AP Biology Test #2 Molecules And Cells

Endocytosis is the process by which cells take in materials from the external environment by engulfing them with their cell membrane. This process involves the formation of a vesicle around the material and then the vesicle is brought into the cell. This is different from exocytosis, which is the process of releasing materials from the cell. Active transport and facilitated diffusion are also different processes that involve the movement of materials across the cell membrane, but they do not involve the engulfment of materials like endocytosis does. Passive transport, on the other hand, refers to the movement of materials across the cell membrane without the need for energy, which is not the case in endocytosis.

The process taking place in the diagram is facilitated diffusion. Facilitated diffusion is the passive movement of molecules across a cell membrane with the help of transport proteins. In this process, molecules move from an area of higher concentration to an area of lower concentration, without the need for energy input. The diagram likely shows the transport proteins embedded in the cell membrane, allowing the molecules to pass through.

The organelle labelled 6 is responsible for the production of ATP. ATP (adenosine triphosphate) is the main energy currency of the cell, and it is produced through cellular respiration in the mitochondria. The mitochondria have an inner membrane that contains enzymes and proteins involved in the production of ATP through oxidative phosphorylation. Therefore, organelle 6 in the cell diagram is most likely the mitochondria.

The researcher determines that the cell is a plant cell because she observes a central vacuole. Central vacuoles are large, membrane-bound organelles that are found in plant cells, but are not typically present in animal cells. The central vacuole plays a crucial role in maintaining the cell's turgor pressure, storing water, nutrients, and waste products, and regulating cell growth and development. Therefore, the presence of a central vacuole indicates that the cell is a plant cell.

The correct answer is that the cell lacks a nucleus and other membrane-bound organelles. This can be determined by observing the diagram, which does not show any distinct structures such as a nucleus or organelles enclosed by membranes. Prokaryotic cells are known to lack these features, unlike eukaryotic cells. The absence of a nucleus and membrane-bound organelles is a characteristic feature of prokaryotic cells.

When red blood cells are placed in a solution that is isotonic to them, it means that the concentration of solutes in the solution is the same as the concentration inside the cells. This creates an equilibrium, where there is no net movement of water into or out of the cells. As a result, the cells do not gain or lose water, and their volume remains the same. Therefore, the correct answer is that the cells remained unchanged.

Phospholipids are the major component of the fluid bilayer of a plasma membrane. They have a hydrophilic (water-loving) head and hydrophobic (water-fearing) tails, which allow them to form a double layer in the membrane. This arrangement provides a barrier that separates the inside and outside of the cell, while still allowing for the passage of certain molecules. Phospholipids play a crucial role in maintaining the integrity and fluidity of the cell membrane.

The graph clearly shows that the catalyzed reaction has a lower activation energy compared to the uncatalyzed reaction. This indicates that the catalyst effectively lowers the energy barrier for the reaction to occur, allowing it to proceed more easily. Therefore, the statement "The Catalyst lowers the energy needed for the reaction to proceed" is true based on the information provided by the graph.

Plasmolysis occurs when the cell membrane separates from the cell wall due to the loss of fluid. This process typically happens in plant cells when they are placed in a hypertonic solution, causing water to leave the cell. The loss of water causes the cell membrane to shrink away from the cell wall, resulting in plasmolysis. This can have detrimental effects on the cell's structure and function.

ATP (adenosine triphosphate) is the main source of energy for cellular activities. It is produced through the process of cellular respiration, which takes place in the mitochondria. Therefore, the presence of ATP in mitochondria supports the statement that mitochondria are the "power-houses" of the cell.

Diffusion is the correct answer because it refers to the movement of particles from an area of higher concentration to an area of lower concentration. In this case, the movement of sodium ions follows the principle of diffusion as they move down their concentration gradient. Active transport refers to the movement of particles against their concentration gradient, osmosis specifically refers to the movement of water molecules across a selectively permeable membrane, and phagocytosis refers to the process of engulfing and digesting solid particles by cells.

Chitin is a complex polysaccharide that forms the exoskeleton of insects, crustaceans, and other invertebrates. It is a structural component that provides strength and protection to their bodies. Chitin is a tough and flexible material that is resistant to degradation, making it ideal for forming the exoskeleton. Cellulose is another polysaccharide, but it is found in the cell walls of plants, not in the exoskeleton of invertebrates. Glycogen is a storage form of glucose in animals, bone is a mineralized connective tissue found in vertebrates, and pectin is a structural polysaccharide found in plant cell walls.

