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 factors can contribute to erectile dysfunction in males?

A. Diabetes
B. Cardiovascular disease
C. Neurological disorders
D. All of the above

Correct answer: D

Rationale: Erectile dysfunction can be caused by various factors, including diabetes, cardiovascular disease, and neurological disorders. These conditions can impact blood flow, nerve function, and hormone levels, all crucial for achieving and maintaining an erection. Diabetes can lead to nerve damage and affect blood circulation. Cardiovascular disease can restrict blood flow to the penis. Neurological disorders can interfere with the transmission of nerve signals between the brain and the reproductive organs. Therefore, all the factors mentioned in options A, B, and C can contribute to erectile dysfunction in males.

3. During micturition, the process involves a combination of:

A. Gravity alone
B. Voluntary muscle contractions only
C. Involuntary muscle contractions only
D. Both voluntary and involuntary muscle contractions

Correct answer: D

Rationale: During micturition, which is the process of urination, both voluntary and involuntary muscle contractions are involved. Voluntary muscle contractions include the relaxation of the external urethral sphincter, allowing the release of urine, while involuntary muscle contractions involve the detrusor muscle in the bladder contracting to expel urine. Choices A, B, and C are incorrect because micturition is not solely dependent on gravity, voluntary muscle contractions, or involuntary muscle contractions alone. The correct answer is D as both types of muscle contractions are necessary for the complete process of urination.

4. A car is moving in a circle at a constant speed. Which of the following is NOT true about its motion?

A. It has a constant centripetal acceleration
B. Its tangential velocity remains constant
C. It experiences a force directed towards the center of the circle
D. It covers the same distance in equal time intervals along its circular path

Correct answer: B

Rationale: In circular motion at a constant speed, the car has a constant centripetal acceleration (choice A), experiences a force directed towards the center of the circle (choice C), and covers the same distance in equal time intervals along its circular path (choice D). However, the tangential velocity of an object in circular motion at a constant speed changes continuously as it moves around the circle, so it is not constant (choice B). The change in tangential velocity allows the car to maintain its motion in a circular path despite moving at a constant speed. Choice A is incorrect because centripetal acceleration is indeed present to keep the car moving in a circular path. Choice C is incorrect as a force towards the center is required to keep the car in circular motion. Choice D is incorrect because the car covers equal distances in equal time intervals to maintain its circular trajectory.

5. What is the main function of the large intestine?

A. To absorb proteins
B. To absorb water and form feces
C. To produce enzymes for digestion
D. To store fat

Correct answer: B

Rationale: The main function of the large intestine is to absorb water and form feces from waste material. Choice A is incorrect because the absorption of proteins primarily occurs in the small intestine. Choice C is incorrect as the production of enzymes for digestion mainly takes place in the pancreas and small intestine. Choice D is incorrect as the storage of fat is not a primary function of the large intestine.