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Questions on Standard 4 Students will understand and apply scientific concepts, principles, and theories pertaining to the physical setting and living environment and recognize the historical development of ideas in science. Key Idea 1—Application of Scientific Principles Living things are both similar to and different from each other and from nonliving things.
In which life function is the potential energy of organic compounds converted to a form of stored energy that can be used by the cell? transport respiration excretion regulation
Which life activity is not required for the survival of an individual organism? nutrition respiration reproduction synthesis
Which function of human blood includes the other three? transporting nutrients transporting oxygen maintaining homeostasis collecting wastes
In the human body, the blood with the greatest concentration of oxygen is found in the left atrium of the heart cerebrum of the brain nephrons of the kidney lining of the intestine
Which type of vessel normally contains valves that prevent the backward flow of materials? artery arteriole capillary vein For the next 4 question, select the excretory structure, chosen from the list below, that best answers the question. Then record its number.
Excretory Structures (1) Alveolus (2) Nephron (3) Sweat gland (4) Liver
Which structure forms urine from water, urea, and salts? Which structure removes carbon dioxide and water from the blood? Which structure is involved in the breakdown of red blood cells? The bones of the lower arm are connected to the muscles of the upper arm by ligaments tendons cartilage skin
The diagram below shows the same type of molecules in area A and area B. With the passage of time, some molecules move from area A to area B.
The movement is the result of the process of phagocytosis pinocytosis diffusion cyclosis
Which is the principal inorganic compound found in cytoplasm? lipid carbohydrate water nucleic acid
A specific organic compound contains only the elements carbon, hydrogen, and oxygen in a ratio of 1:2:1. This compound is most probably a nucleic acid carbohydrate protein lipid
Compared to ingested food molecules, end-product molecules of digestion are usually smaller and more soluble larger and more soluble smaller and less soluble larger and less soluble
The cellular function of the endoplasmic reticulum is to provide channels for the transport of materials convert urea to a form usable by the cell regulate all cell activities change light energy into chemical bond energy
In which organelles are polypeptide chains synthesized? nuclei vacuoles ribosomes cilia
Which organelle contains hereditary factors and controls most cell activities? nucleus cell membrane vacuole endoplasmic reticulum
Centrioles are cell structures involved primarily in cell division storage of fats enzyme production cellular respiration
Which cell structure contains respiratory enzymes? cell wall nucleolus mitochondrion vacuole
Which process is represented below? hydrolysis synthesis digestion respiration
Amino acids derived from the digestion of a piece of meat are transported to living cells of an animal. In the cell they are converted to cellulose used to attack invading bacteria synthesized into specific proteins incorporated into glycogen molecules
Which of the following variables has the least direct effect on the rate of a hydrolytic reaction regulated by enzymes? temperature pH carbon dioxide concentration enzyme concentration
Which term refers to the chemical substance that aids in the transmission of the impulse through the area indicated by X? neurotransmitter synapse neuron nerve
Which lists human nervous-system structures in order of increasing size? neuron, nerve, ganglion, receptor nerve, ganglion, neuron, receptor neuron, receptor, ganglion, nerve ganglion, receptor, nerve, neuron
Glands located within the digestive tube include gastric glands and thyroid glands gastric glands and intestinal glands thyroid glands and intestinal glands adrenal glands and intestinal glands
In humans, which substance is directly responsible for controlling the calcium levels of the blood? adrenalin insulin parathormone thyroxin
Base your answer to this question on the word equation below.
The process represented by the word equation is known as aerobic respiration fermentation chemosynthesis dehydration synthesis
The excretory organelles of some unicellular organisms are contractile vacuoles and cell membranes cell walls ribosomes centrioles
Which is a type of asexual reproduction that commonly occurs in many species of unicellular protists? external fertilization tissue regeneration binary fission vegetative propagation
Questions on Standard 4—Biological Concepts, Key Idea 1— Application of Scientific Principles: Answers and Explanations
Answers Explained
QUESTIONS ON STANDARD 4—Biological Concepts
2 Respiration is the life function by which ATP is made available to cells. Carbohydrate molecules are organic compounds. The breakdown of the carbohydrate molecules releases the energy stored in the bonds of the compounds. Potential energy is stored energy. The released potential energy is used to produce ATP. Wrong Choices Explained: (1) Transport is the life function by which materials are distributed throughout an organism. (3) Excretion is the life function by which the wastes of metabolism are removed from an organism. Carbon dioxide, water, ammonia, and urea are metabolic wastes. (4) Regulation is the life activity by which an organism responds to changes in its environment. The responses are controlled by the nervous system and the endocrine system.