Buffers are important in living systems because they tend to prevent drastic changes in pH. Buffers are substances that can resist changes in pH by accepting or donating protons (H+ ions) when necessary. They help to maintain the pH within a narrow range, which is crucial for the proper functioning of biological processes. Without buffers, even slight changes in pH could have harmful effects on enzymes, proteins, and other biomolecules, disrupting their structure and function. Therefore, buffers play a vital role in maintaining the stability and homeostasis of living systems.

If the number of electrons of an atom were changed, it would result in a change in the ionic charge. The number of electrons determines the overall charge of an atom, and if this number is altered, the atom will either gain or lose electrons, leading to a change in its ionic charge.

Exocytosis is the process where cells release substances from their cytoplasm to the external environment. This process involves the fusion of vesicles containing the substances with the cell membrane, resulting in the release of the contents outside the cell. This is the opposite of endocytosis, where substances are taken into the cell. Neither pinocytosis nor phagocytosis involve the release of substances from the cell. Cyclosis refers to the movement of cytoplasm within a cell, which is not the process described here. Therefore, the correct answer is exocytosis.

Phospholipids form a selectively permeable structure because of their unique composition. They have a hydrophilic (water-loving) head and hydrophobic (water-repelling) tails. When phospholipids arrange themselves in a bilayer, the hydrophilic heads face outward towards the watery environment while the hydrophobic tails face inward, creating a barrier that only allows certain molecules to pass through. This selective permeability allows the plasma membrane to control the movement of substances in and out of the cell, maintaining homeostasis and allowing for essential cellular processes to occur.

Cholesterol is a steroid that is present in the plasma membrane. It plays a crucial role in regulating the fluidity of the membrane. Cholesterol molecules are interspersed between the phospholipids in the membrane, reducing their mobility and preventing the membrane from becoming too fluid or too rigid. This helps maintain the integrity and stability of the plasma membrane. Therefore, cholesterol affects the fluidity of the plasma membrane.

The given molecule is a sterol found in cell membranes and is associated with atherosclerosis. Sterols are a type of lipid and are important components of cell membranes. Atherosclerosis is a condition characterized by the buildup of plaque in the arteries, and sterols, such as cholesterol, play a role in this process. Therefore, the given molecule fits the description of a sterol found in cell membranes and associated with atherosclerosis.

Proteins are the carrier molecules in the plasma membrane. They play a crucial role in transporting various substances across the membrane, including ions, nutrients, and waste products. Proteins also help in cell signaling and communication by acting as receptors or channels. Additionally, proteins provide structural support and help maintain the integrity of the plasma membrane. Therefore, proteins are essential components of the plasma membrane and function as carrier molecules.

Prokaryotic cells are characterized by the absence of a nucleus, which means they lack a nuclear envelope. Instead, their genetic material is present in the form of circular DNA. Prokaryotic cells do have a plasma membrane, ribosomes, and may also contain plasmids, which are small, circular DNA molecules separate from the main chromosome.

Starch is a polymer of glucose. Glucose is a simple sugar molecule that is used by cells as a source of energy. Starch is a polysaccharide, which means it is made up of many glucose molecules bonded together. It is commonly found in plants and serves as a storage form of energy. When consumed, starch is broken down into glucose molecules by enzymes in the body, which can then be used for energy production.

The plasma membrane is composed of two layers of phospholipids, with proteins embedded within these layers. This arrangement is known as the fluid mosaic model, where the phospholipids form a fluid bilayer and the proteins are dispersed throughout, either partially or fully spanning the membrane. The proteins play crucial roles in various cellular functions, such as transport of molecules across the membrane, cell signaling, and structural support.

Receptor-mediated endocytosis is the process that requires membrane proteins. This process involves the binding of specific ligands to receptors on the cell membrane, which then triggers the formation of vesicles that transport the ligands into the cell. These receptors are integral membrane proteins that are responsible for recognizing and binding to the specific ligands. Without these membrane proteins, receptor-mediated endocytosis would not be possible. Exocytosis, phagocytosis, and pinocytosis do not necessarily require membrane proteins for their execution.

