Control And Coordination - Practice Test, Class 10 Science - Class 10 MCQ

The junction between two neurons is called a synapse.
The synapse is a specialized structure that allows neurons to communicate with each other. It is a small gap between the axon of one neuron and the dendrite or cell body of another neuron. Here is a detailed explanation of the synapse:
1. Definition of a synapse:
- A synapse is a junction or connection point where two neurons meet.
- It is the site where one neuron releases chemical messengers called neurotransmitters, which then bind to receptors on the other neuron.
2. Structure of a synapse:
- Presynaptic neuron: The neuron that sends the signal.
- Postsynaptic neuron: The neuron that receives the signal.
- Synaptic cleft: The small gap between the presynaptic and postsynaptic neurons.
- Axon terminal: The end of the presynaptic neuron where neurotransmitters are released.
- Receptor sites: Proteins on the postsynaptic neuron that bind to neurotransmitters.
3. Process of synaptic transmission:
- Action potential: When an electrical signal reaches the end of the axon terminal, it triggers the release of neurotransmitters.
- Neurotransmitter release: The neurotransmitters are released into the synaptic cleft.
- Diffusion: The neurotransmitters diffuse across the synaptic cleft.
- Binding: The neurotransmitters bind to the receptor sites on the postsynaptic neuron.
- Signal transmission: The binding of neurotransmitters to the receptors triggers a response in the postsynaptic neuron, either exciting or inhibiting its activity.
4. Types of synapses:
- Chemical synapse: The most common type of synapse, where neurotransmitters are released and bind to receptors.
- Electrical synapse: A less common type of synapse, where electrical signals pass directly between neurons through gap junctions.
In conclusion, the junction between two neurons is called a synapse. It is a crucial structure for transmitting signals and allowing communication between neurons.

The hormone which increases fertility in males is called Testosterone.
Testosterone is a hormone that plays a crucial role in male fertility and reproductive function. It is primarily produced in the testes and is responsible for the development of male sexual characteristics and the production of sperm.
Here are some key points about testosterone and its role in male fertility:
1. Testosterone production: The testes are responsible for producing testosterone, which is regulated by the pituitary gland in the brain. The production of testosterone increases during puberty and continues into adulthood, ensuring the development and maintenance of male reproductive organs and secondary sexual characteristics.
2. Sperm production: Testosterone plays a vital role in the production of sperm. It stimulates the seminiferous tubules in the testes, where sperm cells are produced. Adequate levels of testosterone are necessary for healthy sperm production and fertility.
3. Libido and sexual function: Testosterone also influences male sexual desire (libido) and sexual function. It helps maintain sexual arousal, erectile function, and overall sexual performance.
4. Muscle and bone health: Testosterone is an anabolic hormone that promotes muscle growth and helps maintain bone density. It is crucial for the development of lean muscle mass and strength, contributing to overall physical well-being.
5. Regulation of other hormones: Testosterone interacts with other hormones, such as luteinizing hormone (LH) and follicle-stimulating hormone (FSH), to regulate the production of sperm and maintain hormonal balance in the male reproductive system.
In summary, testosterone is the hormone responsible for increasing fertility in males. It plays a vital role in sperm production, sexual function, muscle development, and overall reproductive health.

Answer:
The activities of the internal organs are controlled by the autonomic nervous system. Here is a detailed explanation:
Autonomic Nervous System:
- The autonomic nervous system (ANS) is a division of the peripheral nervous system that controls the involuntary functions of the internal organs.
- It regulates processes such as heart rate, digestion, respiratory rate, and blood pressure.
- The ANS works in conjunction with the central nervous system (CNS) to maintain homeostasis in the body.
Central Nervous System:
- The central nervous system consists of the brain and spinal cord.
- It receives, processes, and interprets information from the sensory organs and sends out signals to the rest of the body.
- While the CNS plays a crucial role in overall body control, it does not directly control the activities of the internal organs.
Peripheral Nervous System:
- The peripheral nervous system includes all the nerves and ganglia outside of the CNS.
- It is divided into the somatic nervous system and the autonomic nervous system.
- The somatic nervous system controls voluntary movements, while the autonomic nervous system controls involuntary functions.
Conclusion:
In conclusion, the activities of the internal organs are primarily controlled by the autonomic nervous system. While the central nervous system plays a role in overall body control, it is the autonomic nervous system that specifically regulates the functioning of the internal organs.

