30 Questions
What fundamental principle is conserved during chemical transformations in living organisms?
Mass and energy
Which reaction example is a slow chemical reaction?
Combination of iron and oxygen to form rust
What are the starting substances in a chemical reaction called?
Reactants
Which of these is necessary for a chemical reaction to occur if it absorbs energy?
A source of energy
Which statement about energy in chemical reactions is correct?
Chemical reactions involve changes in energy due to the formation or breaking of chemical bonds.
What term describes the substances produced by a chemical reaction?
Products
What is an example of an organism's interaction with the environment being based on chemical reactions?
The twinkle of a firefly's body
Which statement is true about chemical reactions that occur spontaneously?
They release energy.
What is the primary role of enzymes in living organisms?
To speed up chemical reactions
What substrate does the enzyme carbonic anhydrase act on in the reaction depicted?
Water and carbon dioxide
Why are enzymes highly specific in the reactions they catalyze?
Their shape and structure allow them to bond with only one type of substrate
How do enzymes affect the activation energy of a chemical reaction?
They lower the activation energy needed for reactions
Which of the following best describes metabolism?
The collective chemical reactions occurring within a living organism
What happens to reactants if they do not have enough energy in an enzyme-catalyzed reaction?
They will be untouchable and the reaction won't proceed
What type of reaction is catalyzed by catalytic enzymes?
Synthesis reactions
What is created temporarily when an enzyme binds to its substrate?
Enzyme-Substrate Complex
What is the term for the energy required to initiate a chemical reaction?
Activation energy
What generally describes the energy comparison between reactants and products in an energy-releasing reaction?
Reactants have more total energy than the products
How do organisms obtain the energy necessary for vital functions such as making new cells and moving?
By extracting energy from sunlight or by consuming plants
Which of the following describes a characteristic of chemical reactions that release energy?
They only happen when reactants have high energy
What occurs during a chemical reaction when the reactant particles collide with sufficient energy?
The reaction is initiated
Which statement correctly identifies a property of energy-absorbing reactions?
Energy is absorbed during the reaction
What is the primary function of catalase in cells?
To breakdown hydrogen peroxide into water and oxygen
Which type of bond predominantly holds the substrates to the enzyme's active site?
Hydrogen bonds
Why do enzymes produced by human cells generally work best at temperatures close to 37°C?
Because 37°C is the optimum temperature for maintaining protein structure and function
Which condition is most likely to cause an enzyme to denature?
Extreme pH
What role do enzymes play in a chemical reaction?
They decrease the energy required for the reaction
How do molecules within cells regulate enzyme activity?
By switching enzymes on or off as needed
What happens to the structure of an enzyme if exposed to high temperatures?
The hydrogen bonds may weaken, causing the enzyme to unfold
In the lock and key model of enzyme activity, what does the enzyme represent?
The key
Study Notes
Chemical Reactions
- Living things are made up of chemical compounds, and chemical reactions occur within them to facilitate growth, interaction, reproduction, and movement.
- A chemical reaction is a process that changes or transforms one set of compounds into another, with mass and energy conserved during chemical transformations.
- Chemical reactions involve changes in chemical bonds, and energy is released or absorbed during these changes.
- Reactants are the elements or compounds that engage in a chemical reaction, while products are the elements or compounds produced by the reaction.
Energy in Reactions
- Energy changes are a crucial factor in determining whether a chemical reaction will occur.
- Chemical reactions that release energy often occur spontaneously, while those that absorb energy require a source of energy.
- An example of an energy-releasing reaction is the burning of hydrogen gas, which releases energy in the form of heat and light.
Energy Sources
- Organisms need energy to carry out reactions, which is obtained directly from sunlight through photosynthesis or by eating and storing energy from plants.
- Activation energy is the energy needed to start a reaction, and it can be represented on an energy graph.
Enzymes
- Enzymes are biological catalysts that speed up chemical reactions that would occur too slowly or not at all on their own.
- Enzymes are made of protein and can work repeatedly, with each enzyme catalyzing only one specific chemical reaction.
- Enzymes play a crucial role in metabolism, and their role is essential to living organisms.
The Enzyme-Substrate Complex
- Enzymes work by creating a temporary bond with their substrate, allowing the reaction to occur.
- The bonds that hold molecules together need enough energy to overcome their bonds, and if the reactants don't have enough energy, the reaction will not occur.
Effect of Enzymes on Speed of Reactions
- Enzymes provide an area where reactants can be brought together, reducing the energy needed for the reaction.
- The mechanism of enzyme-catalyzed reactions involves the substrate binding to the active site of the enzyme.
- The addition of an enzyme lowers the activation energy in a reaction, speeding up the reaction.
Nature's Catalysts Enzymes
- Enzymes are biological catalysts that speed up chemical reactions, making them essential to life.
- The activation energy required for a reaction without an enzyme is very high, but with an enzyme, the activation energy is significantly lower.
Regulation of Enzyme Activity
- Enzymes play essential roles in chemical pathways, making materials that cells need, releasing energy, and transferring information.
- The activity of an enzyme depends on the structure of its active site, which can be affected by conditions such as high temperatures and extreme pH.
- Enzymes produced by human cells generally work best at temperatures close to 37°C, the normal temperature of the human body.
- The activities of most enzymes are regulated by molecules that carry chemical signals within cells, switching enzymes "on" or "off" as needed.
Temperature and Enzymes
- Temperature affects the rate of an enzyme-catalyzed reaction, and enzymes are sensitive to temperature changes.
- The optimal temperature for an enzyme's activity depends on the specific enzyme and its function.
Review
- Chemical reactions involve changes in chemical bonds, and energy is released or absorbed during these changes.
- Enzymes speed up chemical reactions, and their role is essential to living organisms.
- The activity of an enzyme depends on the structure of its active site, which can be affected by conditions such as temperature and pH.
Learn about the role of chemical reactions in living things, including growth, interactions, reproduction, and movement. Discover how chemical reactions occur in organisms, including the twinkling of fireflies.
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