2025 Marking Scheme
Atom - Answer-smallest chemical unit of matter
/.Element - Answer-composed of one type of atom
/.Molecule - Answer-two or more atoms combined
/.Chemical bonds - Answer-formed between atoms through interactions of electrons in
their outer shells
/.Ion - Answer-An atoms that has a positive or negative charge
/.Ionic Bonds - Answer-result from attraction between ions of opposite charges
/.Covalent bonds - Answer-Chemical bond that shares pairs of electrons
/.Hydrogen Bonds - Answer-Occur when hydrogen atom is covalently bonded to oxygen
or other large molecules
/.4 characteristics of water that make it highly useful - Answer-can dorm four hydrogen
bonds with other water molecules, excellent solvent, facilitates the splitting and joining
of hydrogen ions and hydroxide ions, excellent temperature buffer
/.Organic compounds - Answer-any compound that contains both carbon and hydrogen
/.4 major classes of organic molecules that compose living things - Answer-
carbohydrates, lipids, proteins, and nucleic acids
/.Carbohydrates - Answer-Ready source of energy for cells, polar, and contain C,H,O
/.3 major groups of carbohydrates - Answer-monosaccharides, disaccharides,
polysaccharides
/.Lipids - Answer-essential to the structure and function of membranes, used for energy
storage
/.Steroids (sterols) - Answer-Lipids found in eukaryotes (not bacteria), have a 4 ring
structure
/.Proteins - Answer-Made up of amino acids (building blocks), contains C,H,O,N.
Required in all aspects of cell structure and function
, /.enzymes - Answer-increase the rate at which chemical reactions take place in living
organisms
/.Proteins contain how many amino acids - Answer-typically 20
/.Nucleic acids - Answer-DNA, RNA
/.3 parts of a Nucleotide - Answer-Nitrogenous base, pentose sugar, phosphate
/.DNA (A,T,C,G) - Answer-2 strands held together by hydrogen bonds
/.Prokaryotes - Answer-DNA is not enclosed within a membrane, lack membrane-
enclosed organelles. Bacteria (and Archaea)
/.Eukaryotes - Answer-DNA is found in the nucleus surrounded by a nuclear membrane.
Micro-organism that have a complex cell structure
/.viruses size - Answer-approx. 20 nm
/.protozoa size - Answer-approx. 5 mm
/.Bacteria size - Answer-0.001 mm
/.Robert Hooke - Answer-Used a crude microscope to view individual cells
/.cell theory - Answer-all living organisms are composed of cells
/.Antoni van Leeuwenhoek - Answer-built microscopes that could view living organisms
(animalcules)
/.Spontaneous generation - Answer-belief that some forms of life can arise from non-
living matter
/.Biogenesis - Answer-Belief that living matter arises only from pre-existing living matter
/.Louis Pasteur - Answer-used swan necked flasks to disprove the theory of
spontaneous generation (aseptic technique)
/.Fermentation - Answer-Microscopic yeast converts sugar to alcohol in the absence of
air
/.Vinegar - Answer-Fermentation causes bacteria to sour when turning into alcohol
/.Pasteurization - Answer-Heating beer or wine after fermentation would kill the bacteria
and prevent spoilage