Answer:
A response is a _reaction to a stimulus. • A stimulus is anything that can cause an individual to respond or react. • Stimuli can be _internal or external.
Explanation:
A change in the cellular make up of an organisms due to response or reaction to a stimulus is called a response. This response can be due to a stimulus inside the body , or due to effect of an external ( stimulus) object on the body-stepping on a sharp pin.
In either cases, the stimulus is receive by the receptors, which transfer the stimulus through the sensory neuron to the inter neuron in the CNS, for the motor neuron to bring an effective response at the effectors.
Chromosems is the right answer
Answer:
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the shape of DNA is double helix
Answer:
Our atmosphere (air) is comprised of 78% of nitrogen. However, this nitrogen is in its elementary state (N₂) and therefore is quite inactive, so the plants can not use it directly. Changing the elementary nitrogen into more reactive forms (NH₃, NO₂, HNO₃) is occurring through the process called nitrogen fixation. It is happening via two processes.
First one is physical nitrogen fixation. When some type of atmospheric physical energy (lightning bolt, for example) reacts with N₂, it splits it in two very reactive N atoms, enabling them to react with oxygen in order to form NO₂.
Second process is biological nitrogen fixation. It's done by bacteria, special bacteria living in the soil, able to use elementary nitrogen for its metabolical pathways resulting in production of ammonia, which can be used by plants. It's noteworthy that bacteria are responsible for about 90% of all nitrogen fixation.
