A. Structural and functional -unit of a myofibril - (iii) Sarcomere

B. Protein of thin filament - (iv) Actin

C. Protein of thick filament - (ii) Myosin

The sarcomeres are fibrous protein filaments that slide past one another when the muscle contracts or relaxes. It is basically the region between two Z-bands. It is also the functional unit of the contractile system in a striated muscle.

So, the correct answer is 'sarcomere'.

Actin is the thin filament in the sarcomere, comprising F-actin, tropomyosin and troponin protein, troponin is attached to tropomyosin, while myosin is a thick filament.

A stimulus is something that causes a physiological response. The ability of an organism or organ to respond to external stimuli is called sensitivity. So, in the above example, the response to stimulus is drawing out hand and not pricking with pin, only pin or hand.

A stimulus is something that causes a physiological response. The ability of an organism or organ to respond to external stimuli is called sensitivity. So, in the above example, the stimulus is pricking with pin and not drawing out hand, only pin or hand. 

• In physiology, a stimulus is a detectable change in the internal or external environment. The ability of an organism or organ to respond to external stimuli is called sensitivity. 
• When a stimulus is applied to a sensory receptor, it normally elicits or influences a reflex. Hence, Internal stimulus comes from

The fixed action patterns to specific stimuli which activate nervous system making the muscular action without any involvement of brain in decision making are known as innate behaviours. Being genetically determined, these responses are nearly alike in all members of a population. 

• The stimulus(singular) is any change in the organism's internal or external environment that causes the organism to react. It is of two types external and internal.
• External stimulus is the stimulus that comes outside of the organism. For example, Light stimulus, heat stimulus, chemical stimulus, etc.
• The internal stimulus is the stimulus that comes from inside an organism. For example, Hunger, thirst, etc.
• Hence Hunger is Internal stimuli.
• So, the correct answer is 'Internal stimuli'.

• The stimulus(singular) is any change in the organism's internal or external environment that causes the organism to react. It is of two types external and internal.
• External stimulus is the stimulus that comes outside of the organism. For example, Light stimulus, heat stimulus, chemical stimulus, sound stimulus, etc.
• The internal stimulus is the stimulus that comes from inside an organism. For example, Hunger, thirst, etc.
• So, the correct answer is 'All of the above'.

• The olfactory receptor neurons are located in a small region within the superior nasal cavity. This region is referred to as the olfactory epithelium.
• When the airborne molecules are inhaled through the nose, they pass over the olfactory epithelial region and the olfactory receptors are stimulated and in turn, the smell is perceived.
• Hence A stimulus for the olfactory receptor is smell.
• So, the correct answer is 'Smell'.

• In physiology, a stimulus is a detectable change in the internal or external environment. The ability of an organism or organ to respond to external stimuli is called sensitivity. 
• When a stimulus is applied to a sensory receptor, it normally elicits or influences a reflex. Hence, Example of stimulus is Hunger, Sadness and Ache.
So, the correct answer is 'All of the above'.

• The stimulus(singular) is any change in the organism's internal or external environment that causes the organism to react.
• The ability of an organism to respond to external stimuli is called sensitivity. For example, Plants grow towards light(external stimuli) sources, and if the direction of light is changed, the plant will also change its direction of growth to accommodate for survival.
  
• So, the correct answer is 'Sensitivity'.

• Nociceptors are sensory receptors which detect signals from damaged tissue 
• These receptors detect the damaged tissue or threat of damage to tissue and send signals to the spinal cord and the brain.
• Examples for Nociceptive pain includes  sprains, bone fractures, burns, bumps, bruises, inflammation .
• Hence Nociceptors detect 'Tissue damage'.
• So, the correct answer is 'Tissue damage'.

• A receptor is a protein molecule usually found embedded in the plasma membrane surface of the cell that receives chemical signals from outside the cell and when such chemical signals bind to the receptor, They cause some form of cellular or tissue response.
• There are four main types of receptors: mechanoreceptors(touch and pressure), thermoreceptors(heat), pain receptors(pain), and proprioceptors(position and movement).
• Hence Receptors to both touch and pressure are called as Mechanoreceptors.
• So, the correct answer is 'Mechanoreceptors'.