chapter 2 Bio: molecules to cells Flashcards
Approximately 96% of the human body is comprised of what four elements?
oxygen, hydrogen, nitrogen, carbon
Trace elements, such as zinc, make up less than 0.01% of the human body. However, just
because they are found in very low concentrations does not mean they are not important. Give an example of a trace element and its biological function.
Boron: essential for living beings in the plant world.
An atom is the smallest unit of matter that still retains the properties of the element. Describe
the atomic structure (the subatomic particles) of a carbon atom. How is it different than a nitrogen
atom?
The subatomic particles in the nucleus of a carbon atom are protons and neutrons.
A nitrogen atom has an atomic number of 7 where carbon is 6.
What are valence electrons? What is the valence number of Oxygen?
An electron in the outer shell associated with an atom and can participate in the formation of a chemical bond if outer shell is not closed.
Number of oxygen = 6
What is the difference between a non-polar and polar covalent bond?
Non-polar covalent bond is made by 2 atoms with similar electronegativity.
Polar bond is made by 2 atoms with different electronegativity.
What is an ion? How is an ionic bond different than a covalent bond?
Atoms in which the number of electrons does not equal the number of protons.
In an Ionic bond one atom essentially donates an electron to stabilize the other atom.
Covalent bond: atoms are bound by shared electrons
Explain the bonding of one oxygen with two hydrogen atoms.
A hydrogen atom has one electron and needs one more, as a result the oxygen atom shares electrons with 2 hydrogen atoms.
Why does salt dissolve in water?
Because its molecules attract each other
Explain how a water strider can keep from sinking?
The surface tension of the water is greater than the force of one foot.
Specific Heat Capacity
Heat required to raise the temperature of the unit mass of a given substance by a given amount.
Adhesion
Attraction between different kinds of molecules.
Cohesion
property of a liquid to stay together, it is caused by interactions between the dame sort of molecules.
How does the polar nature of water contribute to an organism’s ability to achieve a desired body temperature, both in maintaining a constant temperature and
cooling?
It maintains temperature by heat and cooling large energy required to break hydrogen bonds that keep individual water molecules from moving.
Why does ice float? Why does warm water not “organize”, whereas cold water freezes? Think about in terms of hydrogen bonding.
It floats because solid water is more dense than liquid water.
Hydrogen bonds space the water molecules apart and it becomes stable.
Hydrophobic
A liquid that will separate from water