3 Reproduction, the life function through which a parent organism gives rise to offspring, is not necessary for the survival of the parent. Although reproduction is not required for the survival of an individual, it is necessary for the survival of a species. If a given species loses its potential for reproduction, it will become extinct. Wrong Choices Explained: (1) Nutrition is a collective term that refers to the biochemical processes by which cells extract nutrient molecules from food substances. The nutrients are used to build tissues, provide energy, and regulate the many biochemical activities that occur in cells. Without nutrition, cells die and, consequently, so do organisms. Each organism is dependent on adequate nutrition for survival. (2) Respiration refers to the series of chemical changes that fuel molecules undergo to release chemical energy for cells. Respiration is necessary for the survival of the individual. Tissue cells cannot live without a means of obtaining chemical energy to power cellular activities such as active transport and metabolism. Of course, death of tissue cells means death of the individual. (4) Synthesis occurs when small molecules are joined chemically to form large molecules. Enzymes, hormones, and body tissues are the results of syntheses, without which an individual organism cannot survive. Synthesis is a building-up process in which molecules vital to the life of the organism are produced.
3 Maintaining homeostasis is the function of human blood that includes the other three. By transporting nutrients, oxygen, wastes, and other materials around the body, the blood helps to make essential materials available to every living body cell while removing potentially harmful materials from these tissues. Equal distribution of these materials helps to promote a steady state in the tissues essential to homeostatic balance. Wrong Choices Explained: (1), (2), (4) Transporting nutrients, transporting oxygen, and collecting wastes are all functions of the blood that are involved in maintaining homeostasis. Nutrients provide cells with dissolved food molecules. Oxygen is used by cells in the release of energy from these food molecules. Wastes such as urea and carbon dioxide are carried away from the cells for excretion into the environment.
1 Blood that has just returned from the lungs has the greatest concentration of oxygen. The left atrium of the heart receives blood directly from the lungs. Wrong Choices Explained: (2) Brain tissue is one of the largest consumers of oxygen. The blood circulating in the cerebellum gives up most of its oxygen to the nerve cells. (3) The largest concentration of metabolic wastes is found in the nephrons. The nephrons are filtering units in the kidney. (4) The largest concentration of digested nutrients is found in the lining of the intestine. Absorption of nutrients occurs through the villi in the small intestine.
4 Veins are blood vessels that carry blood to the heart. They contain valves that prevent the backflow of blood. The blood in veins is usually deoxygenated; the exception is the pulmonary vein in which the blood is rich in oxygen. Wrong Choices Explained: (1) Arteries are blood vessels that transport blood away from the heart. Arteries are rather thick-walled and pump blood in rhythm with the heart. They have no valves. (2) Small arteries are arterioles. This type of blood vessel functions similarly to arteries. Arterioles lead into capillaries. (3) Capillaries are the smallest blood vessels. They are one cell thick and permit diffusion of water, nutrients, gases, and other substances into and out of the bloodstream. Capillaries have no valves; they are the connecting vessels between arterioles and venules.
2 The nephron is the unit of structure of the kidney. Each nephron has a glomerulus, Bowman’s capsule, and kidney tubules. The kidney tubules filter out excess water, salts, and the wastes from protein metabolism. Urea and salts dissolved in water form urine.
1 The alveolus is an air sac in the lung. It not only permits the diffusion of oxygen from the lungs into the bloodstream but also aids in the diffusion of carbon dioxide and water vapor out of the blood into the lungs. 4 The liver is the largest gland in the body. One of its functions is to destroy old red blood cells and change the waste products into bile. The liver also synthesizes the anticoagulant known as heparin. 2 Tendons are tough connective tissues made strong by fibers. Tendons connect muscles to bones. The movable joints function when muscles pull on tendons. Wrong Choices Explained: (1) Ligaments are strong connective tissues that contain elastic muscle fibers. Ligaments connect bone to bone. (3) Cartilage is a supporting tissue that provides strength to body structures without rigidity. Cartilage supports structures such as the ears and nose and covers the ends of bones that form joints. The ground substance, or matrix, of cartilage is made of protein. (4) Skin is composed of epithelial tissue. Skin serves as a body covering and has no function in the movement of bones or muscles.
