cell characterized by the
absence of a distinct, membrane-bound nucleus or membrane-bound organelles, and
by DNA that is not organized into chromosomes.
2) Nucleoid – An undefined nuclear region of the prokaryotic cell,
containing the genetic material (nucleic acids).
3) Eukaryotic cell – A cell containing a membrane-bounded nucleus and
membrane-bounded organelles.
4) Unicellular organism – Organism having only one cell.
5) Multicellular organism - Organism consisting of more than one cell,
wherein the differentiated cells perform specialized functions in the organism.
6) Diffusion – The spontaneous movement of a substance from a region of
its higher concentration to a region of its lower concentration.
7) Osmosis – The movement of water through a semi-permeable membrane from
a region of high water concentration to a region of low water concentration.
8) Hypertonic solution - A solution that has a higher solute
concentration than the one to which it is compared (eg - some kind of cell).
9) Hypotonic solution - A solution that has a lower solute concentration
than the one to which it is compared (eg - some kind of cell).
