CONTROL AND COORDINATION

1) Draw a neat diagram of a neuron and label (i) dendrite and (ii) axon.
(b) Which part of the human brain is:
(i) the main thinking part of the brain: Forebrain which includes cerebrum, olfactory lobes
(ii) responsible for maintaining the posture and balance of the body: Cerebellum, part of hindbrain

2) State the two types of movements seen in plants. Give one example of each type.
A) Two types of movements seen in plants are:
(i) Nastic movements are movements independent of growth that are non-directional and fast occur
due to turgor changes, e.g., closing of leaves in response to touch stimulus in ‘touch me not’ plant.
(ii) Tropic movements or tropism are movements due to growth, that are directional and very
slow, e.g., movement of a part of the plant in response to light.
3) What are plant hormones? Give its functions.
A)Plant hormones or phytohormones are chemical substances produced naturally in plants and capable of
translocation and regulating one or more physiological processes when present in low concentration.
These are also known as plant growth regulators.

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4) What happens when a growing plant detects light? OR why do plant bends towards sunlight?
A) Plants respond to light by showing growth movement towards light (phototropism). This growth
movement of the plant part (stem) is caused by the action of auxin hormone. The auxin hormone is
synthesised at the tip of the stem. When sunlight is unidirectional, auxin- gets accumulated
towards the shady region of the shoot. This causes the cells to elongate in shady side and stem to
bend towards light.
5) A squirrel is in a scary situation. Its body has to prepare for either fighting or running away. State the
immediate changes that take place in its body so that the squirrel is able to either fight or run .

A)When squirrel is in a scary situation then its nervous system stimulates the adrenal glands to secrete
more adrenaline hormone into blood.This adrenaline hormone increases heartbeat, breathing rate, blood
flow into muscles and causes liver to put more stored glucose into its blood. All these actions of
adrenaline hormone produces a lot of energy in squirrel’s body. In this way, squirrel prepares itself for
fighting or running away action.

6) How does tendrils coil around a support?

A)Tendrils are sensitive to touch. When they come in contact with any support, the part of the tendril in
contact with the object does not grow as rapidly as the part of the tendril away from the object. This
causes the tendril to circle around the object and thus cling to it.

7) Define reflex arc. Draw a flow chart showing the sequence of events which occur during sneezing.
A) Reflex arc is defined as the pathway or route taken by nerve impulses in a reflex action. Sequences
of events that occur during sneezing can be depicted as :

8)Why is chemical communication better than electrical impulses as a means of communication between
cells in a multicellular organisms? Or
Give limitations of chemical communication.
A) a)
CHEMICAL COMMUNICATION ELECTRICAL COMMUNICATION
1)It can reach to each and every cell 1)It can not reach to each and every cell
 2) It do not take time to reset 2) It take time to reset and takes time to
generate next impulse.

9)It is advised to use iodised salt. Give reason

A) Iodine is necessary for the making of thyroxine hormone by thyroid gland. Therefore, deficiency of
iodine in the diet can cause deficiency of thyroxine hormone in the body. Thyroxine is important
for the metabolism of carbohydrate , fats and protiens.
10)A gland secretes a particular hormone. The deficiency of this hormone in the body causes a particular disease in
which the blood sugar level rises.
a. Name the gland and the hormone secreted by it. PANCREAS SECRETES INSULIN
b. Mention the role played by this hormone. Insulin regulates the conversion of glucose to
glycogen, i.e., it lowers blood glucose level.
c. Name the disease caused due to deficiency of this hormone. Diabetes
11)Differentiate between nastic movement and tropic movement.

IMPORTANT TERMS:

1)STIMULUS: Change in internal and external environment.

2) RESPONSE : Reaction according to stimulus
Q) What are reflex action?
A) Reflex action is automatic , involuntary and unconscious (AIU) response of effectors according to stimulus
received by receptors. ( a sudden and involuntary response to stimuli )

Q ) Write functions of following:

A) a) frontal lobe: facial expressions

b) Parietal lobe: touch, pain,
c) temporal lobe: for hearing
d) occipital lobe: For vision
Q) Why is the flow of signals in a synapse from axonal end of one neuron to dendritic end of another
neuron but not the reverse or why flow of signal is unidirectional?
A) Flow of signals in a synapse is unidirectional as neurotransmitters are only released from one end of
the synapse and their receptors are only present on the other end.

Q) Touch me not plant belongs to which family –

A) Mimosa pudica
Q) How does touch me not plant detect the touch ? And how do the leaves move in
response?
A) 1)The point of touch and the part of plant that actually moves is different.
 The movement happens at a point different from the point of touch
2) plants use electrical - chemical means to convey this information from cell to cell.
3) As they don't have specialised tissue for the conduction of information, so the cells of plants change
their shape in order for movement to happen.
4) Plant cells change shape by changing the amount of water in them , resulting in swelling or
shrinking therefore in changing shape .
This is called as nastic movement which is growth independent movement and shows non directional
response to stimulus . Here the stimulus is touch ( thigmotropism)
Q) How does our body respond when adrenaline is secreted in blood?
A) Adrenaline is a hormone secreted by the adrenal glands in case of any danger or emergency or any kinds of
stress. It is secreted directly into the blood and is transported to different parts of the body.When secreted in
large amounts it speeds up the heartbeat and hence supplies more oxygen to the muscles. The breathing rate
also increases due to contractions of diaphragm and rib muscles. It also increases the blood pressure. All these
responses enable the body to deal with any stress or emergency.
Q) What is feed back mechanism ? Give one example.
A) Feedback mechanism : Timing and amount of hormones released by various glands is regulated by a
mechanism called feedback mechanism.
For instance, the glucose level in the blood increases when we eat food that is rich in carbohydrate. The pancreas
synthesizes and releases insulin as the amount of blood glucose rises. It will stimulate the blood glucose absorption by
the cells. This is the process by how the blood glucose level drops. Now, when insulin remains present in the blood,
more and more glucose get transported into the cell, and glucose in the blood scarcity. To prevent these scarcities of
glucose, the low glucose level inhibits the insulin secretion in the blood produces negative feedback.

