Cell Processes and Energy

Cell Processes and Energy

Middle School

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Learning Objectives

• Describe the main stages of the cell cycle, including Interphase and Mitosis.

• Identify the inputs and outputs of photosynthesis and where it occurs.

• Explain the purpose of cellular respiration, its inputs, and its outputs.

• Compare and contrast the processes of photosynthesis and cellular respiration.

Key Vocabulary

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Chromosome

A chromosome is tightly organized and wound DNA, making it easy to split during cell division.

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Interphase

This is the longest phase of the cell cycle, where a cell grows and copies its DNA.

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Mitosis

Mitosis is the process where one cell divides its nucleus to form two identical daughter cells.

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Photosynthesis

Organisms use sunlight to convert carbon dioxide (CO₂) and water (H₂O) into sugar for energy.

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Cellular Respiration

This is the process cells use to release stored energy from sugar, creating usable ATP energy.

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Mitochondria

This organelle produces energy for the cell by performing the process of cellular respiration.

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The Cell Cycle and Interphase

• All cells come from pre-existing cells through the cell cycle.

• One parent cell creates two identical new daughter cells.

• A cell spends about 90% of its life in interphase.

• It grows, lives, and duplicates its chromosomes before dividing.

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Multiple Choice

What is the main outcome of the cell cycle?

• Two parent cells combine to create one new cell.

• One parent cell grows to twice its original size.

• One parent cell divides into two different daughter cells.

• One parent cell divides into two identical daughter cells.

Multiple Choice

What is the primary role of interphase within the cell cycle?

• To actively divide the cell into two separate parts.

• To shrink the cell to a smaller size before it divides.

• To allow the cell to rest and stop all activity.

• To prepare the cell for division by growing and copying its chromosomes.

Multiple Choice

If a cell failed to duplicate its chromosomes during interphase, what would be the most likely result after division?

• The parent cell would produce four cells instead of two.

• The daughter cells would not be identical to the parent cell.

• The cell would divide faster than usual.

• The daughter cells would be much larger than the parent cell.

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The Stages of Mitosis

• Mitosis is cell division with four stages: Prophase, Metaphase, Anaphase, and Telophase.

• During prophase, the nuclear membrane dissolves and visible chromosomes begin to form.

• In metaphase, the chromosomes meet and line up in the cell's middle.

• During anaphase, chromosome copies are pulled apart to opposite ends of the cell.

• During telophase, chromosomes arrive at the poles, nuclear envelopes reform, and the chromosomes begin to de-condense.

Multiple Choice

What is the main purpose of mitosis?

• To serve as the cell division phase

• To make DNA condense into chromosomes

• To pull chromosomes to opposite ends

• To dissolve the nuclear membrane

Multiple Choice

Which of the following correctly describes the events of prophase?

• Chromosomes line up in the middle of the cell

• Chromosomes are pulled to opposite ends of the cell

• The cell membrane begins to pinch inward

• DNA condenses and the nuclear membrane dissolves

Multiple Choice

If a cell's chromosomes lined up in the middle, what would be the very next step in the process?

• The nuclear membrane would dissolve.

• The chromosomes would be pulled apart to opposite ends.

• The DNA would condense into chromosomes.

• The chromosomes would meet in the middle of the cell.

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Photosynthesis: Capturing Energy

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Multiple Choice

What is the primary purpose of photosynthesis?

• To help an organism reproduce

• To create food by capturing energy from sunlight

• To release energy by breaking down food

• To absorb nutrients from the environment

Multiple Choice

Which statement correctly identifies the materials used and produced during photosynthesis?

• Photosynthesis uses sugar and oxygen to produce carbon dioxide and water.

• Photosynthesis uses oxygen and water to produce sugar and carbon dioxide.

• Photosynthesis uses carbon dioxide and sugar to produce oxygen and water.

• Photosynthesis uses carbon dioxide and water to produce sugar and oxygen.

