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Virty [35]
2 years ago
11

1 point

Biology
1 answer:
ololo11 [35]2 years ago
3 0
Chromosomes is the answer I think
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The arctic fox and gray fox evolved from the same species over thousands of years. can you place these steps in the process of a
elena55 [62]
Allopatric speciation, also referred to as geographic speciation, is a method of the formation of new species due to isolation of the species from one another through geographic means.

The first step in this process is geographic isolation, which means that the original population is divided into two groups due to geographical reasons such as movement of continents or formation of water bodies.

Next, the species are subjected to different selection pressures due to their different environments. Eventually, the gene pool becomes very different for the two species due to the different selection pressures and because they are not allowed to mix.

Finally, after enough time passes, speciation occurs, which means that the two populations cannot breed to form fertile offspring.
8 0
2 years ago
What object is thousands of kilometers?
uranmaximum [27]

If we talk about "space" as being anything in the universe outside the atmosphere of Earth, then space is very, very big indeed.  How big?  The diameter of the Earth is 12 000 kilometers.  The distance from the Earth to the moon is 400 000 kilometers.  The diatance from the Earth to the sun is 150 million kilometers.  The diameter of the entire solar system, as measured by the orbit of Neptune, is about 8000 million kilometers.  The distance from here to the nearest star (other than our own sun) is 40 million million kilometers.  The distance from here to the center of our galaxy is about 250 000 million million kilometers.  The distance to the great nebula in Andromeda, the nearest galaxy believed to be similar to our own, is 15 million million million kilometers.  And the distance to the edge of the known universe is around 100 000 million million million kilometers.

To allow astronomers to use reasonably small numbers in conversation when they're talking about the distances between planets, they use a distance called the Astronomical Unit.  One Astronomical Unit, or A.U., is just the average distance between the Earth and the sun, which works out to 149 597 870 kilometers.  A beam of light would take 8-and-1/3 minutes to cross this distance, which, to put it another way, means that anything we see happening on the surface of the sun actually took place 8 minutes and 20 seconds ago.  In terms of this unit, Pluto's orbit is only 40 A.U.s from the sun, and Mercury orbits the sun a scant 0.4 A.U.s away from it.  However, the nearest star is still 260 000 A.U.s from us, which means that such a large unit is still too small to use to talk about the distances to nearby stars.

Distances to nearby stars are measured by using trigonometric parallax.  Put simply, if you measure where in the sky a star is in December, and then measure its position again in June, it will have shifted a tiny tiny bit in relation to distant background stars.  This is similar to the way the position of a nearby object seems to shift in relation to the background if you look at it with your left eye, then with your right.  This tiny movement is called the parallax angle.  Even for the closest stars, the parallax angle measures less than one arc-second (1/3600 of one degree), which is about the diameter of the small white disk that the star makes on a photographic plate if you take a picture of it with a really big telescope.  The distance a star would have to be away to have a parallax angle of only one arc-second is called a parsec, and works out to a whopping 206 265 A.U.s; a star whose parallax angle was 1/2 an arc-second would be two parsecs away.  Such small angles can be measured if done carefully, and have been measured for most of the stars believed to be nearby.  Compared with the planets of our own solar system, the stars are extremely distant and extremely far apart.

The stars are so far apart, in fact, that astronomers and science fiction authors alike prefer to talk about interstellar distances in terms of "light-years."  A light-year is the distance that a beam of light, uninterrupted and in empty space, would travel in a year -- which is about 9 470 000 000 000 (nine million million, four hundred seventy thousand million) kilometers.  A star with a parallax angle of one arc-second works out to be 3.262 light-years away.  In terms of this unit, the nearest star (Proxima Centauri) is only 4.22 light-years away, which is a reasonably low and palatable number.

To put it another way, though, this means that anything we see happening on or near Proxima Centauri actually happened 4.22 years ago.  When we look out at Proxima Centauri through a telescope, we are looking 4.22 years into the past.  When we look at the center of our own galaxy, we're looking 25 000 years into the past.  When we look at the nearest spiral-type galaxy to our own, we're looking one-and-a-half million years into the past.  Thus, when we say the edge of the visible universe is about 10 000 million light-years away, we are also, in a way, saying that the universe is at least 10 000 million years old.

To sum it up, then:

1 A.U. = 149 597 870.61 kilometers

1 light-year = 63 239.7 A.U.s = 9 460 530 000 000 kilometers

1 parsec = 3.261633 light-years = 206 264.806 A.U.s = 30 856 780 000 000 kilometers

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3 years ago
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kumpel [21]
Picture B
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Explain why the elbow joint of a cow and the elbow joint of a human have similar, but not identical structure. Think about the a
MrRissso [65]
Our elbow bends all the time, we bend it when we pick up things, when we eat, when we do mostly everything. Cows on the other hand dont pick up food with there feet, they use there mouths, and they probably only bend when they are walking.
3 0
3 years ago
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Dichotomous Keys and branching diagrams organize different types of information about classification. how are these tools used d
Vadim26 [7]
To show the different levels of classification and divide among species, and different organisms on planet Earth. It also creates a universal "language" for scientists around the world when referring to organisms (cougar & puma are the same animals; different name)
Example: The American Alligator and the Chinese Alligator (look it up!) are in the same family and genus, but are not the same species.
4 0
3 years ago
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