Edexcel Biology GCSE - Key Concepts in Biology
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Questions and Answers

What is the primary function of egg cells?

  • To accept a single sperm cell and develop into an embryo. (correct)
  • To transport nutrients to the developing embryo.
  • To secrete hormones for embryo development.
  • To provide structural support to the embryo.

    • How do ciliated epithelial cells help defend the body against illness?

  • By engulfing and digesting harmful pathogens.
  • By producing antibodies that neutralize bacteria.
  • By absorbing nutrients from digested food.
  • By wafting bacteria trapped by mucus down to the stomach. (correct)

    • What structural adaptation do root hair cells have to maximize water uptake?

  • A small vacuole for efficient water storage.
  • A thick cell wall to prevent damage.
  • A layered membrane to filter contaminants.
  • A large surface area due to root hairs. (correct)

    • What causes xylem cells to become hollow tubes?

    <p>The deposition of lignin which leads to cell death.</p> Signup and view all the answers

    How do root hair cells transport mineral ions from the soil?

    <p>By active transport which requires energy.</p> Signup and view all the answers

    What role does mitochondria play in egg cells?

    <p>They supply energy for the developing embryo.</p> Signup and view all the answers

    What is the function of cilia on ciliated epithelial cells?

    <p>To waft bacteria trapped by mucus toward the stomach.</p> Signup and view all the answers

    What characteristic of xylem cells helps them withstand the pressure from moving water?

    <p>The lignin deposited in spirals enhances their strength.</p> Signup and view all the answers

    Which reagent is used to test for reducing sugars?

    <p>Benedict’s solution</p> Signup and view all the answers

    What method is used to identify the presence of reducing sugars?

    <p>Heat the sample with Benedict's solution in a water bath</p> Signup and view all the answers

    Which enzyme is primarily involved in building carbohydrates, lipids, and proteins?

    <p>Complex enzymes</p> Signup and view all the answers

    What observation indicates that reducing sugars are present after testing?

    <p>Change to reddish-brown</p> Signup and view all the answers

    What happens to glucose during the process of respiration?

    <p>It is used to generate energy</p> Signup and view all the answers

    What must occur before the presence of starch can be confirmed with iodine solution?

    <p>The sample must be boiled</p> Signup and view all the answers

    Which nutrient do enzymes specifically build, aside from carbohydrates and lipids?

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

    What indicates the presence of proteins when conducting a Biuret test?

    <p>Change from blue to violet</p> Signup and view all the answers

    Which substances are added to test for lipids in the Emulsion Test?

    <p>Ethanol and deionised water</p> Signup and view all the answers

    In calorimetry, what is the first step when measuring the energy in food?

    <p>Record the starting temperature of cold water</p> Signup and view all the answers

    What is the purpose of using a control in the Biuret and Emulsion tests?

    <p>To establish a baseline for positive and negative results</p> Signup and view all the answers

    What color change is observed if lipids are present in the Emulsion Test?

    <p>Formation of a white emulsion layer</p> Signup and view all the answers

    What is the correct procedure after adding 2cm​3 ​of ethanol to the food sample in the Emulsion Test?

    <p>Shake thoroughly and add water</p> Signup and view all the answers

    At what angle should the test tube be held during the calorimetry experiment?

    <p>45 degrees</p> Signup and view all the answers

    Which of the following is a positive control for the Biuret test?

    <p>Egg white</p> Signup and view all the answers

    What is the primary function of phloem cells in plants?

    <p>To carry the products of photosynthesis to all parts of the plants</p> Signup and view all the answers

    Which type of microscope would be best for viewing the internal structures of organelles like mitochondria?

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

    What does the resolving power (RP) of a microscope indicate?

    <p>The ability to distinguish between two points</p> Signup and view all the answers

    Which microscope type requires the use of electrons to form an image?

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

    What major advancement does the electron microscope provide over the light microscope?

    <p>Higher magnification and resolving power</p> Signup and view all the answers

    Which microscope is specifically known for producing 3D images?

