Tuesday, 16 August 2016
Friday, 12 August 2016
Lesson- Tissue
Class-
9
1. What is a tissue?
Ans-
Tissue is a group of structurally and functionally similar cells having common
origin and common function.
2. What is the utility of tissues in
multicelluar organisms?
Ans-
Tissues provide division of labour, complex organization and higher efficiency.
This provides multicellular organisms more successful a better survival.
3. Name types of simple tissues.
Ans-
The simple tissues in plants are basically of three types: a) parenchyma, b)
collenchymas, and c) sclerenchyma.
4. Where is apical meristem found?
Ans-
At the tip of roots, shoots, branches and leaves, i.e., in the growing parts of
the plant.
5. Which tissue makes up the husk of
coconut?
Ans- The husk of a coconut is made up of
fibers of sclerenchymatous tissue.
6. What are the constituents of phloem?
Ans-
Phloem is made up of four type’s cells, sieve tube cells, companion cells,
phloem parenchyma cells and phloem fibers.
7. Name the tissue responsible for
movement in our body.
Ans-
Muscular tissue. Muscle cells contain special contractile proteins with the
ability to contract and relax to cause movement.
8. What does a neuron look likes?
Ans- A
neuron looks like a star. The cell body or cyton with its projecting dendrites
gives the impression of a twinkling star.
9. Give three features of cardiac
muscles.
Ans-
a. Cardiac muscles are involuntary.
b.Cardiac muscles cells are
cylindrical , branched and uninucleate.
c. Cardiac muscles show
rhythmic contraction and relaxation throughout life.
10. Give three features of cardiac
muscles.
Ans-
a. Aerolar tissue fills spaces between tissues and organs.
b. It provides support, elasticity and
strength to body parts.
c. It binds different tissues
together.
d. It helps in healing wounds and in
tissue repair.
e. It helps in fighting foreign
antigens and toxins.
11. How many types of elements together make up
xylem tissue? Name them.
Ans-
four types of elements make up xylem tissue. They are:
a. Tracheids c. vessels
b. Xylem parenchyma d. Xylem sclerenchyma.
12. How are simple tissues different from
complex tissues?
Ans-
|
s.no.
|
Simple tissues
|
Complex tissues
|
|
1.
2.
|
Made up
of one type of cells.
They
perform a variety of functions like protection, storage, mechanical supports,
etc.
Examples:
parenchyma, collenchymas and sclerenchyma.
|
1.
Made up of more
than one type of cells.
2.
They help in
conduction of water, minerals and food to different parts of plant body.
Examples:
Xylem and phloem.
|
13. Differentiate between parenchyma, collenchymas and sclerenchyma on the basis of their cell wall.
Ans-
|
Parenchyma
|
Collenchyma
|
sclerenchyma
|
|
1. Cell
wall is primary.
2. Cell
wall is thin and made up of cellulose.
|
1. Cell
wall is primary.
2. Cell
wall has localized thickening of cellulose.
|
1. Cell
wall is secondary.
2. Cell
wall is very thick obliterating internal cellular space. Cell wall is
thickened due to deposition of lignin.
|
14. Differentiate among striated, unstriated and cardiac muscles on the basis of their structure and site in the body.
Ans-
|
|
Striated
muscles
|
Non-striated
muscles
|
Cardiac
muscles
|
|
1.Location
2.Shape of fibers
3.No. of nuclei
4.Position of nuclei
5.Cross striations or bands
6.Sacrolemma
7.Internalated disc
8.Speed of contraction
9.Abilitu to remain contracted
10.Type of control
11.Nervous supply
|
Attached to bones in limbs, etc.
Form bundles.
Long, cylindrical with blunt ends.
Multinucleate
Peripheral
Dark and light bands
Present
Absent
Most rapid
Least, get fatigued very soon.
Voluntary
From central nervous system
|
Walls
of viscera, stomach, intestine, blood vessels, etc.
Form
sheet or occur as sphincter.
Long
and spindle-shaped.
Uninucleate
Central
Band
not found
Absent
Absent
Slowest
Greatest,
can remain contracted for long.