3 Diffusion is the process that results in the movement of molecules from a region of higher concentration (area A) to a region of lower concentration (area B). This net movement occurs until the concentrations of molecules have reached equilibrium between area A and area B. Wrong Choices Explained: (1), (2) Phagocytosis and pinocytosis are processes by which certain protists engulf their food and enclose it within a vacuole for digestion. (4) Cyclosis refers to the streaming of cytoplasm in the cell, a simple form of intracellular transport.
3 Inorganic compounds are compounds that do not contain carbon atoms. Water, the universal solvent, is the principal inorganic compound of cytoplasm. Water is the medium through which all chemical reactions take place in the cell. Wrong Choices Explained: (1), (2), (4) Lipids, carbohydrates, and nucleic acids are organic compounds. Organic compounds are carbon-containing compounds.
2 Glucose is the building block of carbohydrate molecules. The ratio of carbon to hydrogen to oxygen is 1:2:1 in glucose and all reducing sugars. By dehydration synthesis, many glucose molecules form complex carbohydrates. However, the 1:2:1 ratio holds. Wrong Choices Explained: (1) A nucleic acid is composed of a phosphate group, a protein base, and a five-carbon sugar. DNA and RNA are nucleic acids. The CHO 1:2:1 ratio is not applicable. (3) Proteins are built from amino acids, which, in addition to carbon, hydrogen, and oxygen, contain nitrogen. Some protein molecules also contain sulfur. The 1:2:1 ratio of elements does not apply to proteins because proteins are tissue builders whereas carbohydrates are fuel molecules. (4) Lipids are fats and are composed of three fatty acid molecules and one glycerol molecule. The 1:2:1 ratio of carbon to hydrogen to oxygen does not apply to fats.
1 The end products of digestion are usually smaller and more soluble than the ingested food molecules. Digestion makes available nutrient molecules that can diffuse across cell membranes and enter the cytoplasm of cells. Carbohydrates are broken down into glucose molecules. Fats are hydrolyzed into fatty acids and glycerol. Proteins are digested into their component amino acid molecules. Each of these end products of digestion is able to diffuse across cell membranes and enter into the biochemical activities of cells. Wrong Choices Explained: (2) Synthesis produces larger molecules. Larger molecules are more complex and are usually less soluble than smaller, simpler ones. Digestion results in smaller nutrient molecules. (3) Smaller molecules are usually more soluble than larger ones. Digestion produces molecules that are more soluble than the complex nutrient molecules that were ingested. (4) Molecules derived from digestion of ingested food are not larger than the molecules from which they came. Molecules produced by the digestion of complex carbohydrates, proteins, and fats are more soluble and are able to dissolve in water. Thus, these molecules can cross cell membranes.
1 The endoplasmic reticulum is a network of membranes that extends throughout the cell. The membranes form channels that provide for the movement of materials through the cell. Wrong Choices Explained: (2) Urea is a metabolic waste. It is a poisonous nitrogen compound. Urea must be removed from the cells if an organism is to survive. (3) The nucleus is the organelle in the cell that regulates all cellular activities. (4) The chloroplasts are organelles in plant cells that contain the green pigment chlorophyll. Chloroplasts are necessary for the process of photosynthesis.
3 Proteins are polypeptide chains. Proteins are synthesized in the ribosomes. Wrong Choices Explained: (1) The nuclei contain the genetic material carried in the chromosomes. (2) Vacuoles are saclike organelles in the cytoplasm. Food vacuoles and contractile vacuoles are two common types of vacuoles. (4) Cilia are microscopic hairs used for locomotion by some protozoans.
