Class 9th Biology
Short
Questions
Chapter No: 4
Cell and Tissues
Q1.
Who proposed cell theory and what are the main points of it?
Ans:
In late 1830 a Botanist Matthias
Schleiden and Zoologist Theodor Schwann proposed cell theory.
Main
points of cell theory:
i.
All
organisms are made of cells.
ii.
Cell
is the structural and functional unit of all living organisms.
iii.
New
cells are arise from pre-existing cells by cell division.
Q2.
Differentiate between simple and compound tissues.
Ans:
Simple tissues:
Those tissues which are composed of
one type of cell are called simple tissues. eg. Ground tissues, epidermal
tissues, and supporting tissues
Compound Tissues:
Those tissues which are composed of
more than one type of cells are called compound tissues. eg. Xylem and phloem tissues
Q3.
How does cell membrane help in maintaining equilibrium while exchanging material with the environment?
Ans:
Each cell is surrounded by the cell
membrane, which is a selectively permeable membrane. The cell takes necessary materials
from surrounding and removes unwanted substances to the surrounding.
Q4.
Differentiate between Endocytosis and Exocytosis.
Ans: Endocytosis:
The process in which the plasma membrane
folded inward around some material and form a packet like structure that deepens
gradually and form a vesicle, separate eventually and migrate into the cytoplasm is
called Endocytosis
Endocytosis
may be;
a-
Phagocytosis: in which the cells take in solid materials.
b-
Pinocytosis: in which the cell takes in liquid materials.
Exocytosis:
The
process in which the material is packed in vesicles comes near the plasma
membrane, fuses with it, releases the material to the outside, and the vesicle
membrane is incorporated into the plasma membrane is called Exocytosis.
Q5.
How does the turger pressure develop in a plant cell?
Ans:
When a cell absorbs water from the
surrounding by osmosis, its vacuoles become filled, increase in size, and push
the cell contents against the cell wall. Thus a pressure developed is called turger
pressure.