Involuntary
From
autonomic nervous system.
|
In the
wall of heart.
Form a
network.
Short,
cylindrical with branched ends.
Uninucleate
Central
Dark
and light bands
Present
Present
Intermediate
Intermediate,
contract rhythmically, and never get tired.
Involuntary
From
autonomic nervous system
|
14. What are the functions of stomata?
Ans- 1. Stomata help in gaseous
exchanges during respiration and photosynthesis.
2. They also help in transpiration by
allowing the water vapor to diffuse into the atmosphere.
15. What is the specific function of
cardiac muscles?
Ans- They contract tirelessly and rhythmically to pump blood in blood vessels so
that blood may reach every part of the body.
17. Draw a labeled diagram of a neuron.
Ans-
18. Name the following:
a. Tissue that forms the inner lining of
our mouth.
b. Tissue that connects muscle to bone
in humans.
c. Tissue that transports food in
plants.
d. Tissue that stores fat in our body.
e. Connective tissue with a fluid
matrix.
f.
Tissue
present in the brain.
Ans- a. squamous epithelium
b.Tendon (fibrous connective tissue)
c.Phloem
d.Adipose tissue
e.Blood
f. Nervous tissue
19. Identify the type of tissue in the following:
a.skin b. bark of tree c. bone d. lining of kidney tubule
e.
vascular bundle
Ans-
a) skin: Squamous epithelium
b)
Bark of tree: cork (protective tissue)
c)
Bone: connective tissue (skeletal tissue)
d) Lining of kidney tubules: cuboidal
epithelium (epithelium)
e) Vascular bundle: Xylem and phloem
20.Name the regions in which parenchyma
tissue is present.
Ans- parenchyma tissue is present in the cortex and ground tissue of
stem and roots in the mesophyll region of leave.
21. What is the role of epidermis in
plants?
Ans- Epidermis protects the plant from i) water loss by desiccation and ii)
infection by preventing of pathogen.
22. How does the cork act as a protective
tissue?
Ans- a) Cork
is formed of several layers of dead cells arranged compactly without
intercellular spaces. The wall of cork cell contains an organic substance
called suberin. The cork cell remains filled by resin or tannins. Suberin and
resin protect the plant from desiccation, infection and mechanical injur
23. Complete the flowchart.
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Thursday, 11 August 2016
Class- X
Biology
Control and coordination
Living organisms are able to detect
changes in their environment and respond to them. This characteristic known as
sensitivity is essential for survival of living organisms.
Sensitivity is a feature of single
celled organisms as it is of flowering plants and animals, e.g. when amoeba
detects a suitable food it moves to take it into a vacuole.
Changes that bring about responses
are called stimuli, e.g. cat runs on seeing a mouse, we close or eyes when a
bright light is focused on our eyes, we withdraw our hands when w touch a hot
object. When we detect the change and respond to it with movement.
All the movements in response to the
environment are carefully controlled.
Coordination is the working together
of parts of the body as a whole, e.g. if you touch something hot, the muscles
in your arm contract, so that your hand is quickly pulled away.
In animals internal communication,
i.e. coordination involves both the nervous system and endocrine system
(hormone producing system).to work together both endocrine and nervous system
involves the following:
1. Stimuli - any detectable change in
the external or internal environment.
2. Receptor- on organ that detects a
specific stimulus.
3. Coordination- system connects
receptor to effectors.
4. Effectors- an organ that produces a
response as a result of stimulus detection.
In plants internal communication is via plant growth
regulator substances.
Plant hormones or phytohormones
The plants do not have a nervous system and sense organs like
eyes, ears, or nose, etc., like the animals, but they can still sense things.
The plants coordinate their behavior against environmental
changes by using hormones.
Plants have no nervous system, so plants use only hormones
for coordination.
The plants respond to various stimuli very slowly by growing.
The function of control and coordination in plants is
performed by the chemical substances called plant hormones.
Many different chemicals help to coordinate the growth of a
plant. These chemicals are called plant hormones or phytohormones.
