Predict changes in biological systems

{"questions":[{"content":"The experimenter studied the biological processes in the athlete’s body during his transition from intense training to the recovery period. The athlete's blood pressure is [[fill_choice_big-1]].","widgets":{"fill_choice_big-1":{"type":"fill_choice_big","options":["decreased","increased","has not changed"],"answer":0}},"explanation":"During training, blood pressure increases (heart rate and force of heart contraction increase). During the transition to recovery, sympathetic activity decreases, vascular relaxation occurs, and heart rate decreases."},{"content":"The experimenter studied the biological processes in the athlete’s body during his transition from intense training to the recovery period. The athlete has a speed of nerve impulse transmission through myelin fibers of [[fill_choice_big-5]].","widgets":{"fill_choice_big-5":{"type":"fill_choice_big","options":["has not changed","increased","decreased"],"answer":0}},"explanation":"This is an anatomical and physiological property that depends on the thickness of the myelin sheath and the diameter of the axon. It does not depend on the load or recovery phase in a healthy person."},{"content":"In an experiment, a researcher placed a piece of rat liver in distilled water. The volume of liver cells some time after the start of the experiment [[fill_choice_big-28]].","widgets":{"fill_choice_big-28":{"type":"fill_choice_big","options":["increased","decreased","has not changed"],"answer":0}},"explanation":"Distilled water is a hypotonic solution (almost zero salt concentration). Water enters cells by osmosis, where the concentration of substances is higher. As a result, the cells swell and their volume increases."},{"content":"In an experiment, a researcher placed a piece of rat liver in distilled water. Concentration of mineral salts in liver cells some time after the start of the experiment [[fill_choice_big-51]].","widgets":{"fill_choice_big-51":{"type":"fill_choice_big","options":["decreased","has not changed","increased"],"answer":0}},"explanation":"Water enters the cells, diluting the mineral salts located there. Consequently, the concentration of salts decreases (although the absolute amount of salts does not change)."},{"content":"The experimenter observed changes in acidity in the stomach of a patient who ate a chicken cutlet. The amount of acid in the patient's stomach is [[fill_choice_big-104]].","widgets":{"fill_choice_big-104":{"type":"fill_choice_big","options":["increased","decreased","has not changed"],"answer":0}},"explanation":"Chicken cutlet contains proteins. When proteins enter the stomach, the secretion of hydrochloric acid is activated, as this is necessary to create an acidic environment → activation of pepsin."},{"content":"The experimenter observed changes in acidity in the stomach of a patient who ate a chicken cutlet. The amount of peptides in the patient's stomach is [[fill_choice_big-121]].","widgets":{"fill_choice_big-121":{"type":"fill_choice_big","options":["increased","decreased","has not changed"],"answer":0}},"explanation":"Under the influence of pepsin, proteins begin to break down into peptides. Chicken cutlet contains a lot of protein → active digestion → more peptides."},{"content":"When the cell membrane is excited, it depolarizes. This is due to the flow of potassium and sodium ions in the opposite direction and the change in their quantity inside and outside the cell. The amount of sodium ions during membrane depolarization inside the [[fill_choice_big-298]] cell.","widgets":{"fill_choice_big-298":{"type":"fill_choice_big","options":["increased","decreased","has not changed"],"answer":0}},"explanation":"When excited (depolarized), sodium channels open. Na ions enter the cell along a concentration gradient. This means that the intracellular amount of Na ions increases."},{"content":"When the cell membrane is excited, it depolarizes. This is due to the flow of potassium and sodium ions in the opposite direction and the change in their quantity inside and outside the cell. The amount of potassium ions during membrane depolarization inside the [[fill_choice_big-273]] cell.","widgets":{"fill_choice_big-273":{"type":"fill_choice_big","options":["increased","decreased","has not changed"],"answer":1}},"explanation":"K ions leave the cell when excited (there are more of them inside than outside). This means that the intracellular amount of K ions decreases."