Lakhmir Singh Test: Control & Coordination - UPSC MCQ

Pituitary gland is called master gland because it controls the secretion of all other endocrine glands.

Cerebral is centre of thinking, will power, reasoning and memory, experience and learning knowledge and articulate speech.

The cerebellum is located behind the brain stem. While the frontal lobe controls movement, the cerebellum " fine - tunes " this movement. This area of the brain is responsible for fine motor movement, balance and thr brain's ability to determine limb position.

The cerebrum, the large, outer part of the brain, controls reading, thinking, learning, speech , emotions and planned muscle movements like walking.

Synapse, also called Neuronal junction, the site of transmission of electric nerve impulses between two nerve cells or between a neuron and a gland or muscle cell.

Olfactory means related to smell hence olfactor receptors help to respond to smell.

The central nervous system (CNS) controls most functions of the body and mind. It consists of two parts: the brain and the spinal cord.

The brain is the center of our thoughts, the interpreter of our external environment, and the origin of control over body movement. Like a central computer, it interprets information from our eyes (sight), ears (sound), nose (smell), tongue (taste), and skin (touch), as well as from internal organs such as the stomach.

Control and coordination are provided by nervous and muscular tissues in animals.

Information is acquired at the end of the dendritic tip of a nerve cell.

Gustatory receptors detect taste while olfactory receptors detect smell.

Sensory information travels from the body to the spinal cord before reaching the brain. This information ascends upwards using first, second, and third-order neurons. 

The peripheral nervous system facilitates communication between the central nervous system and other parts of the body.

Plants respond to stimuli by changing cell shape and direction of growth.

The leaves of a sensitive plant move in response to touch by changing cell shape.

Plants communicate information between cells via hormonal secretions.

Auxin promotes cell elongation in response to light.

1. Tendrils are sensitive in nature.
2. They mainly respond to touch by growing and winding around the object.
3. The coiling mechanism occurs when the part of the tendril which touches the object stops growing.
4. Thus, the remaining part grows faster because of the plant hormone auxin which cause the coiling effect.
5. Auxin stimulates cell growth on the opposite side so that the coil forms rapidly.
6. The coiled portion of the tendrils is later concentrated with sclerenchyma cells to provide rigidity.
7. The twining tendency of the tendril causes it to encircle or coil around the object it comes in contact with.

Directional growth movements in response to stimuli are termed as tropism.

Abscisic acid inhibits growth in plants.

Auxin concentration increases on the shaded side of the plant.

• Plants react to gravity with a process called gravitropism or geotropism.
• Roots:
  • Positive Gravitropism: Roots grow downward towards gravity to anchor the plant and get water and nutrients.
• Stems and Shoots:
  • Negative Gravitropism: Stems and other above-ground parts grow upwards, opposite to gravity, to reach light for photosynthesis.
• This reaction to gravity is controlled by special cells called statocytes, housing dense structures termed statoliths.
• These statoliths settle at the base of statocytes due to gravity, prompting chemical signals guiding plant tissue growth.
• Overall, plants utilize gravitropism to position their growth correctly: roots head down for stability and nourishment, while stems and shoots grow up for light exposure.

Gibberellins are a group of plant hormones that regulate various growth and development processes. Their main function is to stimulate cell elongation, making plants grow taller.

Plants detect light for directional growth movements by sensing changes in light intensity.

Hormonal secretions cause the directional movement of plant parts in response to environmental triggers.