Biology Chapter: Cell Structure and Biological Molecules
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Questions and Answers

What is the primary function of mitochondria in eukaryotic cells?

  • Storage of genetic information
  • Cellular respiration and ATP production (correct)
  • Modification and packaging of proteins
  • Protein synthesis

    • Which of the following accurately describes the role of enzymes in biological reactions?

  • Enzymes change the equilibrium constant of a reaction.
  • Enzymes increase the activation energy required for reactions to occur.
  • Enzymes provide the energy needed for reactions to proceed.
  • Enzymes lower the activation energy, speeding up the reaction rate. (correct)

    • Which of the following is NOT a difference between prokaryotic and eukaryotic cells?

  • Presence of membrane-bound organelles
  • Presence of ribosomes
  • Presence of a cell membrane (correct)
  • Presence of a nucleus

    • Which type of molecule is primarily responsible for long-term energy storage in organisms?

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

    Which of the following is NOT a feature of plant cells that distinguishes them from animal cells?

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

    What is the primary function of DNA?

    <p>Storage and transmission of genetic information</p> Signup and view all the answers

    Which type of molecule is a polymer of amino acids?

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

    What is the active site of an enzyme?

    <p>The region of the enzyme where the substrate binds.</p> Signup and view all the answers

    What is the primary purpose of photosynthesis?

    <p>To convert carbon dioxide and water into glucose</p> Signup and view all the answers

    Where does respiration occur within a cell?

    <p>In the mitochondria</p> Signup and view all the answers

    Which of the following accurately describes a negative feedback mechanism?

    <p>Maintains stable blood glucose levels</p> Signup and view all the answers

    What do alleles refer to in genetics?

    <p>Different versions of a gene</p> Signup and view all the answers

    How does natural selection affect a population over time?

    <p>It leads to adaptations based on environmental pressures</p> Signup and view all the answers

    What is a key characteristic of semipermeable cell membranes?

    <p>They regulate the passage of some substances while excluding others</p> Signup and view all the answers

    Which ecological relationship exemplifies mutualism?

    <p>A bee pollinating a flower</p> Signup and view all the answers

    Which of the following contributes to the resilience of an ecosystem?

    <p>Biodiversity and complex food webs</p> Signup and view all the answers

    Study Notes

    Cell Structure and Function

    • Eukaryotic cells have membrane-bound organelles (nucleus, mitochondria, chloroplasts in plants), prokaryotic cells do not.
    • Cell membranes control substance passage (diffusion, active transport, osmosis).
    • Organelles have specific roles: nucleus directs gene expression, mitochondria produce ATP, ribosomes synthesize proteins, Golgi modifies and packages proteins.
    • Plant cells have cell walls, chloroplasts, and large central vacuoles, unlike animal cells.

    Biological Molecules

    • Carbohydrates:

      • Monosaccharides (glucose, fructose) are simplest carbohydrates.
      • Disaccharides (sucrose) form from two monosaccharides via condensation.
      • Polysaccharides (starch, glycogen, cellulose) are complex carbohydrates from many monosaccharides.
      • Carbohydrates are crucial for energy and structure.

    • Lipids:

      • Lipids include fats, oils, and phospholipids.
      • Fats (glycerol + fatty acids) store long-term energy.
      • Phospholipids form cell membranes.
      • Lipids provide insulation and protection.

    • Proteins:

      • Proteins are amino acid polymers.
      • Proteins have diverse roles (enzymes, hormones, structural components like collagen, transport molecules like hemoglobin).
      • Protein function depends on its structure (primary, secondary, tertiary, quaternary).
      • Enzymes lower reaction activation energy, crucial for biological processes.

    • Nucleic Acids:

      • DNA and RNA store and transmit genetic information.
      • DNA is a double helix, RNA is single-stranded.
      • DNA replicates to pass genetic information.
      • RNA is vital for protein synthesis.

    Enzymes

    • Enzymes are biological catalysts.
    • Specific enzyme shapes bind to substrates (reactants).
    • Substrate binds to the enzyme's active site.
    • Temperature, pH, and substrate concentration affect enzyme activity.
    • Enzyme activity can be regulated (inhibited or activated).

    Photosynthesis and Respiration

    • Photosynthesis converts light energy into chemical energy to make glucose, using carbon dioxide and water.
    • Respiration breaks down glucose to release ATP energy.
    • Photosynthesis occurs in chloroplasts, respiration in mitochondria.
    • Photosynthesis products are respiration reactants, and vice-versa.
    • Respiration includes aerobic (oxygen use) and anaerobic (no oxygen) types.

    Biological Membranes

    • Cell membranes are semipermeable.
    • The fluid mosaic model describes the cell membrane structure (phospholipid bilayer, embedded proteins).
    • Membranes control substance passage (active/passive transport).
    • Membranes are involved in cell signalling.

    Homeostasis and Control Systems

    • Homeostasis maintains a stable internal environment (temperature, pH, blood glucose).
    • Feedback mechanisms regulate homeostasis.
      • Negative feedback reduces deviations from set points (e.g., blood glucose).
      • Positive feedback amplifies deviations from set points (e.g., childbirth).
    • Nervous and endocrine systems regulate homeostasis.

    Inheritance

    • Genes are DNA segments that carry genetic code.
    • Alleles are gene variations.
    • Dominant alleles mask recessive alleles in heterozygotes.
    • Genotype is genetic makeup, phenotype is observable traits.
    • Mendel's laws describe trait inheritance.

    Variation, Adaptation, and Selection

    • Species variation is crucial for natural selection.
    • Adaptations enhance survival/reproduction.
    • Natural selection shapes populations over time.
    • Mutations enable evolution and adaptation.

    Ecology

    • Ecology studies organism-environment relationships.
    • Key ecological concepts include populations, communities, ecosystems, and biomes.
    • Relationships between organisms include competition, predation, mutualism, parasitism.
    • Populations are influenced by biotic (living) and abiotic (non-living) factors.
    • Food chains/webs show energy flow.
    • Biodiverse ecosystems with many food webs are more stable.

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    Description

    This quiz focuses on the fundamental concepts of cell structure, including eukaryotic and prokaryotic cells, along with their organelles and functions. Additionally, it covers biological molecules such as carbohydrates, including monosaccharides, disaccharides, and polysaccharides. Test your knowledge on these essential topics in biology.

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