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2 years ago

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Scientists have created trains that use magnets to make the trains float above the tracks as they travel. These trains float bec

ause
(a) the track is waxed (c) the like poles repel
(b) the train has a low density (d) a chemical change occurs

1 answer:

Arada [10]2 years ago

7 0

Answer:

the poles repel

Explanation:

i believe this is the best answer

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Almost all the South American and Central American

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Answer:

O founder's effect

Explanation:

A founder effect can be defined as the loss of genetic variation when a new population is established from a few individuals. This process is known to increase the frequency of particular gene variants (alleles) at different <em>loci</em> when they are selectively neutral (or nearly neutral), and thereby such genes are fixed by genetic drift (i.e., through the random sampling of founder individuals). Interestingly, it has been discovered that the majority of South American and Central American Indians are nearly exclusively in the O blood group, which has been further associated with random genetic drift and a founder effect.

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3 years ago

Both intrasexual and intersexual selection usually cause changes in phenotypes for males and little changes in female phenotypes

saveliy_v [14]

<em>The question is incomplete. Please read below to find the missing content.</em>

<em />

Selection is usually strongest in the male of the species. D) because sperm are small and plentiful, while eggs are large and energy-rich.

Phenotype refers back to the observable traits of an organism as a multifactorial effect of genetic trends and environmental influences. The organism phenotype includes its morphological, biochemical, physiological, and behavioral residences.

A person's genotype is their specific collection of DNA. extra especially, this term is used to refer to the two alleles a person has inherited for a selected gene. Phenotype is the detectable expression of this genotype – a patient's clinical presentation.

The sum of an organism's observable traits is its phenotype. A key difference between phenotype and genotype is that, even as genotype is inherited from an organism's parents, the phenotype isn't.

Both intrasexual and intersexual selection usually cause changes in phenotypes for males and little changes in female phenotypes. Why is sexual selection usually strongest in the male of the species?

a. Males are naturally more aggressive

b. Males have a smaller genetic component than females due to fewer X chromosomes

c. Males do not pass on their mitochondria and therefore have more invested in each individual mating event

d. Because sperm are small and plentiful, while eggs are large and energy-rich.

Learn more about phenotypes here brainly.com/question/902712

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1 year ago

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Under nose is the answer

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For radioactive materials with short half-lives, you use a very sensitive calibrated detector to measure how many counts per second it is producing. Then using the exact same set up you do the same at a latter time. You use the two readings and the time between them to determine the half-life. You don’t have to wait exactly a half-life, you can do the math with any significant time difference. Also, you don’t need to know the absolute radioactivity, as long as the set up is the same you only need to know fraction by which it changed.

For radioactive materials with long half-lives that won’t work. Instead you approach the problem differently. You precisely measure the mass of a very pure sample of the radioactive material. You can use that to calculate the number of atoms in the sample. Then you put the sample in a counter that is calibrated to determine the absolute number of disintegrations happening in a given time. Now you know how many of them are disintegrating every second. You use the following equations:

Decays per Second = (Number of Atoms) x (Decay Constant)

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3 years ago

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Answer:

the end or close; final part. the last main division of a discourse, usually containing a summing up of the points and a statement of opinion or decisions reached. ... final decision: The judge has reached his conclusion. a reasoned deduction or inference.

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