what effect does a catalyst have on a chemical reaction

ATI TEAS 7

ATI TEAS Science Test

1. What effect does a catalyst have on a chemical reaction?

A. It speeds up the reaction.
B. It slows down the reaction.
C. It makes a reaction go in reverse.
D. It prevents a reaction from taking place.

Correct answer: A

Rationale: A catalyst is a substance that increases the rate of a chemical reaction without being consumed in the process. It works by providing an alternate pathway for the reaction to occur, lowering the activation energy needed for the reaction to proceed. As a result, more reactant molecules can overcome this energy barrier and participate in the reaction, leading to a faster overall reaction rate. This explanation contradicts choices B, C, and D as a catalyst does not slow down, reverse, or prevent a reaction; instead, it accelerates the reaction by facilitating a more efficient route for the reaction to take place. Therefore, the correct answer is that a catalyst speeds up the reaction.

2. What role does DNA play in evolution?

A. It stores genetic information that can be passed on to offspring.
B. It allows for mutations that can introduce new variations.
C. It regulates the expression of genes that influence traits.
D. All of the above

Correct answer: D

Rationale: A) DNA stores genetic information that is passed on from parents to offspring through the process of reproduction. This genetic information contains instructions for the development and functioning of an organism. It serves as the hereditary material that carries the blueprint for an organism's traits and characteristics, allowing for the transmission of genetic information from one generation to the next. B) DNA can undergo mutations, which are changes in the genetic sequence. These mutations can introduce new variations in the DNA, leading to genetic diversity within a population. These variations are essential for natural selection and adaptation to changing environments. C) DNA plays a crucial role in regulating the expression of genes. Gene expression determines which proteins are produced in an organism, influencing its traits and characteristics. By controlling gene expression, DNA contributes to the development and maintenance of an organism's traits. D) Therefore, DNA is involved in all of the above processes, making it a key factor in evolution by driving genetic variation, inheritance, and gene expression. The interplay of these functions allows for the diversity and adaptation of species over time, shaping the evolutionary process.

3. Urinary system health can be maintained through various lifestyle practices. Which of the following is NOT recommended for optimal urinary system health?

A. Limiting high-sodium foods in the diet
B. Consuming adequate amounts of cranberry juice
C. Holding urine in the bladder for long periods
D. Getting regular moderate-intensity exercise

Correct answer: C

Rationale: Holding urine in the bladder for long periods is not recommended for optimal urinary system health. It can increase the risk of urinary tract infections and other bladder-related issues. When urine is held for a long time, bacteria have more time to multiply in the bladder, leading to infections. Additionally, holding urine for prolonged periods can also contribute to bladder distension, which may affect bladder function over time. Therefore, it is crucial to empty the bladder regularly to maintain good urinary system health. Limiting high-sodium foods helps reduce the risk of kidney stones and high blood pressure, while consuming cranberry juice may help prevent urinary tract infections by interfering with the adhesion of bacteria to the bladder walls. Regular moderate-intensity exercise promotes overall health, including maintaining a healthy weight and reducing the risk of chronic conditions that can impact the urinary system.

4. A ball is thrown upwards. Which of the following statements is TRUE about its potential energy and kinetic energy at the peak of its trajectory?

A. Both potential and kinetic energy are zero.
B. Potential energy is maximum and kinetic energy is minimum.
C. Potential energy is minimum and kinetic energy is maximum.
D. Both potential and kinetic energy remain constant.

Correct answer: B

Rationale: At the peak of its trajectory, the ball momentarily stops moving before falling back down. This means its kinetic energy is at a minimum because it has come to a stop. At the same time, its potential energy is at a maximum because it is at the highest point in its trajectory, where it has the most potential to fall and convert that potential energy into kinetic energy as it descends. Choice A is incorrect because at the peak, the ball still has potential energy due to its height. Choice C is incorrect because kinetic energy is at a minimum when the ball is momentarily at rest. Choice D is incorrect because the energy conversion between potential and kinetic energy occurs at different points in the trajectory.

5. Which of the following functions is not controlled by the autonomic nervous system?

A. Digestion
B. Walking
C. Heartbeat
D. Temperature regulation

Correct answer: B

Rationale: The correct answer is B: Walking. Walking is not directly controlled by the autonomic nervous system. Walking is a voluntary action governed by the somatic nervous system, which controls voluntary skeletal muscle movement. The autonomic nervous system, on the other hand, regulates functions that are involuntary, such as digestion, heartbeat, and temperature regulation. Choices A, C, and D are all functions controlled by the autonomic nervous system. Digestion involves processes like peristalsis and secretion of digestive enzymes, heartbeat is regulated by the autonomic nervous system to maintain blood pressure and circulation, and temperature regulation includes responses like sweating or shivering to maintain body temperature within a narrow range.