1. They are produced in small amounts.
Small amounts of these have profound effects on target cells.
2. Plant hormones are very specific and
unlike animal hormones are produced in the very organ where they have their
effect.
3. They synthesis and action of phythormones
are greatly influenced by the external stimuli.
4. Phytohormones regulate several
functions in a plant like growth of roots, stems, leaves, flowering, seed
germination, photoperiodism, geotropism, breaking of seed dormancy, ripening of
fruits and opening and closing of stomata etc.
5. They may promote or inhibit a
process.
So far five types of phytohormones have been identified.
Their names and major functions are given below--
Name of the plant hormones
|
Functions
|
Auxins
|
1.
Stimulate
growth of shoot and root tips.
2.
Promote fruit
growth and apical dominance
3.
Suppress
shedding of leaves and fruits
|
Gibberllins
|
1.
Promote stem
elongation
2.
Stimulate
flowering and fruit development.
3.
Promote seed
and bud germination
|
Cytokinins
|
1.
Stimulate cell
division and growth
2.
Promote seed
germination
3.
Delay ageing in
plants.
|
Abscisic acid
|
1.
Bring falling
of leaves and fruits.
2.
Maintain seed
dormancy.
3.
Inhibit growth.
|
Ethylene
|
1.
Promote fruit
ripening.
2.
Along with ABA,
stimulate abscission of leaves.
|
Movement in plants
Plants do not show locomotion and are rooted to one place.
However, they do show movements in response to external stimuli and exhibits
growth movements like bending, twisting, coiling and elongation etc. plant
movements are caused by changes in the size of cells. These could be temporary
or permanent.
Plant movement in response to external stimuli can be grouped
into categories:
a.
Tropic
movement or tropism
b.
Nastic
movement
A.
Tropic movement: A growth movement of a plant part
in response to an external stimulus in which the direction stimulus determines
the direction of response is called tropism. If the growth (or movement) of a
plant part is towards the stimulus, it is called positive tropisms, and if the
growth (or movement) of a plant part is away from the stimulus, then it is
called negative tropism.
Tropisms are namely according to the stimulus. This will
become
Stimulus
|
Types of tropism
|
Light
|
Phototropism
|
Gravity
|
Geotropism
|
Chemicals
|
Chemotropism
|
Water
|
Hydrotropism
|
Touch
|
Thigmotropism
|
Types of tropism:
i.
Phototropisms:
it is a response of plant to light. When a growing plant is illuminated by
unidirectional light, the shoot bends towards the light. The shoots are said to
be positively phototropic as they grow towards’ the light while roots are
negatively, phototropic as they grow away, from light.
ii.
Geotropism:
It refers to the response induced by gravity. Roots of a plant grow downwards
towards the gravity and show positive geotropism. Stem are said to be
negatively geotropic as they grow away from gravity.
iii.
Chemotropism:
it is a response of a plant or a part of it to chemical, like the pollen tube
is positively chemotropic as it moves towards the ovules due to chemicals
produces over there.
iv.
Hydrotropism-
the movement of plant part in response to water is called hydrotropism. If the
plant moves towards water, it is called positive hydrotropism. On the other
hand if the plant part moves away from water then it is called negative
hydrotropism.
v.
Thigmotropism-
the directional movement of plant part in response to the touch of an object is
called thigmotropism.for e.g. the climbing parts of the plant such as tendrils
grow any support which they happen to touch and wind around that support.so,
tendrils of plant are positive thigmotropism.
B.
Nastic movement: The movement of a plant part in
response to an external stimulus in which the direction of response is not
determination by the direction of stimulus is called nastic movement.
Types of nastic movement
Photonasty : The movement of a plant part in
response to light is called photonasty.
The opening and closing of petals of
dandelion flowers in response to the intensity of light is an example of nastic
movement.
Thigmonasty movement in touch me not
plant, the leaflets are sensitive to touch’ the fold upwards in seconds on
touching the plant. It is due to rapid loss of water from specialized cells at
the base of leaflets. If the plant is left undisturbed in about 10 minutes the
plant comes back to its original form.
