Unit 2 Biology Test
Centrioles (Prokaryote)
Enzyme-mediated chromosome movement.
Predict what would happen to typical animal cells placed in 0.0 M and 1.0 M sucrose solutions, and explain your prediction.
0.0 M - Gain water/burst Water potential is greater in 0.0 M environment 1.0 M - Lose water Sucrose solution is hypertonic to cell
Researchers propose a model to explain variation in phytoplankton cell sizes in a marine environment. They base their model on the idea that smaller cells absorb nutrients more efficiently. The researchers predict that the mean diameter of phytoplankton cells will change by 50 micrometers for every 5-kilometer increase in distance from the shore because of a gradual decrease in nutrient availability. To test their model, the researchers determine that the phytoplankton cells found closest to shore have a mean diameter of 900 micrometers. Based on the model, what will be the mean diameter of the phytoplankton cells that are found 25 kilometers from shore? Responses
650 micrometers
membrane lipids
75% phospholipids 5% glycolipids 20% cholesterol
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.
A nucleus in a prokaryotic cell also contains the hereditary information, the vacuoles help maintain water balance and large molecules in cytosol, and the ribosomes also function as the site of protein synthesis
Exocytosis
A process by which the contents of a cell vacuole are released to the exterior through fusion of the vacuole membrane with the cell membrane.
Endocytosis
A process in which a cell engulfs extracellular material through an inward folding of its plasma membrane.
ATP (adenosine triphosphate)
A substance present in all living cells that provides energy for many metabolic processes and is involved in making RNA.
What needs ATP?
ATP is consumed for energy in processes including ion transport, muscle contraction, nerve impulse propagation, substrate phosphorylation, and chemical synthesis.
Which of the following statements best predicts the effect of increasing the permeability of the mitochondrial membranes to large molecules?
ATP production will decrease because of an increase in the occurrence of uncontrolled chemical reactions.
Mitochondria (Eukaryote)
ATP synthesis or aerobic/cellular respiration.
Figure 1 shows a model of how a channel protein influences the movement of a particle across a cell's plasma membrane. An investigator wants to understand whether a newly found membrane protein is involved in membrane transport of a certain particle. Which investigation will help determine whether the new membrane protein is a channel protein involved in membrane transport? Responses
Add more of the proteins to the plasma membrane and measure the rate of the particle movement.
Which of the following best describes the numbered areas?
Areas 1 and 3 are polar, since the membrane molecules are aligned with water molecules.
Centrioles (Eukaryote)
Assist chromosome movement in mitosis.
Two different models of a living cell are represented in the figure. Of the two cells represented in the figure, which would likely be more efficient at exchanging substances with the surrounding environment?
Cell A, because it has the larger surface-area-to-volume ratio.
Aquaporins are channel proteins that facilitate the transport of water across the cell membrane. One group of researchers hypothesizes that without functional aquaporins, no water will be able to enter the cell. A different group proposes an alternative hypothesis, stating that even with nonfunctional aquaporins, a small amount of water will still cross the cell membrane. An experiment is set up in which plant cells with mutated (nonfunctional) aquaporins and plant cells with normally functioning aquaporins are both placed in distilled water. Which of the following data would support the alternative hypothesis?
Cells with mutated aquaporins exhibit moderate turgor pressure and are hypertonic.
What are the components of water potential, and why is water potential important for the movement of water in plants?
Components: pressure and solute potential Importance:ensures water moves into plant root
Nucleus (Eukaryote and Prokaryote)
Contains hereditary information/DNA/chromosomes or is the site of RNA synthesis.
ER (Prokaryote)
Diffusion of molecules in cytosol.
All eukaryotic cells contain at least one Golgi complex, typically located in the cytoplasm and near the endoplasmic reticulum. Which of the following best describes a process that occurs within the Golgi complex?
Enzymatic modification of newly synthesized integral membrane proteins. The Golgi complex is a membrane-bound structure to which some proteins are moved from the rough endoplasmic reticulum, where they are enzymatically modified before being sent to a cellular membrane.
Lysosomes (Eukaryote and Prokaryote)
Enzymatic hydrolysis of wastes/metabolites/pathogens.
Which of the following claims is scientifically accurate and consistent with an observation that a decrease in lysosome production within a cell leads to a decline in mitochondrial activity?
Fewer lysosomes will be available to break down macromolecules to provide the necessary nutrients for cellular respiration. A function of the lysosomes is the breakdown and recycling of macronutrients, such as carbohydrates. Products of carbohydrate breakdown such as glucose are utilized by the mitochondria in the process of cell respiration.
The illustration shows the active transport of hydrogen ions through a membrane protein. Which of the following best predicts the effect of not having ATPATP available to supply energy to this process?
H+ ions will stop moving through the protein.