},{"content":"The experimenter investigated the conditions under which certain enzymes of the digestive tract are active. He compared the pH values at which the enzymes under study were most active. At pH value = 2,5, the activity of chymotrypsin is [[fill_choice_big-433]].","widgets":{"fill_choice_big-433":{"type":"fill_choice_big","options":["will decrease","will increase","will not change"],"answer":0}},"explanation":"pH = 2,5 is an acidic environment that is not typical for the intestines. Chymotrypsin loses activity - the structure is disrupted."},{"content":"The experimenter investigated the conditions under which certain enzymes of the digestive tract are active. He compared the pH values at which the enzymes under study were most active. At pH value = 2,5, pepsin activity is [[fill_choice_big-502]].","widgets":{"fill_choice_big-502":{"type":"fill_choice_big","options":["will increase","will decrease","will not change"],"answer":0}},"explanation":"pH = 2,5 is the optimum or close to it pH level. Pepsin is active precisely at these values."},{"content":"The experimenter found out the functions of hormones secreted by the pancreas. By the middle of the distance (21 km), the level of glucagon in the blood of a marathon athlete is [[fill_choice_big-619]].","widgets":{"fill_choice_big-619":{"type":"fill_choice_big","options":["will increase","will decrease","will not change"],"answer":0}},"explanation":"Glucagon is a hormone that increases blood glucose levels. It stimulates glycogenolysis (the breakdown of glycogen in the liver) and gluconeogenesis (the synthesis of glucose from amino acids and fats).<br />During prolonged exercise (marathon), glucagon levels increase to maintain glucose concentrations."},{"content":"The experimenter found out the functions of hormones secreted by the pancreas. By the middle of the distance (21 km), the blood glucose level of the marathon athlete is [[fill_choice_big-735]].","widgets":{"fill_choice_big-735":{"type":"fill_choice_big","options":["will decrease","will increase","will not change"],"answer":0}},"explanation":"During a long run, glucose is actively consumed by the muscles. Despite the action of glucagon, its levels decrease, especially if glycogen stores are depleted."},{"content":"When a neuron is excited, the concentration of sodium ions on both sides changes. Concentration of sodium ions outside the membrane [[fill_choice_big-902]].","widgets":{"fill_choice_big-902":{"type":"fill_choice_big","options":["will decrease","will increase","will not change"],"answer":0}},"explanation":"During excitation, depolarization of the membrane occurs. Sodium channels open, Na ions flow into the cell, which means that there is less sodium outside."},{"content":"When a neuron is excited, the concentration of sodium ions on both sides changes. Concentration of sodium ions in the [[fill_choice_big-853]] cell.","widgets":{"fill_choice_big-853":{"type":"fill_choice_big","options":["will increase","will decrease","will not change"],"answer":0}},"explanation":"During excitation, depolarization of the membrane occurs. Sodium channels open, Na ions flow into the cell, which means that there is more sodium inside."},{"content":"It is known that water rises through plants as a result of the work of two “engines” - root pressure and the suction force of the leaves. The magnitude of osmotic pressure during transpiration in root hairs [[fill_choice_big-1175]].","widgets":{"fill_choice_big-1175":{"type":"fill_choice_big","options":["will not change","will increase","will decrease"],"answer":0}},"explanation":"The main function of root hairs is to absorb water from the soil through osmosis. Inside the root cells, osmotic pressure is always high (due to salts and sugars) to draw water.<br />During transpiration (the evaporation of water from leaves), osmotic pressure is kept at a constant level to continue to attract water."},{"content":"It is known that water rises through plants as a result of the work of two “engines” - root pressure and the suction force of the leaves. The magnitude of osmotic pressure during transpiration in the stomata [[fill_choice_big-1232]].","widgets":{"fill_choice_big-1232":{"type":"fill_choice_big","options":["will increase","will not change","will decrease"],"answer":0}},"explanation":"During active transpiration (evaporation of water by leaves), cells lose water, which leads to an increase in osmotic pressure in the cells surrounding the stomata."},{"content":"When the temperature of the environment increases to 56 °C, the level of activity of the pepsin enzyme is [[fill_choice_big-1536]].","widgets":{"fill_choice_big-1536":{"type":"fill_choice_big","options":["will decrease","will not change","will increase"],"answer":0}},"explanation":"Enzymatic proteins are sensitive to temperature: above 45-50°C they begin to lose activity."