Cell And Molecular Biology Practice Test

Proteins are formed by the bonding of smaller units called monomers, and the monomers that make up proteins are amino acids. Amino acids are organic compounds that contain an amino group (-NH2) and a carboxyl group (-COOH). They are the building blocks of proteins and are linked together through peptide bonds to form long chains, which then fold into complex three-dimensional structures. Therefore, amino acids are the correct answer as they are the monomers that make up proteins.

All organic compounds contain the element carbon. Carbon is unique in its ability to form covalent bonds with other carbon atoms and a variety of other elements. This property allows carbon to form the backbone of organic molecules, giving them their diverse structures and functions. Carbon's ability to form stable bonds with other elements makes it the essential element in all organic compounds.

The correct answer is chloroplast. Chloroplasts are the structures in plant cells that carry out photosynthesis. They contain chlorophyll, a pigment that captures sunlight and converts it into energy. This energy is used to convert carbon dioxide and water into glucose, which is the primary source of energy for the plant. The chloroplasts are enclosed by a double membrane and contain stacks of thylakoids where the photosynthetic reactions take place.

The correct term for the energy gaining graph below is endothermic. Endothermic refers to a process or reaction that absorbs energy from its surroundings, resulting in a decrease in temperature. In the given graph, the energy is being gained or absorbed, indicating an endothermic reaction.

Adhesion is the term that describes the tendency of a water molecule to stick to different types of molecules. This property allows water to adhere to surfaces, such as the walls of a container or the surface of a plant, which is important for many biological and physical processes. Cohesion, on the other hand, refers to the tendency of water molecules to stick to each other. Density and buoyancy are unrelated terms in this context.

ATP (adenosine triphosphate) is the correct answer because it is the main source of energy in cells. ATP is synthesized during cellular respiration and provides the necessary energy for active transport processes, such as moving molecules against their concentration gradient across the cell membrane. This energy is released when ATP is hydrolyzed into ADP (adenosine diphosphate) and inorganic phosphate, providing the energy needed for various cellular functions.

The graph shows that the catalyzed reaction has a lower activation energy compared to the uncatalyzed reaction. This indicates that the catalyst lowers the energy needed for the reaction to proceed.

Homeostasis refers to the ability of organisms and cells to maintain a stable internal environment. It involves regulating various physiological processes such as temperature, pH, and nutrient levels to ensure optimal functioning. Protein synthesis, digestion, and photosynthesis are all important biological processes, but they do not specifically refer to the maintenance of a stable internal environment. Therefore, the correct answer is homeostasis.

Respiration is a process in which energy is released by breaking down organic molecules. Since it releases a lot of energy, it is considered an exothermic reaction. In exothermic reactions, energy is released to the surroundings, resulting in an increase in temperature. Thus, the given correct answer is exothermic.

During photosynthesis, plants use energy from sunlight to convert carbon dioxide and water into sugar and oxygen. The sugar produced is used as a source of energy for the plant, while the oxygen is released into the atmosphere as a byproduct. Therefore, sugar and oxygen are the products of the photosynthesis reaction.

Passive transport refers to the movement of molecules across the plasma membrane without the need for the cell to expend energy. This type of movement occurs due to the concentration gradient, where molecules move from an area of higher concentration to an area of lower concentration. It does not involve the use of transport proteins or kinetic energy. Active transport, on the other hand, requires the cell to use energy to move molecules against their concentration gradient.

Acidic solutions have a pH that is less than 7 because pH is a measure of the concentration of hydrogen ions in a solution. In acidic solutions, there is a higher concentration of hydrogen ions, which lowers the pH value. A pH value less than 7 indicates that the solution is acidic.

The process taking place below is called endocytosis. Endocytosis is the process by which cells engulf substances from their external environment by forming a vesicle around the substance and bringing it into the cell. This process is used to transport large molecules, such as proteins, into the cell. It is an active process that requires energy expenditure by the cell.

Osmosis is the correct answer because it refers to the diffusion of water through a semipermeable membrane down a concentration gradient. This process occurs when there is a difference in solute concentration on either side of the membrane, causing water molecules to move from an area of lower solute concentration to an area of higher solute concentration. Osmosis is an essential process for maintaining the balance of water and solutes in cells and is involved in various biological processes.

The molecule depicted in the question is a carbohydrate. Carbohydrates are organic compounds composed of carbon, hydrogen, and oxygen atoms. They are a major source of energy for living organisms and play a crucial role in various biological processes. The molecule shown in the question likely consists of multiple carbon, hydrogen, and oxygen atoms arranged in a specific structure characteristic of carbohydrates.

A selectively permeable membrane is one that allows certain substances to pass through while restricting the passage of others. It acts as a barrier, only allowing molecules of a certain size or charge to diffuse across it. This type of membrane is essential for maintaining cellular homeostasis by controlling the movement of ions, nutrients, and waste products in and out of cells. It plays a crucial role in various biological processes, such as osmosis and active transport.

