CONTROL AND CO-ORDINATION: Long Answer Type Question for Class 10th Chapter 10 JKBOSE/NCERT
Question 1: Describe the scheme of how nervous impulses travel in the body.
Ans: The scheme of how nervous impulses travel in the body can be described as follows:
The process begins with the stimulation of sensory receptors located throughout the body. These receptors detect changes in the environment or internal conditions and convert them into electrical signals called nerve impulses or action potentials.
The nerve impulses are then transmitted to the sensory neurons, which are specialized cells that carry these signals towards the central nervous system (CNS), which consists of the brain and spinal cord.
Within the CNS, the sensory information is processed, integrated, and interpreted. This involves the transfer of signals between different regions of the brain and the generation of appropriate responses.
After processing, the motor neurons, another type of specialized nerve cells, receive the signals from the CNS and carry them to the effectors, which can be muscles or glands.
In the case of muscle effectors, the motor neurons stimulate muscle contraction, leading to movement. If the effectors are glands, the motor neurons stimulate the release of specific hormones or other substances.
This coordinated transmission of nerve impulses from sensory receptors to the CNS and then to effectors allows for rapid and precise control of various bodily functions and responses.
Question 2: How does the nervous tissue cause action?
Ans: Nervous tissue causes action through the following mechanism:
Nervous tissue consists of specialized cells called neurons, which are the functional units of the nervous system. Neurons transmit electrical signals called nerve impulses, which enable communication and coordination within the body.
The action potential, or nerve impulse, is generated when there is a change in the electrical charge across the cell membrane of a neuron. This change is initiated by a stimulus, which can be external or internal.
Once the action potential is initiated in a neuron, it propagates along the length of the neuron, from the dendrites (input) to the axon (output) through a process called electrochemical signalling.
When the nerve impulse reaches the end of the neuron’s axon, it triggers the release of chemical messengers called neurotransmitters into the synapse, which is the small gap between the neuron and its target cell.
The neurotransmitters then bind to specific receptors on the target cell, which can be another neuron, a muscle cell, or a glandular cell.
The binding of neurotransmitters to receptors on the target cell initiates a response, which can be the generation of a new action potential in another neuron, contraction of a muscle, or secretion of a specific substance from a gland. This response is how nervous tissue causes action in the body.
Question 3: What is the difference between how movement takes place in a sensitive plant and movement in our legs?
Ans: The difference between movement in a sensitive plant (Mimosa pudica) and movement in our legs can be described as follows:
Movement in a sensitive plant: The movement in a sensitive plant is known as thigmonasty, and it is a rapid plant movement in response to touch or mechanical stimulation. When the sensitive plant’s leaves are touched, they rapidly fold up and droop. This response is due to changes in turgor pressure in specialized cells called pulvinus located at the base of each leaflet. The movement occurs within minutes and is reversible. It is a protective mechanism to defend against potential harm or to reduce water loss.
Movement in our legs: The movement in our legs involves the contraction and relaxation of muscles, controlled by the nervous system. The nervous system sends electrical signals from the brain or spinal cord to the muscles, causing them to contract or relax, leading to movement. The movement in our legs is voluntary and allows us to walk, run, jump, and perform various activities. It is controlled by the conscious control of our skeletal muscles through the motor neurons of the somatic nervous system.
Question 4: State how the concentration of auxin stimulates the cells to grow longer on the side of the shoot which is away from the light.
Ans: The concentration of auxin stimulates the cells to grow longer on the side of the shoot away from the light through a process called phototropism. Here’s how it works:
When light is received by a plant shoot, it causes the movement of auxin hormone from the illuminated side to the shaded side of the shoot.
The accumulation of auxin on the shaded side promotes cell elongation and growth in that region.
Auxin stimulates the synthesis of proteins called expansins, which loosen the cell wall structure.
As a result, the cell walls on the shaded side become more flexible, allowing the cells to elongate more readily compared to the cells on the illuminated side.
This differential growth between the shaded and illuminated sides causes the shoot to bend towards the light.
The elongation of cells on the shaded side and the resulting bending of the shoot towards the light maximize light exposure and enhance photosynthesis in the plant.
Question 5: Nervous and hormonal systems together perform the function of control and coordination in human beings. Justify the statement.
Ans: The statement that the nervous and hormonal systems together perform the function of control and coordination in human beings is justified because:
The nervous system coordinates rapid and precise responses to external and internal stimuli. It uses electrical impulses to transmit signals between different parts of the body, allowing for quick communication and immediate action. The nervous system controls voluntary and involuntary movements, sensory perception, and cognitive functions.
