AP BIO U2

Multiple Choice Questions (MCQS)

Question 1:

  • Which statement best describes why water is a polar molecule?

    • A. Oxygen and hydrogen share electrons equally, creating partial positive and negative charges.

    • B. Oxygen and hydrogen form hydrogen bonds with each other and covalent bonds with other atoms.

    • C. Oxygen and hydrogen unequally share electrons which creates partial charges on oxygen and hydrogen.

    • D. The ionic bond between oxygen and hydrogen create partial charges on the molecule.

Question 2:

  • Water molecules interact with one another through:

    • A. Covalent bonds

    • B. Hydrogen bonds

    • C. Ionic bonds

    • D. Intramolecular forces

Question 3:

  • Which element symbols best summarize the elements commonly found in living things?

    • A. CHO

    • B. NPS

    • C. CON

    • D. CHNOPS

Question 4:

  • Finish the analogy: Carbon: 4 bonds :: Hydrogen:

    • A. 1 bonds

    • B. 2 bonds

    • C. 3 bonds

    • D. 4 bonds

Question 5:

  • A macromolecule has several chains containing carbon rings with one oxygen per ring. Which macromolecule must it be?

    • A. Lipid

    • B. Nucleic Acid

    • C. Carbohydrate

    • D. Protein

Question 6:

  • Which statement best explains why water molecules adhere to other surfaces?

    • A. Water can make hydrogen bonds with other water molecules.

    • B. The polarity of water allows it to bind covalently to other surfaces.

    • C. Water can only bind to surfaces that are nonpolar.

    • D. As a polar molecule, water is attracted to other polar substances.

Question 7:

  • If 10 monomers join to form a polymer through the process of dehydration synthesis, how many water molecules form?

    • A. 9

    • B. 10

    • C. 11

    • D. Not enough information to answer

Question 8:

  • Which pair of monomer: macromolecule is incorrect?

    • A. monosaccharide: carbohydrate

    • B. amino acid: nucleic acid

    • C. glycerol/fatty acid: lipid

    • D. nucleotide: nucleic acid

Question 9:

  • What gives DNA its negative charge?

    • A. The nitrogenous base

    • B. The pentose sugar

    • C. The nucleotide

    • D. The phosphate group

Question 10:

  • Protein folding is essential to proper protein function. Which level of folding is incorrectly paired with its description?

    • A. primary: string of amino acids connected by peptide bonds

    • B. secondary: hydrogen and covalent bonds between R groups.

    • C. tertiary: interactions between R groups

    • D. quaternary: interaction with more than 1 polypeptide

Question 11:

  • Every amino acid consists of:

    • A. an amine group, R-group, and a central carbon

    • B. a hydroxyl side chain, a central carbon with R-group, carboxyl group

    • C. an amine group, a central carbon with a variable R group, and carboxyl group

    • D. a phosphate, pentose sugar, and nitrogenous base

Question 12:

  • Students running a food analysis lab find that a food particle contains carbon, hydrogen and nitrogen. To which macromolecule group does it belong?

    • A. Carbohydrate

    • B. Protein

    • C. Lipid

    • D. Nucleic Acid

Question 13:

  • The structure of biological molecules determines how they behave. In a cell's plasma membrane the saturation of carbon found in the fatty acid tails can change membrane flexibility. Which statement best explains this?

    • A. Unsaturated fatty acids have C-C double bonds creating bends in the fatty acid tails.

    • B. Saturated fatty acids have C-C double bonds creating bends in the fatty acid tails.

    • C. The presence of cholesterol increases the space between phospholipids, creating a more flexible membrane.

    • D. When carbon's fully saturated the carbon chain does not have double bonds, creating a more flexible membrane.

Question 14:

  • As a double stranded helix, each nucleotide within a DNA molecule displays base pairing between nitrogenous bases. Which statement best describes the correct base pair and number of hydrogen bonds between them?

    • A. Adenine and thymine pair with two hydrogen bonds

    • B. Adenine and thymine pair with three bonds

    • C. Cytosine and Guanine pair with two bonds

    • D. All four bases can pair and make two bonds

Question 15:

  • Two of the four biological macromolecules display directionality and functions that rely on specific sequences of monomers. Identify the correct pair:

    • A. Proteins and Carbohydrates

    • B. Proteins and Nucleic Acids

    • C. Nucleic Acids and Lipids

    • D. Carbohydrates and Lipids

Free Response Questions (FRQs)

Setup

  • Quality proteins are required for optimal health.

  • In the healthcare and fitness industries, different protein powders are often used to meet nutritional standards or to maximize muscle growth and development.

  • Protein powders may be manufactured from dairy or vegetable sources, including whey, casein, soy, and peas.