Plant cells have a unique structure called the cell wall, which provides rigidity and support to the cell. This rigid outer layer is composed of cellulose and other polysaccharides, and it is absent in animal cells. The cell wall helps maintain the shape of the plant cell and protects it from mechanical stress. It also allows plants to grow upright and provides resistance against pathogens. Animal cells, on the other hand, have a flexible cell membrane but lack the additional layer of protection provided by the cell wall.

The diagram shows a water molecule with a bent shape. The oxygen atom is larger and more electronegative than the hydrogen atoms, causing it to pull the shared electrons closer to itself. This creates a partial negative charge on the oxygen atom and partial positive charges on the hydrogen atoms. The charges on either end of the water molecule indicate that it is polar, meaning it has an uneven distribution of charge.

Living cells continuously make proteins through a process called protein synthesis. This process occurs on ribosomes, which are organelles responsible for translating the genetic information from DNA into proteins. Ribosomes are found both in the cytoplasm and on the rough endoplasmic reticulum (ER). They play a crucial role in protein production and are essential for the functioning and survival of cells. Therefore, the correct answer is ribosome.

The shape of an enzyme is likely to be affected by both temperature and pH. Enzymes are proteins that have specific three-dimensional structures, and their shape is crucial for their function. Changes in temperature can disrupt the weak bonds that maintain the enzyme's shape, causing it to denature and lose its activity. Similarly, alterations in pH can affect the charges on the amino acids that make up the enzyme, leading to changes in its shape. Therefore, both temperature and pH can significantly impact the shape and function of an enzyme.

The correct answer is "the cell lacks a nucleus and other membrane bound organelles". This is because prokaryotic cells are characterized by the absence of a nucleus and other membrane-bound organelles. Instead, their DNA is located in the cytoplasm, and they typically have a single circular chromosome. The presence of a flagellum does not necessarily indicate a prokaryotic cell, as some eukaryotic cells also have flagella. The statement "the cell lacks DNA" is incorrect, as all cells, including prokaryotic cells, contain DNA.

Activation energy is the term used to describe the amount of energy that must be absorbed before a chemical reaction can start. It is the energy barrier that needs to be overcome for the reactants to transform into products. Activation energy is necessary to break the existing bonds in the reactants and initiate the formation of new bonds in the products.

The hydrophobic part of a phospholipid is the fatty acid tails. These tails are made up of long hydrocarbon chains that are nonpolar and repel water molecules. The hydrophobic nature of the fatty acid tails allows phospholipids to form a lipid bilayer in aqueous environments, such as cell membranes. The phosphate group and glycerol head of a phospholipid are hydrophilic, meaning they are attracted to water molecules.

The term that describes the sugar in a glass of lemonade is solute. In a solution, the solute is the substance that is dissolved in the solvent, which in this case would be the water in the lemonade. The sugar molecules dissolve in the water, making it a solution. Therefore, solute is the correct answer.

Carbohydrates are organic compounds composed of carbon, hydrogen, and oxygen atoms. These elements combine in specific ratios to form various types of carbohydrates, including starches and sugars. Nitrogen is not a component of carbohydrates, so the correct answer is carbon, hydrogen, and oxygen.

The number of protons in the nuclei of their atoms distinguishes one element from another. This is because the number of protons determines the atomic number of an element, which is unique to each element. The atomic number defines the identity of an element and determines its properties. Therefore, different elements have different numbers of protons, making this the characteristic that sets them apart from each other.

To calculate the correct power of magnification, the student should multiply the power of the eyepiece with the power of the objective. This is because the eyepiece and the objective lens work together to magnify the image. Adding the powers would not give an accurate measure of the magnification. Similarly, the power of the iris and the power of the condenser are not relevant in this calculation.

Cohesion refers to the tendency of water molecules to stick to one another. This attraction between water molecules is due to hydrogen bonding. The positive end of one water molecule is attracted to the negative end of another water molecule, creating a cohesive force. This cohesive force is responsible for many of the unique properties of water, such as its high surface tension and ability to form droplets.

Saturated fatty acids contain only carbon-carbon single bonds, while unsaturated fatty acids contain at least one carbon-carbon double bond. This means that saturated fatty acids have a higher number of hydrogen atoms bonded to their carbon atoms, making them more saturated with hydrogen. This makes saturated fatty acids solid at room temperature, while unsaturated fatty acids are usually liquid. Additionally, saturated fatty acids are not exclusively found in oils, as they can also be found in animal fats.

The lock-and-key model of enzyme function suggests that enzymes (lock) and substrates (key) fit together perfectly, like a lock and key. Enzymes are proteins that act as catalysts, speeding up chemical reactions. Substrates are the specific molecules that the enzyme acts upon. In this model, the enzyme's active site (lock) is complementary in shape to the substrate (key), allowing them to bind together. This binding facilitates the chemical reaction, resulting in the formation of products. Therefore, the correct answer is "enzyme and substrates."

An enzyme acts on the reactants called substrates. Substrates are the specific molecules that bind to the active site of an enzyme, where the enzyme catalyzes a chemical reaction. The active site of an enzyme is specifically shaped to fit the substrate molecules, similar to a lock-and-key mechanism. The enzyme-substrate complex formed allows the enzyme to facilitate the conversion of substrates into products. Therefore, the correct term to describe the reactants that an enzyme acts on is substrate.

