116 Questions
What cell component is responsible for the synthesis and accumulation of carotenoids in red pepper cells?
Chloroplasts
Which cell component aids in the conversion of fat to carbohydrates?
Microbodies
What is the function of peroxisomes in a cell?
Serve in photorespiration
What type of DNA molecule encodes for certain proteins for photosynthesis?
Small circular DNA molecule
Which organelle releases energy from cellular respiration?
Mitochondria
What is the primary function of the cell wall?
To provide structural support and protection to the cell
Which of the following is NOT a component of the fluid-mosaic model of the plasma membrane?
Ribosomes
What is the primary function of plasmodesmata?
To facilitate the movement of substances between adjacent cells
Which of the following is NOT a component of the cell nucleus?
Ribosomes
What is the primary function of the plasma membrane?
To regulate the movement of substances in and out of the cell
Which of the following is a component of the secondary cell wall?
Cellulose microfibrils
Which of the following organelles are found in plant cells but not in animal cells?
Chloroplasts
What is the primary difference between animal cells and plant cells in terms of obtaining energy?
Plant cells are photoautotrophic, meaning they create food from solar energy.
Which of the following structures is found in plant cells but not in animal cells?
Cell wall
According to the endosymbiotic theory, which organelles are thought to have originated from endosymbiotic bacteria?
Mitochondria and chloroplasts
Which of the following is a component of cellular membranes?
Phospholipid bilayer
What are plasmodesmata in plant cells?
Structures that allow for the transport of materials between cells
What happens to an animal cell when it is placed in a hypotonic solution?
The cell swells due to water moving into the cell
What happens to a plant cell when it is placed in an isotonic solution?
The cell remains unchanged as there is no net movement of water
Which process is responsible for moving substances against a concentration gradient?
Active transport
What is the term used to describe the shrinking of a cell due to water moving out in a hypertonic solution?
Crenation
Which type of cells require a large amount of ATP for active transport?
Kidney cells
What is the name given to the carrier proteins involved in active transport processes?
Pumps
What is the primary role of the cell membrane according to the Fluid Mosaic Model?
To regulate the passage of molecules in and out of the cell
Which of the following processes requires energy in the form of ATP?
Active transport
Which of the following statements about passive transport is correct?
It includes processes like diffusion and facilitated diffusion
What is the primary difference between simple diffusion and facilitated diffusion?
Simple diffusion involves the movement of small, non-polar molecules, while facilitated diffusion involves ions and polar molecules
What is the primary driving force for the movement of molecules in passive transport processes?
The concentration gradient between two different areas
Which of the following statements best describes the role of the cell membrane in maintaining homeostasis?
It allows the cell to control its chemical composition despite changes in the external environment
What is the main function of stroma in a chloroplast?
Encodes for certain proteins for photosynthesis
Which type of plastids synthesize and accumulate carotenoids in cells like red pepper?
Chromoplasts
What is the main function of microbodies called peroxisomes in a cell?
Serve in photorespiration
Which organelle releases energy from cellular respiration by increasing surface area through cristae?
Mitochondria
In mature cells, what percentage of the volume may be occupied by central vacuoles?
90%
What is a key similarity between mitochondria and bacteria according to the endosymbiotic theory evidence?
Both have circular DNA and ribosomes
Which organelles are unique to plant cells and not typically found in animal cells?
Chloroplasts
What is the primary function of plasmodesmata in plant cells?
Cell communication
What is a defining characteristic of animal cells in terms of obtaining energy?
Lack of chloroplasts
Which component is NOT a part of cellular membranes?
Mitochondria
What is the main difference between animal and plant cells in terms of food production?
Plant cells create food from solar energy, while animal cells obtain it from their environment
What is the function of plasmodesmata?
Regulate movement of substances in and out of the cell
Which component is NOT part of the Fluid-Mosaic Model of the plasma membrane?
Cholesterol molecules
What is the primary role of the nucleus in a cell?
