Biology Test: The Chemical Basis Of Life

The most abundant elements in most living things are oxygen, carbon, hydrogen, and nitrogen. These elements are essential for the structure and function of biological molecules such as carbohydrates, lipids, proteins, and nucleic acids. Oxygen is necessary for respiration and energy production, carbon is the backbone of organic molecules, hydrogen is involved in bonding and chemical reactions, and nitrogen is a key component of proteins and nucleic acids. Together, these elements make up the majority of the composition of living organisms.

An ion is a term used to describe an atom that has gained or lost an electron, resulting in a positive or negative charge. This charge imbalance makes the atom an ion. Compounds, bonds, molecules, and acids do not specifically refer to atoms that have gained or lost electrons, so they are not the correct answer.

In chemical reactions, atoms undergo rearrangement due to bonding. This means that the atoms involved in the reaction form new bonds with each other, resulting in a rearrangement of their positions within the molecules or compounds. Bonding plays a crucial role in this process as it allows atoms to form stable arrangements by sharing or transferring electrons. Therefore, the correct answer is "rearranged--thanks to bonding."

A water strider can walk on water but not oil because of surface tension caused by hydrogen bonds between the water molecules, that aren't found between the oil molecules. Surface tension is the property of a liquid that allows it to resist an external force and form a "skin" on its surface. Water molecules are attracted to each other through hydrogen bonding, which creates a strong surface tension. This allows the water strider's legs to distribute its weight and stay on the water's surface. Oil, on the other hand, lacks hydrogen bonding and therefore has a lower surface tension, making it unable to support the weight of the water strider.

In a chemical reaction, reactants are the atoms and/or molecules that undergo a change to form new substances called products. Reactants are the starting materials of a chemical reaction and are typically written on the left side of a chemical equation. They are the substances that are consumed or used up during the reaction, while products are the new substances that are formed. Dependent variables refer to the variables that are being measured or observed in an experiment, and valence electrons are the outermost electrons in an atom that participate in chemical bonding. Therefore, the correct answer is reactants.

Amino acids are the building blocks of proteins, and when combined, they form protein molecules. Similarly, glucose is a monosaccharide and is the basic unit of starch, which is a complex carbohydrate. When glucose molecules are linked together, they form starch molecules. Therefore, the relationship between amino acid and protein is analogous to the relationship between glucose and starch.

The atomic number of an element represents the number of protons in its nucleus. In this case, the correct answer is 8, which means that an oxygen atom has 8 protons.

Carbohydrates provide the largest percentage of an average human's energy. This is because carbohydrates are the body's primary source of fuel. When consumed, carbohydrates are broken down into glucose, which is then used by the body for energy production. Carbohydrates are easily metabolized and provide a quick and efficient source of energy. Proteins, nucleic acids, and lipids also contribute to energy production, but carbohydrates are the main source due to their abundance in the human diet and their efficient conversion into usable energy.

Polymers are made of monomers because polymers are large molecules composed of repeating subunits called monomers. These monomers are linked together through chemical bonds to form the polymer. This process is known as polymerization.

Oxygen and magnesium are most likely to react with each other because they are close to each other on the periodic table. Oxygen is a highly electronegative element and magnesium is a highly electropositive element. This means that oxygen has a strong tendency to gain electrons while magnesium has a strong tendency to lose electrons. This creates a favorable condition for the transfer of electrons from magnesium to oxygen, resulting in the formation of a stable compound, OMg.

Water molecules are made up of two hydrogen atoms and one oxygen atom. The oxygen atom has a higher electronegativity, meaning it attracts electrons more strongly than the hydrogen atoms. As a result, the oxygen atom pulls the shared electrons towards itself, creating a partial negative charge (δ-) on the oxygen side of the molecule. The hydrogen atoms, having less electronegativity, have a partial positive charge (δ+) on their side. This creates a polar molecule, with the oxygen side being slightly negative and the hydrogen side being slightly positive.

Atoms react with other atoms in order to achieve a full outer energy level of electrons. This is because atoms are most stable when their outer energy level is filled with electrons. By reacting with other atoms, they can either gain or lose electrons to achieve this stable configuration. This process allows atoms to achieve a more balanced state by balancing the number of protons and electrons they have, ensuring that they have a complete outer energy level.

The correct answer is "Kind of, if we bounce electrons off of them in the world's most expensive, complex microscopes." This answer explains that although humans cannot see individual atoms with the naked eye or a regular light microscope, it is possible to observe them using advanced microscopes that utilize electron scattering techniques. These microscopes are highly sophisticated and expensive, allowing scientists to indirectly visualize atoms by studying the patterns formed when electrons interact with them.

Ice floats on water because its molecules are less densely packed than those in liquid water. When water freezes and turns into ice, the water molecules arrange themselves in a hexagonal lattice structure, which creates open spaces or gaps between the molecules. This results in a decrease in the density of the ice compared to the liquid water. As a result, the ice becomes less dense and floats on top of the denser liquid water.

Polysaccharides are complex carbohydrates made up of long chains of monosaccharides. Starch is a polysaccharide found in plants and serves as a storage form of glucose. Glycogen is a polysaccharide found in animals and serves as a storage form of glucose in the liver and muscles. Cellulose is a polysaccharide found in plant cell walls and provides structural support. Therefore, the correct answer is starch, glycogen, and cellulose as they are all examples of polysaccharides.

Individual organic macromolecules are not alive because they do not possess the characteristics of life, such as the ability to grow, reproduce, respond to stimuli, or undergo metabolism. While organic macromolecules are essential for life and are found in living organisms, they are not considered alive on their own. They serve as building blocks for cells and are involved in various biological processes, but they require a cellular environment to function and contribute to the overall life processes of an organism.

A hydrogen bond is a type of bond formed between the slightly positive side of one molecule and the slightly negative side of another molecule. This bond occurs when a hydrogen atom is attracted to an electronegative atom, such as oxygen, nitrogen, or fluorine. The hydrogen bond is weaker than a covalent or ionic bond, but it still plays a crucial role in various biological and chemical processes, such as DNA replication and protein folding.

The data (average test grades on a 0-100 scale) is going to be quantitative, not qualitative. Qualitative data refers to non-numerical information, such as descriptions or observations, while quantitative data refers to numerical information that can be measured or counted. In this case, the test grades are measured on a 0-100 scale, making it quantitative data.

Non-polar molecules do not form hydrogen bonds, which is true. However, the statement that they tend to heat up more slowly than water does is false. In fact, non-polar molecules heat up faster than water because they have weaker intermolecular forces, such as London dispersion forces, compared to the strong hydrogen bonds present in water. This results in non-polar molecules having lower boiling points and evaporating more easily than water.