Question

2.4 chemical reactions and enzymes
biot.ls1.5

1. which are the catalysts of reactions in living things?

a. enzymes
b. lipids
c. carbohydrates
d. substrates

1. what changes during a chemical reaction between two compounds?

a. number of atoms
b. chemical bonds
c. total mass
d. total energy

1. which type of chemical reaction tends to occur on its own, or spontaneously?
2. what is the name for the amount of energy that a reaction needs to get started?
3. how do enzymes act as catalysts in a chemical reaction?
4. what changes to the environment can affect the activity of enzymes?

critical thinking
bi01.ls1.2, bi01.ls1.5

1. integrate information an oxygen atom has eight protons. from this information, can you determine numbers of neutrons and electrons in an oxygen atom? explain.
2. interpret visuals describe the process shown in this diagram. what will the outcome of the process be?

Explanation:

1. Enzymes are biological catalysts in living things. Lipids are energy - storage molecules, carbohydrates are energy sources, and substrates are what enzymes act on.
2. In a chemical reaction between two compounds, chemical bonds change. The number of atoms, total mass, and total energy are conserved according to the laws of conservation.
3. Exothermic reactions tend to occur spontaneously as they release energy.
4. The amount of energy that a reaction needs to get started is called activation energy.
5. Enzymes lower the activation energy of a chemical reaction, increasing the reaction rate without being consumed in the reaction.
6. Changes in temperature, pH, and substrate concentration can affect enzyme activity.
7. An oxygen atom has 8 electrons (equal to the number of protons in a neutral atom). The number of neutrons can vary in different isotopes of oxygen. The most common isotope of oxygen has 8 neutrons, but there are other isotopes with different numbers of neutrons.
8. The diagram shows the dissociation of sodium chloride (NaCl) in water. Sodium ions (Na⁺) and chloride ions (Cl⁻) separate and are surrounded by water molecules. The outcome is a homogeneous solution of sodium and chloride ions in water.

Answer:

1. A. enzymes
2. B. chemical bonds
3. Exothermic reactions
4. Activation energy
5. Enzymes lower the activation energy of the reaction.
6. Temperature, pH, substrate concentration.
7. 8 electrons (in a neutral atom). The number of neutrons can vary among isotopes (common isotope has 8 neutrons).
8. The process is the dissociation of sodium chloride in water. The outcome is a solution of sodium and chloride ions surrounded by water molecules.