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dusya [7]
3 years ago
9

1. When did stromatolites appear on Earth? Archean Hadean Mesozoic Proterozoic

Biology
1 answer:
professor190 [17]3 years ago
7 0

Answer:

Proterozoic

Explanation:

Stromatolites appear on Earth in the end of Proterozoic era because Proterozoic extended from 2500 million years to 542 million years. The stromatolites were present on earth about 542 million years ago. The stromatolites present in large number on the sea shores around the world and are considered as the Earth's first visible life form which can be seen through naked eye. These stromatolites were the first known organisms in which photosynthesis occurs and produce free oxygen..

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Which pregnancy-specific structure is responsible for delivering nutrients and oxygen to the fetus and removing waste products?
Arlecino [84]

Answer:

Blastocyst placenta.

Explanation;

  • During pregnancy the fetus depends on its mother for nourishment and oxygen since it cannot breathe air it's blood circulates differently than it does after birth.
  • Due to the circumstances stated above the mothers womb develops an organ known as the placenta that develops and implants in the mother's womb during pregnancy to provide oxygen and nutrients to the growing baby and remove waste products from the baby's blood
  • The fetus is connected to the placenta by the umbilical cord which contains blood vessels that transport nutrients and oxygen from the mothers blood to the baby and also transports waste products and carbon dioxide from the baby to the placenta and then to the mothers circulatory system to be eliminated.

8 0
4 years ago
Outline the events of protein synthesis (transcription and translation)
Yuliya22 [10]

Answer:

The events of protein synthesis are simple- First of all, protein synthesis is the process for which cells make proteins. Protein synthesis occurs in only two stages, transcription and translation.

Transcription-

Transcription is the transfer of genetic instructions in DNA and mRNA in the nucleus. It includes three steps: initiation, elongation, and termination.

Translation-

Translation occurs at the ribosome, which consists of rRNA and proteins. During translation, the genetic code in mRNA is read and is used to make protein.

Explanation:

The two processes (transcription and translation ) are pretty much summed up by the 'central dogma of molecular biology' which goes- DNA → RNA → Protein.

4 0
3 years ago
Acell membrane is very specific about what it allows across. How does this help the cell?
9966 [12]

Explanation:

It helps the cell absorb as many different molecules as possible.

8 0
3 years ago
What are the contributions of each of these scientists to the cell theory? And how did that information contradict what was beli
SpyIntel [72]

M. J. Schleiden:

In the year 1838, a German botanist presented the first cell theory (Although his theory was ultimately disproved, it did contribute to a change in scientific focus to cellular processes.)

<h3>What is cell?</h3>

All living creatures and body tissues are made up of the smallest unit that can live on its own. The cell membrane, nucleus, and cytoplasm are the three primary components of a cell. The cell membrane encloses the cell and regulates the molecules that enter and exit it.

His theory: Cells make up all plant tissues, and an embryonic plant is made up of just one cell. He declared that the cell is the fundamental building block of all plant matter.

Louis Pasteur- 1855 - German physiologist, physician, pathologist; and anthropologist. Added a third to the cell theory: Omnis Cellula e cellula (all cells develop only from existing cells).- Implied that there was no Spontaneous generation.

Rudolf Virchow- In 1862 he conducted a famous experiment supporting the theory that cells can only come from other cells.

His experiment:

Steralized flasks with straight and curved necks were used to heat nutrient broths. Bacteria only developed in the straight necks because bacteria cells from the air settled in the S-shaped necks' curves. Spontaneous gen did not produce proven cells in the broth.

For more information regarding cell theory, visit:

brainly.com/question/1594446

#SPJ1

5 0
2 years ago
Read 2 more answers
What is the name for a large region with consistent organisms and weather?
Nonamiya [84]

Answer:

C   Biome

Explanation:

8 0
4 years ago
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