<span>First, we need to clarify what negative feedback means. Negative feedback is a response that is fed back to the input and that tends to reduce the fluctuation of the output. Negative tries to confer stability to the system. So, you can see that the option B. cannot be because if you add more wood to a fire the fire will increase instead of extinguish. The option A implies a signal (from the high temperature) that starts the air conditioner, so it brings the system out of the equilibrium. The option C. indeed signals that the "full" signal es fed back and the organism will stop eating and so it reaches equilibrium. The answer is the option C. not eating any more when you are full.</span><span />
In times of stress the sympathetic nervous system stimulates the adrenal medulla which then secretes catecholamines. The catecholamines includes; Dopamine, epinephrine and norepinephrine. Catecholamines are made by nerve tissue, the brain, and the adrenal glands. They help the body respond to stress or fright and prepare the body for "fight or flight" reactions.
Answer:
This question lacks options, the options are;
A. All cells have a cell wall.
B. All cells arise from pre-existing cells.
C. All cells are capable of photoshynthesis.
D. All cells can develop into any other type of cell.
The answer is B.
Explanation:
The widely accepted universal cell theory is known to be contributed to by three scientists viz: Matthias Schleiden, Theodor Schwann and Rudolph Virchow.
As rightly stated in this question, Botanist Mathias Schleiden and Zoologist Theodor Schwann proposed that plants and animals are made up of cells in the year 1838 and 1839 respectively. However, in 1855, biologist Rudolph Virchow expanded the cell theory by adding that all living things are composed of cells and that these cells arise from pre-existing cells.
The collaboration of these three scientists brought about the cell theory that states:
* Cells are the basic unit of all living things.
* All living things are made up of one or more cells.
* All cells arise from pre-existing cells.
Most likely located in the nucleus, mitochondria and chloroplasts! The nucleus contains the most DNA!
<span>b they could eat unicellar organisms
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Multicellular organisms arose because of the process called endosymbiosis. The endosymbiosis theory posits that other unicellular organisms ate other organisms which has benefitted them into processing new mechanisms and functions.
A Eukaryotic cell contains a nucleus; more than one chromosome and is typically a multi-celled organism. Both plant and animal cells are eukaryotic cells.
