Chapt_3_Cell_part-3
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Questions and Answers

What is the process called when a living plant cell loses water and shrinks away from its cell wall?

  • Plasmolysis (correct)
  • Osmosis
  • Exocytosis
  • Endocytosis

    • Which of the following best describes the nucleus of a cell?

  • Solid structure with no membranes
  • An organelle responsible for generating energy
  • A double membrane-bound body controlling metabolism (correct)
  • A non-organelle structure maintaining cell shape

    • What is the primary function of the nucleolus within the nucleus?

  • Storing genetic information
  • Site for the formation of ribosomes (correct)
  • Controlling metabolic activities
  • Regulating cell division

    • What structure separates the nucleus from the cytoplasm?

    <p>Nuclear membrane</p> Signup and view all the answers

    Which of the following components is NOT found in the nucleus?

    <p>Cytoplasm</p> Signup and view all the answers

    Which statement correctly describes chromatin material?

    <p>It is made of DNA and proteins</p> Signup and view all the answers

    Which of the following is true about human red blood cells (RBC)?

    <p>They lack a nucleus</p> Signup and view all the answers

    What is found within the nucleoplasm?

    <p>Chromatin fibers and nucleoli</p> Signup and view all the answers

    What role does the nucleus play during cell division?

    <p>It plays a major role</p> Signup and view all the answers

    What is the primary component that makes up the nuclear membrane?

    <p>Lipids and proteins</p> Signup and view all the answers

    The phenomenon of plasmolysis occurs when a plant cell gains water, leading to cell expansion.

    <p>False</p> Signup and view all the answers

    Protoplasm is the colorless material that includes the nucleus and cytoplasm of a cell.

    <p>True</p> Signup and view all the answers

    The nucleolus is the site for the synthesis of ribosomes and is surrounded by the nuclear membrane.

    <p>True</p> Signup and view all the answers

    Chromatin material is made up of proteins and carbohydrates that do not contain hereditary material.

    <p>False</p> Signup and view all the answers

    Human red blood cells (RBCs) and sieve tubes in plants both have a nucleus.

    <p>False</p> Signup and view all the answers

    Match the components of the nucleus with their descriptions:

    <p>Nuclear membrane = Double-layered and porous, separates nucleus from cytoplasm Nucleoplasm = Fluid containing chromatin fibres and nucleoli Nucleolus = Site for the formation of ribosomes, rich in proteins Chromatin material = Contains heredity material, thread-like structures</p> Signup and view all the answers

    Match the cell structures with their functions:

    <p>Nucleus = Controls cellular metabolism and genetic information Nucleolus = Responsible for ribosome production Nuclear membrane = Protects the nucleus and regulates passage of substances Chromatin = Packages DNA within the nucleus</p> Signup and view all the answers

    Match the following statements about cell components:

    <p>Protoplasm = Colorless material containing living content of the cell Plasmolysis = Shrinkage of the cell due to loss of water Chromosomes = Thread-like structures containing DNA Endoplasmic reticulum = Site for synthesis and transport within the cell</p> Signup and view all the answers

    Match the cell organelles with their roles:

    <p>Nucleus = Main controlling center of a cell Cytoplasm = Site of various cellular activities Ribosomes = Protein synthesis Cell Wall = Provides structure and support to plant cells</p> Signup and view all the answers

    What percentage of the cytoplasm is composed of water?

    <p>90%</p> Signup and view all the answers

    Which part of the cytoplasm excludes the cell organelles?

    <p>Cytosol</p> Signup and view all the answers

    Which of the following correctly defines a nucleoid?

    <p>Undefined nuclear region in some organisms</p> Signup and view all the answers

    What term is used to describe non-living cell inclusions in the cytoplasm?

    <p>Ergastic bodies</p> Signup and view all the answers

    Which component is NOT typically part of the cytoplasm?

    <p>DNA</p> Signup and view all the answers

    What is the longest type of cell in the human body?

    <p>Nerve cells</p> Signup and view all the answers

    In plant cells, what structure is considered non-living?

