All biology is based on chemistry
Example of water and hydrogen peroxide
Sample MCAS questions
The chemistry of water
Water is the basis of all life on Earth.
H2O dihydrogen monoxide , or just dihydrogen oxide
H2O2 hydrogen peroxide
Pure H2O2 is rocket fuel. It would burn through your skin.
H2O2 that you buy in the store is weak – It’s only 3% . The rest is water.
H2O2 is not stable – it eventually breaks down into regular water and oxygen gas bubbles.
You see those oxygen bubbles fizzing when you put H2O2 on a wound.
Chemistry of carbon atoms
Atoms of the same element will have totally different properties, depending on how they are arranged. Consider how the same carbons act in
(a) coal (b) graphite – used in pencils, or golf clubs
(c) diamond (d) buckyball
(e) nanotube (f) graphene
Carbon with oxygen
What happens when carbon bonds with oxygen?
CO carbon monoxide
It prevents your red blood cells from carrying oxygen
Extremely tiny amounts of CO exist naturally and safely.
But when larger amounts form they quickly become deadly.
CO forms when we burn fuel, but there is not enough oxygen to produce carbon dioxide (CO2). That can happen when we use a stove or internal combustion engine, in an enclosed space.
CO2 carbon dioxide
Forms during cellular respiration, the process by which cells get energy from burning sugar.
CO2 is a waste product made by animal life. We excrete it through our lungs.
are based on Carbon and Hydrogen (with a few other atoms)
C = Carbon H = Hydrogen
O = Oxygen N = Nitrogen
S = Sulfur P = Phosphorus
Glucose – a simple sugar
Glucose is the most common source of energy for animals. It is made by plants during photosynthesis.
Chemical formula for glucose: C6H12O6
This is a simple way to show the glucose molecule
This is a ball-and-stick model of the same molecule
Feb 2016 MCAS.
ATP molecules in cells undergo a process called hydrolysis. The equation below represents this process.
ATP + H2O → ADP + Pi
( Pi = inorganic phosphate)
What always happens within cells as a result of ATP hydrolysis?
A. Water is produced.
B. Chemical energy is released.
C. Phosphorus atoms are used up.
D. Carbohydrate building blocks are formed.
Feb 2017 MCAS.
Some bacteria produce cellulase, a substance that speeds up the breakdown
of cellulose in plant cell walls. Cellulase is an example of which of the following?
A. a carbohydrate . B. an enzyme . C. a hormone . D. an organelle
Feb 2017 MCAS. Protein pumps actively transport ions across a cell’s plasma membrane. What molecule directly supplies the energy required for this transport?
A. ATP . B. cholesterol . C. oxygen . D. tRNA
8.MS-PS1-1. Develop a model to describe that (a) atoms combine in a multitude of ways to
produce pure substances which make up all of the living and nonliving things that we
encounter, (b) atoms form molecules and compounds that range in size from two to
thousands of atoms, and (c) mixtures are composed of different proportions of pure
Clarification Statement: Examples of molecular-level models could include drawings, three-dimensional ball and stick structures, and computer representations showing different molecules with different types of atoms.
HS-LS1-6. Construct an explanation based on evidence that organic molecules are primarily composed of six elements, where carbon, hydrogen, and oxygen atoms may combine with nitrogen, sulfur, and phosphorus to form monomers that can further combine to form large carbon-based macromolecules.
• Monomers include amino acids, mono- and disaccharides, nucleotides, and fatty acids.
• Organic macromolecules include proteins, carbohydrates (polysaccharides), nucleic acids, and lipids.
Disciplinary Core Idea Progression Matrix: PS1.A Structure of matter
That matter is composed of atoms and molecules can be used to explain the properties of substances, diversity of materials, how mixtures will interact, states of matter, phase changes, and conservation of matter.