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DiKsa [7]
2 years ago
15

The heart of an embryo starts to pump blood by the ________.

Biology
2 answers:
astra-53 [7]2 years ago
6 0
Emerging from the placenta is the umbilical vein, which carries oxygen-rich blood from the mother to the fetal inferior vena cava via the ductus venosus to the heart that pumps it into fetal circulation.
melamori03 [73]2 years ago
5 0

Answer:

fourth week of pregnancy

Explanation:

Mark me brainly please

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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
30. Describe why air enters the lungs during inhalation. In your answer, include the the terms diaphragm, rib cage, and air pres
iVinArrow [24]

Answer:

When you breathe in, or inhale, your diaphragm contracts and moves downward. This increases the space in your chest cavity, and your lungs expand into it. The muscles between your ribs also help enlarge the chest cavity. They contract to pull your rib cage both upward and outward when you inhale.

4 0
3 years ago
PLEASE ANSWER FIRST GETS BRAINLIEST
nikklg [1K]

Answer:

1. The numbers of amphibians are declining only in the high-risk areas of the world - False. Amphibians are declining all over the world, in which many are going extinct due to climate change and changes inside their ecosystem. Failure to adapt to the 'new' setting leads to their demise.

2. Many amphibian species are threatened, but none have recently become extinct. - False. Within the previous century, there has been documentation of either extinct or a high-chance of extinction due to failure to see any sign of existence.

3. The health of falcon populations in the 1960s indicated that pesticide use was harming the environment - True. Pesticide is generally made of poison that either kill or dissuade the pests to eat all of the crop. Any animals that falcons eat (primary consumers) that eat the pests infected by the pesticide, would in turn infect the falcon in a larger percentile, leading to death. This is a slow destruction of the Food web from the bottom up, and would lead to a collapse when one or more level of the food web is wiped out.

4. Amphibians have been part of life on Earth for only about 4 million years - False. This highly depends on the person's own beliefs, however, as the Big Bang theory has already been proved false, and school's only clutch onto it in hope.

5. Birds and fish are frequently used as indicator species - True. The usage of animals that are either primary or secondary consumers (but not producers are tertiary consumers) are good indicators of the other populations within the area. A shortage of the population can mean that the Apex has eaten way too much, and that the base animals may have overpopulated.

6. I do not have the selection, so I cannot answer it.

7. Amphibians are good indicators species, for they are secondary consumers, meaning that they consume other animals, and are also consumed by other animals.

8. Scientists can learn how certain amphibians breed with each other (mating), as well as what key factors they try to find in their environments when choosing breeding grounds. They also can then take notice on how the amphibians grow, and what factors may keep them from growing, or vice versa.

9. Additive causes means that a "cause" is added into the ecosystem, for example, the adding of pollution or other man-made waste, as well as the introduction of competing species against the native species, or an introduction of a new predator species that preys on the native one. This means that since there is a larger population of consumers, the base population of amphibians would slowly decrease.

10. Inductive reasoning allows for people (specifically scientists in this case) to try to find out about changes in a certain ecosystem by trying to prove the  hypothesis created and whether they are right or not. For example, the Inductive reasoning can be that "the Secondary Consumer's population is dropping". This reasoning (conclusion) would then have to be proved.

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3 0
3 years ago
Point out the predators, consumers, producers, primary consumers, etc
zalisa [80]

Grass : producer

Mouse & Deer : primary consumers

fox : predator or secondary consumers

Lion & Eagle : Tertiary consumers

5 0
2 years ago
Read 2 more answers
Which statement is evidence used to support the endosymbiotic theory?
inessss [21]

Answer;

Mitochondria and chloroplasts contain their own DNA.

Explanation;

-Mitochondria and chloroplasts have striking similarities to bacteria cells. They have their own DNA, which is separate from the DNA found in the nucleus of the cell.

-From the Endosymbiotic theory, even though both organelles are found in eukaryotic cells, both mitochondria and chloroplast have characteristics often found in prokaryotic cells. These prokaryotic cell characteristics include: an enclosed double membrane, circular DNA, and bacteria-like ribosomes.

7 0
3 years ago
Read 2 more answers
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