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sergey [27]
2 years ago
5

Why do veins have valves

Biology
1 answer:
Dimas [21]2 years ago
4 0
Unlike arteries, veins contain valves that ensure blood flows in only one direction. (Arteries don't require valves because pressure from the heart is so strong that blood is only able to flow in one direction.) Valves also help blood travel back to the heart against the force of gravity.
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The scientific term for the formation of a new species is speciation. So, the correct answer would be letter d. :)
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Mot nucleoxom co cau truc gom
sukhopar [10]
Sorry i didn’t understand
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7 0
3 years ago
Read 2 more answers
Classical conditioning is
leonid [27]

Answer:

Classical conditioning (also known as Pavlovian or respondent conditioning) is learning through association and was discovered by Pavlov, a Russian physiologist. In simple terms, two stimuli are linked together to produce a new learned response in a person or animal.

The most famous example of classical conditioning was Pavlov's experiment with dogs, who salivated in response to a bell tone. Pavlov showed that when a bell was sounded each time the dog was fed, the dog learned to associate the sound with the presentation of the food.

John Watson proposed that the process of classical conditioning (based on Pavlov’s observations) was able to explain all aspects of human psychology.

Everything from speech to emotional responses was simply patterns of stimulus and response. Watson denied completely the existence of the mind or consciousness. Watson believed that all individual differences in behavior were due to different experiences of learning. He famously said:

Explanation:

8 0
2 years ago
Explain how mutations in the photoreceptor genes result in different vision defects.
Artyom0805 [142]

Answer:

The human eye is the prime organ of the body, which associates with the photons of light and allows one to see various things. The unique cells found in retina, which does activity of seeing are cones and rods cells. Rods help to see in dim light vision, while on the other hand, cone cells are unique in recognizing different colors.  

These cells comprise photoreceptor proteins that help in trapping photons at particular wavelength. Mutation in the gene encrypting for these proteins results in permanent or temporary vision issues. The extremity of defects relies upon the degree to which mutation takes place.  

The mutation in rod cells photoreceptor proteins leads to night blindness and retinitis pigmentosa. Retinitis pigmentosa refers to an inherited disorder that takes place because of early loss of rod cell, which destructs retina. On the other hand, night blindness does not mean complete blindness night, however, inadequate tendency to see in low light.  

Identically, the mutation in the cone cell also results in vision issues, known as red color blindness and tritanopia. Tritanopia refers to a kind of color blindness, which originates because of insensitivity of blue receiving protein gene towards blue light. On the other hand, red color blindness refers to insensitivity of red receiving cone cells in captivating long-wavelength photons.  

5 0
2 years ago
Comprehension Questions:
Annette [7]

Photosynthesis and cellular respiration are<u> chemical reactions</u> that occur in cells.

<h3>What is photosynthesis and cellular respiration?</h3>

Photosynthesis is the process of making food through carbon dioxide, water and sunlight. It is an anabolic reaction.

Cellular respiration is the process of breaking down of food molecules by oxygen. It is a catabolic reaction.

Thus, the correct option is a, chemical reaction

Learn more about cellular respiration

brainly.com/question/13721588

#SPJ1

8 0
2 years ago
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