    <p>Cell wall</p> Signup and view all the answers

    What happens to RBCs when placed in a hypertonic solution?

    <p>Shrink in size</p> Signup and view all the answers

    What distinguishes human cheek cells from onion peel cells?

    <p>Presence of cell wall in onion peel cells</p> Signup and view all the answers

    What is the jelly-like substance where all organelles float inside the plasma membrane?

    <p>Cytoplasm</p> Signup and view all the answers

    Chromosomes contain genetic information necessary for cellular activity.

    <p>False</p> Signup and view all the answers

    90% of the cytoplasm is composed of water.

    <p>True</p> Signup and view all the answers

    Cytosol is the part of the cytoplasm that contains cell organelles.

    <p>False</p> Signup and view all the answers

    A nucleoid is a well-defined nuclear region found in all types of cells.

    <p>False</p> Signup and view all the answers

    Ergastic bodies are living cell inclusions found in the cytoplasm.

    <p>False</p> Signup and view all the answers

    What is the primary function of mitochondria within eukaryotic cells?

    <p>Cellular respiration</p> Signup and view all the answers

    Which of the following describes the structure of mitochondria?

    <p>Rod-shaped structures with double-membrane</p> Signup and view all the answers

    What do cristae in the mitochondria primarily provide?

    <p>Increased surface area for metabolic activities</p> Signup and view all the answers

    Mitochondrial DNA is significant because it indicates that mitochondria:

    <p>Can replicate independently from the cell</p> Signup and view all the answers

    Which statement best describes the outer membrane of the mitochondria?

    <p>Porous and smooth</p> Signup and view all the answers

    Which of the following processes occurs in the mitochondria?

    <p>Kreb's cycle</p> Signup and view all the answers

    Mitochondria are referred to as the 'Powerhouses of the cell' because they:

    <p>Generate energy in the form of ATP</p> Signup and view all the answers

    How do mitochondria help in regulating calcium ion concentration in cells?

    <p>By storing and releasing calcium ions as needed</p> Signup and view all the answers

    Which of the following components is NOT typically found in mitochondria?

    <p>Chlorophyll</p> Signup and view all the answers

    Who first observed mitochondria and who named them?

    <p>Mitochondria were first observed by Köliker and named by Benda in 1898.</p> Signup and view all the answers

    What is the primary function of mitochondria in eukaryotic cells?

    <p>The primary function of mitochondria is to serve as the site for cellular respiration, releasing energy.</p> Signup and view all the answers

    Describe the structure of the inner membrane of mitochondria.

    <p>The inner membrane of mitochondria is thrown into finger-like projections called cristae.</p> Signup and view all the answers

    How do mitochondria regulate calcium ion concentration in cells?

    <p>Mitochondria regulate calcium ion concentration by storing and releasing calcium ions as needed.</p> Signup and view all the answers

    Study Notes

    Plant Cell Water Loss

    • Osmosis leads to cell shrinkage when a plant cell loses water; this is known as plasmolysis.

    Protoplasm

    • Colorless material comprising the living content of a cell, including the nucleus and cytoplasm.
    • Contains various organelles responsible for cellular activities.
    • Includes cytoplasmic inclusions.

    Nucleus

    • Discovered by Robert Brown in 1831.
    • Double membrane-bound protoplasmic body controlling cellular metabolism and housing genetic information.
    • Generally centrally located and spherical.

    Structure of the Nucleus

    • Nuclear membrane:
      • Double-layered and porous, made of lipids and proteins.
      • Separates nucleus from cytoplasm, providing transparency and density.
    • Nucleoplasm:
      • Contains chromatin fibers and nucleoli suspended within; surrounded by nuclear membrane.
    • Nucleolus:
      • Spherical and non-membranous; varies in number.
      • Rich in proteins and RNA, and the site for ribosome formation.
    • Chromatin material:
      • Thread-like structures containing hereditary material.

    Functions of the Nucleus

    • Acts as the main control center of the cell.
    • Plays a crucial role in cell division.
    • Regulates metabolic activities through the action of enzymes.

    Chromosomes

    • Thread-like structures that tightly package DNA within the nucleus.

