The Devonian Period was part of the better known Paleozoic Period. Some scientist think it was 416 million years ago. It was the time of the great fish. It gets its name from when red rocks from Devon, England were also found in North America. It is believed that during this period parts of North America, Europe, Russia and Greenland crashed together making a new land mass. Scientists believe this period ended about 354 million years ago when land plants began to take over and much of what was an ocean disappeared.
They are rich in hydrogen and helium, they have unlimited supply of hydrogen, they have a strong gravitational pull.
Explanation:
Space where huge size of gaseous and dust cloud is present is called nebula. It is mainly made of hydrogen and helium. Nebula exist in the space which is between the stars and it is call as interstellar space.
Helix nebula is closest nebula which is near the earth. It’s distance from earth is about 700 light years.
Dark nebulae are very dense as well as cold. Nebula can be divided into dark nebula and bright nebula. The gas which is present between the stars is always combine with solid grains cosmic dust.
No, the arrangement of vascular bundles in the stem same for all plant species.
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☆ <u>In</u><u> </u><u> Monocot </u><u> </u><u>Stems</u></h2>
In monocots, xylem and phloem are organized in vascular bundles scattered throughout the stem. As the plant grows, monocot stems generate new vascular bundles for the new tissue. Monocot stems in general possess a simpler arrangement than that found in dicots.
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☆ <u>
In Dicots</u>
<u> </u><u>Stems</u></h2>
Within the class of plants known as dicots, herbaceous dicots and woody dicots have different arrangements of vascular tissues. In herbaceous dicots (plants, mostly annuals, with soft, non-woody stems), vascular tissue remains in discrete bundles even at maturity. In contrast, when mature woody dicots (plants, mostly perennials, with woody stems) reach maturity, the vascular bundles join together to form continuous rings around the interior of the stem.
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<em><u>ThankYou</u></em><em><u> </u></em>✔✔</h2>
So?? what?
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<h2>Answer is option "B"</h2>
Explanation:
- Our brain requires an enormous measure of vitality and so as to meet this needs the progression of blood must be accurately arranged to guarantee that oxygen is being conveyed where it is required and when it is required.
- Vitality in the mind is created solely from a type of digestion that requires oxygen. However, neurons just keep up a little save of vitality and these cells require a constant inventory of oxygen, particularly when the cells are terminating and speaking with their neighbors.
- Blood dashing through a brain district's trap of vessels is an indication that nerve cells in that region have kicked vigorously. The blood races to dynamic territories to supply terminating neurons with the oxygen and glucose they require for vitality.
- Hence, the correct answer is option B "Active areas of the brain take up more oxygenated blood than they need for their energy requirements"
