Biology Grade 9: Lipids
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Questions and Answers

What are lipids?

Fatty compounds that perform a variety of functions in your body.

What are the two main types of fatty acids?

  • Hydrophobic and Hydrophilic
  • Simple and Complex
  • Polar and Non-polar
  • Saturated and Unsaturated (correct)

    • Saturated fats are typically found in plants and fish, and are usually liquid at room temperature.

    False

    What are Phospholipids composed of?

    <p>Two fatty acids, a glycerol unit, and a phosphate group.</p> Signup and view all the answers

    What are the four fused carbon rings in a steroid structure?

    <p>Cholesterol, testosterone, and estrogen</p> Signup and view all the answers

    What are the four main components of an amino acid?

    <p>A carboxyl group, an amino group, a hydrogen atom, and a side chain.</p> Signup and view all the answers

    Proteins are formed by a dehydration reaction, where water molecules are added between amino acids.

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

    What are the four levels of protein structure?

    <p>Primary, secondary, tertiary, and quaternary.</p> Signup and view all the answers

    Sickle-cell disease is caused by a change in the amino acid sequence of hemoglobin, leading to the production of abnormal hemoglobin molecules that tend to crystallize, deforming red blood cells into sickle-shaped cells.

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

    What are nucleic acids made of?

    <p>Nucleotides.</p> Signup and view all the answers

    What are the two main types of nucleic acids?

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

    What are the three main functions of nucleic acids?

    <p>Storing information, providing instructions for building proteins, and telling cells what to do to stay alive.</p> Signup and view all the answers

    DNA is single-stranded, while RNA is double-stranded.

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

    What are the four nitrogenous bases found in DNA?

    <p>Adenine, guanine, cytosine, and thymine.</p> Signup and view all the answers

    Uracil is found in both DNA and RNA.

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

    What are the two main categories of cells?

    <p>Prokaryotic and eukaryotic cells.</p> Signup and view all the answers

    Which of the following is NOT a characteristic of prokaryotic cells?

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

    The cell theory states that all living things are composed of cells, the cell is the basic unit of organization for all living things, and all cells come from other cells.

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

    What are the two main types of microscopes used to study cells?

    <p>Light microscopes and electron microscopes.</p> Signup and view all the answers

    Which type of microscope provides the highest magnification and can be used to visualize detailed internal structures and organelles?

    <p>Transmission electron microscope</p> Signup and view all the answers

    Scanning electron microscopes are used to study the surface texture and external morphology of cells, providing a 3D perspective.

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

    What is the function of the plasma membrane?

    <p>It acts as a barrier, regulating the movement of molecules in and out of the cell to maintain homeostasis.</p> Signup and view all the answers

    What is the function of the cytoplasm?

    <p>Suspends cellular components and allows metabolic reactions and molecular movement.</p> Signup and view all the answers

    Chromosomes are composed of DNA and contain genes that instruct cellular functions and direct protein synthesis.

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

    What is the function of ribosomes?

    <p>They build proteins by translating genetic instructions from DNA, crucial for cell structure and function.</p> Signup and view all the answers

    What is the function of the cell wall in plant cells?

    <p>Provides rigidity, strength, and protection against mechanical stress and infection.</p> Signup and view all the answers

    What is the function of chloroplasts?

    <p>They contain chlorophyll and are the site of photosynthesis, converting light energy into chemical energy.</p> Signup and view all the answers

    Lysosomes are organelles found in both plant and animal cells.

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

    What is the function of centrioles?

    <p>They become prominent during cell division and anchor for cytoskeletons.</p> Signup and view all the answers

    The plasma membrane is selectively permeable, meaning that some substances can pass through, while others are blocked.

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

    Why is the plasma membrane described as a fluid mosaic?

    <p>Because it is made up of a phospholipid bilayer, where molecules can move past one another, and contains a variety of proteins embedded within it.</p> Signup and view all the answers

    What are the main components of the cell surface in plant cells?

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

    Animal cells lack a cell wall and instead secrete a sticky coat called the extracellular matrix.

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

    What is the function of the extracellular matrix in animal cells?

    <p>It provides structural support, adhesion, and communication between cells.</p> Signup and view all the answers

    Study Notes

    Biology Study Notes - Grade 9

    • Lesson 1: Lipids
      • Lipids are fatty compounds performing various functions in the body
      • Lipids are polymers of fatty acids and glycerol
      • They're hydrophobic (water-fearing), insoluble in water
      • Four major lipid types exist: triglycerides, phospholipids, steroids, and waxes
      • Triglycerides: composed of fatty acids and glycerol, found in animal fats and plant oils
      • Phospholipids: have a glycerol backbone, two fatty acid tails, and a phosphate group; primary component of cell membranes
      • Steroids: have a four-fused-ring structure, including cholesterol, testosterone, and estrogen
      • Waxes: composed of fatty acids and alcohols, provide waterproofing functions
      • Saturated fatty acids have no double bonds, typically solid at room temperature; contribute to LDL cholesterol increase
      • Unsaturated fatty acids have one or more double bonds, typically liquid at room temperature; tend to decrease LDL cholesterol

    Lesson 2: Proteins

    • Proteins are polymers made of amino acids
      • Amino acids have a central carbon atom bonded to an amino group, a carboxyl group, a hydrogen atom, and a side chain (R group)
      • The side chain (R group) determines the specific properties of each amino acid
      • 20 types of amino acids
      • Amino acids link via dehydration reactions to form peptide bonds
      • Protein structure includes primary (sequence of amino acids), secondary (alpha-helices and beta-sheets), tertiary (3D shape), and quaternary (multiple polypeptide chains) structures
      • Protein shape and function are determined by their amino acid sequence

    Lesson 3: Nucleic Acids

    • Nucleic acids (DNA and RNA) are polymers of nucleotides
      • Nucleotides: composed of a five-carbon sugar (deoxyribose in DNA, ribose in RNA), a phosphate group, and a nitrogenous base (adenine, guanine, cytosine, thymine, or uracil)
      • DNA: double-stranded helix; stores genetic information
      • RNA: single-stranded; involved in protein synthesis
      • DNA's bases pair up: A with T, and G with C
      • RNA's bases pair up: A with U, and G with C

    Lesson 4: The Two Major Categories of Cells

    • Cells are the basic unit of life, either prokaryotic or eukaryotic
      • Prokaryotic cells: lack a nucleus and membrane-bound organelles (e.g., bacteria)
      • Eukaryotic cells: have a nucleus and membrane-bound organelles (e.g., plants, animals)

    Lesson 5: Membrane Structure

    • Cell membranes are selectively permeable, regulating the passage of substances into and out of a cell
      • The primary component is the phospholipid bilayer, with hydrophilic heads and hydrophobic tails, creating a barrier between the cell's interior and the external environment
      • Membrane proteins carry out various functions, such as transport and cell signaling
      • Cholesterol adds fluidity and stability to the membrane

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    Description

    Explore the fascinating world of lipids in this quiz designed for Grade 9 biology students. Learn about the different types of lipids, their structures, and functions in the body. Test your knowledge of triglycerides, phospholipids, steroids, and waxes.

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