Biology Quiz Practice Questions

The polypeptide sequence of hemoglobin in the new organism has the fewest differences with frogs, indicating a closer evolutionary relationship between them. The larger number of differences with humans suggests a more distant relationship. Therefore, the data suggests that the new organism is more closely related to frogs than to humans.

In this hypothetical world, where people over 6 feet tall are eliminated every 50 years, natural selection would favor individuals who are shorter in height. Over time, the genes for shorter height would become more prevalent in the population, leading to a gradual decline in average height. This is because shorter individuals would have a higher chance of survival and reproduction, passing on their genes for shorter height to future generations.

Living things are characterized by their ability to process energy, which is essential for their survival and functioning. They also exhibit growth and reproduction, allowing them to increase in size and produce offspring. Living organisms also possess evolutionary adaptations, which are changes over time that enhance their survival and reproductive success. Finally, living things can respond to their environment, adjusting their behavior or physiology in order to adapt and survive. Therefore, all of the listed properties and processes are associated with living things.

The correct answer is the H of one water molecule and the O of another water molecule. Hydrogen bonding occurs when a hydrogen atom is attracted to an electronegative atom, such as oxygen or nitrogen, in another molecule. In the case of water, the oxygen atom is highly electronegative, causing the hydrogen atoms to be slightly positively charged. This allows the hydrogen atoms to form bonds with neighboring oxygen atoms in other water molecules, creating a network of hydrogen bonds. This is responsible for many of the unique properties of water, such as its high boiling point and surface tension.

The correct answer is the flow of energy from sunlight to producers and then to consumers, and the recycling of chemical nutrients. This answer encompasses two major processes that are essential for the dynamics of any ecosystem. The flow of energy from sunlight to producers and then to consumers represents the transfer of energy through the food chain, where producers (such as plants) convert sunlight into chemical energy through photosynthesis, and consumers obtain energy by consuming these producers. Additionally, the recycling of chemical nutrients refers to the continuous cycling of essential elements (such as carbon, nitrogen, and phosphorus) within the ecosystem, ensuring their availability for different organisms and maintaining the overall balance of the ecosystem.

Denaturation is the correct answer because it refers to the process of altering a protein's three-dimensional shape or conformation. This change occurs when the protein's hydrogen bonds, disulfide bridges, or ionic bonds are disrupted. Denaturation can be caused by various factors such as heat, pH changes, or exposure to certain chemicals. This disruption of the protein's structure often leads to loss of function and can be irreversible in some cases.

Atom 6X refers to carbon (C), which has an atomic number of 6. When carbon reacts with hydrogen (H), it forms methane (CH4). In methane, carbon is bonded to four hydrogen atoms, arranged tetrahedrally around the carbon atom. The representation of methane molecule is H-X-H, where X represents the carbon atom and the dashes (-) represent single covalent bonds between carbon and hydrogen atoms. Option C, H-X-H, accurately represents the formation of methane molecule (CH4) through the reaction of carbon with hydrogen.

Pure, freshly-distilled water has a pH of 7, which indicates that it is neutral. A pH of 7 means that the concentration of H+ ions in the water is equal to the concentration of OH- ions in the water. In other words, the water is neither acidic nor basic, as the concentrations of both types of ions are balanced.

Evolution is the correct answer because it encompasses all the given statements. It explains the unity and diversity of life by showing how different species share common ancestors and have evolved over time. It also explains why certain traits are present in multiple organisms, as these traits may have been advantageous and selected for through natural selection. Additionally, evolution accounts for the phenomenon of convergent evolution, where distantly related organisms develop similar traits due to similar environmental pressures. Lastly, evolution explains how organisms become adapted to their environment through the process of natural selection, where individuals with favorable traits are more likely to survive and reproduce.

Ice floats in liquid water because hydrogen bonds stabilize and keep the molecules of ice further apart than the water molecules of liquid water. This means that the density of ice is lower than that of liquid water, causing it to float. The hydrogen bonds in ice create a lattice structure, which gives it a lower density and allows it to float on the denser liquid water.

The high surface tension of water allows water striders to walk across the surface of a small pond. Surface tension is the cohesive force between water molecules at the surface, which creates a "skin" that is strong enough to support the weight of small insects like water striders. This is possible because water molecules are polar and can form hydrogen bonds with each other, creating a cohesive force. As a result, water acts like a flexible membrane that can support the weight of these insects without breaking.

The size limits for certain types of cells are primarily caused by the need for a surface area of sufficient area to allow the cell's function. This is because as cells grow larger, their volume increases at a faster rate than their surface area. This can lead to a decreased surface area-to-volume ratio, which is essential for efficient exchange of nutrients, gases, and waste products with the environment. Therefore, to maintain optimal functioning, cells must stay within a size range that allows for an adequate surface area-to-volume ratio.

