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Questions and Answers
Who was the first scientist to describe living cells?
Who was the first scientist to describe living cells?
Which statement is NOT one of the postulates of cell theory?
Which statement is NOT one of the postulates of cell theory?
What is the main component of the cell membrane?
What is the main component of the cell membrane?
Which type of cell is characterized by the absence of a nucleus?
Which type of cell is characterized by the absence of a nucleus?
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What role does the nucleus play within a cell?
What role does the nucleus play within a cell?
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Which of the following is a feature specific to plant cells?
Which of the following is a feature specific to plant cells?
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Which scientist proposed that all cells arise from pre-existing cells?
Which scientist proposed that all cells arise from pre-existing cells?
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What is the fluid inside the nucleus called?
What is the fluid inside the nucleus called?
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What role do enzymes play in chemical reactions within the cell?
What role do enzymes play in chemical reactions within the cell?
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What can be said about the flow of energy in a food chain?
What can be said about the flow of energy in a food chain?
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According to the second law of thermodynamics, what happens to energy as it moves through trophic levels in an ecosystem?
According to the second law of thermodynamics, what happens to energy as it moves through trophic levels in an ecosystem?
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Which statement is true about the relationship between photosynthesis and cellular respiration?
Which statement is true about the relationship between photosynthesis and cellular respiration?
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What is the primary function of ATP in cells?
What is the primary function of ATP in cells?
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In terms of energy dynamics, what does the first law of thermodynamics state?
In terms of energy dynamics, what does the first law of thermodynamics state?
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Which of the following statements accurately describes food webs?
Which of the following statements accurately describes food webs?
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Why are enzymes highly specific in their function?
Why are enzymes highly specific in their function?
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What is the primary function of the Smooth Endoplasmic Reticulum?
What is the primary function of the Smooth Endoplasmic Reticulum?
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Which type of ribosomes are found on the Rough Endoplasmic Reticulum?
Which type of ribosomes are found on the Rough Endoplasmic Reticulum?
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What is the main function of the Golgi Apparatus?
What is the main function of the Golgi Apparatus?
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Which cellular structure is primarily responsible for the breakdown of fatty acids and detoxification of harmful substances?
Which cellular structure is primarily responsible for the breakdown of fatty acids and detoxification of harmful substances?
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What characteristic is unique to chloroplasts compared to other organelles?
What characteristic is unique to chloroplasts compared to other organelles?
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What role do membrane proteins play in cellular communication?
What role do membrane proteins play in cellular communication?
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What type of mechanism does facilitated diffusion describe?
What type of mechanism does facilitated diffusion describe?
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What is the primary role of the mitochondria within the cell?
What is the primary role of the mitochondria within the cell?
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In what type of environment would a cell become hypotonic?
In what type of environment would a cell become hypotonic?
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What distinguishes integral membrane proteins from peripheral proteins?
What distinguishes integral membrane proteins from peripheral proteins?
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What is the main structural component of the cell membrane?
What is the main structural component of the cell membrane?
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What mechanism allows the sodium-potassium pump to maintain ion concentration differences across the membrane?
What mechanism allows the sodium-potassium pump to maintain ion concentration differences across the membrane?
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Which component of the cell membrane contributes to its fluidity?
Which component of the cell membrane contributes to its fluidity?
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What is the primary function of proteins in the body?
What is the primary function of proteins in the body?
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Which of the following describes the tertiary structure of proteins?
Which of the following describes the tertiary structure of proteins?
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What distinguishes RNA from DNA?
What distinguishes RNA from DNA?
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Which nitrogenous base in DNA pairs with guanine?
Which nitrogenous base in DNA pairs with guanine?
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What is the role of mRNA in protein synthesis?
What is the role of mRNA in protein synthesis?
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Which structure directly assists in the synthesis of proteins?
Which structure directly assists in the synthesis of proteins?
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What is the primary energy carrier in cells?
What is the primary energy carrier in cells?
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Which of the following best exemplifies the First Law of Thermodynamics?
Which of the following best exemplifies the First Law of Thermodynamics?
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What is one function of antibodies in the body?
What is one function of antibodies in the body?
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Which part of the nucleotides in DNA is responsible for its unique genetic information?
Which part of the nucleotides in DNA is responsible for its unique genetic information?
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What happens to energy when it flows through an ecosystem?
What happens to energy when it flows through an ecosystem?
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What is the basic unit of a protein?
What is the basic unit of a protein?
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Study Notes
Cell Structure and Function
- Robert Hooke first observed cells in cork, coining the term.
- Anton van Leeuwenhoek first described living cells, calling them "animacules".
- The cell is the fundamental unit of life.
- Cells exchange materials and energy with their environment.
- ATP is the primary energy form in cells.
- Cells maintained in a suitable lab environment remain viable.
- Multicellular organisms are composed of cells.
- Schleiden and Schwann established that plants and animals are made of cells (1839).
- Virchow's work (1855) stated cells arise from pre-existing cells.
- Weismann added to the cell theory, cells arose from a common ancestor (1880).
Cell Theory
- The cell theory states: all organisms are composed of cells; all cells come from pre-existing cells; the cell is the basic unit of life.
Cell Types
-
Prokaryotes:
- Simplest and oldest cell type, e.g., bacteria.
- Lack a nucleus and membrane-bound organelles.
- May have a cell wall, membrane, and flagella.
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Eukaryotes:
- More complex, with membrane-bound organelles.
- Characterized by a "true nucleus" containing DNA within a membrane.
- Protoplasm is the jelly-like substance.
- Cytoplasm is the protoplasm outside the nucleus.
