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 Class 11 Biology – Assertion-Reason Based Question Paper

Chapters Covered:

1. Locomotion and Movement

2. Neural Control and Coordination

3. Chemical Coordination and Integration (Endocrine System)

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Instructions:

Each question consists of an Assertion (A) and a Reason (R).

Choose the correct option:

(a) Both A and R are true, and R correctly explains A.

(b) Both A and R are true, but R does not correctly explain A.

(c) A is true, but R is false.

(d) A is false, but R is true.

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Section 1: Locomotion and Movement

Q1.

Assertion (A): Skeletal muscles work in antagonistic pairs.

Reason (R): When one muscle of the pair contracts, the other muscle relaxes to produce movement.

Q2.

Assertion (A): Actin and myosin are the two main proteins involved in muscle contraction.

Reason (R): Myosin binds to actin filaments and pulls them using ATP, causing muscle relaxation.

Q3.

Assertion (A): Calcium ions play a crucial role in muscle contraction.

Reason (R): Calcium ions bind to troponin, causing a conformational change that exposes myosin-binding sites on actin filaments.

Q4.

Assertion (A): Arthritis is a condition affecting the synovial joints.

Reason (R): It is caused by excessive secretion of synovial fluid, leading to increased joint flexibility.

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Section 2: Neural Control and Coordination

Q5.

Assertion (A): The cerebrum is responsible for voluntary actions and higher cognitive functions.

Reason (R): The cerebrum contains the medulla oblongata, which controls involuntary actions like breathing and heartbeat.

Q6.

Assertion (A): Reflex actions occur quickly and do not require brain involvement.

Reason (R): Reflex arcs are processed at the spinal cord level for faster response.

Q7.

Assertion (A): The myelin sheath increases the speed of nerve impulse conduction.

Reason (R): The myelin sheath allows continuous conduction of nerve impulses along the axon.

Q8.

Assertion (A): Synaptic transmission occurs through neurotransmitters like acetylcholine.

Reason (R): Neurotransmitters help in the conduction of electrical signals directly from one neuron to another without any gap.

Q9.

Assertion (A): The autonomic nervous system is divided into sympathetic and parasympathetic divisions.

Reason (R): The sympathetic nervous system is responsible for "rest and digest" functions, while the parasympathetic system controls "fight or flight" responses.

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Section 3: Chemical Coordination and Integration (Endocrine System)

Q10.

Assertion (A): The hypothalamus controls the secretion of hormones from the pituitary gland.

Reason (R): The hypothalamus secretes releasing and inhibiting hormones that regulate the anterior pituitary gland.

Q11.

Assertion (A): Insulin is responsible for reducing blood glucose levels.

Reason (R): Insulin stimulates glycogenolysis, converting glycogen into glucose.

Q12.

Assertion (A): The thyroid gland regulates the body's basal metabolic rate (BMR).

Reason (R): Hyperthyroidism can lead to weight gain and sluggish metabolism.

Q13.

Assertion (A): Parathyroid hormone (PTH) increases blood calcium levels.

Reason (R): PTH promotes calcium absorption from the intestines, reabsorption in kidneys, and calcium release from bones.

Q14.

Assertion (A): The adrenal medulla secretes adrenaline and noradrenaline.

Reason (R): These hormones help the body respond to stress by increasing heart rate and blood pressure.

Q15.

Assertion (A): Growth hormone (GH) is secreted by the anterior pituitary gland.

Reason (R): Excess secretion of GH in adulthood leads to gigantism.

This Assertion-Reason Based Question Paper covers key concepts from Locomotion and Movement, Neural Control and Coordination, and Endocrine System. Let me know if you need modifications!