Which of the following best describes the result of using a catalyst in a chemical reaction?

A. The reaction is completed in a shorter amount of time.

B. The yield of product is increased.

C. A greater amount of heat energy is released by the reaction.

D. A more desirable product is often formed.

Answer Explanation:

A catalyst is a substance that lowers the activation energy of a chemical reaction, which means that it allows the reaction to proceed faster without being consumed or changed itself. A catalyst does not affect the equilibrium of a reaction, so it does not change the amount or the type of product that is formed.

Therefore, the Correct Answer is A.

Q #1: In a hypertonic solution, water flows through aquaporins embedded in the plasma membrane of the cell. This type of transport is best known as which of the following?

A. Osmosis

B. Diffusion

C. Facilitated diffusion

D. Active transport

Answer Explanation

One of the ways that cells regulate their water balance is by adjusting to different solute concentrations in their environment. When a cell is placed in a solution that has a higher concentration of solutes than the cell itself, the solution is called hypertonic. In this case, water will tend to move out of the cell through special channels called aquaporins, which are embedded in the plasma membrane. This movement of water across a selectively permeable membrane is a type of passive transport called osmosis. Osmosis does not require any energy input from the cell, unlike other forms of transport such as diffusion, facilitated diffusion, or active transport.
Q #2: Which of the following is the approximate threshold value for mammalian neurons?

A. +35 mV

B. -55 mV

C. 0 mV

D. -80 mV

Answer Explanation

The approximate threshold value for mammalian neurons is -55mV.
Q #3: Which of the following substances protects the skin from ultraviolet radiation?

A. Melanin

B. Perspiration

C. Sebum

D. Keratin

Answer Explanation

One of the functions of the skin is to protect the body from harmful effects of ultraviolet (UV) radiation. UV rays can damage the DNA of skin cells and cause mutations that may lead to skin cancer. The skin has a natural defense mechanism against UV radiation, which is the production of a pigment called melanin. Melanin is synthesized by specialized cells called melanocytes, which are located in the basal layer of the epidermis. Melanin absorbs UV rays and prevents them from reaching the deeper layers of the skin.

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Which of the following best describes the result of using a catalyst in a chemical reaction?

More Questions on TEAS 7 Science

Q #1: In a hypertonic solution, water flows through aquaporins embedded in the plasma membrane of the cell. This type of transport is best known as which of the following?

Answer Explanation

Q #2: Which of the following is the approximate threshold value for mammalian neurons?

Answer Explanation

Q #3: Which of the following substances protects the skin from ultraviolet radiation?

Answer Explanation

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