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.
Answer:
External fertilization usually occurs in aquatic environments where both eggs and sperm are released into the water Most external fertilization happens during the process of spawning where one or several females release their eggs and the male(s) release sperm in the same area, at the same time.
Typically, frogs lay eggs. This process usually occurs through external fertilization, where the female releases her eggs from her body into water. Then, the male releases his sperm to fertilize them In this case, the eggs are fertilized inside the female's body before they are released.
atom, molecule, cells, tissues, organ, organ system, organism
Answer:
The correct answer is - a lunar eclipse (total lunar eclipse).
Explanation:
When the sun and moon align opposite one another and earth between them and blocks the light of the sun to reach the moon known as a lunar eclipse. A lunar eclipse can be a partial or total lunar eclipse.
A partial lunar eclipse occurs when a part of the earth covers the moon to get the light or between the sun and the moon. The total lunar eclipse occurs when the whole moon is opposite to the sun and earth between them.