Plant Hormone:


There are several types of plant hormones that regulate various physiological processes in plants. Among the given options, the correct answer is B: Cytokinin. Here is a detailed explanation:
Thyroxin:
Thyroxin is not a plant hormone. It is a hormone produced by the thyroid gland in vertebrates, including humans. It regulates metabolism and growth in animals, not plants.
Cytokinin:
Cytokinin is a plant hormone that plays a crucial role in plant growth and development. It is responsible for promoting cell division and differentiation, as well as regulating various physiological processes in plants. Cytokinins are involved in promoting shoot formation, delaying senescence, and stimulating root growth.
Insulin:
Insulin is a hormone produced by the pancreas in animals, including humans. It regulates blood sugar levels and is not involved in plant physiology.
Oestrogen:
Oestrogen is a hormone found in animals, including humans. It is responsible for regulating the development and functioning of the female reproductive system. Oestrogen does not play a role in plant physiology.
In conclusion, of the given options, only cytokinin is a plant hormone. It is involved in regulating various processes such as cell division, shoot and root growth, and delaying senescence in plants.

Tropic movements:
Tropic movements are directional growth responses exhibited by plants in response to external stimuli. These movements are essential for plants to adapt and optimize their growth and survival in their environment. There are several types of tropic movements, including phototropism (response to light) and gravitropism (response to gravity).
Key points:
- Tropic movements are directional growth responses exhibited by plants.
- They are essential for plants to adapt to their environment.
- There are different types of tropic movements.
- Phototropism is a tropic movement in response to light.
- Gravitropism is a tropic movement in response to gravity.
- Tropic movements are uni-directional, meaning they occur in a specific direction.
- Tropic movements help plants optimize their growth and survival.
Overall, tropic movements in plants play a crucial role in their growth and adaptation to the environment. They allow plants to respond to external stimuli such as light and gravity, enabling them to optimize their growth and survival strategies.

Auxins promote cell enlargement and cell differentiation in plants leading to growth. They are produced by cells at the tip of stem and roots. They can also drastically affect plant orientation by promoting cell division in one side of the plant in response to sunlight and gravity.

Why Mimosa Leaves are Sensitive to Touch?

• Thigmonasty: Mimosa leaves exhibit a phenomenon called thigmonasty, which is a response to touch or physical disturbance. When the leaves are touched, they quickly fold up and droop as a defense mechanism.


• Protective Mechanism: This sensitivity to touch helps the plant protect itself from potential harm like herbivores or strong winds. By closing up when disturbed, the plant reduces the risk of damage to its leaves.


• Rapid Response: Mimosa leaves are known for their rapid response to touch, showing movement within seconds of being touched. This quick reaction is essential for the plant's survival in its natural environment.


• Communication: The sensitivity of mimosa leaves to touch can also be considered a form of communication within the plant. It allows different parts of the plant to respond to stimuli and coordinate their actions for overall protection.

Answer: a) Brain and spinal cord

Thigmonastic Response in Plants
Thigmonastic response refers to the movement of plant parts in response to touch or mechanical stimulation. Among the given options, the plant that exhibits thigmonastic response is the insectivorous plants. Here's why:
Insectivorous Plants
- Insectivorous plants, such as Venus flytrap and sundew, show thigmonastic response as a mechanism to capture and digest insects for nutrient uptake.
- These plants have specialized structures, such as sensitive trigger hairs or tentacles, which can detect the presence of prey.
- When an insect touches these trigger hairs or tentacles, it triggers a rapid movement response, leading to the closure of leaf lobes or trapping of the prey.
- This movement is a thigmonastic response and is essential for the survival and nutrition of these plants.
Sunflower
- Sunflowers do not exhibit thigmonastic response as their movement is primarily driven by phototropism, which is the growth or movement of plants in response to light.
Lotus
- Lotus plants do not display thigmonastic response. They primarily rely on phototropism and nyctinasty (movement in response to light and darkness) for their growth and survival.
Bryophyllum
- Bryophyllum plants do not exhibit thigmonastic response. They are known for their ability to produce small plantlets along the margins of their leaves, a process called vegetative propagation.
In conclusion, among the given options, insectivorous plants are the ones that exhibit thigmonastic response.

Endocrine glands secrete hormones.
- Endocrine glands are specialized glands in the body that produce and release hormones directly into the bloodstream.
- Hormones are chemical messengers that travel through the bloodstream to target cells or organs, where they regulate various bodily functions.
- The endocrine system is responsible for maintaining homeostasis and coordinating activities such as growth, metabolism, reproduction, and response to stress.
- Some examples of endocrine glands include the pituitary gland, thyroid gland, adrenal glands, pancreas, and ovaries/testes.
- These glands produce and release specific hormones that have specific functions in the body.
- The hormones secreted by endocrine glands act on target cells or organs by binding to specific receptors and initiating a response.
- Hormones can have a wide range of effects on the body, including regulating growth and development, controlling metabolism, influencing mood and behavior, and maintaining fluid balance.
- Imbalances in hormone production or function can lead to various disorders and diseases, such as diabetes, thyroid disorders, and hormonal imbalances.
- Endocrine glands work in conjunction with the nervous system to regulate and coordinate bodily functions, ensuring the body functions properly and maintains equilibrium.

