Control & Coordination - 2 - Free MCQ Practice Test with solutions, UPSC

Involuntary actions in the body are primarily controlled by the medulla oblongata, a crucial part of the brain. This area is located in the hindbrain and plays a vital role in maintaining essential functions.

• The medulla oblongata regulates automatic processes such as breathing, heart rate, and blood pressure.
• It acts as a pathway for signals between the brain and spinal cord.
• This structure also controls reflex actions like swallowing, coughing, and sneezing.

Understanding the role of the medulla oblongata helps clarify how our body manages critical involuntary functions without conscious thought.

Neuromuscular junctions are between axon ending and muscles and junction between axon ending of one neuron and dendrites of another neuron is termed synapse.

Abscisic acid is generally associated with inhibiting growth, inducing dormancy, and helping the plant to withstand stress conditions such as drought. It is often referred to as a stress hormone or a growth inhibitor in plants, rather than a promoter of growth. On the other hand, auxins, gibberellins, and cytokinins are hormones that promote various aspects of plant growth and development.

The pancreas is the only unpaired endocrine gland in the human body. It plays a crucial role in regulating blood sugar levels by producing insulin and glucagon. Here are some key points about the pancreas:

• It is located behind the stomach.
• The pancreas has both endocrine and exocrine functions.
• As an endocrine gland, it releases hormones directly into the bloodstream.
• Insulin lowers blood sugar, while glucagon raises it.

Other glands, like the ovaries and testes, are paired, meaning there are two of each in the human body.

Statement A: Gustatory receptors detect taste while olfactory receptors detect smell

Explanation:

Receptors are specialized cells or structures that detect and respond to specific stimuli. In the case of taste and smell, there are specific receptors involved:

• Gustatory Receptors: These receptors are responsible for detecting taste. They are located primarily on the taste buds, which are found on the tongue and other parts of the oral cavity.


• Olfactory Receptors: These receptors are responsible for detecting smell. They are located in the olfactory epithelium, which is found in the upper part of the nasal cavity.

Therefore, Statement A: Gustatory receptors detect taste while olfactory receptors detect smell is the correct statement.

The question asks which action is not a natural reflex. The correct answer is salivation at the sight of food. Here's why:

• Knee-jerk, blinking due to strong light, and sneezing are all natural reflexes. They occur automatically without conscious thought.
• However, salivation at the sight of food is not a true reflex. It is a conditioned response where the brain anticipates eating and triggers salivation.

The correct answer is d

According to immunity theory, ageing is associated with the disappearance of the thymus gland by the late middle age in man and replaced by fat. It causes a weakening in the defense mechanisms of the body and in the course of time, leads to a large-scale decay and destruction of cells and tissues.

Excess secretion of growth hormone by pituitary gland causes gigantism while its deficiency causes dwarfism.

For secretion of thyroid, iodine is essential and not iron.

Pancreas are both exocrine and endocrine glands ; they are exocrine glands because they secrete products - pancreatic juice and endocrine because they secrete other substances directly into the blood stream. 

When the electrical impulse reaches the axon ending at synapse chemicals are released which on reaching the dendrite of next neuron again give rise to electrical impulse.

Cerebellum is responsible for maintenance of body balance and posture.

Abscisic acid  is a plant  hormone that plays important role abscission of leave. It inhibits  stem elongation by inhibiting gibberellic acid. It prevents loss of dormancy in seeds. 

Medulla is the last part of hind-brain, spinal cord arises from it.

Cytokinin are a class of plant growth substances that promote cell division, in plant roots and shoots. They are involved primarily in cell growth and differentiation, but also affect apical dominance, axillary bud growth. Cytokinin are the plant hormones which promote cell division in plants. So, the correct answer is " Stimulate cell division. "