1.
Scientists use observations and data to form and test ___.
Correct Answer
B. Hypotheses
Explanation
Scientists use observations and data to form and test hypotheses. Hypotheses are educated guesses or proposed explanations for a phenomenon that can be tested through further experimentation and observation. Scientists use these hypotheses as a starting point to conduct research and gather evidence to support or refute them. By testing hypotheses, scientists can gain a deeper understanding of the natural world and develop theories that explain the observed phenomena.
2.
During an experiment, which factors are observed and measured?
Correct Answer
A. Dependent variables
Explanation
During an experiment, the factors that are observed and measured are called dependent variables. These variables are influenced by the independent variables, which are manipulated by the researcher. The dependent variables are the outcomes or results of the experiment and are measured to determine the effect of the independent variables. Constants are factors that are kept the same throughout the experiment to ensure that any changes observed can be attributed to the independent variables. Hypotheses, on the other hand, are proposed explanations or predictions about the relationship between the independent and dependent variables.
3.
What gives water many properties that are important to living things?
Correct Answer
B. Hydrogen bonds
Explanation
Hydrogen bonds are responsible for giving water many properties that are important to living things. These bonds are formed between the hydrogen atoms of one water molecule and the oxygen atoms of neighboring water molecules. This creates a network of interconnected water molecules, leading to properties such as high surface tension, cohesion, and adhesion. Hydrogen bonds also contribute to water's ability to dissolve many substances, making it an excellent solvent. Additionally, these bonds give water a high heat capacity, allowing it to absorb and release heat slowly, which helps regulate temperature in living organisms.
4.
The four main types of carbon-based molecules in organisms are carbohydrates, lipids, nucleic acids, and ___.
Correct Answer
C. Proteins
Explanation
Proteins are the fourth main type of carbon-based molecules in organisms. They are large, complex molecules made up of amino acids and play crucial roles in various biological processes. Proteins are involved in structural support, enzymatic reactions, transportation, communication, and defense mechanisms in living organisms. They are essential for the growth, development, and functioning of cells and tissues.
5.
When graphing experimental results, you should place the ______ onto the y axis.
Correct Answer
B. Dependent variables
Explanation
When graphing experimental results, the dependent variables should be placed on the y-axis. The dependent variables are the ones that are being measured or observed and are expected to change as a result of the independent variables. By placing the dependent variables on the y-axis, we can easily visualize and analyze how they are affected by the independent variables.
6.
If an organic molecule model contains carbon atoms arranged in a long chain, it is probably a model of ___.
Correct Answer
B. A lipid
Explanation
If an organic molecule model contains carbon atoms arranged in a long chain, it is likely a model of a lipid. Lipids are organic molecules that consist of long hydrocarbon chains, which are made up of carbon and hydrogen atoms. These chains can be found in various types of lipids, such as fatty acids, triglycerides, and phospholipids. Therefore, if a model shows carbon atoms arranged in a long chain, it indicates a lipid structure.
7.
Many factors should remain unchanged during an experiment. These factors are referred to as ___.
Correct Answer
C. Controlled variables
Explanation
Controlled variables are factors that are intentionally kept constant or unchanged during an experiment. This is done to ensure that any observed changes or effects can be attributed to the independent variable being tested. By controlling these variables, researchers can minimize the influence of external factors and increase the reliability and validity of their results.
8.
DNA and RNA are two types of ___.
Correct Answer
D. Nucleic acids
Explanation
DNA and RNA are both nucleic acids. Nucleic acids are macromolecules that carry genetic information and are essential for the storage, transmission, and expression of genetic information in living organisms. DNA (deoxyribonucleic acid) is found in the nucleus of cells and contains the genetic instructions for the development and functioning of living organisms. RNA (ribonucleic acid) is involved in the synthesis of proteins based on the instructions provided by DNA. Both DNA and RNA play crucial roles in the functioning and development of living organisms, making nucleic acids the correct answer.
9.
The smallest basic unit of matter is the ___.
