AP Bio Unit 1 Essay Questions
Proteins-large complex molecules are major building blocks of all living organisms. Discuss the following in relation to proteins a. The chemical composition and levels of structure of proteins
A protein is a string of amino acids held together by peptide bonds. Every protein has free amino and a free carboxyl end. proteins have a primary, secondary, tertiary, and sometimes quaternary structure. The primary structure is the order of the amino acids in the protein. The secondary structure has the long string of amino acids bent into the shape of either alpha helices, beta coiled sheets, or both. the tertiary structure bends the polypeptide chain using bonds or interactions such as disulfide bridges, hydrophobic interactions, ionic bonds, and hydrogen bonds. The protein molecule will bend and twist in such a way as to achieve maximum stability or lowest energy state. the quaternary structure is the final level of a protein where polypeptides interact with one another using disulfide bridges, hydrophobic interactions, ionic bonds, and hydrogen bonds to hold them in place and become a functional protein.
Water has some really cool chemical properties that are important for life. Choose three of these properties. a. For each of the three properties you have chosen, define it and explain it in terms of the physical/chemical nature of water
Adhesion- hydrogen bonding between water and other substances. Cohesion- hydrogen bonding between water molecules. High specific heat- water resists changes in temperature because of its high specific heat. It takes a lot of energy to heat it up or cool it down. Water moderates the temperature of the earth.
The following data were collected by observing subcellular structures of three different types of eukaryotic cells. (Look at paper for data table). Based on the analysis on the data, IDENTIFY a likely primary function of each cell type and EXPLAIN how the data support the identification
Cell X likely functions in locomotion because it has a large number of mitochondria, which perform cellular respiration and synthesize ATP, which provides the energy needed for movement. Cell X also has cilia, which are used for movement. Cell Y likely functions to synthesize and excrete proteins and compounds needed elsewhere in the organism, because it has a large amount of smooth and rough ER, which function in protein synthesis and processing (and rough ER has ribosomes, which actually perform protein synthesis), and a large number of Golgi bodies, which package and ship out proteins. Cell Z may be a surface or epithelial cell that serves no function except for protection or insulation, since it lacks many organelles use for other functions.
Water has some really cool chemical properties that are important for life. Choose three of these properties. b. For each of the three properties you have chosen, describe one example of how it affects the functioning of living organisms
Cohesion: Surface Tension - Water sticks to itself to form a weak layer on top of the liquid Adhesion: When you put a straw in water, the water is at a higher level in the straw than in the rest of the liquid - The water molecules bond to the molecules that make up the straw and slightly climb their way up the straw High Specific Heat: In large bodies of water, the temperature stays fairly constant because there needs to be a lot of heat/cold to change the temperature significantly
Proteins-large complex molecules are major building blocks of all living organisms. Discuss the following in relation to proteins b. The roles of DNA and RNA in protein synthesis
DNA provide the "coding" of each protein and allows for the production of mRNA in the nucleus. The mRNA is then "read" by ribosomal subunits to produce proteins
A scientist created solution of 0.9 M, 0.7 M, 0.5 M, and 0.3 M glucose, but didn't label them. After realizing this oversight, the scientist randomly labeled the containers as A, B, C, and D. Design an experiment (involving the principles of diffusion and osmosis) that could be used to determine which container has each of the four unknown solutions. b. The results you would expect from your experiment
Depending on which solution is the highest on the left side amongst the four U-tubes determines the respective molarity of each molarity. The U-tube with the highest volume of water on the left side is the 0.9M solution. The second highest volume of water on the left side is the 0.7M solution. The highest volume of water on the left side is the 0.5M solution. And the lowest volume of water on the left side is the 0.3M solution. By the end of the experiment, the left side of the U-tube will be isotonic. Therefore, if a U-tube has a higher concentration of water on the left side compared to the other three U-tubes, then it will also have a higher concentration of solute.
A scientist created solution of 0.9 M, 0.7 M, 0.5 M, and 0.3 M glucose, but didn't label them. After realizing this oversight, the scientist randomly labeled the containers as A, B, C, and D. Design an experiment (involving the principles of diffusion and osmosis) that could be used to determine which container has each of the four unknown solutions. c. An explanation of those results based on the principles involved
Each solution is hypertonic compared to the pure water. Therefore, osmosis will occur as the water moves across the permeable membrane to make the left side an isotonic solution. An isotonic solution contains equal parts solute and water. Therefore if the left side has a larger volume of water, then there is a higher concentration of the solute.