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

    Why are electron microscopes particularly useful for identifying viruses?

    <p>They can magnify specimens to 2,000,000x</p> Signup and view all the answers

    What is a significant characteristic of light microscopes?

    <p>They can view living cells without preparation</p> Signup and view all the answers

    What effect does a change in pH have on proteins?

    <p>It affects the amino acid chain structure.</p> Signup and view all the answers

    What happens to the active site of an enzyme when it is denatured?

    <p>It changes shape and can no longer bind with the substrate.</p> Signup and view all the answers

    What is the saturation point in enzyme activity?

    <p>The concentration beyond which increasing substrate does not increase reaction rate.</p> Signup and view all the answers

    What color indicates the presence of starch when iodine is used?

    <p>Blue-black</p> Signup and view all the answers

    Which enzyme is being tested for activity in this practical?

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

    How is the optimal pH for amylase activity determined in this experiment?

    <p>By timing how long it takes for starch to be broken down.</p> Signup and view all the answers

    What materials are used to test the effect of pH on enzyme activity?

    <p>Amylase solution, starch solution, iodine, and buffer solutions.</p> Signup and view all the answers

    What is the primary role of amylase in the experiment?

    <p>To convert starch into simple sugars.</p> Signup and view all the answers

    What does the term 'enzyme specificity' refer to?

    <p>The unique shape of an enzyme's active site that allows only specific substrates to bind.</p> Signup and view all the answers

    What happens to an enzyme when the temperature exceeds its optimum level?

    <p>The enzyme becomes denatured and its active site changes shape.</p> Signup and view all the answers

    What is the relationship described by the Lock and Key Hypothesis?

    <p>The shape of the substrate must match the active site of the enzyme for binding to occur.</p> Signup and view all the answers

    Which of the following statements about the optimum conditions for enzyme activity is true?

    <p>Most enzymes have an optimum pH of around 7, but some require a lower pH.</p> Signup and view all the answers

    What defines the process of denaturation in enzymes?

    <p>The alteration of the enzyme's structure, preventing it from functionally binding to the substrate.</p> Signup and view all the answers

    How does substrate concentration affect enzyme activity up to the point of saturation?

    <p>Higher substrate concentrations lead to a constant enzyme activity level.</p> Signup and view all the answers

    Why are enzymes considered biological catalysts?

    <p>They remain unchanged after the reaction and increase the rate of reaction.</p> Signup and view all the answers

    Which factor is most critical for the binding of a substrate to an enzyme?

    <p>The matching shapes of the substrate and the enzyme's active site.</p> Signup and view all the answers

    Study Notes

    Edexcel Biology GCSE - Key Concepts in Biology

    • Topic 1.1: Eukaryotic and Prokaryotic Cell Functions

      • Living things are made of cells (prokaryotic or eukaryotic)
      • Animal and plant cells are eukaryotic
        • Cell membrane
        • Cytoplasm
        • Nucleus containing DNA
      • Bacterial cells are prokaryotic
        • Cell wall
        • Cell membrane
        • Cytoplasm
        • Single circular strand of DNA and plasmids
      • Organelles have specific functions within cells

    • Topic 1.2: Specialised Cells and Their Functions

      • Cells specialise through differentiation, gaining new sub-cellular structures for their role
      • Some cells differentiate once early in life, others throughout their lifetime (stem cells)
      • Animal examples:
        • Sperm cells: streamlined head, long tail, many mitochondria, acrosome
        • Egg cells: surrounded by a membrane, many mitochondria, large size
        • Ciliated epithelial cells: long hair-like cilia to waft mucus
      • Plant examples:
        • Root hair cells: large surface area, large permanent vacuole, mitochondria
        • Xylem cells: hollow, lignin for strength, transport water and minerals

