Biology 1 Midterm Exam Review A

Proteins are the fourth main type of carbon-based molecules in organisms. They are composed of amino acids and play a crucial role in various biological processes such as cell structure, enzyme catalysis, and immune response. Proteins are involved in providing structure to cells and tissues, transporting molecules, and acting as enzymes to catalyze chemical reactions. They are essential for the growth, development, and functioning of organisms.

DNA and RNA are two types of nucleic acids. Nucleic acids are biomolecules that play a crucial role in storing and transmitting genetic information in living organisms. DNA (deoxyribonucleic acid) is found in the nucleus of cells and carries the genetic instructions for the development and functioning of all living organisms. RNA (ribonucleic acid) is involved in the synthesis of proteins based on the instructions provided by DNA. Both DNA and RNA are essential components of the genetic material and are responsible for the inheritance of traits from one generation to the next.

All of the mentioned factors can affect the rate of biochemical reactions. The use of a catalyst can speed up the reaction by lowering the activation energy required. Increasing the temperature provides more energy to the reactant molecules, increasing their collision frequency and therefore the reaction rate. Changing the pH can alter the ionization state of reactants and enzymes, affecting their activity and subsequently the reaction rate. Therefore, all of these factors have the potential to influence the rate of biochemical reactions.

The major principle upon which cell theory is based is that all organisms are made of cells. This principle states that cells are the basic structural and functional units of all living organisms. It recognizes that all living things, whether they are single-celled or multicellular, are composed of cells. This principle was proposed by scientists Matthias Schleiden and Theodor Schwann in the 19th century and has since been widely accepted in the field of biology.

Hydrogen bonds give water many properties that are important to living things. These bonds are formed between the hydrogen atoms of one water molecule and the oxygen atom of another water molecule. This results in a strong attraction between water molecules, giving water its high boiling point, high heat capacity, and cohesive properties. Hydrogen bonds also contribute to water's ability to dissolve many substances, making it an excellent solvent for biological processes.

The correct answer is nucleus. The nucleus is the storehouse for a cell's genetic information because it contains the cell's DNA. DNA carries the instructions for the cell's functions and characteristics, and it is passed on to new cells during cell division. The nucleus also regulates the activities of the cell by controlling gene expression. The other organelles listed (mitochondrion, chloroplast, and centriole) have different functions and are not directly involved in storing genetic information.

Scientists use observations and data to form and test hypotheses. A hypothesis is a proposed explanation or prediction based on available evidence. By gathering observations and data, scientists can make educated guesses about the relationship between variables and then test those hypotheses through experiments or further observations. This process allows scientists to refine their understanding of the natural world and develop theories, which are well-supported explanations for a wide range of phenomena.

Protein polymers are made of a series of amino acids. Amino acids are the building blocks of proteins and are linked together through peptide bonds to form long chains called polypeptides. These polypeptides then fold into specific three-dimensional structures to create functional proteins. Monosaccharides are the building blocks of carbohydrates, histones are proteins that help organize DNA in the nucleus, and DNA strands are the genetic material that carries the instructions for protein synthesis.

Fats, oils, and cholesterol are all types of lipids. Lipids are a broad class of organic compounds that are insoluble in water but soluble in organic solvents. They play various roles in the body, including energy storage, insulation, and protection of organs. Fats and oils are examples of triglycerides, which are a type of lipid composed of glycerol and fatty acids. Cholesterol is another type of lipid that is essential for the formation of cell membranes and the production of hormones. Therefore, lipids encompass all of these substances.

An atom is the smallest basic unit of matter that retains the chemical properties of an element. It consists of a nucleus, which contains protons and neutrons, and electrons that orbit the nucleus. Atoms combine to form molecules and compounds, but they cannot be further divided without losing their chemical properties. Cells, on the other hand, are the basic structural and functional units of living organisms, and compounds are substances composed of two or more elements. Therefore, the correct answer is atom.

Chemical reactions involve the breaking and formation of bonds between atoms or molecules, resulting in the transformation of substances into different substances. This process occurs when the reactants undergo chemical changes to form products. Chemical equilibrium refers to a state where the forward and reverse reactions in a chemical system occur at equal rates, but it does not necessarily involve the formation of new substances. Ion formation refers to the process of atoms gaining or losing electrons to become charged particles, but it does not necessarily involve the breaking and reforming of bonds. Hydrogen bonding refers to the attractive force between a hydrogen atom and an electronegative atom, such as oxygen or nitrogen, but it does not involve the breaking and formation of bonds between different substances. Therefore, the correct answer is chemical reactions.

An ion is formed when an atom gains or loses electrons. When an atom gains electrons, it becomes a negatively charged ion called an anion. When an atom loses electrons, it becomes a positively charged ion called a cation. Ions play a crucial role in chemical reactions and the formation of compounds.