Correct Answer
A. Atom
Explanation
An atom is the smallest basic unit of matter. It is composed of subatomic particles such as protons, neutrons, and electrons. Atoms combine to form molecules, compounds, and cells, but they themselves cannot be broken down into smaller particles without losing their fundamental properties. Therefore, atom is the correct answer as it represents the smallest indivisible unit of matter.
10.
Which of the following is formed when an atom gains or loses electrons?
Correct Answer
D. Ion
Explanation
An ion is formed when an atom gains or loses electrons. When an atom gains electrons, it becomes negatively charged and is called an anion. When an atom loses electrons, it becomes positively charged and is called a cation. Ions are formed through the process of ionization, which occurs when atoms interact with other atoms or molecules and transfer electrons. Ions play a crucial role in chemical reactions and are important in various biological processes.
11.
Atoms in molecules share pairs of electrons when they make ___.
Correct Answer
B. Covalent bond
Explanation
Atoms in molecules share pairs of electrons when they make covalent bonds. In a covalent bond, atoms share electrons in order to achieve a stable electron configuration. This sharing of electrons allows the atoms to fill their outermost energy levels and become more stable. Ionic bonds involve the transfer of electrons, hydrogen bonds are a type of weak attraction between a hydrogen atom and an electronegative atom, and polymers are large molecules made up of repeating subunits.
12.
Substances are changed into different substances when bonds break and reform during ___.
Correct Answer
B. Chemical reactions.
Explanation
Chemical reactions involve the breaking and reforming of bonds between atoms, resulting in the transformation of substances into different substances. This process occurs when reactant molecules collide and undergo a rearrangement of atoms, forming new bonds and breaking existing ones. Chemical equilibrium refers to a state in which the forward and reverse reactions are occurring at equal rates, but it does not necessarily involve the formation of new substances. Ion formation and hydrogen bonding are specific types of chemical bonding and do not encompass the overall process of substances changing into different substances.
13.
Fats, oils, and cholesterol are all types of ___.
Correct Answer
B. Lipids.
Explanation
Fats, oils, and cholesterol are all types of lipids. Lipids are a group of organic compounds that are insoluble in water but soluble in organic solvents. They play a crucial role in storing energy, providing insulation, and cushioning 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 production of hormones, vitamin D, and cell membranes. Therefore, lipids encompass all these substances mentioned in the question.
14.
Protein polymers are made of a series of ___.
Correct Answer
A. Amino acids
Explanation
Protein polymers are made of a series of amino acids. Amino acids are the building blocks of proteins. They are organic compounds that contain an amino group (-NH2), a carboxyl group (-COOH), and a side chain that varies between different amino acids. When amino acids are linked together through peptide bonds, they form long chains called protein polymers. These chains can fold and interact with each other to create the complex structures and functions of proteins. Monosaccharides are the building blocks of carbohydrates, histones are proteins that help organize DNA, and DNA strands are nucleic acids that carry genetic information.
15.
The activation energy needed for a chemical reaction is decreased by a ___.
Correct Answer
A. Catalyst
Explanation
A catalyst is a substance that increases the rate of a chemical reaction by lowering the activation energy required for the reaction to occur. It does this by providing an alternative pathway for the reaction with a lower activation energy. Therefore, the correct answer is catalyst.
16.
In the lock-and-key model of enzyme function shown in Figure 2.2, what is happening in step 2?
Correct Answer
C. The enzyme is causing new bonds to form between the substrates.
Explanation
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 formation of chemical bonds between the substrates, which leads to the formation of a product. This is a key step in the catalyzed reaction, where the enzyme acts as a catalyst to lower the activation energy required for the reaction to occur. By facilitating the formation of new bonds, the enzyme increases the efficiency of the reaction and allows it to proceed at a faster rate.
17.
Which aspect of a chemical reaction is affected by enzymes?
Correct Answer
B. Rate
Explanation
Enzymes are biological catalysts that speed up the rate of chemical reactions. They accomplish this by lowering the activation energy required for the reaction to occur. Therefore, enzymes directly affect the rate of a chemical reaction.
