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 are the products of anaerobic respiration in humans?

A. Ethyl alcohol and CO2
B. Ethyl alcohol only
C. Lactic acid and CO2
D. Lactic acid only

Correct answer: C

Rationale: During anaerobic respiration in humans, lactic acid and CO2 are produced. Choice A, 'Ethyl alcohol and CO2,' is incorrect because ethyl alcohol is not a product of anaerobic respiration in humans. Choice B, 'Ethyl alcohol only,' is incorrect as ethyl alcohol is not a product of anaerobic respiration in humans. Choice D, 'Lactic acid only,' is incorrect because CO2 is also a product of anaerobic respiration in humans.

3. Which mineral is essential for muscle function and nerve transmission?

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

Correct answer: D

Rationale: Potassium is the correct answer as it is essential for muscle function and nerve transmission. Potassium plays a crucial role in regulating muscle contractions, including the heart's beating, and is vital for transmitting electrical signals within the nervous system. Calcium (Choice A) is important for muscle contraction but is not the primary mineral for nerve transmission. Iron (Choice B) is important for oxygen transport in the blood. Sodium (Choice C) is important for fluid balance but is not primarily responsible for muscle function and nerve transmission.

4. Which of the following is the cartilaginous flap that protects the larynx from water or food while still allowing the flow of air?

A. epiglottis
B. bronchioles
C. epithelium
D. tongue

Correct answer: A

Rationale: The epiglottis is the cartilaginous flap that protects the larynx from water or food while still allowing the flow of air. When we swallow, the epiglottis covers the entrance to the larynx, preventing food or liquid from entering the airway and instead directing them towards the esophagus for digestion. Choice B, bronchioles, are small airway branches within the lungs and are not involved in protecting the larynx from food or water. Choice C, epithelium, refers to the tissue that lines the surfaces of organs and structures in the body, but it is not the specific structure that protects the larynx as described. Choice D, tongue, plays a role in taste, speech, and swallowing, but it is not the cartilaginous flap that protects the larynx.

5. The above experimental design description is an example of which of the following types of experiments?

A. field experiment
B. natural experiment
C. controlled experiment
D. observational study

Correct answer: C

Rationale: The above experimental design description involves the manipulation of an independent variable (light exposure) to observe its effects on the dependent variable (plant growth) under controlled conditions. In a controlled experiment, researchers actively manipulate one or more variables while keeping all other variables constant to establish cause-and-effect relationships. Choice A, a field experiment, typically takes place in a real-world setting but still involves manipulation and control of variables. Choice B, a natural experiment, involves observing naturally occurring differences in variables without researcher intervention. Choice D, an observational study, does not involve manipulation of variables, making it different from the described experimental design.