Photoperiodism
Photoperiodism-it can be defined as a
phenomenon or response of plants to the changing relative lengths of day and
night called photoperiodiisam.
Photoperiod: it refers to the
relative length of the day or the light period.
Control
and coordination in animals-
What
are receptors?
A receptor is a cell (or a group of cells) in a sense organ
which is sensitive to particular type of stimulus (or a particular type of
change in the environment) such as light.
The common receptors are-
1. Photo receptors detect light (eyes)
2. Phanoreceptor detect sound (ear)
As the complexity in the animals
increases the coordination of different parts of the body amongst themselves
and with the external environment become necessary. All vertebrates have two
systems
a. Nervous system
b. Endocrine system
Which not only control and coordinate various cellular
activities but also help the animals to respond to the stimulus?
The nervous system is comparatively faster and localized in
action while the endocrine system is slower and has a widespread action in the
body. Both the systems interact and involved in the:
1. Control and coordination of various
functions in the body.
2. Interaction between the environment
and the body.
Human nervous system
Human nervous system consists of
network or specialized cell called neuron.
A neuron is a structural function
unit of nervous system.
Neurons vary in shape and size
depending in their position and function but all neurons have a similar basic
structure.
1. An neuron posses three distinct
regions:
a. Cell body or cyton
b. Dendrites
c. Axon
Structure and functions of the parts of neuron have been
explained in the given below:
Parts of
the neuron
|
Structure
and function
|
Cell
body
|
The main
part of the neuron consisting and nucleus.
|
Dendrites
|
Short,
branched processes which receive nerve impulses and transmit the towards the
cell body. They are grey in color and make up the grey matter of the brain
and spinal cord.
|
Axon
|
Single,
longer, unbranched processes which transmits impulses away from the cell body
to the target cell. They are white in color and make up while matter of brain
and spinal cord.
|
Myelin
sheath
|
Made up
of individual cells (Schwann cells) with abundant fatty material surrounding
the axon, acts as an electrical insulator and speeds up the passage of
impulses.
|
Nodes of
ranvier
|
The gaps
between the Schwann cells where the myeline sheath is absent.
|
There are three types of neurons-
sensory neurons, motor and interneuron depending on their action.
Sensory neurons: they carry nerves
Sensory neurons: They carry nerve impulses from peripheral tissues or receptor to central
nervous system (CNS). They carry stimulus from receptors.
Motor neurons:
they take nerve impulses from CNS to peripheral tissue and organs, (called effectors).
They carry message s from CNS to effectors.
Interneuron:
also called association neurons, they are found completely within the CNS and
make link between sensory and motor neurons.
Nerve impulses-
Unlike the electrical impulses that
are sent along the telephone lines, nerve impulses are caused by chemical
changes in and around the nerves.
Nerve impulses travel rapidly in one
direction, starting at the dendrites and finishing at the end of axon.
Synapses-
Minute gaps called synapse separate
neuron from one another. Each synapse separates the end of the axon of one
neuron from the dendrite of the next.
When nerve impulse arrives at the end
of the axon they stimulate a production of a special chemical called
neurotransmitter which diffuses across the synapse to the dendrites of the
neighboring neurons.
Neuromuscular junction-
When the axon reaches the muscles, it
splits into branches which make connection with the muscle fibers. The point
where the two join is called the neuromuscular junction. There is a gap here,
and the message gets across by means of a chemical substance just as it does
between neuron at synapse. Synapse occurs between the swollen tips of terminals
of the axon of one neuron and dendrites of cell body of another neuron. The
tiny gap between the neuron is known as synaptic cleft. Impulses are also
conducted at the point of contact between the terminals fibers of motor neurons
and muscle fibers. Such a junction is a special type of synapse called a motor
end plate. Each muscle fiber contains many nuclei lying in the cytoplasm just
below the membrane, the sarcolemma. The sacroplasm contain numerous
mitochondria. The bulk of the muscles fibers contain of a mass of parallel,
fibrous, myofibrils the length of fiber.
