Answer:
Main sequence stars fuse hydrogen atoms to form helium atoms in their cores. About 90 percent of the stars in the universe, including the sun, are main sequence stars. These stars can range from about a tenth of the mass of the sun to up to 200 times as massive.
Stars start their lives as clouds of dust and gas. Gravity draws these clouds together. A small protostar forms, powered by the collapsing material. Protostars often form in densely packed clouds of gas and can be challenging to detect.
"Nature doesn't form stars in isolation," Mark Morris, of the University of California at Los Angeles (UCLS), said in a statement. "It forms them in clusters, out of natal clouds that collapse under their own gravity."
Smaller bodies — with less than 0.08 the sun's mass — cannot reach the stage of nuclear fusion at their core. Instead, they become brown dwarfs, stars that never ignite. But if the body has sufficient mass, the collapsing gas and dust burns hotter, eventually reaching temperatures sufficient to fuse hydrogen into helium. The star turns on and becomes a main sequence star, powered by hydrogen fusion. Fusion produces an outward pressure that balances with the inward pressure caused by gravity, stabilizing the star.
How long a main sequence star lives depends on how massive it is. A higher-mass star may have more material, but it burns through it faster due to higher core temperatures caused by greater gravitational forces. While the sun will spend about 10 billion years on the main sequence, a star 10 times as massive will stick around for only 20 million years. A red dwarf, which is half as massive as the sun, can last 80 to 100 billion years, which is far longer than the universe's age of 13.8 billion years. (This long lifetime is one reason red dwarfs are considered to be good sources for planets hosting life, because they are stable for such a long time.)
Explanation:
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Answer:
4. transforming the energy in glucose and related molecules in a chemical form that cells can use for work
Explanation:
Glycolysis breaks down glucose into two molecules of pyruvate which is transformed into acetyl CoA to enter the Kreb's cycle. Kreb's cycle breakdown the acetyl CoA into CO2 and H2O. The energy stored in the glucose molecule is released during glycolysis and Kreb's cycle. The released energy is stored in the form of NADH and FADH2 as well as in few molecules of ATP.
The NADH and FADH2 enter the final step of cellular respiration, the oxidative phosphorylation. Here, NADH and FADH2 are oxidized with the help of electron transport chain (ETC). During the transfer of electrons through ETC, the proton motive force is generated which then helps in ATP synthesis.
Hence, the three steps of cellular respiration (glycolysis + Kreb's cycle + oxidative phosphorylation) retrieve the energy from nutrients such as glucose and store it in the form of ATP. ATP is used by cells as an energy source for various other functions.
Answer:
Some diseases are more common in certain groups of people, such as Caucasians or African Americans because individuals in such ethnic groups often share certain alleles (versions of their genes), that have been passed down to them from common ancestors and a particular genetic disorder may be more frequently seen in such groups if one of these shared genes contains a disease-causing mutation.
Explanation:
Some genetic diseases are frequently seen in certain ethnic groups like Caucasians or African Americans. Individuals in such groups often share certain alleles (versions of their genes), that have been passed down to them from common ancestors and one of these shared genes may contains a disease-causing mutation.
Examples of certain genetic disorders that are more common in particular ethnic groups include the Tay-Sachs disease, which is more common in people of eastern and central Europe (Ashkenazi), Jewish or French Canadian ancestry and the sickle cell disease, which occur among people of African, African American, or Mediterranean heritage.
Some genetic disorders are more common in people whose ancestry can be traced to a particular geographic area. The factors that can lead to development of populations with very different genetic allele frequencies include their geographic origin, selection, patterns of migration, historic events, etc. Certain natural barriers like oceans and other water bodies, high mountains, large deserts, or major cultural factors had prevented communication and interaction between people. So mating was restricted within the group, and this produces genetic marker differences and differences in the presence of specific disease-related alleles.
Answer:
- E/e ; T/t ⇒ Square eyes and long tail (Option D)
- 3/16 will have round eyes and long tails (Option C)
- 1/4 of the progeny will be heterozygous for both traits (Option A)
Explanation:
<u>Available data</u>:
- Two diallelic unlinked genes
- Gene E controls eye shape: Dominant allele E expresses square eyes, and recessive allele e expresses round eyes.
- Gene T controls the tail size. Dominant allele T expresses long trail, and recessive allele t expresses short tail.
<u>Genotypes Phenotypes</u>
EETT, EeTT, EETt, EeTt Square eyes and Long tail
eeTT, eeTt Round eyes and Long tail
EEtt, Eett Square eyes and Short tail
eett Rounf eyes and short tail.
<em>1. An individual of this new species is heterozygous for gene E and heterozygous for gene T. What is their genotype and phenotype?</em>
The heterozygous individual is E/e ; T/t, expressing square eyes and a long tail.
<em>2. Two individuals, who are both heterozygous for eye shape and tail size, mate. Which of the following is a correct statement about the phenotype ratios expected for their offspring?</em>
Cross: between two heterozygous individuals
Parentals) EeTt x EeTt
Gametes) ET, Et, eT, et
ET, Et, eT, et
Punnett square) . ET Et eT et
ET EETT EETt EeTT EeTt
Et EETt EEtt EeTt Eett
eT EeTT EeTt eeTT eeTt
et EeTt Eett eeTt eett
F1) Genotype:
- 1/16 EETT
- 2/16 EETt
- 1/16 EEtt
- 2/16 EeTT
- 4/16 EeTt ⇒ 1/4 EeTt
- 2/16 Eett
- 1/16 eeTT
- 2/16 eeTt
- 1/16 eett
Phenotype
- 9/16 E-T-, Square eyes and Long tails
- 3/16 E-tt, Square eyes and short tails
- 3/16 eeT-, Round eyes and Long tails
- 1/16 eett, round eyes and short tail
Phenotypic ratio 9:3:3:1
<em>3. From the mating described in question ABOVE, what proportion of ALL of the offspring in will be heterozygous for both traits?</em>
4/16 = 1/4 = 25% of the progeny are expected to be heterozygous for both traits, EeTt.
Answer:
Plato Answer
Explanation:
Embryonic stem cells are plentiful, and they can create every cell in the human body. Researchers can use these cells to create tissues. They can possibly grow new organs in a lab to treat diseased organs. Adult stem cells are rarer in the human body, and they’re limited in the types of cells they can make.
An embryo can’t grow without its stem cells, so people have ethical concerns about their use. Adults can provide consent to donate their stem cells, so there are fewer ethical issues regarding the use of adult stem cells.
