Test: Control & Coordination - 2 - Class 10 MCQ

The Reflex Arc is the shortest pathway for an impulse to travel from the receptor organ via the central nervous system to the effector, allowing for quick and automatic reactions to stimuli, such as pulling back from something hot.

• Option A: Fore-brain - Controls posture and balance: This is incorrect. The fore-brain, specifically the cerebrum, is responsible for complex functions such as thinking, voluntary actions, memory storage, and sensory information integration.
• Option B: Mid-brain - Controls voluntary actions: This is incorrect. The mid-brain primarily controls involuntary actions such as changes in pupil size and reflex movements of the head, neck, and trunk.
• Option C: Hind-brain - Controls involuntary actions such as blood pressure: This is correct. The hind-brain, which includes the medulla, controls involuntary actions such as blood pressure, salivation, and vomiting.
• Option D: Cerebellum - Controls memory and thinking: This is incorrect. The cerebellum, part of the hind-brain, is responsible for controlling posture, balance, and the precision of voluntary actions, not memory and thinking.

The central nervous system (CNS) controls and coordinates body movements by processing sensory information and sending signals from the brain to the muscles. This enables both voluntary actions (like walking) and involuntary responses (like reflexes), ensuring smooth and balanced movements. Options A, C, and D pertain to other bodily systems, not the CNS's main functions.

• The Assertion (A) is true because the movement of tendrils around objects does indeed occur due to differential growth rates, where the part of the tendril that is further from the object grows more quickly, allowing the tendril to curl around the object.
• The Reason (R) is also true, as tendrils generally exhibit positive geotropism, which means they grow towards the ground.
• Despite both statements being true, the reason provided does not explain the assertion regarding how tendrils move around objects.
• Therefore, the correct answer is Option B.

• The type of movement that occurs in plants and is independent of growth is exemplified by the rapid leaf folding in sensitive plants, often referred to as the "Touch-me-not" plant.
• This movement is an immediate response to stimuli, specifically touch, and does not involve growth processes.
• Interestingly, while animals use a nervous system to respond to stimuli, plants rely on electrical-chemical signals and changes in cell water content to facilitate such movements.
• This unique mechanism showcases the adaptability of plants in interacting with their environment.

• The Assertion is correct because hormones indeed need to be released in specific quantities to maintain homeostasis and ensure proper bodily functions.
• The Reason is also correct as feedback mechanisms, such as those involving insulin and blood sugar levels, play a critical role in monitoring and adjusting hormone secretion.
• Furthermore, the Reason directly explains the Assertion, as these feedback systems are essential for achieving the precise hormone levels necessary for physiological balance.
• Therefore, both statements are true, and the Reason provides the correct explanation for the Assertion.

• Option A: (a) Cytokinins - Inhibit growth
  • Cytokinins actually promote cell division and are found in higher concentrations in fruits and seeds. Therefore, this pair is incorrectly matched.
• Option B: (b) Auxin - Promotes cell division
  • Auxin is primarily responsible for promoting cell elongation, especially at the shoot tip, and is involved in phototropism. It does not primarily promote cell division. Therefore, this pair is incorrectly matched.
• Option C: (c) Gibberellin - Growth of stem
  • Gibberellins are hormones that indeed promote the growth of the stem. Therefore, this pair is correctly matched.
• Option D: (d) Abscisic Acid - Promotes cell division
  • Abscisic Acid is known for inhibiting growth and causing the wilting of leaves. It is also known as the stress hormone. Therefore, this pair is incorrectly matched.

• Hence, the correctly matched pair is Option C: (c) Gibberellin - Growth of stem.

• The pancreas produces insulin, which plays a crucial role in regulating blood sugar levels by facilitating the uptake of glucose into the cells.
• This is essential for maintaining energy balance in the body.
• An interesting fact about insulin is that its discovery in 1921 revolutionized the treatment of diabetes, transforming it from a fatal disease to a manageable condition with proper care.

• Feedback systems are essential for regulating hormone secretion, ensuring that hormones are released in the precise amounts needed for proper bodily function.
• These systems react to fluctuations in the body's internal environment, such as blood sugar levels.
• For example, when blood sugar rises, the pancreas increases insulin production, and when levels drop, insulin secretion is decreased.
• This dynamic regulation helps maintain homeostasis, which is the body's state of stable internal conditions.
• An interesting fact is that the feedback mechanism can be classified as either negative or positive, with negative feedback being the most common in hormonal regulation, as it opposes changes to maintain balance.

The pituitary gland, often referred to as the master gland, regulates the functions of other endocrine glands and is crucial for maintaining hormonal balance in the body. Its ability to control various hormones makes it a key player in the endocrine system.

• Insulin is produced by the pancreas in response to rising blood sugar levels.
• This process is part of the body's feedback mechanism to regulate blood sugar.
• Insulin secretion corresponds to changes in blood glucose levels.
• When blood sugar levels rise, insulin is released to help lower them back to a normal range.

• The correctly matched pair is “Pancreas - Produces Insulin in response to high blood sugar levels”.
• When blood sugar levels rise, special cells in the pancreas, known as beta cells, sense this change and produce insulin to help lower the blood sugar levels back to normal.
• This is an example of a feedback mechanism that helps regulate hormone levels in the body.
• Options A and D are incorrect because glucagon is produced in response to low blood sugar levels, not high.
• Option C is incorrect because insulin production decreases when blood sugar levels fall, not rise.

• The Assertion (A) is correct because the nervous system indeed controls and coordinates body functions through the transmission of electrical impulses. This is a fundamental aspect of how the nervous system operates.
• However, the Reason (R) is incorrect. While the brain and spinal cord are major components of the central nervous system (CNS), the nervous system also includes peripheral nerves that extend from the CNS to other parts of the body. Thus, the Reason does not accurately explain the Assertion.
• Therefore, the correct answer is Option B: both Assertion and Reason are true, but Reason is not the correct explanation of Assertion.

• The assertion is correct because the pituitary gland does indeed regulate various endocrine glands, earning it the title of the master gland.
• The reason is also true, as the pituitary gland secretes several hormones including TSH (Thyroid Stimulating Hormone), ACTH (Adrenocorticotropic Hormone), and gonadotropins which affect the thyroid gland, adrenal glands, and gonads respectively.
• Therefore, the reason accurately explains why the assertion is true.
• Thus, the correct choice is Option A.

Let's analyze each option to determine which pair is correctly matched:

• Option A: (a) Pituitary Gland - Thyroxine
• This is incorrect. The Pituitary gland secretes Growth Hormone (GH), not Thyroxine. Thyroxine is secreted by the Thyroid gland.
• Option B: (b) Thyroid Gland - Insulin
• This is incorrect. The Thyroid gland secretes Thyroxine, not Insulin. Insulin is secreted by the Pancreas.
• Option C: (c) Pancreas - Glucagon
• This is correct. The Pancreas secretes both Insulin and Glucagon, which regulate blood sugar levels.
• Option D: (d) Adrenal Gland - Melatonin
• This is incorrect. The Adrenal glands secrete Adrenaline, not Melatonin. Melatonin is secreted by the Pineal gland.

Hence, the correctly matched pair is Option C: (c) Pancreas - Glucagon.