CHAPTER No. 4
Ans: The
use of microscope is called microscopy. It is used to measure small things.
2.
When and
where was the first microscope made?
Ans: The first compound microscope was developed
by Zacharias Janssen, in Holland in 1595.
It was simply a tube with lenses at each end and its magnification
ranged from 3X to 9X.
3.
What is the
difference between the magnification and resolution of a microscope?
Ans: Magnification
is the increase in the apparent size of an object. While resolution is the
measure of the clarity of an image.
4.
What is micrograph?
Ans: A
photograph taken through a microscope is called a micrograph.
5.
What is
meant by resolving power of a microscope?
Ans: It is
the measure of the clarity of an image. It is the minimum distance at which two
objects can be seen as separate objects.
6.
Differentiate between Transmission Electron
Microscope and Scanning Electron Microscope./ Define transmission electron microscope.
Ans: TEM:
In TEM electrons are transmitted through the specimen. It is used to study
internal cell structure.
SEM:
Here, the electrons are reflected through metal-coated surface. It is used to
study structure of cell surface.
7.
How does Electron
Microscope Works?
Ans: In EM, object and lens are placed in a
vacuum chamber and a beam of electrons is passed through object. Electrons pass
through or are reflected from object and make image. Electromagnetic lenses
enlarge and focus the image onto a screen or photographic film
8.
Describe the contribution of Mathias Schleiden
and Theodar Schwan
Ans: Mathias
Schleiden is a German botanist. In 1838, he studied plant tissue and made the
first statement of cell theory. He stated that all plants are aggregates of
individual cells which are fully independent
Contribution
of Theodor Schwan: He was German Zoologist, in 1839, he reported
that all animal tissues are also composed of individual cells.
9.
Write main points (principles) of cell theory. Or Write schleiden and schwan cell
theory.
Ans: 1-
All organisms are composed of one or more cells.
2-
Cells are the smallest living things, the basic unit of organization of all
organisms.
3-
Cells arise only by division in previously existing cells.
10.
What are the
contributions of Rudolf Virchow and Louis Pasteur in the formation of Cell Theory?
Ans: (i) Contribution of Rudolf Virchow: He
proposed an important extension of cell theory. He proposed that all living
cell arise from pre-existing cell (Omnis Cellula e).
(ii) Contribution of Louis Pasteur: In 1862, Louis Pasteur provided experimental
proof of Rudolf Virchow experiment.
11.
Who discovered cell theory?
Ans: Schleiden
and Schwann discovered the cell theory.
12.
What is meant
by cell wall? In which living things is it present?
Ans: Cell
wall is a non-living and strong component of cell, located outside the plasma
membrane. The cell wall is found in plants. It is composed of cellulose.
13.
Differentiate
between primary and secondary wall.
Ans:
|
Primary Wall |
Secondary wall |
|
It is composed
of cellulose |
It contains lignin and some other chemical. |
|
It is the outer
layer of plant. |
It is present on inner side of the primary wall. |
14.
Name the chemical found in plant cell
wall.
Ans: 1- Cellulose
in primary cell wall
2-
Lignin and some other chemicals in secondary cell wall
15.
What are
plasmodesmata? Where are these found in cell?
Ans: The outer layer of plant cell wall is known
as primary wall and cellulose is the most common in it. Some plant cells, for
example xylem cells, also have secondary walls on the inner side of primary
wall. It is much thicker and contains lignin and some other chemicals. There
are pores in the cell walls of adjacent cells, through which their cytoplasm is
connected. These pores are called plasmodesmata.
16.
Describe chemical composition of cell wall of fungi and prokaryotes
Ans: The
cell wall of fungi is made up of chitin while cell wall of prokaryotes composed
of peptidoglycan that is a complex of amino acids and sugar.
17.
Differentiate
between cell wall and cell membrane,
Ans: Cell Wall: 1- It is outermost protective layer of plant
cell.
2-
It is composed of cellulose in eukaryotic cell while in prokaryotic cell it is
composed of peptidoglycan
Cell Membrane: 1-
It is outer most protective layer of animal cell.
2-
It is composed of proteins, Lipids and carbohydrates.
18.
What is
difference between cell membrane and plasma membrane?
|
Cell membrane |
Plasma membrane |
|
When we talk about all the membranes of a cell we say them as
cell membrane. |
When we say about only the outer membrane of cell, we say it as
plasma membrane. |
19.
Why cell
membrane is called semi permeable membrane?
Ans: Because
it allows a very few molecules across it while fencing the majority of
molecules of chemicals inside the cell.
20.