Table 1: Amino Acid Availability 240 min. Post Consumption

Amino Acid

Protein Blend

Casein

Whey

Soy

Pea

Leucine (μmol/L)

140.13

135.12

135.76

138.83

133.92

Methionine (μmol/L)

30.7

27.59

28.98

27.61

27.74

Arginine (μmol/L)

117.11

116.54

115.30

115.13

112.09

Glycine (μmol/L)

360.25

390.62

360.54

370.37

360.24

Questions

Part (a)

  • A nutritionist is working with a patient who is trying to run a marathon. In addition to protein, identify which macromolecule will be most essential to their training and explain why.

Part (b)

  • Describe how the structure of the amino acids relates to the function of the protein as a whole.

Part (c)

  • Using the template provided, construct a graph of the availability of methionine across all five protein options.

Part (d)

  • Collagen peptides are a popular powder to mix into foods and drinks. These peptides contain collagen proteins, which support hair, skin, and nail health. However, nutritionists advise against relying on collagen as a source of protein because it does not contain the amino acid tryptophan, and therefore it is not a complete protein. Explain why the absence of tryptophan makes collagen peptides incomplete and inadequate as a primary source of protein.

Key Points on Cell Structure and Transport

Types of Cells

  • Prokaryote:

    • Bacteria cells

  • Eukaryote:

    • Animal cells

    • Plant cells

Prokaryotic Cells

  • Characteristics:

    • Simple cells

    • No membrane-bound nucleus or organelles

    • Genetic material is circular DNA in a region known as the nucleoid

    • Reproduce by binary fission to produce identical daughter cells

    • Classified in the kingdom Monera (bacteria group)

  • Structures:

    • Plasma Membrane:

      • Selective barrier composed of phospholipid bilayer (lipids, proteins, carbohydrates)

    • Cell Wall:

      • Shapes and protects cells, present in ALL prokaryotes

    • Ribosomes:

      • Build enzyme parts (proteins); smaller (70S vs. 80S in eukaryotes)

    • Flagella:

      • Deliver motion by twisting like a screw

Eukaryotic Cells

  • Characteristics:

    • More complex than prokaryotes

    • Membrane-bound nucleus

    • Can be unicellular or multicellular

    • Contain membrane-bound organelles

The Nucleus

  • Structure:

    • Two phospholipid bilayers resembling plasma membrane

    • Contains DNA, hereditary information of the cell

    • DNA is normally spread out as chromatin

    • Nuclear envelope has pores for protein and RNA passage

Why Organelles?

  • Specialized structures for specific functions:

    • Cilia/flagella for locomotion

    • Containers that create compartments to contain distinct environments

    • Membranes as sites for chemical reactions with unique combinations of lipids & proteins (e.g. chloroplasts, mitochondria)

Jobs of Cells

  • Building Proteins:

    • Control every cell function

  • Make Energy:

    • For daily activities and growth

  • Build More Cells:

    • For growth, reproduction, and repair

DNA

  • Important because:

    • DNA provides the instruction to make proteins, which perform cellular functions.

    • "DNA gets the glory, but proteins do all the work!"

Building Proteins

  • Organelles involved:

    • Nucleus, ribosomes, ER, Golgi apparatus

Endoplasmic Reticulum (ER)

  • Smooth ER:

    • Membrane production, lipid synthesis, detoxification

  • Rough ER:

    • Processes proteins and manufactures membranes

Golgi Apparatus

  • Function: Finish, sort, tag & ship cell products (like a shipping department)

Lysosomes

  • Function: Digest macromolecules, clean up broken organelles

  • Structure: Vesicles with digestive enzymes (only in animal cells)

Mitochondria & Chloroplasts

  • Generate ATP, have double membranes, semi-autonomous organelles

  • Structure:

    • Mitochondria with internal compartments and folds (cristae)

    • Chloroplasts for photosynthesis with thylakoids for ATP synthesis

Endosymbiosis Theory

  • Explains the origin of mitochondria and chloroplasts as former prokaryotes engulfed by ancestral eukaryotes.

Limitations to Cell Size

  • Smaller cells have greater surface area to volume ratios which enhance cellular metabolism

  • The solution for larger organisms is to become multicellular.

Cell Membrane and Transport

  • Composed of phospholipid bilayer

  • Functions as a selective barrier controlling passage of substances

Passive vs Active Transport

  • Passive Transport:

    • Movement of substances down a concentration gradient without energy

  • Active Transport:

    • Movement against a concentration gradient requiring energy (ATP)

Osmosis

  • Diffusion of water from high concentration of water to low across a semipermeable membrane

  • Direction determined by solute concentrations: hypertonic, hypotonic, isotonic.

Aquaporins

  • Special water channel proteins that facilitate rapid water movement across plasma membranes

Membrane Proteins

  • Integral proteins span the membrane; peripheral proteins are loosely bound to the membrane surface.

Cell Cell Recognition

  • Membrane carbohydrates help in cell recognition, important in immunology and tissue development

MCQs & Further Questions

  • Additional questions focusing on cell functions, implications of cell structures, and transport mechanisms.