- Nucleoplasm is inside the nucleus.
- Cytosol is the liquid part of cytoplasm, with suspended organelles.
- Divided into animal and plant cells.
Cell Organelles
-
Cell Membrane (All cells):
- Isolates the cell, regulates entry/exit, maintains form and communication.
- Primarily composed of phospholipids.
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Cell Wall (Plant cells only):
- Outermost layer, composed of cellulose and water.
- Provides structural support.
-
Nucleus:
- Largest organelle, centrally located.
- Double membrane structure.
- Controls cell activity, harbors genetic material (DNA).
-
Endoplasmic Reticulum (ER):
- System of membranous sacs.
- Lipid and protein synthesis.
- Smooth ER: lipid production, detoxification.
- Rough ER: protein synthesis (ribosome-studded).
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Ribosomes (All cells):
- Tiny organelles that build proteins.
- Composed of RNA and proteins.
- Free ribosomes (cytoplasm) or bound ribosomes (Rough ER).
-
Golgi Apparatus:
- Stacked membranous sacs.
- Modifies, sorts, and packages materials, mainly proteins.
-
Lysosomes:
- Digest macromolecules.
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Peroxisomes:
- Sacs with enzymes.
- Involved in metabolic reactions.
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Glycosomes:
- Sacs storing carbohydrates.
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Vacuoles (Mostly in plants, algae, and fungi):
- Storage of water, nutrients, and waste.
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Mitochondria:
- Double-membrane organelle.
- Powerhouse of the cell (cellular respiration, converting glucose to ATP).
- Contains its own DNA.
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Chloroplasts (Plant cells only):
- Site of photosynthesis.
- Double membrane structure.
- Contains chlorophyll, enzymes for energy conversion.
- Thylakoid and stroma are internal structures.
- Contains its own DNA.
-
Cytoskeleton:
- Provides structure and support to the cell.
- Interactions with motor proteins for movement.
- Microtubules, microfilaments (actin), intermediate filaments.
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Centrosomes/Centrioles (animal cells):
- Involved in cell division.
-
Cilia and Flagella:
- Movement of cells or materials.
- Motile extensions.
Membrane Structure and Function
-
Membranes:
- Single membrane: Endoplasmic Reticulum, Golgi Apparatus, Lysosomes, Peroxisomes, Vacuoles.
- Double membrane: Nucleus, Mitochondria, Chloroplasts.
- No membrane: Ribosomes, Cytoskeleton, Cilia, Flagella, Centrioles.
- Membrane structure: Fluid mosaic model.
- Lipid bilayer:
- Hydrophilic (polar) heads.
- Hydrophobic (nonpolar) tails.
-
Functions:
- Barrier: Isolates the cell, regulates entry/exit.
- Selectively permeable: allows certain substances to cross.
- Cell signaling, communication, and recognition: Proteins embedded in the membrane facilitate these functions.
Membrane Components
-
Cholesterol:
- Stabilizes the membrane.
- Minimizes water permeability.
-
Membrane Proteins:
- Integral: Embedded within the bilayer.
- Peripheral: Attached to the surface.
- Functions: transport, enzymatic activity, signaling, intercellular recognition, junctions, adhesion.
Membrane Permeability and Transport
- Selectively permeable: Cell regulates passage of molecules.
-
Passive transport (no ATP):
- Diffusion: Movement from high to low concentration.
- Osmosis: Water movement across a selectively permeable membrane.
- Isotonic: equal concentrations inside and outside the cell.
- Hypertonic: higher concentration outside the cell; cell loses water.
- Hypotonic: higher concentration inside the cell; cell gains water.
- Facilitated diffusion: Use of transport proteins for faster movement of molecules.
-
Active transport (requires ATP):
- Movement against concentration gradients.
- Pumps, using ATP to move molecules.
- Sodium-potassium pump: example of active transport.
- Exocytosis: Release of substances from the cell.
- Endocytosis: Uptake of substances into the cell. (Phagocytosis, pinocytosis)
Nucleic Acids and Proteins
-
Proteins:
- Made of amino acids.
- Four levels of structure (primary, secondary, tertiary, quaternary).
- Functions: enzymes, transport, antibodies, hormones.
-
Nucleic Acids:
- DNA (deoxyribonucleic acid)
- Stores genetic information.
- Double-stranded helix.
- Nucleotide bases: adenine (A), thymine (T), cytosine (C), guanine (G).
- RNA (ribonucleic acid)
- Carries out DNA instructions.
- Single-stranded.
- Nucleotide bases: A, U, C, G (uracil instead of thymine).
- Three main types (mRNA, tRNA, rRNA).
- DNA (deoxyribonucleic acid)
- Relationship: DNA dictates protein synthesis, RNA facilitates the process, proteins execute the actions.
Energy in the Cell, Ecosystems, and Enzymes
- Energy in the cell: ATP is the main energy currency.
- Cellular Respiration: Breaks down glucose to release energy as ATP.
-
Laws of Thermodynamics:
- First Law: Energy cannot be created or destroyed, only changed.
- Second Law: Energy transformations create disorder (entropy).
- Enzymes: Speed up chemical reactions, lowering activation energy.
- Active Site & Substrate Interaction: Specific matching between enzyme and substrate.
- Energy Transfer in Ecosystems: Flow of energy through food chains and webs.
- Photosynthesis: Converts light energy into chemical energy (glucose).
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Description
Test your knowledge on cell structure, function, and the foundational cell theory. This quiz covers key historical figures, types of cells, and the principles that define biological life. Explore how cells interact with their environment and the significance of ATP in cellular processes.
