Answer:
Explanation: Collenchyma cells are elongated cells with unevenly-thickened walls. They provide structural support, mainly to the stem and leaves.
That is true, species can breed within
Answer:
The correct answer will be option-
1. UV light strikes the skin and converts a steroid molecule into an inactive form of vitamin D.
2. Inactive vitamin D is transported to the liver where it is modified.
3. Vitamin D is activated under the influence of PTH.
4. Inactive, chemically altered vitamin D is transported to the kidneys.
Explanation:
Vitamin D is a fat-soluble metabolite which helps maintain the health of the bone by maintaining the calcium homeostasis.
The vitamin D is synthesized mainly in the liver and kidney from the biologically inactive precursor of vitamin D called ergocalciferol and Cholecalciferol.
The inactive vitamin is synthesized in the skin when the skin is exposed to UV rays. The UV rays convert the 7-dehydrocholesterol, a steroid molecule to Vitamin D3, This inactive vitamin is then transported to the liver where it is converted to 25-hydroxyvitamin D.
This vitamin D form is further metabolized in the kidney controlled and regulated by the Parathyroid glands.
Answer: A.it is a relatively new human adaptation.
Explanation:
Fight or flight response is a response shown by a human or animal body towards acute stress. It is a physiological reaction that occurs in response to the perceived attack, survival threat and attack. The animals or humans react to threats by the hormonal secretion from sympathetic nervous system. This prepared animals for fighting. The hormonal secretions like catecholamines, epinephrine and nonepinephrine helps in generation of response. Neurotransmitters dopamine, estrogen, testosteron e and cortisol affects how organisms react to the stress.
Fight-or-flight reaction is not a relatively new human adaptation but it is evolved as a survival mechanism which was also present in primitive human beings and mammals and helped them to react in the life-threatening situations.
Hello.
The answer is <span>Passive transport.
</span>The movement of substances<span> in and out of a </span>cell<span> membrane </span>without the use of energy<span> by the </span><span>cell.
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