Exocytosis is the process by which cells release substances from their internal compartments to the external environment. It involves the fusion of vesicles containing the substances with the cell membrane, allowing their release. In this case, the process described in the question involves substances being released from the cell, rather than taken in, indicating that it is exocytosis.

Passive transport refers to the movement of substances across a cell membrane without the use of energy. Diffusion is a process in which molecules move from an area of high concentration to an area of low concentration, down the concentration gradient. This movement occurs naturally and does not require the cell to expend energy. Therefore, diffusion is an example of passive transport.

The correct term for the energy releasing 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 less energy than the reactants, resulting in a negative change in enthalpy. The graph shows a decrease in energy as the reaction progresses, indicating that energy is being released.

The presence of a cell wall, a large vacuole, and chloroplasts in the diagram of a plant cell indicates that all of these structures are present in a plant cell. The cell wall is a rigid outer layer that provides support and protection to the cell. The large vacuole is a storage organelle that helps maintain the cell's shape and stores water, nutrients, and waste products. Chloroplasts are responsible for photosynthesis, the process by which plants convert sunlight into energy. Therefore, the presence of all these structures confirms that the diagram represents a plant cell.

Active transport is the term that describes the movement of molecules that are pumped from an area of low concentration to an area of high concentration. Unlike passive transport, which relies on the natural movement of molecules from high to low concentration, active transport requires the use of energy to move molecules against the concentration gradient. This process is essential for maintaining proper concentration gradients and carrying out various cellular functions, such as nutrient uptake and waste removal.

An ionic bond is formed between two atoms when there is a transfer of electrons from one atom to another, resulting in the formation of oppositely charged ions. The electrical force then attracts these oppositely charged ions, causing them to bond together. This type of bonding typically occurs between a metal and a non-metal, where the metal atom loses one or more electrons to become a positively charged ion, while the non-metal atom gains those electrons to become a negatively charged ion. The attraction between these ions creates the ionic bond.

A catalyst lowers the activation energy of a chemical reaction. Activation energy is the energy required for a reaction to occur. By lowering the activation energy, a catalyst provides an alternative pathway for the reaction to proceed with lower energy barriers. This allows the reaction to occur more easily and at a faster rate. The catalyst itself is not consumed in the reaction and can be used repeatedly, making it an efficient and effective way to increase the rate of a reaction.

Photosynthesis is a process in which plants convert light energy into chemical energy in the form of glucose. This process requires energy input from the surroundings, usually in the form of sunlight. Since the energy input is greater than the energy released, photosynthesis is considered an endothermic reaction.

Water moves from a hypotonic solution into the cell. In a hypotonic solution, the concentration of solutes outside the cell is lower than inside the cell. As a result, water moves from an area of lower solute concentration (the hypotonic solution) to an area of higher solute concentration (inside the cell) through a process called osmosis. This causes the cell to swell or even burst if the solution is extremely hypotonic.

The cell membrane is composed of phospholipids, cholesterol, and proteins. Phospholipids form a bilayer structure, with hydrophilic heads facing the aqueous environment and hydrophobic tails facing inward. Cholesterol is embedded within the phospholipid bilayer, providing stability and regulating fluidity. Proteins are also embedded within the membrane, serving various functions such as transport, cell signaling, and structural support.

The dialysis bag doubled in weight when placed in distilled water, indicating that water molecules moved into the bag through osmosis. This means that the concentration of solutes inside the bag is higher than the concentration of solutes in the water. Therefore, the solution in the beaker is hypotonic compared to the cell.

Stereoisomers are molecules that have the same molecular formula and connectivity but differ in the arrangement of atoms in space. They are mirror images of each other and cannot be superimposed on one another. This phenomenon is known as chirality, and stereochemistry is the study of the three-dimensional arrangement of atoms in molecules. Therefore, the term for molecules that are mirror images of each other is stereoisomers.

Cells must be small in size in order to function because if a cell gets too large, diffusion cannot take place effectively. Diffusion is the process by which molecules move from an area of higher concentration to an area of lower concentration. It occurs across the cell membrane and is essential for the exchange of nutrients, gases, and waste products. If a cell becomes too large, the distance for diffusion becomes too great, and important molecules may not be able to reach the center of the cell efficiently. This can lead to cellular dysfunction and ultimately affect the cell's ability to carry out its functions.

Intracellular receptors are located within the cell, typically in the cytoplasm or nucleus. They are responsible for sensing and binding to specific molecules, such as hormones or signaling molecules, that can pass through the cell membrane. Once bound, these receptors can directly influence gene expression and cellular processes. This is in contrast to membrane receptors, which are located on the cell surface and transmit signals from outside the cell into the cell's interior. Intercellular receptors and ligand receptors are not commonly used terms in the context of cellular receptors.

Boiling off some water from a hypertonic solution would decrease the concentration of solutes in the solution, making it less concentrated and closer to isotonic. This is because boiling off water would remove solvent, causing the solutes to become more diluted in the remaining solution. As a result, the solution would have a lower osmotic pressure and be closer to isotonic with the surrounding environment.