18.
What pH would be considered a strong base?
Correct Answer
D. 12
Explanation
A pH of 12 would be considered a strong base. The pH scale measures the acidity or alkalinity of a substance, with values below 7 indicating acidity and values above 7 indicating alkalinity. A pH of 12 is significantly higher than 7, indicating a highly alkaline solution. Strong bases are substances that completely dissociate in water to release hydroxide ions, and a pH of 12 suggests a high concentration of hydroxide ions, making it a strong base.
19.
Which of the following molecules found in the food we eat is most commonly broken down to make ATP (providing us with the most readily available energy)?
Correct Answer
A. Carbohydrates
Explanation
Carbohydrates are the molecules found in food that are most commonly broken down to make ATP, providing us with readily available energy. Carbohydrates are easily digested and converted into glucose, which is then used by our cells to produce ATP through cellular respiration. Lipids and proteins can also be used for energy, but they require more complex processes to be broken down and converted into ATP. Vitamins, on the other hand, do not provide energy directly but are essential for various metabolic reactions in the body.
20.
Which of the following is a major principle upon which cell theory is based?
Correct Answer
C. All organisms are made of cells.
Explanation
The major principle upon which cell theory is based is that all organisms are made of cells. This principle states that cells are the fundamental units of life and that all living things are composed of one or more cells. This concept was proposed by scientists Schleiden and Schwann in the 19th century and has been widely accepted since then. It forms the foundation of modern biology and our understanding of the structure and function of living organisms.
21.
Identify the type of cell shown in Figure 3.1.
Correct Answer
D. Eukaryotic
Explanation
The cell shown in Figure 3.1 is identified as eukaryotic. This is because eukaryotic cells are characterized by having a nucleus enclosed within a membrane, as well as other membrane-bound organelles. This can be observed in the image provided, where the cell clearly shows a distinct nucleus and other organelles such as mitochondria.
22.
Which organelle is the storehouse for a cell's genetic information?
Correct Answer
D. Nucleus
Explanation
The nucleus is the storehouse for a cell's genetic information. It contains the cell's DNA, which carries the instructions for the cell's functions and characteristics. The DNA is organized into structures called chromosomes, which are located within the nucleus. The nucleus is surrounded by a nuclear membrane, which helps protect the DNA and regulate the passage of molecules in and out of the nucleus. Overall, the nucleus plays a crucial role in storing and safeguarding the cell's genetic information.
23.
Which phrase best describes rough ER?
Correct Answer
A. Studded with ribosomes
Explanation
Rough ER is described as "studded with ribosomes" because it is a network of membranous tubules and sacs that have ribosomes attached to their surface. These ribosomes are responsible for protein synthesis, making rough ER involved in the production, folding, and modification of proteins. The ribosomes give the rough ER a "rough" appearance under a microscope, distinguishing it from smooth ER, which lacks ribosomes.
24.
Which organelles supply energy to the cell?
Correct Answer
C. Mitochondria
Explanation
Mitochondria are the organelles responsible for supplying energy to the cell. They are often referred to as the "powerhouses" of the cell because they generate adenosine triphosphate (ATP), which is the main source of energy for cellular processes. Mitochondria produce ATP through a process called cellular respiration, where they break down glucose and other molecules to release energy. This energy is then used by the cell to perform various functions such as movement, growth, and reproduction.
25.
Which organelles contain enzymes that break down old cell parts?
Correct Answer
C. Lysosomes
Explanation
Lysosomes are organelles that contain enzymes responsible for breaking down old cell parts. They function as the recycling centers of the cell, breaking down and digesting cellular waste, damaged organelles, and foreign substances. This process, known as autophagy, helps maintain cellular health and remove unnecessary or dysfunctional components. Therefore, lysosomes are the correct answer to the question.
26.
Which organelles are found only in plant cells?
