what is the structure of dna

ATI TEAS 7

ATI TEAS Science Practice Test

1. What is the structure of DNA?

A. Single-stranded, linear
B. Double-stranded, linear
C. Double-stranded, helix
D. Single-stranded, helix

Correct answer: C

Rationale: The correct answer is C: Double-stranded, helix. DNA is structured as a double helix formed by two strands of nucleotides. The nucleotides are paired with complementary bases (A-T and C-G) in the center, held together by hydrogen bonds. This double-stranded helical structure is a fundamental characteristic of DNA and essential for its function in storing genetic information. Choices A, B, and D are incorrect because DNA is not single-stranded; it consists of two strands that run antiparallel to each other and are connected via hydrogen bonds. Additionally, DNA does not have a linear structure but rather a helical one, providing stability and protection to the genetic information it carries.

2. Which element is essential for the formation of hemoglobin?

A. Calcium
B. Iron
C. Potassium
D. Sodium

Correct answer: B

Rationale: The correct answer is Iron. Iron is essential for the formation of hemoglobin, the protein in red blood cells that binds and transports oxygen throughout the body. Calcium (Choice A), Potassium (Choice C), and Sodium (Choice D) are not directly involved in the formation of hemoglobin and its oxygen-carrying function.

3. Which of the following is a characteristic phenomenon associated with Cherenkov radiation?

A. Alpha particle emission
B. Beta particle emission
C. Gamma ray emission
D. Charged particles exceeding the speed of light in a medium

Correct answer: D

Rationale: Cherenkov radiation is produced when charged particles travel through a medium at speeds greater than the speed of light in that medium. It is not specific to a particular type of particle emission but rather to the speed of the charged particles. This phenomenon results in the emission of a characteristic blue light, which is a visual indicator of charged particles exceeding the speed of light in that medium. Choices A, B, and C are incorrect because Cherenkov radiation is not limited to a specific type of particle emission but is based on the speed of the charged particles relative to the speed of light in the medium.

4. Blood type is a trait determined by multiple alleles, with IA coding for A blood, IB coding for B blood, and i coding for O blood being recessive. If an individual with A heterozygosity and an O individual have a child, what is the probability that the child will have A blood?

A. 25%
B. 50%
C. 75%
D. 100%

Correct answer: B

Rationale: When an A heterozygote individual (IAi) and an O individual (ii) have a child, there are four possible combinations of alleles that the child can inherit: IA from the A parent and i from the O parent; IA from the A parent and i from the O parent; i from the A parent and i from the O parent; i from the A parent and i from the O parent. Out of these combinations, 50% of the offspring will inherit the A allele from the A parent, resulting in A blood type. Therefore, the correct answer is 50%. Choice A is incorrect because the probability is not 25%. Choice C is incorrect as it overestimates the likelihood. Choice D is incorrect as it suggests a certainty which is not the case in genetics.

5. What is the relationship between genetic drift and the founder effect?

A. Founder effect is a cause of genetic drift within a small population
B. Genetic drift is a cause of the founder effect in new populations
C. They are the same phenomenon with different names
D. They are unrelated concepts.

Correct answer: A

Rationale: - The founder effect is a specific type of genetic drift that occurs when a small group of individuals establishes a new population, leading to a loss of genetic variation. - Genetic drift, on the other hand, is a broader concept that refers to random changes in allele frequencies in a population over time due to chance events. - Therefore, the founder effect is a specific scenario within the broader concept of genetic drift, where the establishment of a new population by a small number of individuals leads to genetic changes in the population.