Cambridge IGCSE Biology: Organism Features & Classifications
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Questions and Answers

What does DNA sequencing help determine about different species?

  • Their lifespan.
  • Their physical characteristics.
  • How closely related they are. (correct)
  • The environment in which they live.

    • Which group of organisms is indicated to have more closely related DNA sequences to each other compared to other vertebrates?

  • Birds
  • Mammals (correct)
  • Amphibians
  • Reptiles

    • What was a significant advancement that improved the classification of organisms?

  • Increased knowledge of anatomy.
  • The study of ecological interactions.
  • Technological advances in DNA sequencing. (correct)
  • Development of microscopes.

    • If two species have identical DNA sequences except for one base, what can be inferred?

    <p>They share a more recent common ancestor.</p> Signup and view all the answers

    Which concept explains that organisms having similar DNA sequences also share similar amino acid sequences in proteins?

    <p>Molecular homology.</p> Signup and view all the answers

    Which characteristic of organisms is primarily used to classify them into the five kingdoms?

    <p>Their anatomy and cellular structure.</p> Signup and view all the answers

    What does a significant similarity in amino acid sequences suggest about two organisms?

    <p>They may be closely related in evolutionary terms.</p> Signup and view all the answers

    What was one of the initial methods for classifying organisms before DNA sequencing became widespread?

    <p>Observing physical features and anatomy.</p> Signup and view all the answers

    Which characteristic of living organisms involves detecting stimuli and making appropriate responses?

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

    What is the primary process by which organisms remove toxic substances and waste products?

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

    Which of the following best describes respiration in living organisms?

    <p>The breakdown of nutrients to release energy</p> Signup and view all the answers

    Which characteristic represents a permanent increase in size and dry mass through cell number or size?

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

    Which characteristic of living organisms is involved in producing offspring of the same kind?

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

    What do animals primarily require for nutrition?

    <p>Organic compounds, ions, and water</p> Signup and view all the answers

    Which of the following is NOT a characteristic of living organisms?

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

    Which mnemonic can help remember the key characteristics of living organisms?

    <p>MRS.GREN</p> Signup and view all the answers

    What does the term 'dichotomous' in 'dichotomous keys' refer to?

    <p>Branching into two options</p> Signup and view all the answers

    What is the primary function of a dichotomous key?

    <p>To identify organisms based on features</p> Signup and view all the answers

    Which step is NOT necessary when using a dichotomous key?

    <p>Repeating the process for additional organisms without starting over</p> Signup and view all the answers

    When using a dichotomous key, what type of information do you use to answer the questions?

    <p>Provided information or images accompanying the question</p> Signup and view all the answers

    What happens when you reach the end of a dichotomous key?

    <p>You must start over for another organism</p> Signup and view all the answers

    How do users navigate through a dichotomous key?

    <p>By selecting one of two descriptions at each stage</p> Signup and view all the answers

    What is the starting point in a typical use of a dichotomous key?

    <p>Starting with a single known organism or an unfamiliar one</p> Signup and view all the answers

    Why is it important to follow the statements in a dichotomous key in order?

    <p>To ensure the accuracy of the result</p> Signup and view all the answers

    Which of the following characteristics is used to classify invertebrates?

    <p>Number of legs</p> Signup and view all the answers

    Which group of invertebrates has jointed legs?

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

    What distinguishes mammals from other vertebrates?

    <p>Presence of fur</p> Signup and view all the answers

    What feature is characteristic of crustaceans compared to other arthropods?

    <p>Two pairs of antennae</p> Signup and view all the answers

    Which of the following statements about vertebrates is true?

    <p>All vertebrates have a backbone.</p> Signup and view all the answers

    Which feature is shared by all arthropods?

    <p>Jointed limbs</p> Signup and view all the answers

    Which of these groups is classified as invertebrates?

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

    What is the main defining feature of arthropods?

    <p>Segmented body</p> Signup and view all the answers

    What type of leaf veins do dicotyledons possess?

    <p>Reticulated leaf veins</p> Signup and view all the answers

    Which statement correctly describes the leaves of monocotyledons?