Eukaryotes have membrane-bound organelles while prokaryotes do not. a. Describe the structure of two eukaryotic membrane bound organelles other than the nucleus
Mitochondria structure= two membranes -Smooth outer membrane -Highly golder inner membrane ->Critae -The space between the membranes is filled with fluid called mitochondrial matrix and has DNA, ribosomes, and enzymes in it. Chloroplasts structure= two membranes -The space between the membranes is filled with fluid called stroma and has DNA, ribosomes, and enzymes in it -The inner membrane surrounds the stroma and the grana (stacks of thylakoids).
During an investigation of freshwater lake, an AP Biology student discovers a previously unknown microscopic organism. Further study shows that the unicellular organism is eukaryotic a. Identify FOUR organelles that should be present in the eukaryotic organism and describe the function of each organelle
Nucleus- Contains hereditary information/DNA/chromosomes or is the site of RNA synthesis. Ribosomes- Site of protein synthesis. Mitochondria- ATP synthesis or aerobic/cellular respiration. Chloroplasts- Light absorption/photosynthesis/carbohydrate synthesis.
During an investigation of freshwater lake, an AP Biology student discovers a previously unknown microscopic organism. Further study shows that the unicellular organism is eukaryotic b. Prokaryotic cells lack membrane-bound organelles found in eukaryotes. However, prokaryotes must perform many of the same functions as eukaryotes. For THREE of the organelles identified in part (a), explain how prokaryotic cells carry out the associated functions
Nucleus- Hereditary information/DNA/chromosomes or RNA synthesis in cytosol. Ribosomes- Site of protein synthesis. Mitochondria- Other membranes or cytosolic molecules function in ATP synthesis. Chloroplasts- Other membranes or cytosolic molecules function in light absorption/photosynthesis/carbohydrate synthesis.
Describe the structure of a plant cell. Indicate the ways in which a non-photosynthetic prokaryotic cell would differ structurally from a plant cell
Plant Cell: - Rigid cell wall and plasma membrane - Large vacuole containing water - Nucleus with DNA - Chloroplasts: Turns light into glucose - Mitochondria: Turns glucose into ATP - Many other organelles Prokaryotic Cell: - No nucleus - Has DNA but not in nucleus - No organelles except for ribosomes - Plasma membrane A nonphotosynthetic prokaryotic cell would differ structurally from a plant cell because it does not include a chloroplast which performs photosynthesis and makes ATP in thylakoids
Estrogens are small hydrophobic lipid hormones that promote cell division and the development of reproductive structures in mammals. Estrogens passively diffuse across the plasma membrane and bind to their receptor proteins in the cytoplasm of target cells. Describe one characteristic of the plasma membrane that allows estrogen to passively cross the membrane.
Plasma membranes are formed of phospholipid bilayers with a middle region made of hydrophobic fatty acid tails. Because these are hydrophobic, the estrogens can diffuse between the tails and into the cell. This allows small and uncharged (hydrophobic) molecules to diffuse into the cell passively.
Proteins-large complex molecules are major building blocks of all living organisms. Discuss the following in relation to proteins c. The roles of proteins in membrane structure and transport of molecules across the membrane
Proteins in the membranes can either be integral proteins, or antigen proteins. Integral proteins allow for the transportation of molecules through the membrane, antigen proteins are used to identify external molecules. Antigen proteins can also be attached to the cytoskeleton.
An experiment was conducted to measure the reaction rate of the human salivary enzyme alpha-amylase. Ten mL of a concentrated starch solution and 1.0 mL of alpha-amylase solution were placed in a test tube. The test tube was inverted several times to mix the solution and then incubated at 25 oC. The amount of product (maltose) present was measured every 10 minutes for an hour. The results are given in the table below. (Look at paper for table) d. Identify TWO environmental factors that can change the rate of an enzyme-mediated reaction. Discuss how each of those two factors would affect the reaction rate of an enzyme
Temperature factor — temperature ↑, rate ↑; temperature ↓, rate ↓; high temperature causes denaturation. If the temperature is above the optimal temperature of an enzyme, then the increased energy level of molecules disrupts bonds in enzyme and between enzyme and substrate. This causes denaturation within the enzyme, causing it to lose tertiary structure. If the temperature is below the optimal temperature of an enzyme, then molecules move slower and there are less collisions between enzymes and substrates. pH: Changes in pH disrupt the hydrogen bonds in the secondary and tertiary structure because it adds or removes H+ ions and denatures enzyme proteins. (active site charge changes).
