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Where does Cellular Respiration take Place — Reading Comprehension

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"This science passage for middle school students (grades 6-8) explores the vital process of cellular respiration and where it takes place within a cell. The text is written in a direct, informative style, explaining the key stages: glycolysis in the cytoplasm and the Krebs cycle and oxidative phosphorylation in the mitochondria. It uses clear, concise language to define important vocabulary like adenosine triphosphate (ATP) and pyruvate. The passage emphasizes the role of mitochondria as the "powerhouses of the cell" and connects the process to the energy required for all living functions. This content aligns with NGSS standards related to the flow of matter and energy in organisms, specifically MS-LS1-7, and is designed to support student comprehension through a structured reading format, followed by targeted questions. The accompanying multiple-choice questions assess factual recall, conceptual understanding, and application of the concepts. The resource is ideal for self-study or classroom use, providing a comprehensive overview of cellular respiration's location and function."

CONTENT PREVIEW

A scientific diagram of a eukaryotic cell, highlighting the cytoplasm and a mitochondrion. A simplified representation shows glycolysis taking place in the cytoplasm and the Krebs cycle and electron transport chain occurring within the mitochondrion, illustrating the locations of cellular respiration's key stages. — Different stages of cellular respiration within a eukaryotic cell, including glycolysis in the cytoplasm and the Krebs cycle and oxidative phosphorylation in the mitochondrion.

Cellular respiration is the fundamental process by which living organisms convert the chemical energy stored in food molecules into a usable form of energy called adenosine triphosphate (ATP). This process is essential for all life, as ATP powers nearly every cellular activity, from muscle contraction to the synthesis of new proteins. Without cellular respiration, cells would lack the energy required to function, and life as we know it would not exist. This complex series of reactions occurs in specific locations within the cell, depending on the stage of the process.

The journey of cellular respiration begins in the cytoplasm, the jelly-like substance that fills the cell. This first stage, known as glycolysis, involves the breakdown of a single glucose molecule into two smaller molecules called pyruvate. Glycolysis does not require oxygen, so it is the initial step for both aerobic and anaerobic respiration. Although it produces a small amount of ATP, its main role is to prepare the pyruvate molecules for the next, more energy-intensive stages.

Following glycolysis, if oxygen is available, the process moves into the mitochondria, often called the "powerhouses of the cell." These bean-shaped organelles have two membranes, creating distinct compartments where the next stages take place. The pyruvate molecules are transported into the mitochondrial matrix, the inner-most compartment, where they are further broken down during the Krebs cycle (also known as the citric acid cycle). This cycle releases carbon dioxide and generates electron-carrying molecules. The final and most productive stage, oxidative phosphorylation, occurs on the inner mitochondrial membrane. Here, a large amount of ATP is produced using the energy from the electron-carrying molecules.

In summary, cellular respiration is a multi-step process with different locations. It begins with glycolysis in the cytoplasm, followed by the oxygen-dependent stages in the mitochondria. This division of labor allows the cell to efficiently extract the maximum amount of energy from food.

Fun Fact: A single cell can contain hundreds or even thousands of mitochondria, especially in energy-hungry cells like those in the heart and muscles.

What is the primary purpose of cellular respiration?

To produce glucoseTo create carbon dioxideTo convert energy into ATPTo store excess water

Where does the process of glycolysis take place?

In the nucleusIn the mitochondriaIn the cytoplasmOn the cell membrane

What is the name of the energy-storing molecule produced by cellular respiration?

GlucosePyruvateCarbon dioxideAdenosine triphosphate

Which of the following is true about glycolysis?

It requires oxygen to occur.It is the final stage of respiration.It produces a large amount of ATP.It breaks down glucose into pyruvate.

Which organelle is referred to as the "powerhouse of the cell"?

NucleusMitochondrionCytoplasmCell membrane

Based on the passage, what would likely happen if a cell's mitochondria stopped working?

Glycolysis would stop immediately.The cell would produce less ATP.The cell would start producing more glucose.The cell would become a plant cell.

What is the main idea of the reading passage?

The function of the nucleus in a cell.The process of photosynthesis.The locations and stages of cellular respiration.The chemical formula for ATP.

If a scientist discovered a new single-celled organism that lacked mitochondria but still produced ATP, what could you infer about its energy production?

It must be a plant.It only performs glycolysis.It performs the Krebs cycle in its nucleus.It does not require food for energy.