Control cellular activities and contain DNA
What is the main function of the cell wall in plant cells?
Facilitate communication between adjacent cells
Which process involves the synthesis of lignin and cellulose microfibrils?
Formation of the secondary cell wall in plant cells
What is the purpose of the series of pores in plasmodesmata?
Allow for extension of cytoplasmic strands between cells
What is the primary driving force for the movement of molecules in passive transport processes?
Concentration gradient
What is the process called when water travels from an area of lower solute concentration to an area of higher solute concentration?
Osmosis
What is the term used to describe the ability of a solution to cause a cell to gain or lose water?
Tonicity
Which type of transport process requires a protein carrier and does not require energy?
Facilitated diffusion
What is the term used to describe a solution that has a higher solute concentration than the cell's interior?
Hypertonic
Which process is responsible for moving substances against their concentration gradient?
Active transport
What is the primary function of vacuoles in plant cells?
To maintain cell pressure and store metabolites
Which of the following is NOT a component of the cytoskeleton in eukaryotic cells?
Cellulose
According to the endosymbiotic theory, which organelle is thought to have originated from cyanobacteria?
Chloroplast
What is the primary role of microtubules in plant cells?
Controlling the addition of cellulose to the cell wall
Which of the following is a key difference between animal cells and plant cells?
All of the above
What is the primary function of plasmodesmata in plant cells?
To allow communication and transport between adjacent cells
Cellulose microfibrils are embedded in ______ for strength.
lignin
Plasmodesmata allow ______ and dissolved substances to pass between cells.
fluids
The ______ is the control center of the cell and contains DNA.
nucleus
The ______ is the semipermeable outer boundary of the living part of the cell.
plasma membrane
The ______ is responsible for the synthesis and accumulation of carotenoids in red pepper cells.
chromoplast
Peroxisomes are ______ involved in the conversion of fat to carbohydrates.
organelles
Sends coded messages from ______ to be used in other parts of the cell
DNA
Bound by two membranes, which together constitute the ______ envelope
nuclear
Structurally complex ______ occupy up to one-third of the total surface area
pores
Rough ER - Ribosomes distributed on outer surface of ER.Associated with ______ synthesis and storage
protein
Smooth ER - Devoid of ribosomes and associated with ______ secretion
lipid
Subunits of ribosomes assembled in the ______
nucleolus
Chloroplasts contain a ______ that encodes for the production of certain proteins for photosynthesis.
small circular DNA molecule
Chromoplasts in plant cells synthesize and accumulate ______.
carotenoids
Mitochondria have ______ membranes and their own DNA and RNA.
double
Peroxisomes and ______ are examples of microbodies found in cells.
glyoxisomes
In mature plant cells, the central ______ may occupy up to 90% of the cell volume.
vacuole
The Golgi body, also known as the ______, acts as the 'post office' of the cell.
dictyosomes
Chloroplasts contain structures called ______, which are made up of thylakoid membranes containing chlorophyll.
grana
The ______ is the most conspicuous type of plastid, responsible for photosynthesis.
chloroplast
The ______ is a type of plastid that synthesizes and accumulates carotenoids in cells like red pepper.
chromoplast
The ______ is a type of plastid that serves as a site of manufacture and storage of important chemical compounds.
leucoplast
The ______ is a type of plastid that is found in aging or senescing cells.
gerontoplast
Active Transport requires a ______ protein
carrier
Simple diffusion involves the movement of small, non-polar molecules and water through micropores along concentration ______
gradients
Facilitated diffusion is the diffusion of ions and polar molecules with the help of a protein but no ______
energy
Passive transport involves no ATP requirement and the flow of molecules with the concentration ______
gradient
The Fluid Mosaic Model describes cell membranes as selectively ______
permeable
Cells can control their chemical composition despite changes in the external environment due to the membrane's ability to regulate the passage of molecules in and out of the cell, making it ______
selectively permeable
All cells come only from preexisting cells.
