Flashcard Set

9th Grade Biology Topics

10 Cards
Medium
March 26, 2026
Jonathan M
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What is the cell theory?
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The cell theory states that all living organisms are composed of cells, cells are the basic unit of life, and all cells arise from pre-existing cells.
Additional Info This theory emphasizes the importance of cells as the fundamental building blocks of life. It was developed in the mid-19th century by scientists such as Schleiden, Schwann, and Virchow.
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Define homeostasis.
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Homeostasis is the process by which an organism maintains a stable internal environment despite changes in external conditions.
Additional Info Examples include temperature regulation in mammals and the regulation of blood sugar levels in humans.
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What are the four macromolecules essential for life?
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The four macromolecules are carbohydrates, lipids, proteins, and nucleic acids. Each plays a crucial role in biological processes.
Additional Info Carbohydrates provide energy, lipids store energy, proteins perform a variety of functions including enzymes and structural components, and nucleic acids (DNA/RNA) store and transmit genetic information.
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Explain the process of photosynthesis.
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Photosynthesis is the process by which green plants, algae, and some bacteria convert light energy into chemical energy in the form of glucose, using carbon dioxide and water, while releasing oxygen as a byproduct.
Additional Info The overall equation is: 6CO2 + 6H2O + light energy → C6H12O6 + 6O2. This process occurs mainly in the chloroplasts of plant cells.
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What is the difference between prokaryotic and eukaryotic cells?
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Prokaryotic cells are simple, unicellular organisms without a nucleus or membrane-bound organelles, while eukaryotic cells are more complex, with a defined nucleus and organelles.
Additional Info Examples of prokaryotes include bacteria and archaea, while examples of eukaryotes include plants, animals, and fungi.
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Describe the structure and function of DNA.
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DNA (deoxyribonucleic acid) is a double-helix structure composed of nucleotides, which include a sugar, phosphate group, and a nitrogenous base. It carries genetic information necessary for the growth, development, and reproduction of organisms.
Additional Info The sequence of bases (A, T, C, G) encodes the instructions for building proteins, which perform most of the functions in a cell.
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What role do enzymes play in biological reactions?
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Enzymes are biological catalysts that speed up chemical reactions by lowering the activation energy required for the reaction to occur.
Additional Info Each enzyme is specific to a particular substrate and operates optimally at a certain temperature and pH. For example, amylase breaks down starch into sugars.
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What is natural selection?
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Natural selection is the process by which organisms better adapted to their environment tend to survive and produce more offspring. It is a key mechanism of evolution.
Additional Info Darwin's theory of evolution by natural selection explains how species evolve over time through variations and adaptations.
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What are the stages of cellular respiration?
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Cellular respiration consists of three main stages: glycolysis, the Krebs cycle (citric acid cycle), and oxidative phosphorylation (electron transport chain).
Additional Info This process converts glucose into ATP, the energy currency of the cell, with carbon dioxide and water as byproducts.
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What is a food chain?
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A food chain is a linear sequence that shows how energy and nutrients flow from one organism to another in an ecosystem, typically starting from producers to various levels of consumers.
Additional Info For example, in a simple food chain: grass (producer) → rabbit (primary consumer) → fox (secondary consumer).
9th Grade Biology Topics
Flashcards
9th Grade Biology Topics
10 Cards | Medium Difficulty
Created by Jonathan M
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What is the cell theory?
Click to reveal answer
Answer: The cell theory states that all living organisms are composed of cells, cells are the basic unit of life, and all cells arise from pre-existing cells.
Additional Info:
This theory emphasizes the importance of cells as the fundamental building blocks of life. It was developed in the mid-19th century by scientists such as Schleiden, Schwann, and Virchow.
Click to see question

Define homeostasis.
Click to reveal answer
Answer: Homeostasis is the process by which an organism maintains a stable internal environment despite changes in external conditions.
Additional Info:
Examples include temperature regulation in mammals and the regulation of blood sugar levels in humans.
Click to see question

What are the four macromolecules essential for life?
Click to reveal answer
Answer: The four macromolecules are carbohydrates, lipids, proteins, and nucleic acids. Each plays a crucial role in biological processes.
Additional Info:
Carbohydrates provide energy, lipids store energy, proteins perform a variety of functions including enzymes and structural components, and nucleic acids (DNA/RNA) store and transmit genetic information.
Click to see question

Explain the process of photosynthesis.
Click to reveal answer
Answer: Photosynthesis is the process by which green plants, algae, and some bacteria convert light energy into chemical energy in the form of glucose, using carbon dioxide and water, while releasing oxygen as a byproduct.
Additional Info:
The overall equation is: 6CO2 + 6H2O + light energy → C6H12O6 + 6O2. This process occurs mainly in the chloroplasts of plant cells.
Click to see question

What is the difference between prokaryotic and eukaryotic cells?
Click to reveal answer
Answer: Prokaryotic cells are simple, unicellular organisms without a nucleus or membrane-bound organelles, while eukaryotic cells are more complex, with a defined nucleus and organelles.
Additional Info:
Examples of prokaryotes include bacteria and archaea, while examples of eukaryotes include plants, animals, and fungi.
Click to see question

Describe the structure and function of DNA.
Click to reveal answer
Answer: DNA (deoxyribonucleic acid) is a double-helix structure composed of nucleotides, which include a sugar, phosphate group, and a nitrogenous base. It carries genetic information necessary for the growth, development, and reproduction of organisms.
Additional Info:
The sequence of bases (A, T, C, G) encodes the instructions for building proteins, which perform most of the functions in a cell.
Click to see question

What role do enzymes play in biological reactions?
Click to reveal answer
Answer: Enzymes are biological catalysts that speed up chemical reactions by lowering the activation energy required for the reaction to occur.
Additional Info:
Each enzyme is specific to a particular substrate and operates optimally at a certain temperature and pH. For example, amylase breaks down starch into sugars.
Click to see question

What is natural selection?
Click to reveal answer
Answer: Natural selection is the process by which organisms better adapted to their environment tend to survive and produce more offspring. It is a key mechanism of evolution.
Additional Info:
Darwin's theory of evolution by natural selection explains how species evolve over time through variations and adaptations.
Click to see question

What are the stages of cellular respiration?
Click to reveal answer
Answer: Cellular respiration consists of three main stages: glycolysis, the Krebs cycle (citric acid cycle), and oxidative phosphorylation (electron transport chain).
Additional Info:
This process converts glucose into ATP, the energy currency of the cell, with carbon dioxide and water as byproducts.
Click to see question

What is a food chain?
Click to reveal answer
Answer: A food chain is a linear sequence that shows how energy and nutrients flow from one organism to another in an ecosystem, typically starting from producers to various levels of consumers.
Additional Info:
For example, in a simple food chain: grass (producer) → rabbit (primary consumer) → fox (secondary consumer).
Click to see question
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