What is
fluid mosaic model?
Ans: According
to this model there is a lipid bilayer in which the protein molecules are
embedded. It gives fluidity and elasticity to membranes.
21.
Where does
cytoplasm lies? Which organic molecules
are in it?
Ans: Cytoplasm
is present between plasma membrane and nuclear envelope. It contains organic
molecules like proteins, carbohydrates and lipids.
22.
Write down two
functions performed by cytoplasm.
Ans: Cytoplasm
provides space for the proper functioning of organelles and also acts as the
sites for various biochemical (metabolic) reactions.
23.
What is meant by cytoskeleton?
Ans: Cytoskeleton
is a network of microfilaments and microtubules. Microfilaments are made of
tubulin protein and are used by cells to hold their shape. They are also the
major component of cilia and flagella. Microfilaments are thinner and are made
of actin protein. They help cells to change their shapes.
24.
What is the difference between
microtubules and microfilaments?
|
Microtubules |
Microfilaments |
|
These are made of tubulin protein |
These are made
of actin protein |
|
These are used by cells to hold their shape |
They help cells to change their shape. |
25.
Write the name of any four cell
organelles.
Ans: 1- Nucleus 2- Mitochondria
3- Golgi complex 4- Plastids
26.
Define Ribosomes, write their function/structure./ Define ribosomes.
Ans: These
are the tiny granular structures that are either floating freely in cytoplasm
or are bound to endoplasmic reticulum. These are the sites for protein
synthesis. These are made of almost equal amount of proteins and ribosomal RNA.
27.
Write the
structure of mitochondria.
Ans: These
are double membrane bounded structures found only in eukaryotes. The outer
membrane is smooth but the inner membrane forms many infolding is called
cristae in mitochondrial matrix. Mitochondria have their own DNA and ribosomes.
28.
What are plastids? Name
their kinds.
Ans: Plastids
are also membrane bound organelles that only occur in cells of plants and
photosynthetic protists.
Kinds: (i)
Chloroplast (ii) Chromoplasts (iii) leucoplast.
29.
What is meant by thylakoids?
Ans: There
are the structures formed by the inner membrane of the chloroplast. These are
sac-like structure.
30.
What are the
functions of leucoplasts and chromoplasts?
Ans: Leucoplasts: They are the third type
of plastids. They are colorless and store starch proteins and lipids. They are
present in the cells of those parts where food is stored.
Chromoplasts: They contain
pigments associated with bright colors and are present in the cells of flower
petals and fruits. Their function is to give colors to these parts and thus
help in pollination and dispersal of fruit.
31.
What are
leucoplasts and where do they occur?
Ans: They
are colorless and store starch, proteins and lipids. They are present in the
cells of those parts where food is stored.
32.
What is the
role of leucoplasts and chloroplasts?
Ans: Leucoplast: These can store starch, proteins and lipids.
Chloroplast: These are the sites of photosynthesis.
33.
What is the function of mitochondria?
Ans: Mitochondria
are the sites of aerobic respiration, and are the major energy production
centers.
34.
What is difference between rough
endoplasmic reticulum and smooth endoplasmic reticulum?/ What is the function of Smooth Endoplasmic Reticulum?
|
Rough Endoplasmic Reticulum |
Smooth Endoplasmic Reticulum |
|
It has rough appearance due to numerous ribosomes that are
attached to it |
It lacks ribosomes. |
|
It serves a function of protein synthesis |
It involve in the lipid metabolism, transport of material and
detoxifies the harmful chemicals. |
35.
What is endoplasmic reticulum? Write the names
of two types of endoplasmic reticulum.
Ans: Endoplasmic
reticulum is a network of interconnected channels that extends from cell
membrane to nuclear envelope. It has two types
(i)
Rough
endoplasmic reticulum (RER)
(ii)
Smooth
endoplasmic reticulum (SER)
36.
Why
endoplasmic reticulum is called rough and smooth endoplasmic reticulum?
Ans: RER: Because
of its rough appearance due to numerous ribosome that are attached to it
(Endoplasmic reticulum).
SER: Because of its smooth appearance
due to absence of ribosome’s on ER.
37.
Describe
structure and function of Golgi apparatus and lysosomes.
Ans: Golgi
apparatus: These are a set of
flattened sacs in cell. In this set cisternae are stacked over each other. It
modifies molecules coming from ER and packs them into small membrane bound sacs
called Golgi complex. These sacs can be transported to various locations in cell
or to its exterior in the form of secretions.
Lysosomes:
These are single membrane bound
organelles. During their functions, lysosomes fuses with the vacuole, that
contains the targeted material and its enzymes breakdown the material.