The hormonal system, also known as the endocrine system, regulates various physiological processes and maintains homeostasis in the body. It involves the secretion of hormones by endocrine glands, which are then released into the bloodstream and carried to target cells or organs. Hormones act as chemical messengers, coordinating and controlling functions such as growth, metabolism, reproduction, and stress response.
The nervous and hormonal systems work in harmony to ensure effective control and coordination in the body. While the nervous system provides rapid and short-term responses, the endocrine system modulates longer-term processes and maintains overall balance. These systems often interact and influence each other’s activities to achieve optimal functioning and adaptability in response to changing conditions. Together, they regulate bodily functions, enable responses to stimuli, and ensure coordination among different organs and systems.
Question 6: Write the names of five animal hormones, the endocrine glands that secrete them and their specific functions.
Ans: Five animal hormones, their endocrine glands, and their specific functions are:
1. Insulin: Secreted by the pancreas. It regulates blood glucose levels by facilitating the uptake of glucose from the bloodstream into cells, thereby reducing blood sugar levels.
2. Thyroxine (T4) and Triiodothyronine (T3): Secreted by the thyroid gland. They regulate metabolism, growth, and development in the body.
3. Adrenaline (Epinephrine): Secreted by the adrenal glands. It plays a role in the “fight or flight” response, increasing heart rate, blood pressure, and energy availability during times of stress or danger.
4. Growth Hormone: Secreted by the pituitary gland. It promotes growth, regulates body composition, and stimulates the production of insulin-like growth factor (IGF-1).
5. Testosterone: Secreted by the testes (in males) and in small amounts by the ovaries (in females). It is the primary male sex hormone and is involved in the development of male reproductive tissues, secondary sexual characteristics, and overall muscle and bone health.
Question 7: (i) Do you know anyone in your family or friends who has been advised to take less sugar by the doctor and why?
(ii) Name the hormone which regulates blood sugar levels.
(iii) Name the gland from where it is secreted.
(iv) Name the disease associated with an imbalance in blood sugar levels.
Ans: (i) Yes, I know someone who has been advised to take less sugar by the doctor. Excessive sugar intake can lead to various health issues, such as obesity, diabetes, dental problems, and an increased risk of heart disease. Limiting sugar consumption is important for maintaining overall health and managing these conditions.
(ii) The hormone that regulates blood sugar levels is insulin.
(iii) Insulin is secreted by the pancreas.
(iv) The disease associated with an imbalance in blood sugar levels is diabetes, which can be characterized by high blood sugar (hyperglycemia) due to insufficient insulin production or the body’s inability to use insulin effectively.
Question 8: What are the main parts of the brain? Write their functions.
Ans: The main parts of the brain and their functions are:
1. Cerebrum: It is the largest part of the brain and is responsible for higher cognitive functions, such as memory, thinking, reasoning, perception, and voluntary movements.
2. Cerebellum: It is involved in coordinating voluntary muscle movements, maintaining balance, and controlling posture.
3. Brainstem: It includes the midbrain, pons, and medulla oblongata. The brainstem is responsible for regulating vital functions such as breathing, heart rate, blood pressure, and consciousness.
4. Hypothalamus: It plays a key role in maintaining homeostasis by regulating body temperature, hunger, thirst, sleep, and the release of hormones from the pituitary gland.
5. Pituitary Gland: Often called the “master gland,” it controls the release of various hormones that regulate growth, metabolism, reproduction, and other functions in the body.
Question 9: State the functions of major plant hormones.
Ans: The major plant hormones and their functions are:
1. Auxins: They promote cell elongation, control phototropism and gravitropism, and stimulate root development.
2. Gibberellins: They stimulate stem elongation, promote seed germination, and regulate flowering and fruit development.
3. Cytokinins: They promote cell division and growth, delay senescence (aging) in leaves, and regulate nutrient transport.
4. Abscisic Acid: It regulates seed dormancy, promotes stomatal closure during water stress, and inhibits growth.
5. Ethylene: It regulates fruit ripening, senescence, and abscission (shedding) of leaves, flowers, and fruits.
Question 10: How are involuntary action and reflex action different from each other?
Ans: Involuntary actions and reflex actions differ in the following ways:
1. Involuntary actions: These are automatic actions that occur without conscious control. They are regulated by the autonomic nervous system and occur in response to internal stimuli or external factors. Examples include the beating of the heart, digestion, and secretion of hormones.
2. Reflex actions: These are rapid, automatic, and protective responses to specific stimuli. They involve the spinal cord and occur without involving the conscious brain. Examples include pulling the hand away from a hot object or blinking in response to a bright light.
The main difference lies in the involvement of conscious control and the level of complexity in the processing of information. Involuntary actions are ongoing, continuous processes that regulate bodily functions, while reflex actions are immediate responses to specific stimuli aimed at ensuring survival and avoiding harm.
