half life refers to the characteristic time it takes for

ATI TEAS 7

ATI TEAS 7 science review

1. What does half-life refer to?

A. Radioactive intensity to completely disappear
B. The number of neutrons in a nucleus to double
C. The number of protons in a nucleus to change
D. An isotope to decay by half of its initial quantity

Correct answer: D

Rationale: Half-life refers to the time it takes for half of the radioactive atoms in a sample to decay. This means that after one half-life, half of the initial quantity of the radioactive substance will have decayed. Choice A is incorrect because radioactive intensity doesn't completely disappear during half-life. Choice B is incorrect as half-life doesn't refer to the number of neutrons doubling. Choice C is incorrect as half-life doesn't relate to the number of protons changing.

2. Which of the following is true regarding adipocytes?

A. They are involved in the secretion of glucose.
B. They are responsible for storing the fat found in adipose tissue.
C. They are critical in the digestive breakdown of fat.
D. They are the foundational element of muscles.

Correct answer: B

Rationale: The correct answer is B. Adipocytes are responsible for storing the fat found in adipose tissue. These specialized cells store energy in the form of fat and play a key role in energy balance and metabolism. Adipocytes do not secrete glucose; that function is typically attributed to other cells like pancreatic beta cells. Adipocytes are not involved in the digestive breakdown of fat, as this process primarily occurs in the gastrointestinal system with the help of enzymes. Adipocytes are distinct from the foundational elements of muscles, which are primarily made up of muscle fibers and associated connective tissues.

3. What is the study of fungi known as?

A. Virology
B. Mycology
C. Bacteriology
D. Parasitology

Correct answer: B

Rationale: Mycology is the correct answer. Mycology is the branch of biology that specifically deals with the study of fungi. Fungi constitute a separate kingdom of organisms that include various forms such as yeasts, molds, and mushrooms. Virology (A) is the study of viruses, while Bacteriology (C) focuses on bacteria. Parasitology (D) is the study of parasites, which may include protozoa, helminths, and some fungi, but it is not solely dedicated to fungi.

4. Molecular clocks utilize the accumulation of mutations in DNA sequences to estimate the evolutionary divergence time between species. This method relies on the assumption that:

A. The rate of mutation is constant across all genes and all species.
B. Species with more morphological similarities diverged more recently.
C. Mutations are always beneficial and contribute to increased fitness.
D. The fossil record provides the most accurate estimates of evolutionary relationships.

Correct answer: A

Rationale: A molecular clock is a method used to estimate the time of divergence between species by measuring the accumulation of mutations in DNA sequences. This method relies on the assumption that mutations occur at a relatively constant rate over time. If the rate of mutation were not constant, it would be challenging to accurately estimate the evolutionary divergence time between species. Therefore, option A is the most appropriate choice as it aligns with the fundamental principle underlying the molecular clock hypothesis. Option B is incorrect because the assumption that species with more morphological similarities diverged more recently does not directly relate to the concept of molecular clocks and the accumulation of mutations in DNA sequences. Option C is incorrect because mutations are not always beneficial and do not always contribute to increased fitness. Mutations can be neutral or deleterious as well, and their accumulation is what is used to estimate evolutionary di