38.
Give the function
of centriole.
Ans: Their function is to help in the formation
of spindle fibers during cell division. In some cells, centrioles are involved
in the formation of cilia and flagella.
39.
What are
Lysosomes? Define it./ Describe the function of
Lysosoms.
Ans: Lysosomes: Lysosomes are single membrane bounded
organelles. Lysosomes contain strong digestive enzymes and work for breakdown
of food and waste material within cells.
40.
Give a
difference between prokaryotic and eukaryotic cells.
|
Prokaryotic
Cell: |
Eukaryotic
Cell: |
|
The prokaryotic cells don’t have prominent nucleus. |
Eukaryotic cells have prominent nucleus (bounded by nuclear
envelop) |
|
Their chromosome consist of DNA only and floats in cytoplasm
near centre. This region is called nucleoid. |
Their nuclear material is not floated or suspended in the
cytoplasm. |
41.
What is meant by Nucleoid?
Ans: Prokaryotic
cells do not have a prominent nucleus. Their chromosome consists of DNA only
and it floats in cytoplasm near centre. This region is called nucleoid
42.
How cells work as an open system?
Ans: A
cell works as an open system i.e. it takes in substances needed for its
metabolic activities through its cell membrane.
Then it performs the metabolic processes assigned to it. Products and
by-products are formed in metabolism. Cell either utilizes the products or
transports them to other cells. The by-products are either stored or are
excreted out of cell.
43.
Differentiate
between diffusion and facilitated diffusion./
Define
diffusion./ Define facilitated diffusion.
Ans:
|
Diffusion |
Facilitated
Diffusion |
|
It is the movement of molecules from an area of higher
concentration to the area of lower concentration i.e, along concentration
gradient. |
When a transport protein moves a substance from higher to lower
concentration the process is called facilitated diffusion. |
44.
What is meant
by passive diffusion?
Ans: This
is a type of diffusion in which molecules diffuse from membrane slowly without
the expenditure of energy called passive diffusion.
45.
Define diffusion and osmosis./ What do you mean by osmosis?
Ans: Diffusion: It is the movement of molecules from an area
of higher concentration to the area of lower concentration.
Osmosis: It is the movement of water across a
semi-permeable membrane from a solutio0n of lesser solute concentration to a
solute of higher solute concentration.
46.
What is the difference between
hypertonic and hypotonic solutions?
|
Hypertonic solutions |
Hypotonic solutions |
|
The solution has relatively more solute. |
The solution has relatively less solute. |
47.
Define
turgor./ Define turgor
pressure.
Ans: The
outward pressure on the cell wall exerted by the internal water is known as
turgor pressure and the phenomenon is known as turgor.
48.
What is
plasmolysis?
Ans: In a
hypertonic environment of plant cell loses water and cytoplasm shrinks. The shrinking
of cytoplasm is called plasmolysis.
49.
What is the effect of hypertonic environment
on plant and animal cell?
Ans: An
animal cell placed in hypertonic solution will lose water and will shrink in
size while plant cell placed in a hypertonic solution loses water and cytoplasm
shrink which is also called plasmolysis.
50.
Write the
function of guard cell.
Ans: Stomata in leaf epidermis are surrounded by
guard cells. During daytime guards cells are making glucose and so are
hypertonic (have higher concentration of glucose) than their nearby epidermis
cells. Water enters them from other cells and they swell. In this form, they
assume a rigid bowed shape and a pore is created between them. At night when
there is low solute concentration in guard cells, water leaves them and they
become flaccid. In this form, both guard cells rest against one another and the
opening is closed.
51.
Define Filtration.
Ans: Filtration
is the process by which small molecules are forced to move across semi
permeable membrane with the aid of Hydrostatic pressure or blood pressure.
52.
What is Active Transport?
Ans: It is
the movement of molecules from an area of lower concentration to the higher
concentration with the use of energy.
53.
Define "Sodium-Potassium
Pump".
Ans: The
membranes of nerve cells have carrier proteins in the form of “sodium-potassium
pump” In a resting (not conducting nerve impulse) nerve cell, this pump spends
energy (ATP) to maintain higher concentrations of K+ and lower conc.
of Na+ inside the cell. For this purpose, the pump actively moves Na+
to the outside of the cell where they are already in higher concentration.
Similarly this pump moves K+ from outside to inside the cell where
they are in higher concentration.
54.
What is endocytosis? Give types./What do you
encytosis?
Ans: It
is the process of cellular ingestion of bulky material by the infolding of cell
membrane is called endocytosis. There are two types of endocytosis
(i) Phagocytosis (ii) Pinocytosis.