Eukaryotes have membrane-bound organelles while prokaryotes do not. c. Explain the endosymbiotic theory of the origin of eukaryotic cells and discuss an example supporting this theory
The endosymbiotic theory states that prokaryotic cells were engulfed by host cells to form symbiotic relationships. It is the idea that prokaryotic cells are living within ancestral eukaryotic cells. Supported by: the fact that mitochondria and chloroplasts both contain their own DNA, ribosomes, a double membrane, and have a similar size to prokaryotic cells
The effects of pH and temperature were studied for an enzyme-catalyzed reaction. The following results were obtained (look at paper) a. How do (1) temperature and (2) pH affect this enzyme? Discuss the relationship between the structure and function, and also how structure and function are affected by temperature and pH generally
The enzyme will work best if it is in the range of temperature and pH shown in the graph. If it in warmer conditions or more acidic/basic the enzyme can denature and lose its shape and function.
Eukaryotes have membrane-bound organelles while prokaryotes do not. b. Prokaryotic and eukaryotic cells have some non-membrane bound components in common. Describe the function of two and discuss how each differs in prokaryotes and eukaryotes
The function of DNA is gene expression, encoding information, and replication. In eukaryotes, DNA exists in the nucleus, chloroplasts, and mitochondria. The shape of eukaryotic DNA is a lot longer than the shape of prokaryotic DNA because it is more complex. Prokaryotic DNA exists within the cytoplasm and has a circular shape. It is less complex also.
A scientist created solution of 0.9 M, 0.7 M, 0.5 M, and 0.3 M glucose, but didn't label them. After realizing this oversight, the scientist randomly labeled the containers as A, B, C, and D. Design an experiment (involving the principles of diffusion and osmosis) that could be used to determine which container has each of the four unknown solutions. a. A description of how you would set up and perform the experiment
Using four U-tubes with a selectively permeable membrane that only allows the diffusion of water. Pour 20 mL of pure water into the right side of the U-tube and 20 mL of each solution container into the left side of the U-tube. Allow the fluids in the U-tubes to reach equilibrium and observe the water levels on the left side of the U-tube. After they reach equilibrium, measure how much water diffused to the other side to check with tube has which solution of glucose.
The effects of pH and temperature were studied for an enzyme-catalyzed reaction. The following results were obtained (look at paper) b. Describe a controlled experiment that could have produced the data shown for either temperature or pH. State the hypothesis tested in your experiment
We are given an enzyme normally found in the human body at pH 7. Starting at zero degrees celsius increase temperature by increments of 5 degrees celsius and see how long it takes for the reaction to ensue. Then we continue and collect data and graph the results. Hopefully, we will see in the results that the optimum conditions for the reactions are 35-40 degrees celsius. This would be the fastest time. Our graph would be temperature vs. time To higher the temperature, use hot plate. To lower the temperature, put in fridge. To higher pH, add an acid. To lower pH, use a base, like bleach.
An experiment was conducted to measure the reaction rate of the human salivary enzyme alpha-amylase. Ten mL of a concentrated starch solution and 1.0 mL of alpha-amylase solution were placed in a test tube. The test tube was inverted several times to mix the solution and then incubated at 25 oC. The amount of product (maltose) present was measured every 10 minutes for an hour. The results are given in the table below. (Look at paper for table) b. Explain why a change in the reaction rate was observed after 30 minutes
the reaction rate levels off because the substrate concentration declines. The Enzyme is inactive by about 40 minutes — enzyme loses activity over time. As the reaction occurs, there are less enzymes available for the starch solution to react with.
During an investigation of freshwater lake, an AP Biology student discovers a previously unknown microscopic organism. Further study shows that the unicellular organism is eukaryotic c. According to the endosymbiotic theory, some organelles are believed to have evolved through a symbiotic relationship between eukaryotic and prokaryotic cells. Describe THREE observations that support the endosymbiotic theory.
• Mitochondria contain their own DNA. • Chloroplasts contain their own DNA. • Mitochondrial chromosomes are circular. • Chloroplast chromosomes are circular