The complimentary system of the nervous system is the endocrine system.
The endocrine system is a complex network of glands that produce and secrete hormones directly into the bloodstream. These hormones act as chemical messengers and play a crucial role in regulating various bodily functions. Here are some key points to understand the relationship between the nervous system and the endocrine system:
1. Function: The nervous system and the endocrine system are both responsible for maintaining homeostasis and coordinating the activities of the body's organs and systems.
2. Communication: The nervous system uses electrical impulses to send rapid signals between cells, while the endocrine system uses hormones to transmit slower, chemical signals. Both systems work together to ensure proper communication and coordination throughout the body.
3. Interaction: The hypothalamus, a region of the brain, serves as a major link between the nervous system and the endocrine system. It produces hormones that regulate the release of hormones from the pituitary gland, which is often referred to as the "master gland" of the endocrine system.
4. Hormonal Control: The endocrine system controls many bodily functions, including growth, metabolism, reproduction, and response to stress. Hormones released by endocrine glands, such as the thyroid gland, adrenal glands, and pancreas, are essential for maintaining these functions.
5. Feedback Mechanisms: Both the nervous system and the endocrine system use feedback mechanisms to regulate their activities. Negative feedback loops help maintain balance and stability by detecting changes in hormone levels and adjusting their secretion accordingly.
In conclusion, the endocrine system works in conjunction with the nervous system to regulate and coordinate various physiological processes. While the nervous system uses electrical signals for rapid communication, the endocrine system relies on hormones for slower, long-lasting effects. Together, these systems ensure proper functioning and overall well-being.

Explanation:

• Medulla in hindbrain: The medulla oblongata, located in the hindbrain, is responsible for controlling many involuntary actions in the body.


• Involuntary actions: These include functions such as heartbeat, breathing, blood pressure regulation, and reflex actions.


• Connection to spinal cord: The medulla oblongata also serves as a bridge between the brain and spinal cord, allowing for communication between the two.


• Role in survival: The medulla oblongata plays a crucial role in maintaining homeostasis and ensuring the body's survival by regulating essential functions without conscious effort.


• Damage consequences: Damage to the medulla oblongata can have severe consequences, impacting vital bodily functions and potentially leading to serious health issues.

Statement Analysis:

A: Iron is essential for the synthesis of thyroxin

B: It regulates carbohydrates, protein, and fat metabolism in the body

C: Thyroid gland requires iodine to synthesize thyroxin

D: Thyroxin is also called thyroid hormone

From the given statements, we need to identify the one that is not true about thyroxin. Let's analyze each statement:

• Statement A: Iron is essential for the synthesis of thyroxin


• Statement B: It regulates carbohydrates, protein, and fat metabolism in the body


• Statement C: Thyroid gland requires iodine to synthesize thyroxin


• Statement D: Thyroxin is also called thyroid hormone

Now let's determine which statement is not true:

• Statement A: Iron is essential for the synthesis of thyroxin - This statement is not true. Iron is not directly involved in the synthesis of thyroxin. Iodine is the essential element required for the synthesis of thyroxin.


• Statement B: It regulates carbohydrates, protein, and fat metabolism in the body - This statement is true. Thyroxin plays a crucial role in regulating the metabolism of carbohydrates, proteins, and fats.


• Statement C: Thyroid gland requires iodine to synthesize thyroxin - This statement is true. The thyroid gland needs iodine to produce thyroxin.


• Statement D: Thyroxin is also called thyroid hormone - This statement is true. Thyroxin is indeed a type of thyroid hormone produced by the thyroid gland.

Therefore, the statement that is not true about thyroxin is Statement A, which states that iron is essential for the synthesis of thyroxin.

Answer:
The unpaired endocrine gland among the options given is the Pituitary gland.
Explanation:
The endocrine system consists of several glands that secrete hormones to regulate various bodily functions. Some of these glands are paired, meaning there is one on each side of the body, while others are unpaired, meaning there is only one.
Among the options given, the adrenal glands, testes, and ovaries are all paired glands. The adrenal glands are located on top of the kidneys and produce hormones such as cortisol and adrenaline. The testes, found in males, produce testosterone, while the ovaries, found in females, produce estrogen and progesterone.
On the other hand, the pituitary gland is an unpaired gland. It is often referred to as the "master gland" because it produces and releases several hormones that regulate other endocrine glands. The pituitary gland is located at the base of the brain and is divided into two parts: the anterior pituitary and the posterior pituitary.
In summary, among the given options, the unpaired endocrine gland is the pituitary gland.

