the concept of punctuated equilibrium suggests that

ATI TEAS 7

TEAS Test 7 science

1. What does the concept of punctuated equilibrium suggest?

A. Evolution occurs gradually through the continuous accumulation of small changes over long periods.
B. Evolution is characterized by long periods of relative stasis punctuated by rapid bursts of evolutionary change.
C. The fossil record is a complete and accurate representation of all past life forms.
D. Natural selection primarily favors extreme phenotypes within a population.

Correct answer: B

Rationale: Punctuated equilibrium suggests that evolution is characterized by long periods of relative stasis punctuated by rapid bursts of evolutionary change. This concept, proposed by Stephen Jay Gould and Niles Eldredge, implies that species remain relatively unchanged for extended periods, followed by sudden bursts of rapid evolution. Option A describes the gradualism model, which is different from punctuated equilibrium. Option C is inaccurate as the fossil record is incomplete and biased. Option D is unrelated to the concept of punctuated equilibrium.

2. What is the small repeating unit in the contractile apparatus of skeletal muscle?

A. Myofibril
B. Actin
C. Sarcomere
D. Myosin

Correct answer: C

Rationale: The correct answer is 'Sarcomere.' The sarcomere is the smallest repeating unit within myofibrils and is responsible for muscle contraction in skeletal muscle. It consists of overlapping actin and myosin filaments arranged in a highly organized structure that allows for the sliding of filaments during muscle contraction. 'Myofibril' (choice A) is incorrect because it is a larger structure composed of sarcomeres. 'Actin' (choice B) and 'Myosin' (choice D) are incorrect as they are individual proteins that are components of the sarcomere, not the smallest repeating unit itself.

3. Which of the following best describes a plane that divides the body into upper and lower portions?

A. Coronal
B. Transverse
C. Oblique
D. Median

Correct answer: B

Rationale: The correct answer is B: Transverse. A transverse plane, also known as a horizontal plane, divides the body into upper and lower portions. This plane is perpendicular to the long axis of the body. Coronal planes divide the body into anterior and posterior portions. Oblique planes pass through the body at an angle, neither strictly horizontal nor vertical. The median plane passes longitudinally through the body, dividing it into equal left and right halves.

4. What is the fatty substance that coats axons to insulate, protect, and speed up impulses?

A. Myelin
B. Dendrite
C. Neuron
D. Synapse

Correct answer: A

Rationale: The correct answer is 'Myelin.' Myelin is a fatty substance that functions as an insulator for axons, providing protection and enhancing the speed of electrical impulses along neurons. This insulation is essential for ensuring efficient and rapid communication within the nervous system. Choices B, C, and D are incorrect. Dendrites are branched extensions of a neuron that receive signals, neurons are the basic building blocks of the nervous system that transmit information, and synapses are the junctions between neurons where communication occurs.

5. What is the function of the rib cage in the human body?

A. To protect the digestive organs
B. To protect the lungs and heart
C. To support movement
D. To regulate body temperature

Correct answer: B

Rationale: The rib cage plays a crucial role in protecting vital organs, specifically the lungs and heart, from external injuries. Choice A is incorrect because the rib cage does not primarily protect the digestive organs. Choice C is incorrect as the primary function of the rib cage is not to support movement, but to protect internal organs. Choice D is incorrect as regulating body temperature is not a function typically associated with the rib cage.