1.
During a scientific experiment, attempts are made to prove a hypothesis______by contrasting changeable factors called______against standard unchangeable factors called ____.
Correct Answer
A. False,variables, controls
Explanation
During a scientific experiment, attempts are made to prove a hypothesis by contrasting changeable factors called variables against standard unchangeable factors called controls. In this case, the correct answer is "false, variables, controls".
2.
The scientific method is based on discovering general principles through observation and experimentation, which is:
Correct Answer
A. Inductive reasoning
Explanation
The scientific method involves making observations, collecting data, and conducting experiments in order to discover general principles or patterns. This process of reasoning from specific observations to general conclusions is known as inductive reasoning. It involves gathering evidence and drawing conclusions based on the patterns or trends observed in the data. Deductive reasoning, on the other hand, involves starting with general principles or theories and using them to make specific predictions or hypotheses. In this case, since the scientific method is focused on discovering general principles through observation and experimentation, the correct answer is inductive reasoning.
3.
All of the following are true except:
Correct Answer
D. Theories are true and cannot be proven false
Explanation
The given statement "theories are true and cannot be proven false" is incorrect. Theories are not absolute truths and can be proven false if new evidence or data contradict them. Theories are developed based on existing evidence and can be modified or discarded if new information emerges. The scientific method encourages the testing and modification of theories to ensure they accurately explain the observed phenomena. Therefore, the statement contradicts the nature of scientific theories and is false.
4.
Which is not included in the cell theory?
Correct Answer
C. All cells require oxygen for their chemical reactions
Explanation
The cell theory states that all cells came from pre-existing cells, all cells are similar in composition, and all cells have homeostasis. However, it does not include the statement that all cells require oxygen for their chemical reactions. This means that there are some cells, such as anaerobic bacteria, that can carry out their chemical reactions without the need for oxygen.
5.
5) If cells>>tissue>>organs>>Organ systems>> the organizational analogy to organs in ecology would be:
Correct Answer
B. Community
Explanation
In ecology, a community refers to a group of interacting species that live in the same area and interact with each other. This is similar to how organs interact and work together within an organism. Just like organs have specific functions and work together to maintain the overall health of an organism, different species in a community have specific roles and interactions that contribute to the functioning and stability of the ecosystem. Therefore, the organizational analogy to organs in ecology is a community.
6.
19) All of the following statements about water are true except:
Correct Answer
C. The oxygen in a water molecule is larger than hydrogen, making oxygen partially positive due to the greater number of protons in it's nucleus
Explanation
Water is a polar molecule due to its bent shape and unequal distribution of charge. The oxygen atom attracts electrons more strongly than the hydrogen atoms, causing oxygen to have a partial negative charge and the hydrogen atoms to have partial positive charges. This polarity allows water to dissolve ionic compounds like NaCl. The statement that the oxygen in a water molecule is larger than hydrogen and partially positive due to the greater number of protons in its nucleus is incorrect. Oxygen is actually partially negative in water due to its higher electronegativity.
7.
28) Which chemical reaction is an example of a dehydration (condensation) reaction?
Correct Answer
D. Protein>>>amino acid+amino acid
Explanation
A dehydration (condensation) reaction involves the removal of a water molecule to form a new compound. In the given options, the reaction "protein>>>amino acid+amino acid" is an example of a dehydration reaction. This is because when proteins are broken down, a water molecule is removed to form a peptide bond between two amino acids, resulting in the formation of a dipeptide.
8.
29) Lactose is a disaccharide composed of:
Correct Answer
D. Glucose and galactose
Explanation
Lactose is a disaccharide composed of glucose and galactose. Disaccharides are formed when two monosaccharides join together through a condensation reaction, resulting in the formation of a glycosidic bond. In the case of lactose, a glucose molecule and a galactose molecule combine to form the disaccharide. This is the correct answer because it accurately describes the composition of lactose.
9.
30) Which of the following is not found in animals?
Correct Answer
C. Glycogen
Explanation
Glycogen is a form of stored glucose that serves as an energy reserve in animals and humans. It is primarily found in the liver and muscles. Unsaturated fatty acids, saturated fatty acids, and mitochondria are all found in animals. Unsaturated fatty acids are important for membrane structure and function, while saturated fatty acids provide energy and insulation. Mitochondria are the powerhouse of the cell, responsible for producing energy in the form of ATP through cellular respiration. Therefore, glycogen is the correct answer as it is not found in animals.
10.
35) Which of the following nitrogenous bases is found only in RNA?
Correct Answer
D. Uracil
Explanation
Uracil is found only in RNA and not in DNA. It is a nitrogenous base that pairs with adenine during RNA synthesis. Thymine, on the other hand, is found only in DNA and pairs with adenine during DNA replication. Guanine and adenine are common bases found in both RNA and DNA. Therefore, the correct answer is uracil.
11.
Which of the following pairs are purines
Correct Answer
A. Adenine and guanine
Explanation
Adenine and guanine are classified as purines. Purines are one of the two types of nitrogenous bases found in DNA and RNA, the other being pyrimidines. Purines have a double-ring structure, consisting of a six-membered ring fused to a five-membered ring. Adenine and guanine both have this double-ring structure, making them purines. On the other hand, cytosine, thymine, and uracil are pyrimidines, as they have a single-ring structure. Therefore, the correct answer is adenine and guanine.
12.
37) Which carbon in the deoxyribose sugar of DNA bears the hydroxyl group that forms a phosphodiesterase bond?