If the number of neutrons of an atom were changed, an isotope of the atom would be created. Isotopes are atoms of the same element that have different numbers of neutrons. Changing the number of neutrons would result in a different isotope of the same element, which may have different physical and chemical properties. This change in the number of neutrons does not affect the ionic charge, pH, or the element itself.

Cellulose is the correct answer because humans lack the enzyme called cellulase, which is required to break down cellulose into its constituent glucose molecules. While humans can digest other carbohydrates such as amylose, sucrose, lactose, and maltose with the help of specific enzymes, cellulose cannot be broken down and remains undigested in the human digestive system.

Calcium is required in ionic form for the activity of many enzymes, the maintenance of bone, and the contraction of muscle fibers. Calcium ions play a crucial role in various enzymatic reactions, including those involved in muscle contraction and bone formation. They also help in the transmission of nerve impulses and the release of neurotransmitters. Additionally, calcium is necessary for the proper functioning of muscles, as it is involved in the interaction between actin and myosin, which allows muscle fibers to contract.

The correct power of magnification is calculated by multiplying the power of the eyepiece with the power of the objective. This is because the eyepiece magnifies the image produced by the objective lens, resulting in a higher overall magnification. Adding the powers of the eyepiece and objective would not accurately calculate the magnification. Similarly, the power of the iris and condenser are not relevant to calculating magnification.

Lipid molecules are known as triglycerides because they consist of three fatty acid molecules. Fatty acids are organic molecules that have a long hydrocarbon chain with a carboxyl group at one end. They are the building blocks of lipids and play a crucial role in energy storage and insulation in the body. Therefore, the correct answer is fatty acids.

Proteins in the plasma membrane are responsible for various functions, including transport of substances across the membrane, catalysis of substances inside the cell, transmission of signals from outside the cell, and formation of junctions between adjacent cells. However, replication of DNA is not a function of proteins in the plasma membrane. DNA replication occurs in the nucleus of the cell and is carried out by enzymes specifically involved in DNA replication, not proteins in the plasma membrane.

An organism could be classified as a bacterium based upon the presence of a circular chromosome. Bacteria are prokaryotic organisms, which means they lack a true nucleus and their genetic material is organized in a circular chromosome. This characteristic distinguishes them from eukaryotic organisms, which have a nuclear membrane and linear chromosomes. The presence of a circular chromosome is a defining feature of bacteria and is used to classify them as such.

If the concentration of the FLACCID CELL is 2%, then the solute concentration in the environment of the cell may be 5.0%. This is because when a cell is in a hypotonic environment, water will move into the cell through osmosis to equalize the concentration of solutes on both sides of the cell membrane. Therefore, the solute concentration in the environment must be higher than the concentration inside the cell, which is 2%. Among the given options, 5.0% is the only concentration that is higher than 2%.

Catabolism is the correct answer because it refers to the biochemical process through which organisms break down complex molecules to release energy. This process involves the breakdown of food molecules such as carbohydrates, proteins, and fats, and the release of energy in the form of ATP. Anabolism, on the other hand, refers to the process of building complex molecules from simpler ones, which is the opposite of catabolism. Saprophytism, parasitism, and commensalism are not related to the extraction of energy from food.

Unsaturated fatty acids have carbon to carbon double bonds, whereas saturated fatty acids do not have any double bonds between carbon atoms. This difference in the chemical structure of the fatty acids affects their physical properties and biological functions.

Saturated fatty acids are different from unsaturated fatty acids because they contain only carbon-carbon single bonds. This means that all of the carbon atoms in a saturated fatty acid are bonded to each other with single bonds, resulting in a straight, rigid structure. In contrast, unsaturated fatty acids contain at least one carbon-carbon double bond, which introduces a kink or bend in the carbon chain. This double bond also allows for the possibility of additional hydrogen atoms to be added, making unsaturated fatty acids more flexible and fluid compared to saturated fatty acids.

Isotopes are atoms of the same element that have different numbers of neutrons. Carbon 13 and Carbon 14 are both isotopes of carbon, but they have different numbers of neutrons. Therefore, the correct answer is neutrons.

Cyanide poisoning is fatal within minutes because it binds irreversibly with the active sites of respiratory enzymes. This means that cyanide acts as a competitive inhibitor, which competes with the substrate for the active site of the enzyme. By binding to the active site, cyanide prevents the substrate from binding and carrying out its normal function. This inhibition of respiratory enzymes ultimately leads to the cessation of cellular respiration and, consequently, cell death.