Correct Answer
A. Chloroplasts
Explanation
Chloroplasts are organelles that are found only in plant cells. They are responsible for photosynthesis, the process by which plants convert sunlight into energy. Chloroplasts contain chlorophyll, a pigment that absorbs light energy, and other molecules necessary for photosynthesis. This organelle is not found in animal cells, making it a unique feature of plant cells.
27.
What is the main function of the Golgi apparatus?
Correct Answer
C. Process and deliver proteins
Explanation
The Golgi apparatus is responsible for processing and delivering proteins. It receives proteins from the endoplasmic reticulum, modifies them by adding sugars and lipids, and packages them into vesicles for transport to their final destinations within the cell or for secretion outside of the cell. This process ensures that proteins are correctly folded, modified, and sorted before being transported to their appropriate locations.
28.
Which phrase best describes the property of selective permeability?
Correct Answer
A. Some molecules pass
Explanation
Selective permeability refers to the property of a membrane or barrier that allows only certain molecules or ions to pass through while blocking others. In this case, the correct answer "some molecules pass" accurately describes this property, indicating that only certain molecules are able to pass through the barrier while others are not.
29.
Mitochondria and chloroplasts are both sites of ___.
Correct Answer
A. Energy conversion.
Explanation
Mitochondria and chloroplasts are both sites of energy conversion. Mitochondria are responsible for converting nutrients into ATP, the main source of energy for cells through cellular respiration. Chloroplasts, on the other hand, convert light energy into chemical energy through photosynthesis, producing glucose and oxygen. Both organelles play crucial roles in energy conversion processes in different ways.
30.
Which word best describes the structure of the cell membrane?
Correct Answer
A. Layered
Explanation
The word "layered" best describes the structure of the cell membrane because it is composed of a phospholipid bilayer, which consists of two layers of phospholipid molecules. This bilayer forms a flexible barrier that separates the inside of the cell from its external environment.
31.
Which of the following statements about succession is correct?
Correct Answer
C. Secondary succession can occur where a disturbance has left soil intact.
Explanation
Secondary succession can occur where a disturbance has left soil intact because secondary succession is the process of ecological succession that occurs in an area that has been previously inhabited by plants and has existing soil. This type of succession happens when there is a disturbance, such as a fire or a flood, that removes the existing vegetation but does not remove the soil. In secondary succession, new plant species can colonize the area and gradually replace the previous plant community. This is different from primary succession, which occurs in areas where there is no existing soil, such as on bare rock or after a volcanic eruption.
32.
While on the nature trail, a student turns over a rotted log. Fungi, termites, pill bugs, ants, slugs, and earthworms are observed living in and around the log. Altogether, these organisms represent a ___.
Correct Answer
A. Community
Explanation
The organisms observed living in and around the rotted log represent a community. A community is a group of different species living in the same area and interacting with each other. In this case, the fungi, termites, pill bugs, ants, slugs, and earthworms are all part of the same community as they inhabit the log and have relationships with each other.
33.
A doctor prescribed leach therapy (purposefully allowing leaches to remove blood) for a person suffering from a blood disorder, resulting in the person being helped. This would then be an example of
Correct Answer
C. Mutualism
Explanation
Leach therapy involves the intentional use of leaches to remove blood from a person's body. In this scenario, the person suffering from the blood disorder is being helped by the therapy. While the leaches benefit from obtaining a blood meal, the person also benefits from the removal of excess blood, which can be beneficial for certain blood disorders. Therefore, this is an example of mutualism, where both parties involved benefit from the interaction.
34.
In a pond...
1) the primary producer is a green alga, Spirogyra,
2) the primary consumer is the crustacean, Daphnia,
3) the secondary consumer is a small fish, the bluegill, and
4) the tertiary consumer is a larger fish, the smallmouth bass.
What changes can be expected in the pond if the Daphnia are killed with pesticides?
Correct Answer
D. The smallmouth bass population will die.
Explanation
If the Daphnia, which are the primary consumers, are killed with pesticides, it would disrupt the food chain in the pond. Since the Daphnia are the primary food source for the bluegill, the bluegill population will likely decrease due to lack of food. As a result, the smallmouth bass, which are tertiary consumers and depend on the bluegill as their food source, will also suffer from the lack of prey and their population is likely to decrease or even die out.
