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Lelechka [254]
3 years ago
6

The earliest cells detectable in fossils were different from the cells in animals, plants, fungi, and protists living today. The

se first prokaryotic cells gave rise to eukaryotic cells approximately 1.7 billion years ago. The structure of eukaryotic cells today suggests how they might have evolved from their prokaryotic ancestors. Scientists examining mitochondria and chloroplasts now think that these organelles were probably free-living prokaryotes before becoming a part of eukaryotic cells long ago.What evidence suggests that mitochondria might have evolved before chloroplasts?
Biology
1 answer:
aalyn [17]3 years ago
5 0

Answer:

In the 1960s, Lynn Magulis came up with the theory of endosymbiosis. Different evidence supports this theory that the cell organelles like chloroplasts and mitochondria were once utilized by the independent living species. Both of these organelles exhibit their own genetic material. The mitochondria cannot differentiate to produce chloroplasts and vice versa.  

However, the fact that the mitochondria are found in all the cells of eukaryotes, while the chloroplast is witnessed only in certain specific cells, shows that the evolution of mitochondria took place much earlier than the chloroplasts.  

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This passage best supports which conclusion about dark matter?​
neonofarm [45]

Answer:D

Explanation:

The passage talks about how it's gravity disrupts the path of light

3 0
3 years ago
How are species introduced to new ecosystems
Sergio039 [100]
Speciation I believe..
5 0
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What do you call the red pigment found in vertebrates that functions in oxygen transport?
slava [35]
There are actually two red pigments found in certain vertebrates that function in oxygen transport (or storage). Hemoglobin is present in the blood of most vertebrates and binds oxygen molecules, in order to transport them to body tissues in need of oxygen for energy (ATP) production.
Myoglobin, mainly in mammals, is a protein (enzyme) found in red (skeletal) muscle cells, that aids in binding oxygen when it's plentiful being delivered via blood. The purpose is that in high stress, low oxygen situations such as strenuous exercise, the myoglobin releases its bound oxygen to provide it to the starving overworked muscle cells.
**Fun fact: it's the hemoglobin that gives the bright red color of blood when it's bound to oxygen, and the myoglobin of mammal flesh gives it the typical pinkish-red hue that is seen in mammalian meat (veal, steak, ham, venison, bison, etc.). Other non-mammalian animals (fish, birds, frogs, snake, alligator, etc.) tend to have lighter-colored skeletal muscle meat due to the lack of myoglobin, amongst other factors.
6 0
3 years ago
In meiosis, 2 cells have been created at the end of telophase 1, halfway through the process. These cells are said to exist in a
tatuchka [14]

Answer:

In some species, cells enter a brief interphase, or interkinesis, before entering meiosis II. Interkinesis lacks an S phase, so chromosomes are not duplicated. The two cells produced in meiosis I go through the events of meiosis II in synchrony. During meiosis II, the sister chromatids within the two daughter cells separate, forming four new haploid gametes. The mechanics of meiosis II is similar to mitosis, except that each dividing cell has only one set of homologous chromosomes. Therefore, each cell has half the number of sister chromatids to separate out as a diploid cell undergoing mitosis.

Prophase II

If the chromosomes decondensed in telophase I, they condense again. If nuclear envelopes were formed, they fragment into vesicles. The centrosomes that were duplicated during interkinesis move away from each other toward opposite poles, and new spindles are formed.

Prometaphase II

The nuclear envelopes are completely broken down, and the spindle is fully formed. Each sister chromatid forms an individual kinetochore that attaches to microtubules from opposite poles.

Metaphase II

The sister chromatids are maximally condensed and aligned at the equator of the cell.

Anaphase II

The sister chromatids are pulled apart by the kinetochore microtubules and move toward opposite poles. Non-kinetochore microtubules elongate the cell.



Figure 1. The process of chromosome alignment differs between meiosis I and meiosis II. In prometaphase I, microtubules attach to the fused kinetochores of homologous chromosomes, and the homologous chromosomes are arranged at the midpoint of the cell in metaphase I. In anaphase I, the homologous chromosomes are separated. In prometaphase II, microtubules attach to the kinetochores of sister chromatids, and the sister chromatids are arranged at the midpoint of the cells in metaphase II. In anaphase II, the sister chromatids are separated.

Telophase II and Cytokinesis

The chromosomes arrive at opposite poles and begin to decondense. Nuclear envelopes form around the chromosomes. Cytokinesis separates the two cells into four unique haploid cells. At this point, the newly formed nuclei are both haploid. The cells produced are genetically unique because of the random assortment of paternal and maternal homologs and because of the recombining of maternal and paternal segments of chromosomes (with their sets of genes) that occurs during crossover. The entire process of meiosis is outlined in Figure 2.



Figure 2. An animal cell with a diploid number of four (2n = 4) proceeds through the stages of meiosis to form four haploid daughter cells.

7 0
3 years ago
Which can change the direction of a downward input force into an upward output force? A. can opener B. ax blade C. crowbar D. sc
kolbaska11 [484]
This would be a crowbar. If you have trouble understand this, just visualize what happens when you pry the lid of a box open with a crowbar. You push one end down, and the other end goes up.
4 0
3 years ago
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