BIOLOGY HIGH SCHOOL

a scientist kept 500 grams of a radioactive material in a container. after 60 minutes, he observed that 62.5 grams of the radioactive material was left in the container. based on the observation, which of these is the most likely inference drawn by the scientist?

Answers

Answer 1
Answer: After the 1st half-life 250 g of the radioactive material will be left. 
After the 2nd half-life 125 g of the radioactive material will be left. 
After the 3rd half-life 62.5 g of the radioactive material will be left. 

Therefore after 60 minutes, 3 half lives would have occurred. 

Therefore the half-life = 60 / 3 = 20 minutes when 250 grams of the original material would have remained radioactive. 

Therefore the answer is A) About 250 gram of the material decayed in 20 minutes.
Answer 2
Answer:

Answer:

A

Explanation:

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The ancestors of elephants inhabited every continent except Antarctica and Australia. But the Asian and African elephants are the only ones to survive. Why?

Answers

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Which of these best demonstrates mutualism between certain types of bacteria and humans

Answers

Mutualisam between types of Bateria and Humans

Bacteria and the human both get benefit from each other and this relation is mutualism. Bacteria stay inside nose, mouth, intestines, and many more areas of the body surface. They help human by giving response to pathogenic bacteria for protection of immune system.

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I cannot find the propositions if it is a MCQ, so I will tell what a bacterial mutualism is:

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Many mutualistic bacteria live and develop in us, for example, the intestinal flora synthesizes vitamin K, a vitamin that is necessary for the absorption of our food. This same intestinal flora also hinders the proliferation of pathogenic bacteria as well as that of commensal bacteria potentially dangerous.

Which of the following activities does NOT contribute to global warming?A.) Driving cars
B.) Releasing gases
C.) Walking
D.) Burning fuel

Answers

WALKING does not contributes to global warming. Global warming is the gradual increase in the total temperature of the earth as a result of green house effects. Green house effects is caused by increased accumulation of carbondioxide and other polutants in the earth's atmosphere. Fossils fuels and gases are the major contributors global warming because their burning add carbon dioxide to the atmosphere.

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Answers

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Nick observes thickening and discoloration of the nail of the index finger. Nick is most likely suffering from a/an infection.

Answers

Answer:

Nick observes thickening and discoloration of the nail of the index finger. Nick is most likely suffering from an onychomycosis infection.

Explanation:

Onychomycosis is a chronic and progressive infection of the nails caused by fungi. In most cases it is produced by dermatophytes, and less frequently by yeasts and molds. It is the most frequent nail disease.

Onychomycosis can affect the appearance, thickness and color abnormally, both in the nails of the hands and the feet, although the nail of the big toe is the most frequently affected.
Nick observes thickening and discoloration of the nail of the index finger. Nick is most likely suffering from a/an infection.

Onychomycosis (or nail mycosis)
a fungus

(a) Describe the process in meiosis that ensures that both maternal and paternal chromosomes are passed on to each spermatozoon.

Answers

Answer:

Explanation:

Meiosis is a type of cell division in which the ploidy of the organism reduces to half in the daughter cells.

Meiosis produces 4 daughter cells from 1 parent cell with a different combination of the genetic material but haploid chromosomes.

The meiosis process takes place in two stages in which during the first stage, the homologous chromosomes separate reducing the chromosome number to half that is from diploid chromosomes of parents to haploid in daughter.

Since the process of meiosis form haploid gametes in both male and female therefore after fertilization restores the diploid chromosomes of the parent cell and form a diploid structure.
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