Answer:
Due to presence at early days of the planet.
Explanation:
We only find the remains of single celled organisms in the oldest fossils because the single celled organisms are the organisms that were present in the early days of this planet. These single celled microbes were present about 3.7 billion years ago while on the other hand, the oldest rocks are only a little older i. e. 3.8 billion years so these single celled organisms are considered as oldest fossils on this planet.
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I would go with c because its tells you right in there that the ecosystem help who lives around that area.
Answer:
The correct answer is option d.
Explanation:
Chemical cycling illustrates the systems of concurrent circulation of elements between other states, compounds, and substances, and then return to their original state, which takes place in space, and on many objects in space comprising the Earth.
Chemical cycling of the nutrients (inorganic) is needed to maintain the conservation of nutrients on Earth. The chemical cycling of nutrients in a natural system requires a pool for the elements, the activities done by human beings, the biotic community and its food chains, and an exchange pool from which producers extract their nutrients. All the mentioned factors are associated with affecting a chemical cycling in exception to the input of geothermal energy.
A type of lymphocyte called NK cell detects cells with abnormal surface proteins and kills them.
<h3>What are lymphocytes?</h3>
One variety of white blood cell is the lymphocyte. They are crucial to the functioning of your immune system, which aids in the body's defense against sickness and infection. An extensive network of immune cells, lymph nodes, lymph tissue, and lymphatic organs makes up your immune system. Immune cells include lymphocytes. The two primary categories of lymphocytes are:
T lymphocytes (T cells): T cells direct your body's immune response and actively hunt down and destroy cancerous and infected cells.
B cells, or B lymphocytes: The B cell produces antibodies. Proteins called antibodies hunt down viruses, bacteria, and other foreign invaders.
Your body's immune system uses lymphocytes to combat cancer and invading viruses and germs (antigens). Your immune system benefits from lymphocytes' assistance in retaining every antigen it encounters. Some lymphocytes develop into memory cells after an encounter. Memory cells detect an antigen and reactbwhen they come into contact with it again. You don't contract illnesses like measles or chickenpox repeatedly because of this. Additionally, it explains why some diseases can be avoided through vaccination.
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