What can enter the cell membrane
Small Fat-soluble + Non-polar molecules Water, carbon dioxide, and oxygen are among the few simple molecules that can cross the cell membrane by diffusion
Plant cell walls are composed of cellulose, while fungal cell walls are composed of chitin. A group of scientists hypothesize that this difference means the cell wall has largely different functions in plant cells and fungal cells. Alternatively, another group of scientists hypothesize that despite their biochemical differences, plant and fungal cell walls serve similar functions. Which of the following observations would best support the alternative hypothesis described above?
In both plant cells and fungal cells, the cell wall surrounds the outside of the cell membrane.
Water is constantly diffusing into the cytosol of freshwater single-celled organisms. In order to maintain the proper solute concentrations in the cytosol, contractile vacuoles pump out the excess water. An experimenter placed single-celled organisms into various saline concentrations and recorded the ATPATP used by the contractile vacuole. The data are shown in the graph. Of the following, which additional investigation can be used to determine when the cells are in an isotonic solution?
Increasing the salinity of the environment a little at a time until the ATP usage reaches a minimum
The transport of a substance across a plasma membrane of a specific organelle requires energy. The rate at which the transport takes place also depends on temperature. A scientist isolated the specific organelle and then used the following treatments to determine the conditions that will result in the maximal transport. All treatments contained the extracted organelle and were maintained at 25°C25°C. The data from this experiment indicate that maximal rate of transport of protein X at 25°C occurs at an ATP concentration of 1.0μm/mL Which procedure should be done next to gather data needed to meet the scientist's objective?
Incubate samples containing 1.0μm/mL of ATP at four temperatures other than 25°C.
ER (Eukaryote)
Internal transport or compartmentalization.
What can't enter in a cell membrane
Larger uncharged polar molecules, such as glucose
Chloroplasts, plastids (Eukaryote)
Light absorption/photosynthesis/carbohydrate synthesis.Vacuole, vesicles-Storage or transport.
Smooth ER =
Lipid Synthesis
Smooth ER (Eukaryote and Prokaryote)
Lipid synthesis or detoxification or transport. (In cytosol for Prokaryotic)
The endosymbiont theory proposes a model for the evolution of mitochondria. According to the model, an ancestral eukaryote engulfed a small, free-living prokaryotic organism. The engulfed prokaryote then formed an endosymbiotic relationship with the eukaryotic host. Which of the following observations best supports the model? Responses
Mitochondria and some prokaryotes share similar metabolic reactions that produce ATP.
Changing the shape or morphology of the mitochondrial inner membrane can change the efficiency of mitochondrial function. Which of the following outcomes will most likely result from a change in the shape of the mitochondrial inner membrane from a highly folded surface to a smooth, flat surface? Responses
Mitochondria will become less efficient because the surface area of the inner mitochondrial membranes will decrease.
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/chloroplast contain their own DNA. Mitochondria/chloroplast can self-replicate. Chloroplast chromosomes lack histones.
Cilia/flagella (Eukaryote and Prokaryote)
Motility via bacterial flagella
Mitochondria (Prokaryote)
Other membranes or cytosolic molecules function in ATP synthesis.
Chloroplast (Prokaryote)
Other membranes or cytosolic molecules function in light absorption/photosynthesis/carbohydrate synthesis.
Which of the following statements best explains the processes of passive and active transport?
Passive transport is the net movement of substances down a concentration gradient that does not require metabolic energy.
Plastids (Prokaryote)
Pigments are distributed throughout cytosol or are associated with membranes.
Peroxisomes (Eukaryote and Prokaryote)
Production/secretion of catalase or detoxification.
Rough ER =
Protein Synthesis
Golgi bodies (Eukaryote and Prokaryote)
Protein modification/packaging/transport. (In cytosol for Prokaryotic)
Rough ER (Eukaryote)
Protein synthesis/packaging/transport (Prokaryote - In cytosol; may be linked to transcription)
Cells contain smaller components called organelles that are necessary for a cell's survival. Organelle functions have often been compared to components of larger systems. Which of the following functional differences between the rough and smooth endoplasmic reticulum (ER) is explained by the structural differences between them?
Rough ER can synthesize and package proteins for export, and smooth ER cannot. The ribosomes associated with rough ER synthesize proteins that are then exported from the cell.
Ribosomes (Eukaryote and Prokaryote)
Site of protein synthesis (makes proteins)
Which of the following statements best supports the claim that certain organelles within eukaryotic cells evolved from free-living prokaryotic cells?
Some organelles contain their own DNA that is more similar to prokaryotic DNA in structure and function than to the eukaryotic DNA found in the cell's nucleus.
Basal bodies (Eukaryote and Prokaryote)
Support cilia/flagella.
Researchers have proposed a model of the process by which a newly synthesized protein is transported to the plasma membrane and secreted into the extracellular space. The model is represented in Figure 1
The Golgi complex
Identify FOUR organelles that should be present in the eukaryotic organism and describe the function of each organelle.
