Cretaceous extinction also known as Paleogene extinction was a period of time when suddenly around three quarter of the animal and plant species began to get extinct from the land. The event happened around 66 million years ago and is considered as the end of cretaceous era that lead to the beginning of Mesozoic era.
Reasons for the mass extinction:
- Scientists think that a major asteroid or comet hit the surface of earth which deteriorated the earth’s environment, especially by making it difficult for plants to perform the process of photosysnthesis. This is called as Impact hypothesis and scientists think that it was the reason of extinction of so many species because they found debris of asteroid in the land.
- There could also be some other reasons like climate changes,volcanic eruptions and changes in the sea level which made the environment unfavorable for the survival of living organisms.
- One of the best known organism that is thought to extinct in cretaceous period was dinosaur.
Extinction of Dinosaurs:
As stated above the exact cause of dinosaur extinction can not be stated with confidence. This is because cretaceous period was the time when so many unfavorable circumstances took place like diseases, geologic events ,climate change etc.
However, the most believed theory is that some Asteroid hit the surface of earth and turned the climate very very old. Therefore, those amazing creatures were not able to survive that climate.
Hope it help!
Answer:
it is because there is less oxygen and creatures need more oxygen to perform their work..
hope this helps you ☺️☺️
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In a situation where the concentration of solute is low inside the cell, the cell will be referred to as a hypotonic cell. The transport in this type is referred to as active transport.
<h3>What is active transport?</h3>
The movement of dissolved molecules into or out of a cell via the cell membrane, from a low concentration region to a high concentration region is referred to as active transport.
These particles use the energy released during respiration to move against the concentration gradient.
Thus, in a situation where the concentration of solute is low inside the cell, the cell will be referred to as a hypotonic cell. The transport in this type is referred to as active transport.
For more details regarding active transport, visit:
brainly.com/question/12133248
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