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patriot [66]
3 years ago
8

Before photosynthesis evolved, ___ was rare in earths atmospherer

Biology
1 answer:
alexdok [17]3 years ago
3 0
I'm pretty sure the answer is oxygen because photosynthesis is the reason we have oxygen
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What are the phases in meiosis and explain
densk [106]

Cell division happens twice during meiosis. One starting cell can produce for gametes (eggs or sperm.) In each round of division, cells go through four phases called prophase, metaphase, anaphase, and telophase.

prophase During prophase the chromosomes become visible as paired chromatids and the nuclear envelope disappears. This phase includes reduction division, which is where the number of chromosomes is decreased from 46 (diploid) to 23 (haploid.)

metaphase This is where the 23 remaining chromosomes become attached to the spindle fibers.

anaphase During this phase, the chromosomes move away from each other to one or the other pole of the spindle fiber.

telophase In which the chromatids or chromosomes move to opposite ends of the cell and two nuclei are formed.

interphase This is a resting period.

6 0
2 years ago
. How long has it taken barren rock to become paradise?
Simora [160]

Answer:

Volcanoes are created over approximately 10,000-500,000 years by thousands of eruptions -- each lava flow covering the one before it. In the case of oceanic island volcanoes, lava erupts first from fissures, or cracks, on the deep ocean floor. The flows continue to build up and finally an island emerges from the sea.

Explanation:

i licked it up... ;-)

4 0
3 years ago
What is the best evidence for a three-domain system?
ch4aika [34]

Answer:

The best evidence for the three domain system is

Sensitivity to Antibiotics

Explanation:

The three domains of life includes :

Archaea - oldest known domain, ancient forms of bacteria.

Bacteria - all other bacteria that are not included in the Archaea domain.

Eukarya - all the organisms that are eukaryotic or contain membrane-bound organelles and nuclei.

Types of evidences for the three domain system are:

1) differences in the sequences of nucleotides in the cell's robosomal RNAs (rRNA)

2) the cells's membrane lipid structure.

3) its sensitivity to antibiotics.

8 0
3 years ago
The concept presented to explain the origin of eukaryotic cells, namely that a bacterial cell parasitized another descendant cel
son4ous [18]

The concept presented to explain the origin of eukaryotic cells form a bacterial cell parasitized by another descendant cell is called endosymbiosis.

<h3>What is the endosymbiotic theory?</h3>

The endosymbiotic theory is a well-sustained theory in biology about the origin of eukaryotic cells.

According to this theory, eukaryotic cells emerged by endosymbiosis between primitive eukaryotic cells and bacteria that converted into mitochondria and chloroplast organelles.

The endosymbiotic theory is well sustained in several scientific observations such as the existence of DNA in mitochondria and chloroplasts that is independent of nuclear DNA, the size of ribosomal units, etc.

In conclusion, the concept presented to explain the origin of eukaryotic cells form a bacterial cell parasitized by another descendant cell is called endosymbiosis.

Learn more about endosymbiosis here:

brainly.com/question/1698852

#SPJ1

5 0
2 years ago
Why are amino acids called "amino acids?"
Papessa [141]

Answer:

Amino acids are called amino acids because of the amino group and the carbonxyl group acts as an acid giving up an H.

6 0
3 years ago
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