Which hormone contains iodine?
The hormone that contains iodine is thyroxine.
Explanation:
- Thyroxine is a hormone produced by the thyroid gland.
- It is also known as tetraiodothyronine because it contains four iodine atoms.
- Thyroxine plays a crucial role in regulating metabolism and growth in the body.
- It helps in controlling the rate at which cells use energy and affects nearly every physiological process in the body.
- An inadequate intake of iodine can lead to a deficiency in thyroxine production, causing thyroid disorders such as hypothyroidism or goiter.
- Other hormones mentioned in the options do not contain iodine:
- Adrenaline is produced by the adrenal glands and does not contain iodine.
- Testosterone is a male sex hormone produced by the testes and does not contain iodine.
- Insulin is a hormone produced by the pancreas and does not contain iodine.
In conclusion, the hormone that contains iodine is thyroxine.

The Cerebellum Controls Posture and Balance
The correct answer is B: Cerebellum. The cerebellum is the part of the brain that primarily controls posture and balance. It is located at the back of the brain, underneath the cerebrum. Here is a detailed explanation of how the cerebellum functions in maintaining posture and balance:
1. Role of the Cerebellum:
- The cerebellum is responsible for coordinating voluntary movements, including those required for maintaining balance and posture.
- It receives information from various sensory systems, such as the inner ear (vestibular system), the eyes, and the muscles and joints.
- It integrates this sensory information with motor commands from the brain to adjust muscle activity and maintain balance.
2. Vestibulocerebellum:
- One part of the cerebellum, called the vestibulocerebellum or flocculonodular lobe, is specifically involved in balance control.
- It receives input from the vestibular system and helps to regulate eye movements and body posture in response to changes in head position or movement.
3. Spinocerebellum:
- Another part of the cerebellum, known as the spinocerebellum or vermis, plays a crucial role in maintaining posture.
- It receives input from the spinal cord and muscles, providing information about the position and tension of muscles.
- The spinocerebellum then adjusts muscle activity to ensure proper balance and stability.
4. Cerebrocerebellum:
- The cerebrocerebellum or lateral hemispheres of the cerebellum are involved in coordinating complex movements and motor planning.
- While it may not directly control posture and balance, it contributes to overall motor control and coordination, which indirectly affects posture.
In conclusion, the cerebellum is the part of the brain that controls posture and balance. It receives sensory input from various sources and uses this information to adjust muscle activity and maintain stability.

Artificial ripening of fruit is carried out by ethylene.
Explanation:

• Artificial ripening is the process of accelerating the natural ripening process of fruit.


• One of the most commonly used methods for artificial ripening is the application of ethylene gas.


• Ethylene is a plant hormone that regulates various physiological processes, including fruit ripening.


• When ethylene gas is applied to unripe fruit, it triggers a series of biochemical reactions that lead to the production of enzymes responsible for fruit ripening.


• These enzymes break down complex compounds in the fruit, such as starches, into simpler sugars, making the fruit sweeter and softer.


• Additionally, ethylene also promotes changes in color, aroma, and texture, which are characteristic of ripened fruit.


• Commercially, ethylene gas is often used to ripen fruits such as bananas, tomatoes, and avocados.

Answer: b) Central nervous system and peripheral nervous system

Blinking of eyes is not a reflex action, but it is an involuntary action.

The processes that conduct signals towards the nerve cell body are the dendrites.
Explanation:
Dendrites are the branch-like structures that extend from the cell body of a neuron. They receive signals from other neurons or sensory receptors and transmit these signals towards the cell body. Here's a detailed explanation of the statement:
1. Dendrites:
- Dendrites are the receiving end of a neuron.
- They are highly branched structures that project from the cell body.
- They have numerous small protrusions called dendritic spines, which increase the surface area for receiving signals.
2. Signal transmission:
- When a signal or impulse is received from another neuron, it travels along the dendritic branches.
- These signals can be either excitatory or inhibitory, depending on the neurotransmitters released by the presynaptic neuron.
3. Integration of signals:
- As the signals travel towards the cell body through the dendrites, they get integrated.
- If the sum of the signals reaches a certain threshold, the neuron generates an action potential or electrical impulse.
4. Axons and Fibres:
- Axons are another part of the neuron responsible for transmitting signals away from the cell body.
- They are long and slender extensions that carry the action potential from the cell body to other neurons or effector cells.
- Fibres, on the other hand, can refer to any type of nerve fibers, including both axons and dendrites.
5. Conclusion:
- While axons and fibers are involved in signal transmission away from the cell body, dendrites specifically conduct signals towards the nerve cell body.
- Therefore, the correct answer is option C: Dendrites.