Answer:
The nitrogen gas must be changed to a form called nitrates, which plants can absorb through their roots. The process of changing nitrogen gas to nitrates is called nitrogen fixation. It is carried out by nitrogen-fixing bacteria. The bacteria live in soil and roots of legumes, such as peas.
Answer:
Option (4)
Explanation:
Carbon forms the basin element for the existence of life. It is present in the atmosphere in the form of CO₂, which is one of the major green house gas. It plays an important role in the carbon cycle.
The increase in the concentration of carbon in the atmosphere can lead to the global rise in the temperature. It can lead to global warming. The amount of carbon in the atmosphere has been rising continuously, right after the industrial revolution.
The carbon is mainly emitted from the heavy industries and factories, vehicles, burning up of fossil fuels. It also increased due to the increasing absorption of solar radiation.
This emission of carbon if not controlled by the humans, then the concentration of carbon in the atmosphere will abruptly increase after some decades.
Thus, the correct answer is option (4).
Answer:
b. Motor Unit
Explanation:
A motor unit is consist of motor neuron and muscles fibers connected through the axon terminal of neuron. Motor unit function for the movement (contraction and relaxation) of muscles.
A neuron is connected with muscles fiber through the axon terminal of neuron and is called neuromuscular junction. Skeletal muscle fiber is consist of a cylindrical muscle cell that contain microfibrils which participate in contraction and relaxation of muscles.
Neuron and muscle fiber coordinate with other other for the proper functioning of motor unit.
Hence, I selected diagram "b" that represents motor unit.
External Stimulus is the answer