The reflex arc connects a sense organ
with a muscle or a gland via the neuron as follows:
1. The sense organ detects the stimulus
in the form of energy such as sound, light or mechanical pressure.
2. The stimulus is converted into an
impulse which is transmitted to an effectors organ.
3. When a impulse arrives at the
effectors, the impulse cause an response for e.g.it may cause a muscle to
contract or a gland to secrete.
The simplest form of response in the nervous system is called
reflex action.
Reflex action can be defined as a rapid automatic short lived
involuntary response to stimulus.
In a reflex action a particular stimulus creates a same
automatic response every time.
Spinal cord
·
It
is a tubular or cylindrical structure extending downwards from.
·
The
medulla oblongata
·
It
is enclosed within the vertebral column and has diameter of that of the little
finger.
·
It
is surrounded by three membranes called meanings.
·
The
distribution of grey and white matter is just the reverse
·
To
what is represented in the brain. In the spinal cord, grey matter forms the
center and the white matter is present in the periphery
·
In
the center of spinal cord runs a narrow central canal containing the
cerebrospinal fluid.
·
From
the spinal cord arise 31 pairs of spinal nerves which are part of the
peripheral nervous system.
Human brain
Human brain has three majors’ parts or regions
a. Forebrain b. Mid Brain c. Hind Brain
Forebrain
Most complex/ specialized part of the brain is CEREBRUM
Functions:
1. Thinking part of the brain
2. Control the voluntary actions
3. Store information (Memory)
4. Center associated with HUNGER
5. Receives sensory impulses from
various body parts and integrates it.
Mid brain:
Hypothalamus: chemical coordination
Pituitary gland: secretes hormones
Hind brain:
1.
Cerebellum
i) Controls posture and balance
ii) Control precision of voluntary actions
2.
Medulla - controls involuntary actions
e.g.
Blood pressure, salivation, vomiting
3.
Pons - involuntary action, regulation of respiration
Cerebrum
|
Cerebellum
|
1.
Part of the
fore brain.
2.
Largest part of
brain covers most of the head region.
3.
Associated with
memory, intelligence, and sensation like pain, touch etc and voluntary and
involuntary muscle activities.
|
1.
Part of the
hind brain.
2.
Comparatively
very small part, present just above the back of the neck.
3.
Associated with
voluntary muscular movement and maintenance of equilibrium.
|
Hormones in animals
Hormones: these are the chemical messengers secreted in very
small amounts by specialized tissues called ductless glands. They act on target
tissues/organs usually away from their source.
Endocrine system helps in control and coordination through
chemical compound called hormones.
s.no.
|
hormone
|
Endocrine
gland
|
Location
|
functions
|
1.
|
Thyroxine
|
Thyroid
|
Neck/
throat region
|
Regulation
of metabolism of carbohydrates, fats and proteins.
|
2.
|
Growth
hormone
|
Pituitary
|
Mid
|
Regulates
growth and development.
|
3.
|
Adrenaline
|
Adrenal
|
Above
both kidneys
|
Regulation(increasing)of
blood pressure, heart beat, carbohydrate metabolism (during emergency)
|
4.
Sex
hormone
|
Testosterone
in males
Estrogen
in females
|
Testes
Ovaries
|
Genital
/ lower abdomen area
|
Estrogen-
Changes
associated with puberty
(sexual
maturity)
Progesterone-
To
control uterus changes and maintenance of pregnancy
|
5.
|
Insulin
|
pancreas
|
Below
stomach
|
Reduces
and regulates blood sugar levels
|
Iodized salt is necessary because:
Iodine mineral is essential part of
thyromine hormone so it is important that we must consume iodised salt as in
turn it is essential for thyroid gland as it controls carbohydrate, proteins
fat metabolism for best balance of growth deficiency of iodine might cause
disease called goiter.
Diabetes:
Cause: it is
due to deficiency of insulin hormone secreted by pancreas that is responsible
to lower/ control the blood sugar levels.
Treatment:
patients have to internally administer injections of insulin hormone which
helps in regulating blood- sugar level.
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