35.
Scientists found that, over a period of 200 years, a mountain pond was transformed into a meadow. During that time, several communities of organisms were replaced by different communities. Which of these best explains why new communities were able to replace older communities?
Correct Answer
C. The abiotic characteristics of the habitat changed.
Explanation
The abiotic characteristics of the habitat changed. This suggests that the physical and non-living factors in the environment, such as temperature, water availability, and soil composition, underwent significant alterations over the 200-year period. These changes likely created new conditions that favored the survival and growth of different species, leading to the replacement of the older communities with new ones.
36.
The carrying capacity of a population in an ecosystem is ___.
Correct Answer
C. An average maximum number of individuals of a population that an ecosystem supports.
Explanation
The carrying capacity of a population in an ecosystem refers to the average maximum number of individuals that the ecosystem can support. It is the point at which the available resources in the ecosystem, such as food, water, and space, are able to sustain the population without causing detrimental effects. This concept helps in understanding the balance between population size and available resources in an ecosystem.
37.
In Fig. 3.3, identify the structure labeled C.
Correct Answer
D. Endoplasmic Reticulum
Explanation
The correct answer is Endoplasmic Reticulum. In Fig. 3.3, structure labeled C resembles the structure of the endoplasmic reticulum. The endoplasmic reticulum is a network of membranes found in eukaryotic cells that is involved in the synthesis, folding, and transport of proteins and lipids. It plays a crucial role in cell metabolism and is responsible for the production of proteins and lipids that are used within the cell or exported to other parts of the organism.
38.
In Fig. 3.3, what is the function of the structure labeled F.
Correct Answer
A. Hold water
Explanation
The structure labeled F in Fig. 3.3 is responsible for holding water. This suggests that it is likely a water-holding structure such as a vacuole or a water-filled cell. It plays a crucial role in maintaining the water balance and hydration of the organism.
39.
What is the function of the entire structure shown in the diagram?
Correct Answer
B. Regulate what goes in/out of a cell
Explanation
The entire structure shown in the diagram is responsible for regulating what goes in and out of a cell. This implies that it controls the movement of substances such as ions, molecules, and nutrients across the cell membrane. It plays a crucial role in maintaining homeostasis and ensuring that the cell's internal environment is stable and suitable for its proper functioning.
40.
The structures labeled B would be made of ___.
Correct Answer
B. Protein
Explanation
The structures labeled B would be made of protein because lipids are not typically involved in structural components, cellulose is a carbohydrate and not a protein, and fatty acid chains are a component of lipids and not a structural component on their own. Therefore, protein is the most likely option for the material that makes up the structures labeled B.
41.
Unlike a eukaryoteic cell, a prokaryotic cell does not have...
Correct Answer
B. A nucleus.
Explanation
A prokaryotic cell does not have a nucleus. Unlike eukaryotic cells, prokaryotic cells lack a membrane-bound nucleus where the genetic material is stored. Instead, their DNA is located in the cytoplasm, which is a gel-like substance that fills the cell. Prokaryotic cells do have DNA, but it is not enclosed within a nucleus.
42.
A membrane-bound sac used to transport substances into and out of cells is a ...
Correct Answer
D. Vesicle
Explanation
A vesicle is a membrane-bound sac that is used to transport substances into and out of cells. It acts as a small storage compartment within the cell and can transport molecules such as proteins, lipids, and other cellular components. Vesicles play a crucial role in processes such as endocytosis, exocytosis, and intracellular trafficking. They are involved in the uptake of nutrients, secretion of hormones and enzymes, and the removal of waste materials from the cell. Therefore, a vesicle is the correct answer as it accurately describes the function of this membrane-bound sac in cellular transport.
43.
Which of the following is a network of proteins that supports and gives shape to a cell?
