what of the following cations is found at the center of a heme

ATI TEAS 7

Practice Science TEAS Test

1. Which of the following cations is found at the center of a heme?

A. Cr (III)
B. Cu (II)
C. Iron (II)
D. Iron (III)

Correct answer: C

Rationale: The correct answer is Iron (II) (Fe2+), which is the cation found at the center of a heme group. Heme contains an iron (II) ion that is coordinated within the porphyrin ring structure. This iron ion is crucial for the function of heme in binding and transporting oxygen in hemoglobin and myoglobin. Choice A (Cr (III)) is incorrect as chromium is not typically found at the center of a heme group. Choice B (Cu (II)) is incorrect as copper is not the cation typically present in heme. Choice D (Iron (III)) is also incorrect as heme predominantly contains iron (II) at its center, not iron (III).

2. Which of the following is NOT a state of matter?

A. Solid
B. Liquid
C. Gas
D. Superfluid

Correct answer: D

Rationale: The correct answer is 'Superfluid.' Superfluid is not considered a traditional state of matter. It is a unique phase of matter that displays zero viscosity and flows without losing kinetic energy. Solids, liquids, and gases are the three classical states of matter distinguished by their physical properties and structures. Therefore, choices A, B, and C are considered states of matter, while choice D, superfluid, is not.

3. Which organ produces insulin?

A. Pancreas
B. Liver
C. Stomach
D. Kidneys

Correct answer: A

Rationale: Insulin is a hormone that regulates blood sugar levels by facilitating the uptake of glucose into cells for energy production or storage. The pancreas, located behind the stomach, is the organ responsible for producing insulin. Within the pancreas, specialized cells known as beta cells synthesize and secrete insulin in response to changes in blood glucose levels. The liver, although vital for metabolism, does not produce insulin. Similarly, the stomach and kidneys do not play a role in insulin production. Hence, the correct answer is the pancreas.

4. What is the term for an organism with two different alleles for a gene?

A. Homozygous
B. Heterozygous
C. Dominant
D. Recessive

Correct answer: B

Rationale: Homozygous refers to an organism with two identical alleles for a gene, either both dominant or both recessive. Heterozygous, the correct answer, refers to an organism with two different alleles for a gene, one dominant and one recessive. Dominant and recessive describe the relationship between alleles, where dominant alleles are expressed over recessive alleles in heterozygous individuals. Therefore, the term for an organism with two different alleles for a gene is 'heterozygous.'

5. What is the function of the pons?

A. Center for emotion and motivation
B. Control production of hormones
C. Relay messages from the cortex to the cerebellum
D. Responsible for involuntary actions like breathing

Correct answer: C

Rationale: The correct function of the pons is to relay messages from the cortex to the cerebellum. The pons acts as a bridge between different brain regions, facilitating communication and coordination of movements. Choices A, B, and D are incorrect. The pons is not the center for emotion and motivation, does not control hormone production, and is not primarily responsible for involuntary actions like breathing. Understanding the role of the pons in relaying messages between brain regions is crucial for comprehending its function in the central nervous system.