1 The nucleus contains the hereditary factors. Nuclei of plant and animal cells house the chromosomes, which are composed of deoxyribonucleic acid. Molecules of DNA function as genes. Points on the chromosomes are genes. Genetic information is passed from parent to offspring by way of the genes. Chromosomes are part of the fine structure of the nucleus. DNA molecules contribute to the chemical structure. Genes are sites or points that dot the length of the chromosome. Genes, DNA molecules, and chromosomes function in passing along hereditary factors. Wrong Choices Explained: (2) The cell membrane encloses the contents of the cell and directs the flow of materials into and out of the cell. The cell membrane does not contribute to the passing of genetic material from one generation to the next. The function of the membrane is to control cellular transport. (3) A vacuole is a fluid-filled space in the cytoplasm. Vacuoles help to regulate the internal pressure of the cell. The vacuoles in fat cells are filled with oil. (4) The membranes that line the cytoplasmic canals within cells are known collectively as the endoplasmic reticulum. This cytoplasmic fine structure aids in the transport of molecules from the cell membrane to various sites within the cell. Neither the endoplasmic reticulum nor the vacuoles of the cell membrane contain hereditary structures.
1 Centrioles are cell structures involved primarily in cell division. Centrioles are organelles that lie in the cytoplasm outside the nucleus; they are also found near the base of each flagellum and cilium. The centrioles of nonflagellated animal cells move to the spindle poles during cell division and seem to send out spindle fibers. The spindle fibers are attached to chromosomes and appear to pull the chromosomes from the center of the cell to the spindle poles. Wrong Choices Explained: (2) Fats are stored in cells. Fat in which the energy is channeled into heat production is stored in brown fat cells of hibernating mammals. At times, fat can be stored in arteries or accumulate around the heart. Fat cells are not involved in cell division. (3) Enzyme production is controlled by the ribosomes that dot the membranes of the endoplasmic reticulum. Molecules of tRNA and mRNA regulate enzyme production. (4) Cellular respiration is the process by which energy is released from glucose molecules. This process takes place in the mitochondria where oxygen is used as the final hydrogen carrier.
3 Cellular respiration occurs in the mitochondria (plural of mitochondrion). Each step in the process of cellular respiration is regulated by enzymes. Respiratory enzymes are located in the mitochondria. Wrong Choices Explained: (1) The cell wall is composed of cellulose. Cell walls give shape and protection to plant cells. (2) The nucleolus contains the materials needed for the synthesis of RNA. It is located in the nucleus of the cell. (4) A vacuole is a rounded sac that serves as a storage place for food and waste products. Some vacuoles, such as contractile vacuoles, maintain a stable internal environment.
2 Synthesis is the formation of complex molecules by combining simpler molecules. Water is removed from the simple molecules in this process. Wrong Choices Explained: (1) Hydrolysis is the addition of water to split complex molecules into simpler molecules. It is the opposite of synthesis. (3) Digestion is another name for hydrolysis. (4) Respiration is the process by which cells obtain energy. Glucose is converted to smaller molecules.
3 Amino acids are the building blocks of proteins. The dehydration synthesis of amino acids produces protein molecules. Wrong Choices Explained: (1) Cellulose is a polysaccharide composed of hundreds of simple sugar molecules. The sugars were joined together by dehydration synthesis. (2) Antibodies attack invading bacteria. Antibodies are protein molecules produced by special white blood cells. (4) Glycogen, a polysaccharide, is a product of the dehydration synthesis of many glucose units.
3 A hydrolytic reaction is a reaction in which a molecule is split. Enzymes are needed to speed up such a reaction. Any factor that affects the operation of the enzyme affects the speed at which the reaction takes place. The concentration of carbon dioxide has the least effect on enzyme activity. Wrong Choices Explained: (1) As the temperature is increased up to a point, the rate of the reaction increases. The increase in temperature increases the speed at which the enzyme and the substrate make contact with each other. The substrate is the molecule on which the enzyme acts. A very high temperature destroys the enzyme, and the reaction stops. (2) Every enzyme works best at a particular pH. The enzymes in the stomach work in an acid environment, whereas the enzymes in the intestine work best in a basic medium. (4) One molecule of an enzyme reacts with one molecule of a substrate. Increasing the concentration of an enzyme means that more substrate molecules will be acted on. The rate of the reaction will increase.
1 A neurotransmitter is a chemical substance that is released by an impulse arriving at the terminal end of a neuron. The neurotransmitter diffuses across the synapse and stimulates the second nerve cell. Acetylcholine is an example of a neurotransmitter. Wrong Choices Explained: (2) A synapse is the space between the terminal end of one nerve cell and the dendrites of a second nerve cell. The area marked by an X in the diagram is a synapse. (3) A neuron is a nerve cell that is specially adapted for the conduction of impulses. (4) A nerve is made up of many neurons.
