The Precambrian era envelopes the major bulk of the history of the Earth, beginning from the creation of the planet approx 4.5 billion years ago and terminating with the origination of composite, multicelled forms of life approximately 4 billion years after.
The Precambrian refers to the earliest of the geologic ages that are signified by the distinct layers of sedimentary rock. The Earth was about more than six hundred million years old when life started. The planet had cooled down from its native molten state, creating a solid crust and oceans formed by water vapor in the atmosphere.
At about three billion years ago, the atmosphere of the Earth was virtually devoid of oxygen. At approximately 2.4 billion years ago, oxygen was discharged from the seas as a waste product of photosynthesis by cyanobacteria. The levels of the gas slowly raised, attaining about 1 percent around two billion years ago.
Approximately 800 million years ago, the levels of oxygen attained about 21 percent and started to breathe life into more composite species. The oxygen-rich ozone layer was also created, protecting the surface of the Earth from the harmful solar radiation.
Because the molecules that are being transported is moving against its concentration gradient. in other words, its moving from where its low in concentration to where its high in concentration
On the earth surface
Explanation:
The long-wavelength radiation is created on the earth surface when electromagnetic radiation is re-emitted.
- The sun releases radiation in form of short-wave.
- They are usually more energetic and with short wavelength and a high frequency.
- When they interact with materials on the earth, they are radiated back as long-wavelength radiation that usually causes heat.
- Ultraviolet rays and other high energy waves are emitted from the sun because it is a very hot body.
- When these radiations enters the earth, they are re-radiated back as long waves with lower energy.
- Earth is cooler than the sun
- When some of the short waves for example, the ultraviolet rays gets to the surface, it is absorbed and re-radiated back.
- When the short waves are absorbed, they lose some of their their energy to the earth surface.
- The remainder is radiated back as less energetic long waves.
- The hotter a body is, the more energetic the radiation it releases.
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The name of the biggest part of the human brain is CEREBRUM.........
Answer: The most affected would be organs that have QUICKLY dividing cells (like the intestine and hair follicles).
Explanation:
Cancer cells are cells that divides uncontrollably giving rise to a mass of tissue called tumour. They grow faster than a normal cell in an uncoordinated manner, and continues to grow after the initial stimulus has ceased.
Paclitaxel is a drug that is approved for the treatment of cancer affecting different parts of the body. It's a microtubule-stabilizing drug whose mechanism of action is to induce mitotic arrest in the cancer cells.
Paclitaxel in its cause of action not only affect cancer cells but normal cells as well. To justify this statement, as stated earlier, the mechanism of action of paclitaxel is to induce mitotic arrest. Therefore the cells of organs where rapid mitosis occurs would be most affected. Skin cells, hair follicles and the cells lining our intestines (epithelial cells) all have high rates of mitosis as these tissues constantly need to be replaced.
