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yulyashka [42]
3 years ago
14

Why are there no samples of rocks from the early Precambrian era?

Biology
1 answer:
xenn [34]3 years ago
4 0

Answer:

The correct answer is -  D. All rocks were molten in that time period.

Explanation:

The early Precambrian era began 4.6 billion years ago. The formation of eath start from this era with dust and gas. The atmosphere at that time was too hot. It was like hades. The rocks were molten and appear to like an ocean of rocks.

Due to the molten rocks, there are no samples of rock from this area as it was too hot to be formed. There were boiling sulfur and gases were everywhere.

You might be interested in
A cow has alleles for both black and
Rina8888 [55]

Answer:B

Explanation:

Codominant is when neither allele is recessive so they are both expressed in the phenotype

7 0
3 years ago
In response to a state of shock, what mechanisms does the sympathetic nervous system utilize in the four distinct stages to help
svetlana [45]

Answer:

Increase in heart rate.

Increase in respiratory rate.

<h2>What is a sympathetic nervous system?</h2>

The peripheral nervous system and the central nervous system are the two primary divisions of the human nervous system, as shown in the image below.

Two additional parts make up the peripheral nervous system. Skeletal muscle movement that is voluntary is controlled by the somatic nervous system. The somatic nervous system is at action when you choose to bring your coffee cup to your lips; it is doing so by engaging the necessary muscles. The autonomic nervous system, which regulates functions outside of our conscious awareness, is the second part of the PNS.

The parasympathetic nervous system and the sympathetic nervous system are additional divisions of the autonomic nervous system (which you are interested in). They have negative consequences on one another, to put it very broadly. While the parasympathetic neural system largely works to calm the body, the sympathetic nervous system often stimulates the body. Although this is a streamlined perspective, it might be helpful to think about it this way.

The sympathetic branch of the autonomic nervous system speeds up heartbeat, slows down digestion, opens up airways in the lungs to allow for greater airflow, triggers the liver to release glucose, and relaxes the bladder. All of this wakes up the body and gets it ready to "fight."

The parasympathetic division, in contrast, slows the heart rate, tightens the bronchi in the lungs, and boosts blood flow to the digestive system. The phrase "relax and digest" has been used to describe it.

The parasympathetic nervous system's nerves originate from the brainstem and spinal cord, as shown in the diagram. The "ganglia" (collections of cell bodies) of the sympathetic nervous system, however, exist beyond the spinal cord.

It's interesting to note that whereas the sympathetic nervous system activates the body using both acetylcholine (ACh) and norepinephrine (NE), the parasympathetic nervous system solely needs ACh to affect organs.

The sympathetic and parasympathetic nerve systems are autonomic, which means we typically have minimal control over them.

7 0
2 years ago
In most vertebrate neurons, an action potential arrives at the axon terminal and causes the release of chemical messenger molecu
erik [133]

The correct answer is option d, that is, neurotransmitters.  

A neurotransmitter refers to a chemical component, which is discharged at the terminal of a nerve fiber by the introduction of a nerve impulse, and by diffusing across the junction or synapse. It helps in the transfer of the impulse to another muscle fiber, nerve fiber, or some other composition. Acetylcholine is a kind of neurotransmitter, that is, used by neurons in the CNS and the PNS in the control of activities ranging from heart rate and muscle contraction to digestion and memory.  


5 0
4 years ago
The kidneys secrete an enzyme called ____________ that aids in the regulation of blood pressure
worty [1.4K]
The kidneys secrete an enzyme called renin
8 0
3 years ago
Read 2 more answers
Why is the menstrual cycle an important adaptation for reproduction in humans?
raketka [301]
The menstrual cycle is practically controlled by a system of hormones that is necessary for reproduction, and when the hormone reaches a heightened level, something called estradiol is made, then the stimulation of the ovaries by a luteinizing hormone.

Once that hormone begins developing, the ovaries make an egg that quickly becomes an ovum. The ovary then releases one egg or two during ovulation. The endometrium (the part that sheds its own cells for the menstruation) peaks after ovulation and changes the lining of the uterus to prepare for the hectic process of pregnancy and child labor. 

Hope that was helpful.
5 0
3 years ago
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