Name ______Date ______Block______
Study Guide for Chapter 2 (Biochemistry) Test KEY
- Draw an atom of sodium. Label the nucleus,
the electrons, the protons and the neutrons.
2. What are the three subatomic particles that make up an atom? What is the charge of each?
Protons: positiveNeutrons: neutral (no charge)Electrons: negative
3. What does the atomic number of an element tell you?
The number of protons in an atom of that element. The number of protons equals the number of electrons.
4. What does atomic mass tell you?
The number of protons + neutrons in an atom of that element.
5. Define:
a. atom – smallest unit of matter
b. element- a pure substance made up of only ONE type of atom
c. molecule - two or more atoms covalently bonded together
d. compound - atoms of two or more DIFFERENT elements joined together
6. Differentiate between and ion and an isotope.
An atom that loses or gains electrons becomes an ion. An atom that have more or less neutrons than usual is an isotope.
7. Differentiate between a covalent bond and an ionic bond.
Covalent bonds form when atoms share electrons in order to become stable.
Ionic bonds form when electrons are transferred from one atom to another in order for the atoms to become stable and the resulting ions are attracted to each other because of their opposite charges.
8. Why to atoms form bonds?
Atoms form bond in order to become stable. They are stable when their outer electron level is full.
9. What is a hydrogen bond?
A hydrogen bond is a weak attraction between H and O in different water molecules (and in a few other types of molecules).
10. Differentiate between cohesion and adhesion.
Cohesion is an attraction to the same type of molecule. Adhesion is an attraction to something different.
11. How do surface tension and capillary action help living things?
Surface tension allows small organisms to move across bodies of water. Capillary action moves water up from the roots to tree to the rest of the plant.
12. Why is it important for living things that water takes a long time to heat up or cool down?
Our bodies are mostly water so it helps our bodies not get too hot or too cold. Helps us maintain HOMEOSTASIS.
13. Why is it important for living things that ice floats?
It keeps lakes and ponds from completely freezing in winter so all the organisms that live in the water can survive.
14. Why is water called a universal solvent?
Water can dissolve many different substances.
15. Where on the pH scale are acids found? What type of ions is most concentrated in acids?
Acids are less than 7 on the scale. H+ (hydrogen ions) are concentrated in acids.
16. Where on the pH scale are bases found? What type of ion is most concentrated in bases?
Bases are more than 7 on the scale. OH- (hydroxide ions) are concentrated in bases.
17. What is the pH of a substance that is neutral? Give an example of a neutral substance.
Neutral is 7 on the pH scale. Water is a neutral substance.
18. What 4 elements make up 96% of any living thing?
Carbon, Hydrogen, Oxygen and Nitrogen
19. How can you tell if a substance is organic or not?
Organic compounds contain carbon.
20. What are the monomers of carbohydrates, proteins and nucleic acids?
Carbs: monosaccharides, Proteins: amino acids, Nucleic acids: nucleotides
21. What are the functions of the different organic compounds?
a. carbohydrates : quick energy or store energy
b. lipids : store energy, cell membranes, insulation, protection
c. proteins : body structure, speed up reactions (enzymes),
d. nucleic acids : store genetic information, help make proteins
22. Write the chemical reaction that we observed in the enzyme lab. Label the reactants and products.
2H2O2 2H2O + O2
Reactants Products
23. Why do living organisms need enzymes?
So that reactions can go fast enough to sustain life.
24. Enzymes speed up reactions by reducing the ______?
Activation energy of a reaction (which is the energy needed to start the reaction).
25. The substance that an enzyme binds to is called the ______?
Substrate.
26. The pocket on the surface of an enzyme where things can bind is called the _____?
Active site.
27. What happens to an enzyme after a reaction?
It is not changed. It is ready to work again if new substrate is added.
28. What happens to an enzyme if you boil it or put it in acid?
The heat or acid makes the shape of the enzyme change so that it can’t function anymore. It denatures the enzyme.