Correct Answer
A. Cytoskeleton
Explanation
The cytoskeleton is a network of proteins that provides structural support and shape to a cell. It is responsible for maintaining cell shape, organizing cell organelles, and facilitating cell movement. The cytoskeleton is made up of three main components: microfilaments, intermediate filaments, and microtubules. These protein filaments work together to give the cell its structure and allow for various cellular processes to occur. The other options, cytoplasm, vesicles, and vacuoles, do not specifically refer to the network of proteins that supports and shapes a cell.
44.
Which of the following organelles can be found on the surface of the endoplasmic reticulum?
Correct Answer
C. Ribosomes
Explanation
Ribosomes can be found on the surface of the endoplasmic reticulum. The endoplasmic reticulum is a network of membranes within the cell that is involved in protein synthesis and lipid metabolism. Ribosomes are responsible for protein synthesis, and they can be found either free in the cytoplasm or attached to the rough endoplasmic reticulum. The presence of ribosomes on the surface of the endoplasmic reticulum allows for the direct transfer of newly synthesized proteins into the ER for further processing and modification.
45.
Which organelle is the storehouse for most of a cell's genetic information?
Correct Answer
A. Nucleus
Explanation
The nucleus is the storehouse for most of a cell's genetic information. It contains the cell's DNA, which carries the instructions for the cell's functions and characteristics. The DNA is organized into structures called chromosomes, which are located inside the nucleus. The nucleus also controls the cell's activities and is responsible for the replication and transmission of genetic information during cell division. The other organelles listed (mitochondrion, centriole, and chloroplast) have different functions and do not store the cell's genetic information.
46.
What is the main function of the Golgi apparatus?
Correct Answer
C. Process and deliver proteins
Explanation
The main function of the Golgi apparatus is to process and deliver proteins. It receives proteins from the endoplasmic reticulum, modifies them by adding sugars and lipids, and packages them into vesicles for transport to their final destinations within the cell or for secretion outside of the cell. The Golgi apparatus plays a crucial role in the sorting, packaging, and distribution of proteins, ensuring that they reach their intended targets and perform their specific functions.
47.
What is the term for the jelly-like substance that is contained insidethe cell membrane?
Correct Answer
A. Cytoplasm
Explanation
Cytoplasm is the correct answer because it refers to the jelly-like substance that is contained inside the cell membrane. It is a semi-fluid substance that fills the cell and contains various organelles and molecules necessary for cellular processes. The nucleus is the control center of the cell, organelles are specialized structures within the cell, and DNA is the genetic material found within the nucleus.
48.
Which of the following is responsible for making membrane and protein?
Correct Answer
A. Rough Endoplasmic Reticulum
Explanation
The rough endoplasmic reticulum is responsible for making membranes and proteins. It contains ribosomes on its surface, which are responsible for protein synthesis. The rough ER is involved in the production of membrane proteins and secretory proteins, which are then transported to other parts of the cell or outside the cell.
49.
Which of the following is responsible for breaking down toxins and drugs in liver cells?
Correct Answer
B. Smooth Endoplasmic Reticulum
Explanation
The smooth endoplasmic reticulum is responsible for breaking down toxins and drugs in liver cells. It contains enzymes called cytochrome P450 that help metabolize and detoxify various substances. These enzymes modify the structure of toxins and drugs, making them easier to eliminate from the body. The rough endoplasmic reticulum is involved in protein synthesis, the Golgi apparatus is responsible for packaging and modifying proteins, and chloroplasts are found in plant cells and are involved in photosynthesis.
50.
A membrane-bound sac that contains digestive enzymes is a ...
Correct Answer
C. Lysosome.
Explanation
A lysosome is a membrane-bound sac that contains digestive enzymes. These enzymes help break down waste materials and cellular debris, aiding in the process of cellular digestion and recycling. Lysosomes play a crucial role in maintaining cellular homeostasis and removing harmful substances from the cell. They are responsible for the degradation of macromolecules such as proteins, nucleic acids, lipids, and carbohydrates.