55.
Differentiate between Phagocytosis
and Pinocytosis./ What is meant by pinocytosis?
Ans: Phagocytosis: In the phagocytosis, cell takes in solid
material.
Pinocytosis: The cell takes in liquid in the form of
droplets.
56.
Differentiate between endocytosis and
exocytosis./ What is exocytosis?
|
Endocytosis |
Exocytosis |
|
It is the process of cellular ingestion of bulky materials by
the infolding of the cell membrane. |
It is the process through which the bulky material is exported. |
|
This process lost the part of cell membrane. |
This process adds new membrane which replaces the part of all
membrane lost during endocytosis. |
57.
What is the
function of connective tissues in the body?
Ans: Connective
tissue serve a “connecting function” in body. It supports other tissue. Unlike
epithelial connective tissue serve a “connecting function” in body. It supports
other tissue. Unlike epithelial tissue, connective tissues has cells scattered throughout
an extra cellular matrix.
58.
Differentiate between skeletal and smooth muscles.
|
Skeletal Muscle |
Smooth Muscle |
|
Muscles attached to bones are striated (striped) cell contain
many nuclei. |
Found in wall of alimentary canal. Their cells are non-striated,
all contain single nucleus. |
59.
How are smooth muscles?
Ans: These
muscles are found in the walls of alimentary canal, urinary bladder, blood
vessels etc. They contain smooth (non-striated cells, each with a single
nucleus). They are responsible for the movement of substances.
60.
Write a note on skeletal
muscles functions
Ans: They
are responsible for the movements of bones.
61.
Define tissues. Write the names of two
main tissues found in plants.
Ans: Tissue: A
group of similar cells specialized for the performance of a common function.
Two main tissues in plants: 1- Simple
tissues 2- Compound tissues
62.
Differentiate between simple tissues
and compound tissues in plants.
Simple tissue | Compound tissue |
The tissues which are made of single types of cells are called simple
tissues. | A plant tissue composed of more than one type of cell is called
a compound or complex tissue. |
Examples are meristematic and permanent tissues | Examples are xylem and phloem tissues |
63.
Write down the
names of two types of simple tissues.
Ans: i. Meristematic tissues. ii. Permanent tissues.
64.
Define meristematic tissue.
Ans: The
tissues that are composed of cells, that have ability to divide is called
meristematic tissues. The cell are thin walled, have large nucleus and small or
no vacuoles. They do not have intercellular space among them. Two main types of
meristematic tissue have been organized that are given below:
(i) Apical meristems (ii) Lateral
meristems
65.
Define
secondary growth.
Ans: Lateral meristems are located on the
lateral sides of roots and shoot. By dividing, they are responsible for
increase in growth of plant parts. This growth is called secondary growth.
66.
What do you mean by intercalary
meristem?
Ans: It
is in the form of small patches among the mature tissues. These are common in
grasses and help in the regeneration of parts removed by herbivores etc.
67.
Define permanent tissues. Name its
types.
Ans: Permanent tissues: These tissues originate form meristematic
tissue. The cells of these tissues do not have the ability to divide.
Types:1- Epidermal tissue 2- Ground
tissues
68.
Define support tissue and write names
of types of support tissue.
Ans: Support Tissue: These tissues provide strength and flexibility
to plants.
Types: 1- Collenchyma Tissue 2- Sclerenchyma
Tissue
69.
What are
sclerenchyma tissues?
Ans: They
are composed of cells with rigid secondary cell wall. Their cell walls are
hardened by lignin, which is the main chemical component of wood.
70.
Write down the
functions of xylem and phloem tissues./ What is the role of xylem tissue in
plants?
Ans: Xylem Tissue: It is responsible for the transport of water
and dissolved substances from roots to the aerial parts.
Phloem tissue: It is responsible for the conduction of
dissolved organic matter (food) between different parts of plant body.
71.
What is difference between xylem and phloem
tissues?
|
Xylem Tissue |
Phloem Tissue |
|
The tissue that are responsible for the
transport of water and dissolved substance from roots to aerial part is
called xylem tissue. |
The tissue that are responsible of dissolved
organic matter (food) between different part of plant body is called phloem
tissue. |
|
Two types of cell are found in xylem tissue
that is vessel elements and tracheids. |
Phloem tissue contain sieve tube cells and
companion cells. |
72.
Write down
two names each of plant and animal tissues.
Ans: Plant tissues: Meristematic tissue, epidermal tissues
Animal tissues:Epithelial tissues, connective tissues.
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