what is the function of introns in eukaryotic genes

ATI TEAS 7

TEAS 7 science quizlet

1. What is the function of introns in eukaryotic genes?

A. They code for protein sequences.
B. They are involved in gene regulation.
C. They are removed during mRNA processing.
D. They are non-functional remnants of ancient DNA.

Correct answer: C

Rationale: A) Introns do not code for protein sequences. Exons are the segments of DNA that code for proteins. B) While introns can indirectly influence gene regulation, their primary function is not directly involved in gene regulation. C) Introns are non-coding regions of DNA that are transcribed into pre-mRNA but are removed during mRNA processing through a process called splicing. This allows only the exons to be included in the mature mRNA that will be translated into proteins. D) While introns were once thought to be non-functional remnants of ancient DNA, research has shown that they can have regulatory functions and play a role in gene expression.

2. Which structure of the endocrine system is responsible for maturing T cells?

A. Hypothalamus
B. Pineal
C. Thymus
D. Thyroid

Correct answer: C

Rationale: The thymus is the primary gland responsible for the maturation of T cells in the immune system. T cells are a type of white blood cell involved in the immune response. The hypothalamus is primarily involved in hormone regulation and maintaining homeostasis. The pineal gland is responsible for secreting melatonin and regulating the sleep-wake cycle. The thyroid gland plays a key role in metabolism regulation through the production of thyroid hormones. Therefore, the correct answer is the thymus because it is specifically associated with the maturation of T cells, making it essential for proper immune function.

3. Calcitonin, a hormone that helps regulate calcium levels, is produced by the:

A. Thyroid gland
B. Parathyroid gland
C. Thymus gland
D. Adrenal gland

Correct answer: A

Rationale: Calcitonin is a hormone produced by the thyroid gland. It helps regulate calcium levels in the body by inhibiting the breakdown of bone and promoting calcium excretion by the kidneys. The parathyroid gland produces parathyroid hormone (PTH), which works in opposition to calcitonin to regulate calcium levels. The thymus gland is involved in the development of the immune system, and the adrenal gland produces hormones such as cortisol and adrenaline. Therefore, the correct answer is the thyroid gland as it specifically secretes calcitonin for calcium regulation.

4. Which statement most accurately compares and contrasts the structures of DNA and RNA?

A. Both DNA and RNA have 4 nucleotide bases. Three of the bases are the same, but the fourth base is thymine in DNA and uracil in RNA.
B. Both DNA and RNA have the same 4 nucleotide bases. However, the nucleotides bond differently in DNA compared to RNA.
C. Both DNA and RNA have different numbers of nucleotide bases. DNA is a double helix while RNA is a single strand.
D. Both DNA and RNA have a double helix structure. However, DNA contains 6 nucleotide bases and RNA contains 4 nucleotide bases.

Correct answer: A

Rationale: The correct answer is A because DNA and RNA both consist of 4 nucleotide bases, namely adenine, cytosine, and guanine, which are common in both. The key difference lies in the fourth base, which is thymine in DNA and uracil in RNA. This distinction is fundamental in understanding the structural variances between DNA and RNA. Choice B is incorrect as it incorrectly states that the nucleotides bond differently in DNA compared to RNA without specifying the crucial base differences. Choice C is inaccurate as it misrepresents the numbers of nucleotide bases in DNA and RNA, and incorrectly describes DNA as a double helix and RNA as a single strand, which is not related to the difference in bases. Choice D is incorrect as it inaccurately portrays DNA with 6 nucleotide bases and RNA with 4, which is not true; both DNA and RNA have 4 nucleotide bases, but with differences in one of the bases.

5. Who is credited with the discovery of nuclear fission?

A. Marie Curie
B. Albert Einstein
C. Enrico Fermi
D. Ernest Rutherford

Correct answer: C

Rationale: Enrico Fermi is credited with the discovery of nuclear fission. In 1934, Fermi bombarded uranium with neutrons, leading to the splitting of the uranium nucleus and the release of energy. This groundbreaking discovery laid the foundation for the development of nuclear power and weapons. Marie Curie is known for her pioneering research on radioactivity, but she did not discover nuclear fission. Albert Einstein made significant contributions to physics, including the theory of relativity, but he was not credited with the discovery of nuclear fission. Ernest Rutherford conducted the famous gold foil experiment and made contributions to the understanding of the atom's structure, but he did not discover nuclear fission.