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. The process by which an organism adapts to its environment through inherited traits is known as

A. Acclimatization
B. Behavioral ecology
C. Natural selection
D. Niche partitioning

Correct answer: C

Rationale: A) Acclimatization refers to the short-term physiological adjustments an individual organism makes in response to changes in its environment. This process is reversible and does not involve inherited traits. B) Behavioral ecology is the study of how behavior contributes to an organism's survival and reproduction in its environment. While behavior can be influenced by natural selection, it is not the process by which an organism adapts through inherited traits. C) Natural selection is the process by which organisms with advantageous traits for their environment are more likely to survive, reproduce, and pass on those traits to their offspring. Over time, this leads to the adaptation of populations to their environments. D) Niche partitioning is the process by which species divide resources to reduce competition within an ecosystem. While this can influence the evolution of species, it is not the process by which an organism adapts through inherited traits.

3. During ejaculation, sperm travels through a tube from the testes to the urethra. What is the name of this tube?

A. Vas deferens
B. Epididymis
C. Seminal vesicle
D. Urethra

Correct answer: A

Rationale: The vas deferens is the correct answer. It is the tube that carries sperm from the testes to the urethra during ejaculation. The vas deferens plays a crucial role in transporting mature sperm for ejaculation. The epididymis is responsible for sperm maturation and storage, not the direct passage of sperm to the urethra. The seminal vesicle produces fluid that combines with sperm to form semen but is not the tube for sperm transport. The urethra serves as the passageway for both urine and semen out of the body but is not the specific tube that transports sperm from the testes to the urethra.

4. What is the breakdown product of creatine phosphate, an energy source used for short bursts of muscle activity?

A. Glucose
B. Lactic acid
C. Carbon dioxide
D. Creatine

Correct answer: B

Rationale: Creatine phosphate is utilized as an immediate energy source for short bursts of muscle activity. When it breaks down, it yields lactic acid as a byproduct. Lactic acid accumulation during intense exercise can lead to muscle fatigue and soreness. Therefore, the correct answer is lactic acid. The other choices are incorrect: Glucose is a different energy source derived from carbohydrates; Carbon dioxide is a waste product of cellular respiration, not specifically from creatine phosphate breakdown; Creatine is the precursor compound to creatine phosphate and is not the breakdown product.

5. Which of the following is an example of a polymer?

A. Methane
B. Ethanol
C. Polyethylene
D. Acetic acid

Correct answer: C

Rationale: The correct answer is C, Polyethylene. Polyethylene is a polymer composed of a large number of repeating ethylene units linked together, forming a long-chain molecule, characteristic of polymers. Methane, ethanol, and acetic acid are small organic molecules that do not demonstrate the repeating unit structure typical of polymers. Therefore, they are not examples of polymers.