True
The plasma membrane is about 5 to 10 µm thick.
False
Large cells have a smaller surface area relative to volume.
True
Prokaryotic cells contain DNA in the nucleus.
False
The cytoplasm contains a semifluid matrix known as cytosol.
True
Diffusion in cells is affected by distance across the cell, but not temperature.
False
The Golgi body functions to modify proteins synthesized in the rough ER.
True
Chloroplasts are bound by a single membrane and contain grana made up of thylakoids.
False
Leucoplasts are plastids responsible for photosynthesis in plant cells.
False
Grana in chloroplasts are the sites where the first steps of photosynthesis occur.
True
Plastids are organelles responsible for the storage of important chemical compounds in plant cells.
True
Chloroplasts are the most conspicuous type of plastid found in plant cells.
True
Tonoplasts are the vacuolar membranes that surround the cell sap in plant cells.
True
The cell sap in plant cells is always basic in nature.
False
Microtubules are involved in the movement of flagella and cilia in plant cells.
True
Plant cells lack cell walls, while animal cells have internal or external skeletons.
False
The endosymbiotic theory suggests that mitochondria and chloroplasts originated from symbiotic relationships with aerobic bacteria.
True
Plasmodesmata are pores that allow water and dissolved substances to pass between animal cells.
False
Chromoplasts are plastids that synthesize and accumulate carotenoids (yellow, orange, red) in plant cells.
True
The stroma is the matrix of enzymes involved in cellular respiration.
False
Leucoplasts are colorless plastids that may synthesize starches (amyloplasts) or oils (elaioplasts).
True
Mitochondria have a single membrane and lack their own DNA and RNA.
False
Glyoxisomes are a type of microbody that aid in the conversion of fat to carbohydrates.
True
The Fluid Mosaic Model describes cell membranes as selectively permeable.
True
Facilitated diffusion requires energy in the form of ATP to transport molecules across the cell membrane.
False
Chromoplasts in plant cells are responsible for the synthesis and accumulation of carotenoids.
True
Mitochondria have only one membrane and their own DNA and RNA.
False
The primary function of the cell wall in plant cells is to provide structural support and protection.
True
The central vacuole in mature plant cells may occupy up to 90% of the cell volume.
True
Study Notes
Cell Structure and Communication
- Cell wall:
- Flexible primary walls laid down on either side of middle lamella
- Secondary walls produced inside primary walls, derived from primary walls by thickening and inclusion of lignin
- Cellulose microfibrils embedded in lignin for strength
- Plasmodesmata:
- Series of pores that allow cytoplasmic strands to extend between cells
- Allow fluids and dissolved substances to pass between cells
- Cellular membranes:
- 4 components: Phospholipid Bilayer, Membrane Proteins, Interior Protein Network, and Cell-Surface markers
- Referred to as the Fluid-Mosaic Model
Cell Components
- Nucleus:
- Control center of cell and contains DNA
- Stroma - Matrix of enzymes involved in photosynthesis
- Small circular DNA molecule encodes for production of certain proteins for photosynthesis
- Mitochondria:
- Release energy from cellular respiration
- Double membranes, own DNA and RNA
- Folded inward membrane = cristae, increases surface area for enzymatic reactions
- Plastids:
- Chloroplast: site of manufacture and storage of important chemical compounds
- Chloroplast contains:
- Grana made up of thylakoids
- Thylakoid membranes contain chlorophyll
- Stroma - Matrix of enzymes involved in photosynthesis
- Other plastids: Chromoplasts, Leucoplasts, Amyloplasts
- Microbodies:
- Small, spherical bodies distributed throughout the cytoplasm
- Contain specialized enzymes
- Bound by a single membrane
- Examples: Peroxisomes, Glyoxisomes
- Vacuoles:
- In mature cells, 90% of volume may be taken up by central vacuoles
- Bounded by vacuolar membranes = tonoplasts
- Filled with cell sap (slightly acidic)
- Acts to maintain pH, cell pressure, and storage for various metabolites