The smooth endoplasmic reticulum is primarily involved in the synthesis of oils, phospholipids, and steroids. It lacks ribosomes on its surface, distinguishing it from the rough endoplasmic reticulum. The smooth endoplasmic reticulum plays a crucial role in lipid metabolism, including the synthesis of various lipids such as oils, phospholipids, and steroids. It is also involved in detoxification processes and the regulation of calcium levels in cells. Therefore, the smooth endoplasmic reticulum is the correct answer for this question.

Small and hydrophobic molecules pass through a cell membrane most easily. This is because the cell membrane is made up of a phospholipid bilayer, which has a hydrophobic interior. Small molecules can easily pass through the hydrophobic region of the membrane, while hydrophilic or polar molecules have difficulty crossing the hydrophobic barrier. Additionally, large molecules like proteins or carbohydrates are generally too big to pass through the membrane without the help of specific transport proteins. Monosaccharides such as glucose, although small, are polar and therefore have a harder time crossing the hydrophobic membrane.

The given statement that is not correct regarding the Calvin cycle of photosynthesis is "these reactions begin soon after sundown and end before sunrise." The Calvin cycle does not have a specific time frame and can occur during both day and night. The cycle is not dependent on sunlight and can continue as long as the necessary substrates and enzymes are available. Therefore, the timing of the Calvin cycle is not restricted to the nighttime hours.

Including a control group in an experiment is important because it allows researchers to compare the results of the experimental group to a group that is not exposed to the variable being tested. This helps to determine if any observed effects are actually caused by the variable being tested or if they are due to other factors. Without a control group, it would be impossible to confidently attribute any observed results to the variable being studied. Therefore, the presence of a control group provides a basis for evaluating the effectiveness or impact of the variable being tested.

Hydrogen bonds are responsible for maintaining the secondary structure of a protein. Secondary structure refers to the local folding patterns within a protein, such as alpha helices and beta sheets. Hydrogen bonds form between the amino acid residues of the protein backbone, specifically between the carbonyl oxygen atom and the amide hydrogen atom. These bonds stabilize the structure and help to maintain its shape. Other types of bonds, such as ionic bonds, phosphodiester bonds, peptide bonds, and disulfide bonds, are involved in other aspects of protein structure and function.

A controlled experiment is one in which there are at least two groups, one of which does not receive the experimental treatment. This is because in a controlled experiment, the goal is to compare the effects of the experimental treatment on the group that receives it, to the group that does not receive it. By having a control group that does not receive the treatment, any observed effects can be attributed to the treatment itself, rather than any other variables. This helps to ensure that the results are accurate and that any differences between the groups can be confidently attributed to the experimental treatment.

Carbon has an atomic number of 6, which means it has 6 protons in its nucleus. The atomic mass of an element is the sum of the number of protons and neutrons in its nucleus. Since 14C is heavier than 12C, it means that it has more neutrons. Therefore, the atomic nucleus of 14C contains 6 protons and 8 neutrons.

Robert Hooke is the correct answer because he was the first person to name and describe cells in 1665. Hooke used a primitive microscope to observe thin slices of cork and noticed small compartments that he called "cells" due to their resemblance to small rooms or cells in a monastery. This discovery laid the foundation for the field of cell biology and was a significant contribution to our understanding of the microscopic world.

The relationship between Atom 1 and Atom 2 is that they are isotopes. Isotopes are atoms of the same element that have different numbers of neutrons in their nuclei. In this case, Atom 1 and Atom 2 have the same number of protons (1) and electrons (1), but they have a different number of neutrons (3 and 1 respectively). Therefore, they are isotopes of each other.

The statement "Virtually all organisms require the same elements in the same quantities" is false. Different organisms have different elemental requirements and may require different quantities of certain elements.

The correct answer is 120 thymine and 120 adenine molecules. This is because in DNA, adenine always pairs with thymine through two hydrogen bonds, while cytosine always pairs with guanine through three hydrogen bonds. Therefore, if there are 120 adenine molecules, there must be an equal number of thymine molecules to form the complementary base pairs and maintain the double-stranded structure of DNA.

Altering any of the levels of structural organization (primary, secondary, tertiary, and quaternary) can change the function of a protein. The primary structure refers to the sequence of amino acids in a protein, and any changes in this sequence can lead to a different protein with a different function. The secondary structure refers to the folding patterns of the protein, and altering these patterns can affect the protein's function. The tertiary structure refers to the overall 3D shape of the protein, and changes in this structure can disrupt the protein's function. The quaternary structure refers to the arrangement of multiple protein subunits, and altering this arrangement can also impact the protein's function. Therefore, any changes in these levels of structural organization can result in a different protein function.