    Additional Information

    • The nucleus is the largest cell structure.
    • Human red blood cells (RBCs) and sieve tubes in plants do not contain a nucleus.

    Osmosis and Plasmolysis

    • Plasmolysis occurs when a plant cell loses water, leading to cell shrinkage or contraction away from the cell wall.

    Protoplasm

    • Protoplasm is the colorless material that constitutes the living content of a cell.
    • It includes essential components like the nucleus and cytoplasm, along with various organelles responsible for cellular activities.
    • Cytoplasmic inclusions, which are substances present within the protoplasm, also play roles in cell functions.

    Nucleus

    • Discovered by Robert Brown in 1831, the nucleus is a double membrane-bound structure that controls cellular metabolism and houses genetic information.
    • Acts as the primary control center of the cell, often referred to as the "director."

    Structure of the Nucleus

    • Nuclear Membrane:
      • Composed of double-layered, porous lipids and proteins, separating the nucleus from the cytoplasm.
    • Nucleoplasm:
      • A jelly-like substance that surrounds chromatin fibers and nucleoli, enclosed by the nuclear membrane.
    • Nucleolus:
      • Spherical and non-membranous, varies in number and is rich in proteins and RNA; serves as the assembly site for ribosomes.
    • Chromatin Material:
      • Comprises thread-like structures called chromatin fibers, containing hereditary material that condenses to form chromosomes.

    Function of the Nucleus

    • Central role in regulating all cellular activities and metabolic processes controlled by enzymes.
    • Major importance in cell division, ensuring proper replication and distribution of genetic material.

    Chromosomes

    • Chromosomes are tightly packed DNA structures located within the nucleus, critical for genetic inheritance.

    Additional Information

    • The nucleus is the largest organelle in a typical cell; however, human red blood cells (RBCs) and sieve tubes in plants lack a nucleus.

    Plasmolysis

    • Occurs when a living plant cell loses water, leading to shrinkage away from the cell wall.
    • The process is driven by osmosis.

    Protoplasm

    • Colourless material containing living contents of the cell, including the nucleus and cytoplasm.
    • Contains organelles that perform various cellular activities.
    • Substances known as cytoplasmic inclusions are present within protoplasm.

    Nucleus

    • Discovered by Robert Brown in 1831.
    • A double membrane-bound dense protoplasmic structure regulating cellular metabolism and housing genetic information.
    • Generally found as a large, spherical body at the center of the cell.

    Structure of Nucleus

    • Nuclear Membrane
      • Double-layered and porous, composed of lipids and proteins.
      • Distinguishes the nucleus from the cytoplasm and is transparent.
    • Nucleoplasm
      • A gel-like substance containing chromatin fibers and nucleoli, surrounded by the nuclear membrane.
    • Nucleolus
      • Spherical, non-membranous structure varying in number.
      • Rich in proteins and RNA, functioning as the site for ribosome formation.
    • Chromatin Material
      • Composed of fine, thread-like structures called chromatin fibers.
      • Contains hereditary material critical for genetic information.

    Function of Nucleus

    • Serves as the main control center of the cell.
    • Plays a significant role in cellular division.
    • Regulates metabolic activities through enzyme management.

    Chromosomes

    • Thread-like structures located within the nucleus, where DNA is tightly packaged.

    Additional Facts

    • The nucleus is the largest cell structure.
    • Human red blood cells (RBC) and sieve tubes in plants do not have a nucleus.

    Functions of Chromosomes

    • Chromosomes hold hereditary information responsible for passing traits from one generation to the next.
    • DNA within chromosomes provides essential instructions for cellular functions and activities.

    Cytoplasm

    • The cytoplasm is a living, colorless, semi-liquid substance that fills most of the cell's volume and is in constant motion.
    • It is bounded by the cell membrane and consists of specialized organelles that perform various functions.
    • Composed of approximately 90% water, with the rest made up of amino acids, vitamins, fats, enzymes, and carbohydrates.
    • Cytosol refers to the part of the cytoplasm that excludes organelles, while ergastic bodies are non-living inclusions found in the cytoplasm.

