Answer:
Eukaryotes:
-Organisms with a well defined nucleus are known as eukaryotes. such cells are called as eukaryotic cells.
- Their nucleus is enclosed within the nuclear membrane.
- They do not posses a mitochondria.
- The cell wall is the outer most layer of a eukaryotic cell (only plant cells have a cell wall)
- The cells are divided by a process called mitosis.
Eg: Plants, Animals.
Prokaryotes:
- Organisms without a well defined nucleus are known as prokaryotes. Such cells are called as Prokaryotic cells.
- They lack nuclear membrane.
- Mitochondria, Golgi bodies, chloroplast and lysosomes are absent.
- The genetic material (DNA) is present on the chromosome.
Eg: Every organism coming under the kingdom monera.
Explanation:
Barbara have both alleles that are dominant. It is because all the
letters for the genotype of the trait are capitalized. It might be that
both of her parents have at least one dominant allele each
<span>B. A virus that causes a common cold
Hope this helps!
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<u>Answer:</u>
Cyanobacteria start producing pure oxygen around 200 million years ago.
<u>Explanation:</u>
Many scientists believed that Earth did not have any oxygen. Cyanobacteria or the blue green algae are the microbes which produced oxygen for the first time with the help of photosynthesis. This was around 4.5 billion years ago: after Hadean eon.
They were very simple, but they produced oxygen in the early earth’s atmosphere. So, they brought evolution on earth. This “blue-green algae” exists in salt water, rocks and soils and play a major role in maintaining the ecosystem.
