Answer:
C.) Selective pressure
Explanation:
Selective pressure is a natural process that occurs in nature in which certain phenotypes are favored in certain environments. When we say these phenotypes are favored, this means individuals with these phenotypes have a better chance at survival and reproduction in particular environments. Certain phenotypes may be beneficial in some environments but harmful in others.
The given blank can be filled with the production of endorphins.
The endorphins are the hormones, which are responsible for the activation of the opiate receptors in the body. They are the natural pain killers. The activation of the opiate receptors causes the analgesic effects on the body.
These endorphins are secreted in the brain and the nervous system. The effect of the endorphins is similar to that of the morphine.
The most common source of contamination with E.coli is by eating contaminated food like meat and eggs.
Well, first of all, the question asks us to to list three different factors that could lead to this variation.
The first one is pressure, so, what happens is that, when the pressure changes with the height change, these plants develop in different ways. The second one is the oxygen, as we know, oxygen in higher elevations is less than in ocean elevation for example, so this can be a reason for this variation. The last one is the quantity of organic material on the soil, this can influence directly on the development of this population.
With that said, we need to write a hypothesis for one of these factors, let's choose the organic material because it's easier and cheaper to test. For that, the hypothesis is that, with less organic material available on the ground, the plant will grow smaller than on a normal soil. To test that, we need to grab samples of this flowering plant and put it at the same conditions as on the mountain, that is a possibility on a good lab, so after that, we'll change the quantity of organic material on some samples, to check if my hypothesis is right or not.
The positive results are that this is the reason why the plants grow smaller, so, with less organic material, the plants won't develop in the same way as it would happen with enough organic material. The negative results are that this is not the reason why these variations exist, so we need to test another factor to check why this variation is happening.
Answer: movement is always voluntary
Explanation:
Muscles are contractile:
- Contractility is the ability of muscle cells to forcefully shorten. Think of having the ability to flex a muscle.
Muscles are excitable:
- Excitable tissue can conduct or transmit electrical impulses. Basically, it can react to stimulus, which may be delivered from a motor neuron or a hormone. For example, the hormone epinephrine helps muscles to produce force.
Muscles respond to stimulus:
- well since muscles are an excitable tissue, they can react to stimulus. (see answer above)
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Muscle movement is NOT always voluntary:
- Some muscle movement is voluntary, which means it is under conscious control. For example, a person decides to open a book and read. Other movements are involuntary, meaning they are not under conscious control, such as the contraction of your pupil in bright light, breathing, blinking, your heart beating, etc.
- Therefore, the correct answer is:
movement is always voluntary
hope this helps :)