    • Topic 1.3: Microscopy

      • Cells too small to see without microscopes
      • Light microscopes:
        • Two lenses
        • Illuminated from underneath
        • Maximum magnification about 2000x
        • Resolving power of 200nm
      • Electron microscopes (1930s):
        • Use electrons instead of light
        • Higher magnification (up to 2,000,000x)
        • Higher resolving power (10nm for SEM, 0.2nm for TEM)
        • Used to view very small structures, including viruses

    • Topic 1.4: Size, Scale, and Estimations

      • Calculations involving magnification and size of specimens
      • Standard form for very large and very small numbers, where a number is multiplied by a power of 10 (e.g. 1.5 x 10-5)
      • Orders of magnitude to describe how much bigger or smaller one thing is than another. (e.g., 101, 103)
      • Estimations useful when exact numbers are not known (e.g., counting plants in a field)

    • Topic 1.5: Units and Standard Form

      • Importance of using correct units in calculations.
      • Using prefixes (e.g., centi, milli, micro, nano) to denote multiples of units

    • Topic 1.6: Core Practical: Investigating Biological Specimens

      • This involves using a light microscope to view biological specimens
      • Steps for using a light microscope:
        • Place slide on the stage
        • Use the objective lens with the lowest magnification initially
        • Adjust the focus wheel
        • Increase magnification and refocus.

    • Topic 1.7, 1.8, and 1.9: Enzymes: Mechanisms, Denaturation, and Factors Affecting Enzyme Activity

      • Enzymes are biological catalysts
      • Enzymes are proteins with specific 3D shapes. Active site corresponds with substrate.
      • Enzymes speed up reactions without being consumed by reacting with substrates.
      • Optimum pH is important for enzymes: Enzymes have a specific pH level at which they work most efficiently.
      • Optimum temperature is also important: The rate of enzyme activity increases with temperature until it reaches a maximum point.
      • Enzymes denature when temperature or pH is too extreme (changes the active site shape).

    • Topic 1.10: Core Practical: Effect of pH on Enzyme Activity

      • Investigating how pH affects the rate of enzyme activity.
      • Amylase as an example enzyme.
      • Iodine solution detects the presence of starch.
      • Optimal pH for the enzyme (e.g. in amylase experiments)

    • Topic 1.11: Rate Calculations for Enzyme Activity

      • Rate = Change / Time (calculating the rate of enzyme-catalyzed reactions).

    • Topic 1.12: Enzymes as Biological Catalysts

      • Different enzymes performing functions (carbohydrases, proteases, lipases)
      • Enzymes convert different types of biomolecules (carbohydrates, proteins, or lipids) into specific products (e.g. simple sugars, amino acids, fatty acids).

    • Topic 1.13: Core Practical: Investigating Macronutrients

      • Tests for the presence of: starch, reducing sugars, proteins, lipids.
      • Specific reagents and methods exist in food testing, leading to specific color changes to indicate the presence of a particular nutrient.

    • Topic 1.14: Core Practical: Calorimetry

      • Measuring the energy in food
      • Using a water bath to calculate heat transferred to water.

    • Topic 1.15: Transport in and Out of Cells

      • Passive transport processes (diffusion, osmosis) do not require energy. Move from high to low concentration.
      • Active transport requires energy (ATP). Moves substances against the concentration gradient.

    • Topic 1.16: Core Practical: Osmosis in Potatoes

      • Investigating the movement of water across cell membranes
      • Determining % change in mass in potato cylinders exposed to different concentrations of sucrose solutions.

    • Topic 1.17: Percentage Gain and Loss of Mass

      • Calculating % change in mass related to osmosis or other experiments.
      • Formula: % Change = (change in mass/ initial mass) x 100

    • Explaining the experiment with controls, independent and dependent variables.

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    Edexcel Biology GCSE Topic 1 Notes PDF

    Description

    Explore the essential concepts of biology covered in the Edexcel GCSE syllabus. This quiz focuses on cell types, their functions, and the specialization of cells through differentiation. Test your knowledge on both prokaryotic and eukaryotic cells, along with specialized animal cells.

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