Carbohydrates are the molecules found in the food we eat that are most commonly broken down to make ATP. When we consume carbohydrates, they are broken down into glucose molecules during digestion. Glucose is then transported to our cells where it undergoes a series of chemical reactions in the presence of oxygen to produce ATP through a process called cellular respiration. ATP is the primary source of energy for our cells, providing us with readily available energy for various physiological processes. Lipids, proteins, and vitamins also play important roles in our body, but they are not the primary source of energy production like carbohydrates.

Controlled variables are the factors in an experiment that are purposely kept constant or unchanged. This is important in order to isolate the effect of the independent variable being tested. By controlling these variables, researchers can ensure that any changes or effects observed are solely due to the manipulation of the independent variable, rather than confounding factors.

Atoms in molecules share pairs of electrons when they make covalent bonds. In a covalent bond, two atoms share a pair of electrons in order to achieve a stable electron configuration. This sharing of electrons allows both atoms to fill their outermost energy levels and become more stable. Covalent bonds are typically formed between nonmetal atoms and are the strongest type of chemical bond.

A catalyst is a substance that increases the rate of a chemical reaction by lowering the activation energy needed for the reaction to occur. It accomplishes this by providing an alternative pathway with a lower energy barrier for the reaction to proceed. Therefore, the correct answer is catalyst.

Carbohydrates are the most important organic molecule in satisfying the energy needs of animals because their bonds are easily broken to release ATP. ATP is the primary energy currency in cells, and it is produced through the breakdown of carbohydrates during cellular respiration. Carbohydrates are the body's preferred source of energy because they can be quickly and efficiently metabolized to produce ATP. Lipids can also be used for energy, but they are not as easily digested as carbohydrates. Nucleic acids are not primarily used for energy production, and proteins are primarily used for building and repairing tissues, not for energy.

A pH of 12 would be considered a strong base. The pH scale ranges from 0 to 14, with values below 7 being acidic, 7 being neutral, and values above 7 being basic. As the pH scale is logarithmic, each unit represents a tenfold difference in acidity or basicity. A pH of 12 is significantly higher than neutral and indicates a high concentration of hydroxide ions, making it a strong base.

Carbon has the ability to form different large and complex structures because it can bond to the atoms of many other elements as well as to other carbon atoms. This property of carbon allows it to form a wide variety of compounds with different structures and properties. Carbon's ability to form multiple bonds and its flexible bonding arrangements contribute to its versatility in forming complex structures, such as hydrocarbons, polymers, and biomolecules.

In step 2 of the lock-and-key model of enzyme function, the enzyme is causing new bonds to form between the substrates. This means that the enzyme is facilitating the reaction by bringing the substrates closer together and helping them interact in a way that promotes the formation of new chemical bonds. This is a key characteristic of enzyme function, as enzymes act as catalysts that speed up the rate of chemical reactions by lowering the activation energy required for the reaction to occur.

The correct answer is eukaryotic. This can be determined by examining the characteristics of the cell shown in Figure 3.1. Eukaryotic cells are typically larger and more complex than prokaryotic cells, and they contain a nucleus and membrane-bound organelles. Bacterial cells are prokaryotic, so they do not have a nucleus or membrane-bound organelles. Animal cells are a type of eukaryotic cell, but without further information, it cannot be determined if the cell in Figure 3.1 is specifically an animal cell. Therefore, the most accurate answer is eukaryotic.

Fats possess the most calories per gram compared to proteins and carbohydrates. This is because fats are more energy-dense, containing 9 calories per gram, while proteins and carbohydrates contain only 4 calories per gram. Therefore, consuming foods high in fat can lead to a higher calorie intake compared to consuming the same weight of proteins or carbohydrates.

Enzymes are biological catalysts that speed up chemical reactions in living organisms. They work by lowering the activation energy required for a reaction to occur, thereby increasing the rate of the reaction. Therefore, the aspect of a chemical reaction that is affected by enzymes is the rate at which the reaction takes place. Enzymes do not affect the direction, equilibrium, or pH of a chemical reaction.

The molecule described in the question is rich in nitrogen, soluble in water, and lacks phosphorus. Additionally, it contains carbon, hydrogen, and oxygen in uneven ratios. These characteristics are consistent with those of an amino acid, which is a small molecule that is the building block of proteins. Amino acids contain an amino group (which contains nitrogen), a carboxyl group (which is soluble in water), and a variable side chain of carbon, hydrogen, and oxygen atoms. Therefore, the molecule described in the question is most likely an amino acid.

If an organic molecule model contains carbon atoms arranged in a long chain, it is probably a model of a lipid. Lipids are organic molecules that consist of carbon, hydrogen, and oxygen. They are characterized by their long hydrocarbon chains, which can be found in various forms such as fatty acids, triglycerides, and phospholipids. These long carbon chains are a distinguishing feature of lipids and differentiate them from other organic molecules like starch, polar molecules, and proteins.