Correct Answer
C. C(3)
Explanation
The hydroxyl group that forms a phosphodiester bond in DNA is located on the C(3) carbon of the deoxyribose sugar. This hydroxyl group reacts with the phosphate group of the adjacent nucleotide to form the phosphodiester bond, which connects the nucleotides together and forms the backbone of the DNA molecule.
13.
38) The primary structure of protein is read from the:
Correct Answer
B. N terminus to the C terminus
Explanation
The primary structure of a protein refers to the linear sequence of amino acids in the protein chain. The N terminus is the end of the protein chain that has an amino group (-NH2), while the C terminus is the end that has a carboxyl group (-COOH). When reading the primary structure, we start from the N terminus and move towards the C terminus. This is because the amino acids are joined together in a specific order, with the amino group of one amino acid bonding with the carboxyl group of the next amino acid, forming a peptide bond. Therefore, the correct answer is N terminus to the C terminus.
14.
39) Of the following molecules, which did Urey and Miller not use in their famous experiment?
Correct Answer
B. O2
Explanation
Urey and Miller did not use O2 (oxygen) in their famous experiment. In their experiment, they simulated the conditions of early Earth's atmosphere and tested the hypothesis that organic molecules, such as amino acids, could be formed under those conditions. They used a mixture of H2O (water), H2S (hydrogen sulfide), and NH3 (ammonia) to mimic the atmosphere of that time. Oxygen was not included because it was believed that the early Earth's atmosphere was reducing, meaning it lacked oxygen. The absence of O2 allowed them to observe the formation of organic molecules in the absence of oxidative reactions.
15.
40) Which of the organisms was responsible for generating an oxidizing environment 2.5 billion years ago?
Correct Answer
D. Cyanobacteria
Explanation
Cyanobacteria were responsible for generating an oxidizing environment 2.5 billion years ago. Cyanobacteria are photosynthetic bacteria that release oxygen as a byproduct of photosynthesis. Through their metabolic activities, they significantly increased the levels of oxygen in the Earth's atmosphere, leading to the development of an oxidizing environment. This event, known as the Great Oxygenation Event, was a crucial turning point in the history of life on Earth, as it paved the way for the evolution of aerobic organisms.
16.
41) Archaebacteria evolved ______ years ago.
Correct Answer
C. 3.5 billion
Explanation
Archaebacteria evolved 3.5 billion years ago. This answer is based on scientific evidence and research that suggests that the earliest forms of life, including archaebacteria, appeared on Earth around this time. This estimation is derived from the analysis of ancient rocks and fossils, which provide clues about the origins and evolution of life on our planet.
17.
Evidence for endosymbiosis includes all of the following except
Correct Answer
C. Free living mitochondria
Explanation
The presence of free-living mitochondria is not evidence for endosymbiosis. Endosymbiosis is the theory that suggests that eukaryotic cells evolved from a symbiotic relationship between different types of cells, where one cell engulfed another and they formed a mutually beneficial relationship. The evidence for endosymbiosis includes circular DNA in chloroplasts, Giardia and Prochloron (organisms that have mitochondria-like structures), and double membranes in energy-producing organelles like mitochondria and chloroplasts. The presence of free-living mitochondria does not support the idea of endosymbiosis because endosymbiosis suggests that mitochondria became integrated into eukaryotic cells and are no longer free-living.
18.
43) The area of a cell is ______, whereas it's volume is______.
Correct Answer
B. Squared, cubed
Explanation
The area of a cell is squared because it is a two-dimensional measurement, representing the amount of surface covered by the cell. On the other hand, the volume of a cell is cubed because it is a three-dimensional measurement, representing the amount of space occupied by the cell.
19.
44) Aqueous solutions are:
Correct Answer
B. Water soluble solutions
Explanation
Aqueous solutions refer to solutions in which water is the solvent. Water soluble solutions are substances that can dissolve in water to form a homogeneous mixture. Therefore, the correct answer is water soluble solutions.
20.
Which statement is false?
Correct Answer
C. Oxygen is more lipid soluble than carbon dioxide
Explanation
Oxygen is less lipid soluble than carbon dioxide. Lipid solubility refers to the ability of a substance to dissolve in lipids or fats. Carbon dioxide is more soluble in lipids compared to oxygen. This is because carbon dioxide is nonpolar and can easily dissolve in the nonpolar lipid bilayer of cell membranes, while oxygen is less soluble due to its polar nature.
21.
The movement of glucose into a cell utilizing sodiums gradient is an example of:
Correct Answer
C. Facilatated diffusion
Explanation
Facilitated diffusion refers to the process by which molecules or ions move across a cell membrane with the help of specific transport proteins. In this case, glucose is being transported into the cell utilizing the sodium gradient, which means that it is moving from an area of higher concentration (outside the cell) to an area of lower concentration (inside the cell) with the assistance of specific transport proteins. This process does not require energy expenditure from the cell, unlike active transport. Therefore, the movement of glucose into the cell utilizing sodium's gradient is an example of facilitated diffusion.
22.
Which is not limited to a Vmax?
Correct Answer
A. Simple diffusion
Explanation
Simple diffusion is not limited to a Vmax because it is a passive process that occurs down a concentration gradient, without the need for carrier proteins or energy. It is a spontaneous movement of molecules from an area of higher concentration to an area of lower concentration until equilibrium is reached. Unlike active transport and facilitated diffusion, simple diffusion does not have a maximum rate of transport that can be reached or saturated. Therefore, it can continue indefinitely as long as there is a concentration gradient present.