Question

Write note on root pressure, transpiration, nerve cell, human brain, reflex action

Answer 1

Root pressure

The Root pressure created in Root cells is called a Root Pressure. Root cells are in contact with water and minerals in the soil... but the concentration inside the cells and the concentration in the surrounding soil is different from each other and thus there is concentration gradient created.

Answer 2

please mark as brainliest


Root pressure is the transverse osmotic pressure within the cells of a root system that causes sap to rise through a plant stem to the leaves. Root pressure occurs in the xylem of some vascular plants when the soil moisture level is high either at night or when transpiration is low during the day.


Transpiration is the process of water movement through a plant and its evaporation from aerial parts, such as leaves, stems and flowers. Water is necessary for plants but only a small amount of water taken up by the roots is used for growth and metabolism. The remaining 97–99.5% is lost by transpiration and guttation


Many nerve cells are of the basic type illustrated above. Some kind of stimulus triggers an electric discharge of the cell which is analogous to the discharge of a capacitor. This produces an electrical pulse on the order of 50-70 millivolts called an action potential. The electrical impulse propagates down the fiber-like extension of the nerve cell (the axon). The speed of transmission depends upon the size of the fiber, but is on the order of tens of meters per second - not the speed of light transmission that occurs with electrical signals on wires. Once the signal reaches the axon terminal bundle, it may be transmitted to a neighboring nerve cell with the action of a chemical neurotransmitter.
The dendrites serve as the stimulus receptors for the neuron, but they respond to a number of different types of stimuli. The neurons in the optic nerve respond to electrical stimuli sent by the cells of the retina. Other types of receptors respond to chemical neurotransmitters.
The cell body contains the necessary structures for keeping the neuron functional. That includes the nucleus, mitochondria, and other organelles. Extending from the opposite side of the cell body is the long tubular extension called the axon. Surrounding the axon is the myelin sheath, which plays an important role in the rate of electrical transmission. At the terminal end of the axon is a branched structure with ends called synaptic knobs. From this structure chemical signals can be sent to neighboring neurons.


The human brain is the central organ of the human nervous system, and with the spinal cord makes up the central nervous system. The brain consists of the cerebrum, the brainstem and the cerebellum. It controls most of the activities of the body, processing, integrating, and coordinating the information it receives from the sense organs, and making decisions as to the instructions sent to the rest of the body. The brain is contained in, and protected by, the skull bones of the head. The cerebrum is the largest part of the human brain. It is divided into two cerebral hemispheres. The cerebral cortex is an outer layer of grey matter, covering the core of white matter. The cortex is split into the neocortex and the much smaller allocortex. The neocortex is made up of six neuronal layers, while the allocortex has three or four. Each hemisphere is conventionally divided into four lobes – the frontal, temporal, parietal, and occipital lobes. The frontal lobe is associated with executive functions including self-control, planning, reasoning, and abstract thought, while the occipital lobe is dedicated to vision. Within each lobe, cortical areas are associated with specific functions, such as the sensory, motor and association regions.

A reflex, or reflex action, is an involuntary and nearly instantaneous movement in response to a stimulus. A reflex is made possible by neural pathways called reflex arcs which can act on an impulse before that impulse reaches the brain.