A solid minute object that is said to come together for the formation of the planet and are believed to produce cosmic dust are called planetesimal.
The options that best describes the planetesimals are:
- Option A. They are the origins of planets.
- Option B. They formed from gas and dust.
- Option D. They are believed to have developed in debris disks.
The descriptions can be explained as:
- It is believed that planets formation occurred through planetesimals. The formation happened from gas, dust particles and debris.
- By the process of accretion, the discs coalesced and became bigger and solid over time. This bigger mass started attracting other matters towards each other because of gravitational force.
- This pull resulted in either breaking or creation a bigger mass of pieces known as planetesimals. The collision continued to become bigger and solid planets we know today.
Therefore, options A, B and D are correct.
To learn more about planetesimals refer to the link:
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For the answer to the question above, p<span>unctuated equilibrium (also called punctuated equilibria) is a theory in evolutionary biology which proposes that most species will exhibit little net evolutionary change for most of their geological history, remaining in an extended state called stasis. When significant evolutionary change occurs, the theory proposes that it is generally restricted to rare and rapid (on a geologic time scale) events of branching speciation called cladogenesis. Cladogenesis is the process by which a species splits into two distinct species, rather than one species gradually transforming into another.</span>
Answer:
A postsynaptic potential is defined as excitatory if it makes it easier for the neuron to fire an action potential. ... A postsynaptic potential is considered inhibitory when the resulting change in membrane voltage makes it more difficult for the cell to fire an action potential, lowering the firing rate of the neuron.
Answer:
Option C.
Scientist explain the incomplete fossil record because not all organisms become fossils. Processes like erosion and mountain building can change rock layers, causing fossils to be spread over multiple layers or destroyed.
Explanation:
- Fossils are the remains of organisms that are found on the rocks after they die.
- So, no one can be 100% sure about the complete fossil record because of the continuous process like erosion and other natural calamities.
- The sediment must cover any organism's remains to start the fossilization process to start. Most of the organisms start decomposing before this process can be executed.
Answer:
Pyramidal decussation is at the junction of medulla and spinal cord.
Explanation:
Pyramidal decussation may be defined as the the fibers that cross the corticospinal tract from one side to the junction and the other side to the central nervous system.
Pyramidal decussation is the point at the junction between spinal cord and medulla. The motor fibers crosses the midline from the medullary pyramids.