Q) How does nervous tissue cause action?

A) 1. Nerve Impulse Transmission:
Neurons, the fundamental units of nervous tissue, receive and transmit electrical impulses, (also known as action
potentials). These impulses travel along the neuron's axon, which is often insulated by a myelin sheath to speed up the
transmission.
2. Muscle Fiber Activation:
When a nerve impulse reaches a muscle fiber, it triggers a series of events that lead to muscle contraction.
3. Muscle Contraction:
Muscle cells contain specialized proteins actin and myosin that change their shape and arrangement in response to the
nerve impulse. This rearrangement of proteins causes the muscle cell to shorten, which generates a force that leads to
movement.
4. Movement:
The coordinated contraction of muscles, triggered by nervous tissue, is responsible for a wide range of movements, from
simple reflexes to complex actions like walking or playing an instrument.
Q) Give function of forebrain.
A) Forebrain consist of cerebrum that consist of two cerebral hemisphere. It has the following lobes:
a) Frontal Lobe: Involved in speech, planning, reasoning, problem-solving, and voluntary movements.
b) Parietal Lobe: Manages movements, sensory perception, and spatial orientation.
c) Occipital Lobe:Dedicated to visual processing.
d) Temporal Lobe: Handles memory, auditory processing, and speech recognition.

Q) Give function of hind brain

A) It consist of :
a) Cerebellum : It is essential for:
Coordinating voluntary movements
Maintaining balance and posture
Fine-tuning motor activities
Predicting the movement outcomes for smooth execution
b) Medulla Oblongata
The medulla oblongata controls autonomic functions such as:
Heartbeat , Breathing, Blood pressure, Reflex actions like swallowing and coughing, sneezing
c) Pons The pons serve as a bridge between different parts of the brain,
facilitating communication between the cerebellum and cerebrum. It regulates:
Sleep cycles, Respiration rate ,Sensory processing like taste and hearing

Q) Give function of mid brain.

A) Contributing to reflexive movements of the head and eyes.
Q) How is brain and spinal cord protected?
A) a) The brain is encased in the skull (cranium), while the spinal cord is protected by the vertebral column
(backbone).
b) Meninges, three layers of connective tissue, surround and cushion both the brain and spinal cord.
c) Cerebrospinal fluid , a clear fluid, acts as a shock absorber within the meningeal layers, further
protecting the brain and spinal cord from impacts.

Q) What is synapse? What happens at synapse?

A) Synapse-- A synapse is the small gap or junction between the axon terminal of one neuron and the dendrite
or cell body of another neuron.
• How it works:
When an electrical impulse (action potential) reaches the axon terminal of a neuron (presynaptic neuron), it
triggers the release of neurotransmitters into the synaptic cleft (the space between the neurons).
• Neurotransmitter Release:
Neurotransmitters are chemical messengers that travel across the synaptic cleft and bind to receptors on the
dendrites or cell body of the next neuron (postsynaptic neuron).
• Signal Transmission:
The binding of neurotransmitters to the receptors on the postsynaptic neuron triggers a new electrical impulse
(action potential) in that neuron, continuing the signal transmission.
• Direction of Signal:
The signal always travels in one direction across the synapse, from the presynaptic neuron to the postsynaptic
neuron, acting like a one-way valve.
• Role of Neurotransmitters:
Neurotransmitters can be excitatory (promoting the firing of the postsynaptic neuron) or inhibitory (preventing
the firing of the postsynaptic neuron).

Q) What is neuromuscular junction?What happens at neuromuscular junction?

A) The neuromuscular junction (NMJ) is a specialized synapse where a motor neuron communicates with a
skeletal muscle fiber to initiate muscle contraction. It's where nerve impulses are converted into electrical
signals in the muscle, ultimately leading to muscle contraction.

Here's a breakdown of what happens at the neuromuscular junction:

1. Nerve Impulse Arrival:
A nerve impulse (action potential) travels down the motor neuron and reaches its terminal, triggering the
opening of voltage-gated calcium channels.
2. Calcium Influx:
Calcium ions rush into the nerve terminal, promoting the release of acetylcholine from synaptic vesicles.
3. ACh Release and Binding:
ACh diffuses across the synaptic cleft and binds to specific ACh receptors on the muscle cell membrane
4. End-Plate Potential:
ACh binding opens sodium channels on the muscle membrane, leading to a localized depolarization called the
end-plate potential.
5. Action Potential Trigger:
If the end-plate potential reaches a threshold, it triggers an action potential in the muscle fiber.
6. Muscle Contraction:
The action potential propagates along the muscle fiber, leading to muscle contraction via the sliding filament
mechanism.