Digestion & Enzymes
What type of digestion happens when you chew food?
mechanical digestion
What process releases energy from food inside cells?
cellular respiration
What do we call substances that start a chemical reaction?
reactants
Which body system brings oxygen into the body?
respiratory system
In the iodine–starch lab, what did the iodine represent?
A nutrient or molecule
What is the job of an enzyme?
To speed up chemical reactions
Which organelle is known as the “powerhouse of the cell”?
mitochondria
What do we call substances made during a chemical reaction?
products
Which system moves nutrients and oxygen to cells?
circulatory system
What did the starch bag represent in the diffusion model?
A cell or membrane
What do we call the substance an enzyme acts on?
What is a substrate?
Which two substances are needed for cellular respiration to begin?
glucose and oxygen
Is digestion a chemical reaction? Why or why not?
Yes—chemical digestion changes substances into new ones.
What is diffusion?
Movement of molecules from high to low concentration
Why do scientists use models?
To understand processes that are too small, big, or slow to see
Where does most nutrient absorption happen?
small intestine
Which substances are the products of cellular respiration?
Carbon dioxide, water, and energy
What is one sign that a chemical reaction has occurred?
Color change, gas production, temperature change, or new substance formed
Why do body systems need to work together?
No single system can meet all the body’s needs alone.
How did the iodine lab show diffusion?
Iodine moved from high concentration outside to lower concentration inside.
Why must food be broken into small molecules before it can be absorbed?
Large molecules cannot pass through membranes or enter the bloodstream.
Explain why oxygen is necessary for releasing energy from food.
Oxygen helps break down glucose in chemical reactions that release energy.
How are enzymes related to chemical reactions?
They lower the energy needed and speed reactions up.
Give an example of how a change in one system affects another.
If breathing slows, cells get less oxygen and make less energy
A student says, “Eating food means you instantly get energy.”
Is this correct? Explain.
Incorrect—food must be digested, absorbed, and used in cellular respiration.