The correct answer is incorrect concentrations of ions in the semen. In cystic fibrosis, the chloride ion channels are missing or non-functional, which can lead to imbalances in the concentration of ions in various bodily fluids, including semen. This can affect the overall quality and viability of the sperm, potentially leading to fertility issues in males with cystic fibrosis.

The correct answer is that carbon has a valence of 4. Valence refers to the number of bonds that an atom can form with other atoms. Carbon has 4 valence electrons, which allows it to form strong covalent bonds with a variety of other elements. This property of carbon enables it to form complex and diverse organic compounds, making it compatible with a greater number of different elements than any other type of atom.

Hydrophobic substances such as vegetable oil are nonpolar substances that repel water molecules. This is because nonpolar substances do not have positive or negative charges, so they do not interact with the polar water molecules. Instead, they form clusters and separate from the water, creating a repulsive effect.

The movement of potassium into an animal cell requires an energy source such as ATP or a proton gradient. This is because potassium ions are positively charged and need to move against their concentration gradient, from an area of low concentration to high concentration. This movement requires energy, which can be provided by ATP molecules or by utilizing the energy stored in a proton gradient across the plasma membrane. A co-transport protein may also be involved in facilitating the movement of potassium ions into the cell. High cellular concentrations of potassium and low cellular concentrations of sodium are not directly responsible for the movement of potassium into the cell.

Lysosomes contain hydrolytic enzymes. These enzymes are responsible for breaking down various molecules, such as proteins, nucleic acids, and carbohydrates, into smaller components that can be used by the cell. This process, known as hydrolysis, is essential for the recycling of cellular components and the digestion of foreign substances that enter the cell. Lysosomes also play a role in the removal of damaged organelles and the regulation of cell death. Therefore, lysosomes are the correct answer as they are the primary site for hydrolytic enzyme activity within the cell.

Cilia and flagella both contain the 9 + 2 arrangement of microtubules. This arrangement refers to the structure of the axoneme, which is the core of cilia and flagella. It consists of nine pairs of microtubules surrounding a central pair, resulting in a "9 + 2" pattern. Centrioles, on the other hand, have a different arrangement of microtubules known as the "9 + 0" pattern, where there are only nine triplets of microtubules and no central pair. Therefore, the correct answer is A and C only.

The P680 chlorophyll donates a pair of protons to NADPH, which is thus converted to NADP+. This statement is false because it is the P680 chlorophyll that donates a pair of electrons, not protons, to NADP+ in order to convert it to NADPH. Protons are involved in the process of chemiosmosis, where they are pumped across the thylakoid membrane to create a proton gradient that drives ATP synthesis.

The correct answer is red and yellow. The leaves of the plant appear reddish yellow, indicating that the pigment in the plant is absorbing all other colors of visible light except for red and yellow. Therefore, the wavelengths of red and yellow light are not being absorbed by this pigment.

This answer represents the hierarchy of biological organization from least to most complex. It starts with the molecule, which is the smallest unit of biological organization. Then, it progresses to the organelle of an intestinal cell, which is a subunit within the cell. Next, it moves to the intestinal cell itself, which is a single cell within the tissue. Then, it goes to the intestinal tissue, which is a group of cells working together. After that, it moves to the digestive system, which is a collection of organs involved in digestion. Finally, it ends with the organism, which is the highest level of biological organization.

NH3 is a weak base because it only partially dissociates in water to form NH4+ and OH- ions. HCl is a strong acid because it completely dissociates in water to form H+ and Cl- ions.

When the pH of a solution increases from 5 to 7, it means that the solution becomes less acidic and more basic. This is because the pH scale is logarithmic, so each unit change represents a tenfold difference in acidity or basicity. Since the concentration of OH- ions is directly related to the basicity of a solution, an increase in pH indicates that the concentration of OH- ions has increased. Therefore, the concentration of OH- is 100 times greater than what it was at pH 5.

Gap junctions are specialized protein channels that allow for direct communication and exchange of ions and small molecules between the cytoplasm of adjacent animal cells. These junctions form small pores called connexons, which connect the cytoplasm of two cells and enable the passage of ions and other signaling molecules. This direct transfer of ions through gap junctions is essential for coordinating cellular activities, such as electrical signaling in the heart and smooth muscle contraction. Tight junctions, desmosomes, intermediate filaments, and plasmodesmata do not facilitate direct ion transfer between cytoplasmic compartments of adjacent animal cells.

Biologists would most likely use a transmission electron microscope to study the internal ultrastructure of cells. Unlike a light microscope, which uses visible light to magnify and visualize cells, a transmission electron microscope uses a beam of electrons to create highly detailed images of the internal structures of cells. This allows biologists to study the fine details of cellular organelles and other internal components at a much higher resolution than is possible with a light microscope. A scanning electron microscope, while useful for studying the surface features of cells, does not provide the same level of detail for internal structures as a transmission electron microscope.