Question 11: How does phototropism occur in plants? Write an experiment to show the growth of plants towards light.
Ans: Phototropism is the growth response of plants to light. It occurs due to the redistribution of auxin, a plant hormone, in response to light direction and intensity. When light is perceived by the plant, auxin accumulates on the shaded side, causing cells to elongate and the plant to bend towards the light source.
To demonstrate the growth of plants towards the light, you can set up the following experiment:
Materials:
1. Potted plant (e.g., a small seedling)
2. Light source (e.g., a desk lamp)
3. Timer or clock
4. Ruler or measuring tape
Procedure:
1. Place the potted plant in a location with uniform light intensity, preferably in a room with a window.
2. Position the light source (lamp) at a fixed distance from the plant.
3. Ensure that the light is directed towards one side of the plant, leaving the other side shaded.
4. Mark the initial position of the plant and measure the distance from the light source.
5. Set a timer or note the start time.
6. Allow the plant to grow for a specific duration (e.g., 24 hours).
7. After the allotted time, measure the new position of the plant from its initial position.
8. Record the distance the plant has moved towards the light source.
By comparing the initial and final positions of the plant, you should observe that the plant has grown and bent towards the light source, demonstrating the phototropic response.
Question 12: What is the function of receptors in our body? Think of situations where receptors do not work properly, what problems are likely to arise?
Ans: Receptors in our body are specialized cells or structures that detect and respond to stimuli from the environment or within the body. They play a crucial role in sensory perception and relay information to the nervous system.
When receptors do not work properly, it can lead to various problems depending on the specific receptors affected. Here are a few examples:
A. Loss of vision: Malfunctioning of the photoreceptors in the eyes can lead to visual impairments or blindness.
B. Hearing loss: Dysfunction of the auditory receptors in the inner ear can result in hearing loss or deafness.
C. Reduced sense of touch: Impaired receptors in the skin can diminish the ability to sense temperature, pressure, or pain.
D. Altered taste and smell perception: Dysfunction of taste buds or olfactory receptors can affect the ability to taste or smell properly.
E. Balance and spatial orientation issues: Problems with receptors in the inner ear responsible for detecting motion and maintaining balance can cause dizziness, vertigo, or difficulties with coordination.
In general, when receptors do not work properly, it can disrupt the transmission of sensory information to the brain, leading to sensory deficits, impaired perception, or difficulties in coordinating responses to the environment.
Question 13: What is meant by reflex action? With the help of a labelled diagram trace the sequence of events which occur when we touch a hot object.
Ans: Reflex action refers to an automatic, involuntary response to a stimulus, which occurs without conscious thought or decision-making. These responses are mediated by the spinal cord or lower brain centres, allowing for swift reactions to potentially harmful or threatening situations.
Here is a labelled diagram tracing the sequence of events when we touch a hot object:
Stimulus: Hot object contacts the skin.
Receptor: Thermoreceptors in the skin detect heat.
Sensory Neuron: The sensory neuron transmits the signal to the spinal cord.
Interneuron: The sensory neuron synapses with an interneuron in the spinal cord.
Motor Neuron: The interneuron activates a motor neuron.
Effector: The motor neuron carries the signal to the muscles.
Response: The muscles contract, causing the hand to quickly withdraw from the hot object.
This rapid reflex action helps protect the body from potential harm by minimizing the duration of contact with the hot object, preventing further damage or injury.
Question 14: What are the functions carried out by the nervous system in human beings
Ans: The nervous system in human beings performs several vital functions, including:
A. Sensory Input: The nervous system receives and processes information from sensory receptors, allowing us to perceive and respond to various stimuli from the environment.
B. Integration: It integrates and processes sensory information, combining it with stored memories and prior experiences to generate appropriate responses.
C. Motor Output: The nervous system sends signals to muscles and glands, initiating voluntary and involuntary movements or secretions.
D. Control and Coordination: It coordinates and regulates the functions of different body systems, maintaining homeostasis, and controlling body temperature, heart rate, blood pressure, and other physiological processes.
E. Cognitive Functions: The nervous system enables cognitive functions such as thinking, learning, memory, problem-solving, and decision-making.
F. Communication: It facilitates communication between different parts of the body through electrical impulses and chemical signals transmitted via neurons and neurotransmitters.
G. Reflexes: The nervous system coordinates reflex actions, allowing for quick, involuntary responses to potentially harmful or dangerous stimuli.
Overall, the nervous system plays a crucial role in our ability to perceive, process, and respond to the world around us, ensuring our survival, well-being, and cognitive functioning.