1 A neuron is a single microscopic nerve cell. A nerve is composed of many nerve cells. A ganglion is a large mass of cell bodies of nerve cells; a ganglion functions as a coordinating center for impulses. A receptor is an organ specialized to receive environmental stimuli. The eye is an example of a receptor. Wrong Choices Explained: (2), (3), (4) In these three choices, either one or several structures are not arranged according to increasing size.
2 Gastric glands are embedded in the walls of the stomach. They are duct glands that secrete gastric juice, a mixture of water, hydrochloric acid, rennin, and pepsin. Gastric juice begins the digestion of protein in the stomach. Intestinal glands are duct glands that line the walls of the small intestine. They secrete intestinal juice, a mixture of water, proteases, amylases, and lipases. Both types of glands lie within the digestive tube. Wrong Choices Explained: (1) Gastric glands are described above. Thyroid glands lie outside the digestive tract at the base of the neck, straddled across the larynx. The thyroid is a ductless gland that secretes the hormone known as thyroxin. Thyroid glands do not function in the biochemical process of digestion. (3) Thyroid glands and intestinal glands are described above. Thyroxin controls the metabolism of cells. The explanation above shows why this choice is wrong. (4) Adrenal glands are dual endocrine glands that lie on top of each kidney. They are not within the digestive tract. The adrenal medulla, the inner gland, secretes the hormone adrenaline, also known as epinephrine. This hormone enables the body to function in emergencies. The adrenal cortex secretes about six active hormones, including cortisone, the antiarthritis hormone.
3 Parathormone is the hormone secreted by the parathyroid glands. The parathyroids are buried in the thyroids. Parathormone controls the level of calcium in the blood. Lack of blood calcium causes muscles to go into tetany. Tetany, or cramping, of the heart muscle causes death. Wrong Choices Explained: (1) Adrenalin is the hormone of the adrenal medulla, a ductless gland called the “gland of combat.” Adrenaline stimulates the heart to beat faster, increases the rate of breathing, and controls the constriction and dilation of the arteriole walls. (2) Insulin is secreted by the beta cells of the islets of Langerhans, which lie in the pancreas. Insulin controls sugar metabolism; specifically, it makes cell walls permeable to glucose and encourages the phosphorylation of fructose. (4) Thyroxin is released by the thyroid gland. The rate of cellular metabolism is controlled by thyroxin. Iodine is used in the synthesis of thyroxin. People whose thyroid glands fail to develop become cretins; they are mentally retarded and physically undersized.
2 Another name for anaerobic respiration is fermentation. In the process of fermentation, glucose is converted to energy, alcohol, and carbon dioxide. Wrong Choices Explained: (1) Aerobic respiration is another name for cellular respiration. This process requires oxygen. The following is an equation for aerobic respiration. (3) Chemosynthesis is the synthesis of carbohydrates from inorganic compounds without the use of sunlight as a source of energy. Chemosynthesis is a form of autotrophic nutrition. It is carried out only by certain species of bacteria such as nitrifying bacteria. (4) Dehydration synthesis is the method by which simple molecules are converted to complex molecules.
1 Cell membranes and contractile vacuoles are excretory organelles of some unicellular organisms. The cell membrane is a selectively permeable membrane. It permits the diffusion of carbon dioxide and ammonia, two metabolic waste gases. Wrong Choices Explained: (2) Cell walls are composed of nonliving materials. Many canals penetrate through these walls, allowing the unrestricted passage of molecules. (3) Proteins are synthesized in ribosomes. (4) Centrioles are rodlike particles found in the centrosome. They function during the processes of mitosis and meiosis. Centrioles are found only in animal cells.
3 A unicellular protist (e.g., an ameba) is composed of a single cell. When this cell divides by mitosis, the process is known as binary fission. Wrong Choices Explained: (1) External fertilization is an element of sexual reproduction in many aquatic multicellular species. Both the sexual nature of this process and the fact that it is carried out by multicellular animals eliminate this as a correct choice. (2) Tissue regeneration implies a process that occurs in multicellular organisms. (4) Vegetative propagation is a form of asexual reproduction common to certain species of multicellular plants; it cannot be carried out by unicellular protists.
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