Natural selection is the process by which individuals with advantageous traits are more likely to survive and reproduce, leading to the evolution of species over time. This process results in descent with modification, as the traits that are advantageous become more common in subsequent generations. Genetic variation is necessary for natural selection to occur, as it provides the raw material for advantageous traits to arise. Additionally, natural selection involves differential reproductive success, meaning that individuals with advantageous traits are more likely to reproduce and pass on their genes to future generations. Therefore, all of the statements A, B, and C are true of natural selection.

Buffer solutions are solutions that resist changes in pH when small amounts of acid or base are added to them. They are able to maintain a relatively constant pH because they contain a weak acid and its conjugate base, or a weak base and its conjugate acid. This allows them to neutralize the added acid or base, preventing drastic changes in pH. Therefore, the correct statement is that buffer solutions maintain a relatively constant pH when either acids or bases are added to them.

The mitochondrial inner membrane has proteins to accept electrons from NADH, the electron transport chain of proteins, proton pumps embedded in the membrane, and integral, transverse ATP synthase. However, it does not have high permeability to protons. Proton permeability would disrupt the electrochemical gradient necessary for ATP synthesis.

If a thylakoid is punctured and the interior is no longer separated from the stroma, it will directly affect the synthesis of ATP. This is because the thylakoid membrane is where the electron transport chain occurs, which generates a proton gradient across the membrane. This proton gradient is necessary for ATP synthase to produce ATP through chemiosmosis. Without a intact thylakoid membrane, the proton gradient cannot be maintained and the synthesis of ATP cannot occur efficiently.

Catabolic pathways involve the breakdown of larger molecules into smaller ones, such as polymers to monomers. This breakdown process releases energy, which can be used by the cell for various activities. Therefore, the statement "they release energy as they degrade polymers to monomers" accurately describes catabolic pathways.

The organism's ability to consume sugar and thrive in the absence of air suggests that it can switch between aerobic and anaerobic respiration. This is a characteristic of facultative anaerobes, which can use oxygen when available but can also survive without it by using alternative electron acceptors in the absence of oxygen. Therefore, the correct answer is that the organism is a facultative anaerobe.

The correct answer is that humans have enzymes that can hydrolyze the alpha glycosidic linkages of starch but not the beta glycosidic linkages of cellulose. This is because the enzymes in the human digestive system, such as amylase, are specifically designed to break down the alpha glycosidic linkages found in starch. However, they do not possess the necessary enzymes to break down the beta glycosidic linkages present in cellulose. This is why humans can digest starch, which is a polysaccharide made up of glucose molecules, but cannot digest cellulose, which is also a polysaccharide but made up of glucose molecules linked by beta glycosidic linkages.

If the nuclear lamina falls into disarray, it would likely result in a change in the shape of the nucleus. The nuclear lamina provides structural support to the nucleus and helps maintain its shape. Disruption of the lamina would lead to a loss of structural integrity, causing the nucleus to become misshapen or deformed. This could have implications for various cellular processes that rely on the proper organization and positioning of the nucleus within the cell.

Dehydration reactions involve the removal of a water molecule to form a covalent bond between monomers, resulting in the synthesis of polymers. This process is commonly used by cells to build complex macromolecules such as proteins, nucleic acids, and carbohydrates. By removing water, cells can link monomers together, allowing for the formation of larger and more complex structures. Therefore, dehydration reactions are the chemical mechanism by which cells make polymers from monomers.

During stage II, pyruvate is oxidized to acetyl CoA, and during stage III (Krebs cycle), acetyl CoA is further oxidized, resulting in the release of carbon dioxide. Therefore, carbon dioxide is released during stages II and III of glucose oxidation.

During cellular respiration, carbon dioxide (CO2) is released during the oxidation of pyruvate to acetyl CoA and the citric acid cycle. In the first step, pyruvate is converted into acetyl CoA, releasing one molecule of CO2. Then, during the citric acid cycle, acetyl CoA is further broken down, resulting in the release of two more molecules of CO2. Therefore, the correct answer is "oxidation of pyruvate to acetyl CoA and the citric acid cycle."

The second law of thermodynamics states that the entropy of an isolated system tends to increase over time. Entropy is a measure of the disorder or randomness in a system. The statement "every time energy changes form, there is a decrease in entropy" contradicts this law because energy changes can lead to an increase in entropy. For example, when energy is converted from a concentrated form (such as chemical energy in fuel) to a dispersed form (such as heat energy), the entropy of the system increases. Therefore, this statement does not align with the second law of thermodynamics.

Singer and Nicolson proposed that the membrane is a mosaic of protein molecules bobbing in a fluid bilayer of phospholipids. This model, known as the fluid mosaic model, suggests that the membrane is not a static structure but rather a dynamic system where proteins and lipids can move laterally within the bilayer. This model has been widely accepted and is still used today to describe the structure and function of biological membranes.