    <p>They are generally narrow and resemble grass.</p> Signup and view all the answers

    Why are viruses not classified as living things?

    <p>They do not have a cellular structure.</p> Signup and view all the answers

    What is the composition of a typical virus?

    <p>Genetic material inside a protein coat.</p> Signup and view all the answers

    Which of the following is NOT a characteristic of dicotyledons?

    <p>Their leaves are generally narrow and grass-like.</p> Signup and view all the answers

    What is a common nutritional method employed by fungi?

    <p>Parasitic nutrition</p> Signup and view all the answers

    Which characteristic is NOT associated with prokaryotes?

    <p>Presence of mitochondria</p> Signup and view all the answers

    Which of the following is true about protoctists?

    <p>Some can photosynthesize</p> Signup and view all the answers

    What is the main feature differentiating the five kingdoms of life?

    <p>The type of cells they contain</p> Signup and view all the answers

    Which organism would likely belong to the fungi kingdom?

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

    Which of the following statements about the cell walls of prokaryotes and fungi is correct?

    <p>Prokaryotes have cell walls not made of cellulose</p> Signup and view all the answers

    What feature is generally true for all fungi?

    <p>They are usually multicellular</p> Signup and view all the answers

    Which kingdom includes organisms that primarily feed on organic substances made by other living things?

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

    Study Notes

    Cambridge IGCSE Biology: Characteristics, Classification & Features of Organisms

    • Characteristics of Living Organisms:

      • Movement: An action causing a change in position.
      • Respiration: Chemical reactions breaking down nutrients to release energy for metabolism.
      • Sensitivity: The ability to detect stimuli and respond.
      • Growth: Permanent increase in size and dry mass.
      • Reproduction: Processes creating more organisms.
      • Excretion: Removal of waste products and toxins.
      • Nutrition: Taking in materials for energy, growth, and development.

    • Examiner Tips & Tricks:

      • Use the mnemonic MRS GREN to remember the characteristics: Movement, Respiration, Sensitivity, Growth, Reproduction, Excretion, and Nutrition.

    Concept & Uses of Classification Systems

    • How Organisms Are Classified:

      • A species is a group of organisms that can interbreed to produce fertile offspring.
      • Species are categorized based on shared features.

    • The Binomial System:

      • Developed by Linnaeus.
      • Organisms are named using Latin in two parts, genus and species (e.g., Homo sapiens).
      • Genus is always capitalized and species is not.
      • The sequence of classification is: Kingdom, Phylum, Class, Order, Family, Genus, Species.

    • Dichotomous Keys:

      • Used to identify organisms.
      • A series of questions with two choices.
      • Each answer leads to another pair of choices until identification is complete.

    Features of Organisms

    • The Five Kingdoms:

      • Animals (multicellular, no cell walls, feed on organic substances).
      • Plants (multicellular, cells with cell walls and chloroplasts, photosynthesise).
      • Fungi (multicellular, cell walls made of chitin, feed by saprophytic or parasitic nutrition).
      • Protoctists (mostly unicellular, may have chloroplasts and cell walls, some photosynthesise).
      • Prokaryotes (unicellular, no nucleus, no mitochondria).

    • Animal Kingdom & Vertebrates:

      • Vertebrates are animals with backbones.
      • Vertebrates are divided into classes (e.g., mammals, birds, reptiles, amphibians, fish).
      • Each class has defining features (e.g., hair, feathers, scales).

    • Arthropod Classification

      • Arthropods have jointed legs.
      • They are divided into groups such as myriapods (centipedes, millipedes), insects (butterflies, spiders), arachnids (spiders, scorpions), and crustaceans (crabs, lobsters).
      • Each group has specific structural features.

    • Viruses:

      • Not considered living organisms.
      • Cannot reproduce independently; they require a host cell.
      • Structure includes genetic material (DNA or RNA) enclosed in a protein coat.

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    Cambridge CIE IGCSE Biology Notes PDF

    Description

    This quiz covers the essential characteristics of living organisms as described in the Cambridge IGCSE Biology syllabus. Understand the MRS GREN mnemonic and the principles behind the classification of species. Test your knowledge and prepare effectively for your exams.

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