The Nucleus which contain hereditary information, the ribosome which is the site of protein synthesis, the vacuoles that offer storage, and Basal bodies that support flagella
Cholesterol is an important component of animal cell membranes. Cholesterol molecules are often delivered to body cells by the blood, which transports the molecules in the form of cholesterol-protein complexes. The complexes must be moved into the body cells before the cholesterol molecules can be incorporated into the phospholipid bilayers of cell membranes. Based on the information presented, which of the following is the most likely explanation for a buildup of cholesterol molecules in the blood of an animal?
The animal's body cells are defective in endocytosis.
In a laboratory experiment, a researcher generates antibodies that bind to purified estrogen receptors extracted from cells. The researcher uses the antibodies in an attempt to treat estrogen-dependent cancers but finds that the treatment is ineffective. Explain the ineffectiveness of the antibodies for treating estrogen-dependent cancers.
The anti bodies are ineffective because extracellular antibodies are not going to attach with intracellular estrogen receptors
A team of biologists develop a new drug, and one team member hypothesizes that the drug is incapable of freely passing across the plasma membrane and requires the help of membrane proteins to enter cells. Alternatively, another biologist on the team hypothesizes that the drug can diffuse passively across the plasma membrane like O2O2 and CO2CO2 can. Which of the following, if true about the drug, best supports the alternative hypothesis that the new drug will exhibit simple diffusion across plasma membranes?
The drug is a small nonpolar molecule.
A spherical bacterial cell has a radius of 3μm. The human egg cell has a radius of 100μm. Which statement correctly indicates the cell that is able to more efficiently exchange materials with the external environment and provides a correct explanation?
The egg cell, because it has the smallest surface-to-volume ratio.
Muscle cells have high ATPATP demands. Which of the following is a scientific claim about how the structure of the mitochondria in muscle cells should be different than it is in other cells because of the high energy demands of mitochondria?
The inner membrane of the mitochondria in muscle cells should have more folds to increase the surface area, allowing more ATPATP to be synthesized.
The figure shows a process by which a cell might absorb food from its surrounding environment and break it down for use as a source of energy and matter. The process involves lysosomes, which are membrane-bound organelles that contain hydrolytic enzymes. Activation of the hydrolytic enzymes requires an acidic pHpH, and lysosomes maintain an internal acidic pHpH by using ion pumps. Which of the following outcomes will most likely result from a loss of ion pump function in the cell's lysosomes?
The internal pH of the lysosomes will increase, which will prevent the activation of hydrolytic enzymes and interfere with the intracellular digestion of food.
Endosymbiotic Theory
Theory that eukaryotic cells formed from a symbiosis among several different prokaryotic organisms Prokaryotic cells have been engulfed by and are living within ancestral/precursor eukaryotes.
A cell's membrane potential is maintained by the movement of ions into and out of the cell. A model showing the influence of membrane proteins on the movement of sodium (Na+Na+) and potassium (K+K+) ions across the plasma membrane is presented in Figure 1. Based on the model presented in Figure 1, which of the following outcomes will most likely result from a loss of protein X function?
The membrane potential will be disrupted by an increase in K+ concentration inside the cell.
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.
The mitochondria and chloroplasts contain their own DNA, they are both circular, and they can self-replicate
Researchers claimed that a particular organelle originated from a free-living prokaryotic cell that was engulfed by a larger cell, as shown in Figure 1. Figure 1. A model showing a cell engulfing a smaller cell Which of the following provides evidence to best support the researchers' claim?
The organelle has a double membrane.
Describe ONE characteristic of the plasma membrane that allows estrogens to passively cross the membrane.
The plasma membrane being hydrophobic allows estrogen to pass easily
Hydrophobic
Water fearing
In an experiment, cells were isolated from an aquatic plant and suspended in pond water, a sucrose sugar solution, or distilled water. All of the cells were then viewed under a microscope. Compared with the cell in the pond water, the cell in the sugar solution appeared shriveled, and the cell in the distilled water appeared inflated. The results of the experiment are represented in Figure 1. Figure 1. The results of an experiment using aquatic plant cells Which of the following statements best explains the observations represented in Figure 1 ?
There was a net movement of water out of the cell suspended in the sugar solution and a net movement of water into the cell suspended in the distilled water.
Organelles such as mitochondria and the endoplasmic reticulum have membranes that compartmentalize reactions and other metabolic processes. To function properly, the organelles must move substances across their membranes. Which of the following statements describes a feature shared by mitochondria and the endoplasmic reticulum that increases the efficiency of their basic functions?
They have highly folded membranes
Vacuole (Prokaryote)
Vesicles-Inclusion bodies/granules/large molecules in cytosol.
Hydrophilic
Water loving
Which statement best describes the effect on water transport across the cell membrane if the aquaporin in the figure ceases to function?
Water molecules will still be able to move across the cell membrane but at a slower rate.