Bio 1A Ch 2 The chemical foundation of life

If xenon has an atomic number of 54 and a mass number of 108, how many neutrons does it have?

A. 54 B. 27 C. 100 D. 108 A-54

A molecule that binds up excess hydrogen ions in a solution is called a(n) ________.

A. Acid B. Isotope C. Base D. Donator C-Base

Which of the following statements is true?

A. Acids and bases cannot mix together. B. Acids and bases will neutralize each other. C. Acids, but not bases, can change the pH of a solution. D. Acids donate hydroxide ions (OH -); bases donate hydrogen ions (H +) C. Acids, but not bases, can change the pH of a solution.

When acids are added to a solution, the pH should ________.

A. Decrease B. Increase C. Stays the same D. Cannot tell without testing A. Decrease

Figure 2.24 Which of the following statements is false?

A. Molecules with the formulas CH3CH2COOH and C3H6O2 could be structural isomers. B. Molecules must have a double bond to be cis-trans isomers. C. To be enantiomers, a molecule must have at least three different atoms or groups connected to a central carbon. D. To be enantiomers, a molecule must have at least four different atoms or groups connected to a central carbon. C-To be enantiomers, a molecule must have at least three different atoms or groups connected to a central carbon.

Which of the following is not a functional group that can bond with carbon?

A. Sodium B. Hydroxyl C. Phosphate D. Carbonyl A- sodium

Which of the following statements is not true?

A. Water is polar. B. Water stabilizes temperature. C. Water is essential for life. D. Water is the most abundant molecule in the Earth's atmosphere. D. Water is the most abundant molecule in the Earth's atmosphere.

Which type of bond represents a weak chemical bond?

A. hydrogen bond B. atomic bond C. covalent bond D. nonpolar covalent bond A. hydrogen bond

Atoms that vary in the number of neutrons found in their nuclei are called ________.

A. ions B. neutrons C. neutral atoms D. isotopes D. isotopes

The presence of a membrane-enclosed nucleus is a characteristic of ________.

A. prokaryotic cells B. eukaryotic cells C. living organisms D. bacteria B-eukaryotic

Potassium has an atomic number of 19. What is its electron configuration?

A. shells 1 and 2 are full, and shell 3 has nine electrons B. shells 1, 2 and 3 are full and shell 4 has three electrons C. shells 1, 2 and 3 are full and shell 4 has one electron D. shells 1, 2 and 3 are full and no other electrons are present C. shells 1, 2 and 3 are full and shell 4 has one electron

Figure 2.3 How many neutrons do carbon-12 and carbon-13 have, respectively?

Carbon-12 has six neutrons. Carbon-13 has seven neutrons.

Figure 2.7 An atom may give, take, or share electrons with another atom to achieve a full valence shell, the most stable electron configuration. Looking at this figure, how many electrons do elements in group 1 need to lose in order to achieve a stable electron configuration? How many electrons do elements in groups 14 and 17 need to gain to achieve a stable configuration?

Elements in group 1 need to lose one electron to achieve a stable electron configuration. Elements in groups 14 and 17 need to gain four and one electrons, respectively, to achieve a stable configuration.

Discuss how buffers help prevent drastic swings in pH.

My answer: Buffers can absorb free H+ ion & OH- ion that comes from chemical reactions. B/c there's bond in these ions, it doesn't allow inc. or dec. in pH. An example of this is the bicarbonate system within the human body. The bicarbonate system absorbs H+ & OH- ions to prevent any changes to the pH. Book: Buffers absorb the free hydrogen ions and hydroxide ions that result from chemical reactions. Because they can bond these ions, they prevent increases or decreases in pH. An example of a buffer system is the bicarbonate system in the human body. This system is able to absorb hydrogen and hydroxide ions to prevent changes in pH and keep cells functioning properly.

What property of carbon makes it essential for organic life?

My answer: Carbon is found in all living things & is known to be unique b/c it forms to four covalent bonds b/w atoms or molecules. It can be polar/non polar covalent bonds & it allows formation of long chains of carbon molecules to form protein & DNA Book: Carbon is unique and found in all living things because it can form up to four covalent bonds between atoms or molecules. These can be nonpolar or polar covalent bonds, and they allow for the formation of long chains of carbon molecules that combine to form proteins and DNA.

Why can some insects walk on water?

My answer: Due to surface tension of the water it can allow some insects to walk on water. Surface tension results from cohesion (attraction from one water molecule to another). Book: Some insects can walk on water, although they are heavier (denser) than water, because of the surface tension of water. Surface tension results from cohesion, or the attraction between water molecules at the surface of the body of water (the liquid-air/gas interface).

What makes ionic bonds different from covalent bonds?

My answer: Ionic bonds are strong bonds but compare to covalent bonds they are weaker. This takes less energy to break an ionic bond than it does w/covalent bond. Book:Ionic bonds are created between ions. The electrons are not shared between the atoms, but rather are associated more with one ion than the other. Ionic bonds are strong bonds, but are weaker than covalent bonds, meaning it takes less energy to break an ionic bond compared with a covalent one.

Why are hydrogen bonds and van der Waals interactions necessary for cells?

My answer:H+ bonds & Van Der Waals interactions are necessary for cells b/c they provide the structure & shape needed for protein & DNA within cells meaning it allows them to function properly. Book: Hydrogen bonds and van der Waals interactions form weak associations between different molecules or within different regions of the same molecule. They provide the structure and shape necessary for proteins and DNA within cells so that they function properly.

Compare and contrast saturated and unsaturated triglycerides.

My answer:Saturated triglycerides has no double bonds b/w carbon atoms. They are also usually solid at room temp. Whereas unsaturated triglycerides has one double bond b/w carbon & are liquid at room temp. Book:Saturated triglycerides contain no double bonds between carbon atoms; they are usually solid at room temperature. Unsaturated triglycerides contain at least one double bond between carbon atoms and are usually liquid at room temperature.