<span>According to the nebular theory stars are formed in which sequence:
a. Interstellar clouds - "nebula" is a Latin word which means clouds. These clouds start to form and are composed of gases like hydrogen and helium.
b.Clumps - as the gases start to form and come together they form clumps of gases that are highly concentrated and they start to grow.
c. Gravitational forces - when clumps have grown into big sizes the gravitational forces that are found within it increases and are converted into kinetic energy of fast-moving particles that continuously bump into each other and create or generate heat.
</span><span>
d. Nuclear fission - as the clumps keep on colliding and creating heat (18 million degrees Fahrenheit), nuclear fission begins.
e. Outward pressure from the nuclear fission prevents the collapse of the gases, stabilizing the gases eventually creating a star. </span>
Answer:
Without an oxygen atmosphere very few things could live on the early Earth. Anaerobic bacteria were probably the first living things on Earth. The early Earth had no oceans and was frequently hit with meteorites and asteroids.
Explanation:
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Speciation is the adaptive divergence and gradual that leads to two different species.
Reproductive isolation results in speciation when the processes of evolutionary mechanisms, physiological and behaviours are collected.
Mechanism of reproductive isolation helps in preventing members of different species from producing offsprings. A zoologist is a classified way of reproductive isolation whereby it(zoologist) is classified to the mechanism of reproductive isolation into two categories
(i) Pre-zygotic. This one acts before fertilization or before mating when it comes to animals.
(ii) Post-zygotic. It acts after fertilization.
The mechanisms appear I species which are genetically controlled and whose geographic distribution overlaps or are separated.
Water accounts for most of a cell's mass!
