Answer:
Evolution occurs about 6 million years ago.
Explanation:
The mammoth evolved from the common ancestor because evolution occurs about 6 million years ago. The modern elephants and woolly mammoths share a common ancestor and they are split into two separate species about 6 million years ago due to change in genetics as well as environment that leads to the evolution in the elephants.
I think sister groups. Imagine them having the same parents.
<h3><u>
The following events are identified as chemical weathering:</u></h3>
- The minerals in a marble statue react with water to form acids and pores in the structure.
- The rocks in a region are streaked orange after being exposed to repeated rains.
<em><u>Reason: </u></em>
When the weathering process occurs due to <em>chemical reaction</em>, then it is considered as chemical weathering.
In <em>the first case</em>, minerals of marble statue are <em>reacting</em> with water to cause weathering. In the <em>second case</em>, due to the <em>acidificaion reaction</em>, the change of the color has happened after exposure to the repeated rains.
<h3><u>
The following events are identified as Mechanical weathering:</u></h3>
- A piece of rock crumbles after being constantly thrashed by strong waves.
- Industrial runoff forms cracks in a rocky structure in its path.
<em><u>Reason:</u></em>
When the rock is broken into simple pieces <em>without any chemical reaction </em>it is considered as mechanical weathering.
In the <em>first cause</em>, due to the <em>abrasion</em> caused by the strong waves, weathering has happened, in the <em>second case</em> industrial run off may be of varying temperature and thus may cause <em>heating or cooling</em> of the rock and causes weathering.
Answer:
b. di uses across a synaptic cleft from a neuron to a muscle cell.
Explanation:
A neurotransmitter is di uses across a synaptic cleft from a neuron to a muscle cell. Neurotransmitters are chemicals which enable neurotransmission. In reaction to an impulse a motor neuron axon secretes a neurotransmitter and causes the muscle fiber to contract. It is a chemical messenger which passes on the signals across the chemical synapse.
Answer:
nuclear fusion
Explanation:
When the density and temperature at the core of the gravitationally collapsing nebula reaches values when nuclear fusion is triggered and sustained, that marks the birth of the star.
