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General Biology: Cell Domains, Elements, and Chemical Bonds

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  • Which domains include unicellular organisms?

    Bacteria, Archaea, and Eukarya include unicellular organisms.

  • What domains have prokaryotic cells?

    Bacteria and Archaea are composed of prokaryotic cells.

  • Which domain do fungi belong to?

    Fungi belong to the domain Eukarya.

  • What kingdoms are included in the domain Eukarya?

    Kingdoms Plantae, Fungi, Animalia, and diverse Protists are in domain Eukarya.

  • What is an element?

    An element is a substance that cannot be chemically broken down into a simpler substance.

  • What is a compound?

    A compound is a substance made of two or more elements combined in a fixed ratio.

  • What are emergent properties?

    Emergent properties are new characteristics that arise at higher levels of biological organization.

  • Which four elements make up the largest percentage of the human body?

    Oxygen (65%), Carbon (18.5%), Hydrogen (9.5%), and Nitrogen (3.3%).

  • What are trace elements? Give two examples important for humans.

    Trace elements are required in small amounts; examples include Iron (for hemoglobin) and Zinc (for immune function).

  • What are the charges and locations of the three subatomic particles?

    Protons: positive, nucleus; Neutrons: neutral, nucleus; Electrons: negative, electron shells.

  • What determines the identity of an element?

    The number of protons in the nucleus determines the element's identity.

  • What are isotopes?

    Isotopes are atoms of the same element with different numbers of neutrons.

  • What is a radioactive isotope?

    A radioactive isotope is unstable and emits energy and particles as it decays.

  • What types of chemical bonds can atoms with incomplete valence shells form?

    They can form ionic bonds (electron transfer), covalent bonds (electron sharing), and hydrogen bonds.

  • What is a covalent bond?

    A covalent bond involves sharing of electron pairs between atoms.

  • Difference between polar and nonpolar covalent bonds?

    Polar covalent bonds share electrons unequally, creating partial charges; nonpolar covalent bonds share electrons equally with no charge separation.

  • What is an ionic bond?

    An ionic bond forms when one atom transfers electrons to another, creating oppositely charged ions attracted to each other.

  • What is a hydrogen bond?

    A hydrogen bond is a weak attraction between a slightly positive region of one molecule and a slightly negative region of another.

  • What is the maximum number of electrons in the innermost electron shell?

    The innermost electron shell can hold up to 2 electrons.

  • What determines the chemical reactivity of an atom?

    The number of electrons in the outermost shell determines an atom's chemical reactivity.

  • What is a molecule?

    A molecule is two or more atoms held together by covalent bonds.

  • What is the difference between an atom and an ion?

    An ion is an atom or molecule with a net electric charge due to loss or gain of electrons.

  • What is the pH of a neutral solution?

    A neutral solution has equal concentrations of H+ and OH- ions.

  • What is a buffer?

    A buffer is a substance that accepts H+ when in excess and donates H+ when their concentration drops, stabilizing pH.

  • What is the atomic number of an atom with 6 protons?

    The atomic number is 6, equal to the number of protons.

  • How many neutrons does fluorine have if its atomic mass is 19 and atomic number is 9?

    Fluorine has 10 neutrons (19 - 9 = 10).

  • What is the highest level of taxonomic organization?

    The highest level is the Domain.

  • What do all members of domains Archaea and Bacteria have in common?

    All members are prokaryotic, lacking a nucleus and membrane-bound organelles.

  • What is the scientific method?

    The scientific method is an approach for understanding natural phenomena through observation and experimentation.

  • What is a hypothesis?

    A hypothesis is a tentative explanation for an observation or set of observations.