Isomers are molecules that have the same molecular formula but different structural arrangements. These different arrangements can result in different biological effects. Therefore, the fact that two molecules with the same molecular formula have different biological effects can be best explained by the possibility that they are isomers.

Based on the appearance of the turgid cell, it can be concluded that the environment is hypotonic to the cell. This is because a turgid cell is swollen and firm, indicating that water has entered the cell due to osmosis. In a hypotonic environment, there is a higher concentration of water outside the cell compared to inside, causing water to move into the cell to equalize the solute concentration.

The molecule referred to in the answer is hemoglobin. Hemoglobin is a protein found in red blood cells that binds to oxygen and transports it throughout the body. It is responsible for the red color of blood and plays a crucial role in oxygen delivery to tissues. Therefore, it is used to transport oxygen in the blood.

The increase in CO2 in the earth's atmosphere is causing the greenhouse effect. The greenhouse effect refers to the trapping of heat in the earth's atmosphere due to the presence of greenhouse gases like CO2. When CO2 levels increase, more heat is trapped, leading to a rise in global temperatures. This phenomenon is responsible for climate change and its associated impacts, such as melting ice caps, rising sea levels, and extreme weather events.

In this question, the solute refers to the substance that is being dissolved in the solvent, which in this case is water. Both sugar and CO2 are being dissolved in water to make soft drinks, so both the sugar and the CO2 are the solutes in this scenario.

Proteins are large, complex molecules that play crucial roles in the body, such as acting as enzymes, antibodies, and structural components like collagen. Dehydrogenase is an enzyme, so it is considered a protein. Steroids, on the other hand, are a type of lipid and not classified as proteins. Therefore, steroids are not considered proteins.

The correct term for the graph below is "Exothermic." This term is used to describe a chemical reaction or process that releases energy in the form of heat. In an exothermic reaction, the products have lower energy than the reactants, resulting in a negative change in enthalpy. This graph likely represents a reaction where the energy of the products is lower than the energy of the reactants, indicating that heat is being released.

Anemia is characterized by a lack of red blood cells, which are responsible for carrying oxygen to the body's tissues. Iron (Fe++) is an essential component of hemoglobin, the protein in red blood cells that binds to oxygen. Without sufficient iron, the body cannot produce enough healthy red blood cells, leading to anemia. Therefore, an insufficient amount of iron could be the cause of the person's anemia.

MHC proteins, also known as major histocompatibility complex proteins, are identity markers present on the surface of an individual's cells. These proteins play a crucial role in the immune system by presenting fragments of foreign substances, such as pathogens, to immune cells. This allows the immune system to recognize and eliminate any potentially harmful invaders. MHC proteins are not related to determining a person's blood type, passing through the membrane multiple times, or being different for each type of tissue in the body.

The correct answer is "they are building blocks of steroids." Amino acids are the building blocks of proteins, not steroids. Steroids are a class of organic compounds that have a different structure and function than amino acids.

Cellulose is a structural polysaccharide because it is a major component of plant cell walls, providing structural support to the plant. It is made up of long chains of glucose molecules linked together, forming a strong and rigid structure. Amylose, amylopectin, and glycogen are all storage polysaccharides, used for energy storage in plants and animals. Starch is a mixture of amylose and amylopectin, also used for energy storage.

Changing the number of protons in an atom would result in a different element because the number of protons determines the atomic number, which defines the identity of an element. Each element has a unique number of protons in its nucleus, so altering this number would change the element itself. This is because the number of protons determines the chemical properties and behavior of an atom. Therefore, the correct answer is that the atom would change to an atom of a different element.

The presence of a cell wall, a large vacuole, and chloroplasts in the diagram indicates that it is a plant cell. Plant cells are characterized by having a cell wall, which provides structural support and protection, a large vacuole, which stores water and nutrients, and chloroplasts, which are responsible for photosynthesis. Therefore, the correct answer is "all of the above."

The correct answer is glycocalyx. The glycocalyx is a carbohydrate-containing layer that is present at the surface of the plasma membrane. It consists of glycoproteins and glycolipids, which are proteins and lipids with attached carbohydrate chains. The glycocalyx has multiple functions, including cell recognition, protection against pathogens, and cell adhesion. It also plays a role in cell signaling and communication. Therefore, the glycocalyx is the most appropriate answer in this context.