Cell-to-Cell Communication
- Plant cells:
- Freely permeable cell wall composed of cellulose
- Plasmodesmata = series of tiny pores between plant cells
- Animal cells:
- Internal or external skeletons; no cell walls
- Divided by pinching in two; no cell plate nor plasmodesmata
- Centrioles present during cell division
Osmosis and Cell Membrane Transport
- Osmosis:
- The diffusion of water across a selectively permeable membrane
- Water travels from an area of lower solute concentration to an area of higher solute concentration
- Cell membranes are selectively permeable:
- Regulates the passage of molecules in and out of the cell
- Allows cell to control chemical composition despite changing external environment
- Types of membrane transport:
- Passive transport: no ATP requirement, molecules flow with concentration gradient
- Active transport: requires carrier protein, molecules flow against concentration gradient, requires energy in form of ATP### Cell Theory
- All organisms are composed of cells
- Cells come only from preexisting cells
- Cells are the smallest structural and functional unit of organisms
Cell Size Perspective
- 1 inch contains 25,400 micrometers (µm)
- Cell size is limited due to diffusion of substances in and out of the cell
- Diffusion is affected by surface area available, temperature, concentration gradient, and distance across the cell
Microscopes
- Dissection/Stereoscope: 3D, live, 40X magnification
- Light Microscope: 2D, live or dead, up to 2000X magnification, 120nm resolution
- Transmission Electron Microscope: 2D, dead, up to 100,000X magnification, 0.2nm resolution
- Scanning Electron Microscope: 3D, dead, up to 100,000X magnification, 10nm resolution
Cellular Components
Cell Membrane
- Phospholipid bilayer, 5-10 nm thick
- Selectively permeable, regulates passage of molecules in and out of the cell
Cell Membrane Transport
- Passive Transport: no ATP requirement, molecules flow with concentration gradient
- Active Transport: requires ATP, molecules flow against concentration gradient
Passive Transport Types
- Simple Diffusion: movement of small, non-polar molecules and water through micropores
- Facilitated Diffusion: diffusion of ions and polar molecules with the help of a protein
Golgi Body (Dictyosomes)
- Stacks of flattened discs or vesicles that act as the "post office" of the cell
- Functions: modify carbohydrates attached to proteins, assemble polysaccharides, and collect them in small vesicles
Plastids
- Site of manufacture and storage of important chemical compounds used by the cell
- Types: Chloroplast, Chromoplast, Leucoplast, Gerontoplast
- Chloroplast: most conspicuous plastid, bound by double membrane, contains grana made up of thylakoids, and thylakoid membranes contain chlorophyll
Cytoskeleton
- Involved in movement within cell and in cell's architecture
- Network of microtubules and microfilaments
- Microtubules: control addition of cellulose to cell wall, involved in movement of flagella and cilia
- Microfilaments: role in cytoplasmic streaming
Eukaryotic Cells
- Originated through endosymbiosis between aerobic bacteria and protomitochondrion
- Mitochondria from non-sulfur purple bacteria
- Chloroplast from cyanobacteria
Mitochondria
- Double membranes, own DNA and RNA
- Folded inward membrane = cristae, increases surface area for enzymatic reactions
Microbodies
- Small, spherical bodies distributed throughout the cytoplasm that contain specialized enzymes
- Peroxisomes: serve in photorespiration, breakdown hydrogen peroxide
- Glyoxisomes: aid in conversion of fat to carbohydrates
Vacuoles
- In mature cells, 90% of volume may be taken up by central vacuoles
- Filled with cell-sap (slightly acidic), maintains pH, cell pressure, and storage for a variety of secondary metabolites
Test your knowledge on the structure and function of cell walls in plant cells. This quiz covers topics such as primary and secondary cell wall layers, composition of cellulose microfibrils, and the role of lignin in providing strength to the cell wall.
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