Multiple Choice

A scientist observes that the oxygen level in a sealed aquarium containing only water and algae is decreasing. What is the most likely reason for this change?

• The algae are using up all the water in the aquarium.

• The algae are not getting enough sunlight or carbon dioxide.

• The algae are releasing carbon dioxide instead of oxygen.

• The algae are producing too much sugar.

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Cellular Respiration: Releasing Energy

• Cells release energy from sugar molecules through a process called cellular respiration.

• ​It happens in the mitochondria and requires oxygen (O₂) and glucose (C₆H₁₂O₆).

• The main products are carbon dioxide (CO₂), water (H₂O), and energy in the form of ATP.

• All eukaryotes, including plants and animals, use this essential process for life.

Multiple Choice

What is the primary purpose of cellular respiration?

• To create glucose molecules for storage

• To absorb oxygen from the atmosphere

• To release the energy stored in glucose

• To produce water for the cell

Multiple Choice

Which statement best describes the process of cellular respiration?

• The cell breaks down ATP in the mitochondria to release oxygen.

• The cell uses glucose and oxygen to produce carbon dioxide, water, and ATP.

• The cell converts water and carbon dioxide into oxygen and glucose.

• The cell uses ATP and carbon dioxide to create glucose and oxygen.

Multiple Choice

If a cell's mitochondria were damaged and could not function, what would be the most likely consequence?

• The cell would not be able to produce carbon dioxide.

• The cell would be unable to store glucose molecules.

• The cell would not have enough energy from ATP to perform its activities.

• The cell would build up an excess of oxygen.

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A Balanced Cycle: Photosynthesis & Respiration

Photosynthesis

• ​Plants use sunlight to make their own food in the form of sugar.

• ​​The reactants, or starting materials, are carbon dioxide (CO₂) and water (H₂O).

• ​The products, or final substances, are glucose (C₆H₁₂O₆) and oxygen (O₂).

Cellular Respiration

• ​Organisms break down sugar to release energy for their cells to use.

• ​​The reactants, or starting materials, are glucose (C₆H₁₂O₆) and oxygen (O₂).

• ​The products, or final substances, are carbon dioxide (CO₂) and water (H₂O).

Multiple Choice

What is the primary purpose of photosynthesis in plants?

• To absorb water and nutrients from the soil.

• To create food for the plant in the form of sugar.

• To break down sugar and release carbon dioxide.

• To release energy for the plant's cells to use.

Multiple Choice

How are the processes of photosynthesis and cellular respiration related to each other?

• They both produce sugar and release oxygen.

• They both use the exact same starting materials.

• One process happens only in plants and the other happens only in animals.

• The products of one process are the starting materials of the other.

Multiple Choice

A scientist places a plant in a sealed, transparent container with water and a light source. If all the carbon dioxide is removed from the container, what is the most likely outcome?

• The plant will produce extra glucose to make up for the missing carbon dioxide.

• The plant will start breaking down water to release energy directly.

• The plant will release oxygen but will not produce any glucose.

• The plant will be unable to produce the glucose and oxygen.

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Common Misconceptions

Misconception	Correction
Mitosis is the longest part of the cell cycle.	Interphase is the longest phase, taking up about 90% of the cell cycle.
Only plants perform photosynthesis.	Algae, some protists, and cyanobacteria also perform photosynthesis.
Plants only photosynthesize and do not perform cellular respiration.	Plants perform both photosynthesis and cellular respiration.
The goal of mitosis is to create genetically different cells.	Mitosis produces two genetically identical daughter cells.

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Summary

• The cell cycle includes Interphase for growth and Mitosis for cell division.

• Mitosis creates two identical daughter cells through its distinct phases.

• Photosynthesis uses sunlight, water, and CO₂ to make sugar and oxygen.

• Cellular respiration breaks down sugar to release energy (ATP), CO₂, and water.

• Photosynthesis and cellular respiration are opposite processes that create a continuous cycle.

• Both plants and animals use cellular respiration to get energy for their cells.

Poll

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