The correct answer is D. temperature difference in the mantle I am an Online Middle Schooler and I got it right
Temperature variations in the fluid start convection currents. The lower mantle in the Earth's mantle heats up due to heat from the core, which causes it to rise. The substance falls back as it cools, causing the convection current. The correct option is D.
Explanation:
Temperature differences in the fluid's area are what cause a convection current to be activated and the flow of a fluid to begin. The Earth's mantle is where this is most noticeable.
The lower mantle's temperature rises in this situation as a result of heat from the core. The density of the mantle material drops as it warms, causing it to rise.
As it rises and moves away from the heat source, however, it cools down, gets denser, and sinks back.This movement of rising and sinking due to temperature differences creates the convection current.The correct option is D.
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The answer is B. Every single amino acid has more than one codon.
There are 20 different amino acids, but there are more than 20 combinations of three nucleotide bases on DNA. There are 64 different combinations of three nucleotide bases on DNA, which is about 3 times more than the number of amino acids. Therefore, every single amino acid has more than one codon is the right answer. But, it should be taken into consideration, that 2 out of 20 different amino acids have only one codon - methionine and tryptophan.
Answer: A.Caffeine
Explanation:
Caffeine works by blocking adenosine, a neurotransmitter that promotes sleep. This makes us feel more awake and alert. It's the most commonly used psychoactive substance and is found in many everyday items like coffee and medicines.
The actual mechanism of A) Caffeine is to block chemicals that inhibit or slow nerve activity in the brain. Caffeine functions as an adenosine antagonist, meaning it inhibits the adenosine receptors. Adenosine is a neurotransmitter that promotes sleep, so caffeine's effect reduces sleepiness and enhances alertness.
This mechanism allows caffeine to indirectly increase adrenergic activity (energy release), promoting a more energetic state. While caffeine is often associated with increased alertness and arousal, it's important to remember that it's acting primarily by blocking the inhibiting effect of certain chemicals on the brain nerve activity.
It's noteworthy that caffeine, as the world's most widely consumed psychoactive drug, is unregulated, found in everyday items like beverages and medicines, and generally not harmful in moderation.
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b. chlorofluorocarbons
c. nitrates
d. dust particles
Answer:
The correct answer is option c. "nitrates".
Explanation:
Nitrates are among the most common contaminants and contributors of water pollution, particularly in rural areas. The presence of nitrates in drinking water is one serious problem because it could cause methemoglobinemia, or the "blue baby" disease. Additionally, the presence of nitrates in groundwater is related with the presence of other contaminants, such as bacteria or pesticides.
c. nucleus
b. endoplasmic reticulum
d. golgi apparatus
yep its b have a nice day :)
Answer:
The correct answer would be a. autotrophs.
Autotrophs, also called producers are the organisms which are able to produce complex organic compounds such as fats, proteins and carbohydrates from simpler substances present in the environment.
They are of two types based on their source of energy:
Photoautotrophs: These are the organisms which use sunlight as the source of energy in order to produce organic compounds.
For example, green plants synthesize their own food (glucose) from carbon dioxide with the help of sunlight and chlorophyll. Oxygen is released as the byproduct. The overall process is termed as photosynthesis (photo meaning photon or light energy).
Chemoautotrophs: They get energy from electron donor compounds such as sulfur, hydrogen sulfide et cetera.
The answer A. autotrophs