    Nucleoid in Bacteria

    • In organisms like bacteria, the nuclear region may lack a defined membrane and is termed a nucleoid.
    • The nucleoid contains nucleic acids but does not have distinct compartments like eukaryotic cells.

    Check Your Concepts - Summary Questions

    • Longest cell in the human body: Nerve cells are considered the longest.
    • Non-living structure in plant cells: The cell wall is non-living.
    • Red blood cells in hypertonic solution: They shrink in size due to water loss.
    • Difference between human cheek cells and onion peel cells: The presence of a cell wall in onion peel cells distinguishes them.
    • Jelly-like substance within plasma membrane: The cytoplasm is where all organelles float.

    Functions of Chromosomes

    • Chromosomes are the carriers of hereditary information, crucial for genetics and inheritance.
    • DNA within chromosomes encodes instructions necessary for cellular processes and activities.

    Cytoplasm

    • The cytoplasm is a viscous, semi-liquid substance filling the cell and is continuously in motion.
    • It comprises approximately 90% water, with the remaining components including amino acids, vitamins, fats, enzymes, and carbohydrates.
    • Specialized organelles essential for cell function are suspended in the cytoplasm.
    • Cytosol is the component of cytoplasm that excludes the organelles, consisting of the liquid portion.
    • Non-living inclusions known as Ergastic bodies are also present within the cytoplasm.

    Nucleoid in Prokaryotes

    • In organisms like bacteria, the nuclear region lacks a defined membrane structure, forming a nucleoid that contains nucleic acids.

    Concept Checks

    • The longest cell type in the human body is nerve cells.
    • The non-living structure found in plant cells is the cell wall.
    • Red blood cells in a hypertonic solution will shrink in size.
    • The main distinction between human cheek cells and onion peel cells is the presence of a cell wall in onion cells.
    • The jelly-like substance within the plasma membrane where organelles are suspended is called cytoplasm.

    Mitochondria Overview

    • Mitochondria were first observed by Köliker and named by Benda in 1898.
    • Function as double membrane-bound organelles found in the cytoplasm of eukaryotic cells, present in both plants and animals.

    Structure of Mitochondria

    • Rod-shaped with an outer membrane that is smooth and porous.
    • Inner membrane features finger-like projections called cristae, which increase surface area for metabolic activities.
    • Cristae host F1 particles (oxysomes) that contain various respiratory enzymes crucial for energy production.
    • Mitochondria possess their own DNA, referred to as mitochondrial DNA.

    Functions of Mitochondria

    • Key site for cellular respiration, known as the "Powerhouses of the cell," releasing energy for cellular functions.
    • Synthesize respiratory enzymes and substances that aid in ATP generation, the energy currency of cells.
    • Play a role in regulating calcium ion concentration by storing and releasing calcium as necessary.
    • Host the aerobic phase of respiration, specifically the Kreb's cycle, which is vital for energy extraction from nutrients.

    Overview of Mitochondria

    • First identified by Köliker and named by Benda in 1898.
    • Double membrane-bound organelles crucial for eukaryotic cells.

    Location

    • Present in the cytoplasm of both plant and animal cells.

    Structure

    • Rod-shaped with a smooth, porous outer membrane.
    • Inner membrane features cristae, which are finger-like projections increasing surface area for metabolic processes.
    • Cristae contain F1 particles (oxysomes) that bear respiratory enzymes.
    • Mitochondria possess their own DNA known as mitochondrial DNA.

    Functions of Mitochondria

    • Serve as the site for cellular respiration, releasing energy and earning the title "Powerhouses of the cell."
    • Energy produced is utilized for various cellular functions.
    • Synthesize specialized respiratory enzymes that facilitate ATP generation.
    • Regulate calcium ion concentration through storage and release based on cellular needs.
    • Host the aerobic portion of respiration known as the Krebs cycle.

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    Description

    This quiz covers key concepts from Chapter 7 of Biology, focusing on protoplasm and the process of osmosis in plant cells. Understand how plasmolysis affects cell structure and learn about the roles of various organelles in cellular activities.

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