},{"content":"When the temperature of the environment increases to 56 °C, the level of activity of the amylase enzyme [[fill_choice_big-1617]].","widgets":{"fill_choice_big-1617":{"type":"fill_choice_big","options":["will decrease","will not change","will increase"],"answer":0}},"explanation":"Enzymatic proteins are sensitive to temperature: above 45-50°C they begin to lose activity."},{"content":"The subject ran 3 kilometers at a fast pace. After this, the volume of blood in the vessels of the skeletal muscles of the subject is [[fill_choice_big-1]].","widgets":{"fill_choice_big-1":{"type":"fill_choice_big","options":["increased","decreased","has not changed"],"answer":0}},"explanation":"During physical activity, muscles work intensely and require more oxygen and nutrients. The lumen of the muscle vessels expands → blood flow is redistributed there."},{"content":"The subject ran 3 kilometers at a fast pace. After this, the volume of blood in the vessels of the stomach walls of the subject is [[fill_choice_big-15]].","widgets":{"fill_choice_big-15":{"type":"fill_choice_big","options":["has not changed","increased","decreased"],"answer":2}},"explanation":"When running, digestion is inactive, the stomach is not a priority.<br />The vessels of the digestive organs narrow (vasoconstriction) to redistribute blood to the muscles."},{"content":"When examining the patient’s blood, he was diagnosed with urinary tract inflammation. The number of red blood cells in the blood test [[fill_choice_big-56]].","widgets":{"fill_choice_big-56":{"type":"fill_choice_big","options":["has not changed","increased","decreased"],"answer":0}},"explanation":"Red blood cells are not directly associated with the inflammatory process, so their levels usually remain stable."},{"content":"When examining the patient’s blood, he was diagnosed with urinary tract inflammation. The number of leukocytes in the blood test [[fill_choice_big-65]].","widgets":{"fill_choice_big-65":{"type":"fill_choice_big","options":["has not changed","increased","decreased"],"answer":1}},"explanation":"During inflammation, the immune system is activated, which leads to an increase in the level of white blood cells."},{"content":"In the study, the scientist measured some parameters of the development of the wheat straw stem in the booting phase over several months. During plant development, the distance between nodes is [[fill_choice_big-120]].","widgets":{"fill_choice_big-120":{"type":"fill_choice_big","options":["increased","decreased","has not changed"],"answer":0}},"explanation":"In the phase of emergence into the tube, intensive growth of the stem occurs - this is the active stage of intercalary growth. In this case, the internodes lengthen, that is, the distances between the nodes increase."},{"content":"In the study, the scientist measured some parameters of the development of the wheat straw stem in the booting phase over several months. During plant development, the number of nodes in the stem is [[fill_choice_big-133]].","widgets":{"fill_choice_big-133":{"type":"fill_choice_big","options":["has not changed","increased","decreased"],"answer":0}},"explanation":"The number of nodes is the underlying number of metameric units (node + internode) in the shoot. In the phase of entry into the tube, new nodes are usually not formed, therefore, their number remains unchanged."},{"content":"In the study, the scientist observed the external changes of the grass frog larva during ontogenesis. During observation, the dimensions of the forelimbs are [[fill_choice_big-238]].","widgets":{"fill_choice_big-238":{"type":"fill_choice_big","options":["increased","decreased","have not changed"],"answer":0}},"explanation":"The tadpole starts out without limbs. During the process of metamorphosis, limbs appear and grow - first the hind ones, then the front ones. Consequently, the size of the forelimbs increases.<br />"},{"content":"In the study, the scientist observed the external changes of the grass frog larva during ontogenesis. During the observation, the tail size of the tadpole [[fill_choice_big-213]].","widgets":{"fill_choice_big-213":{"type":"fill_choice_big","options":["decreased","has not changed","increased"],"answer":0}},"explanation":"In a tadpole, the tail is the main organ of movement. As it turns into a frog, the tail is reduced and disappears, which means the size of the tail decreases."},{"content":"The experimenter observed the biological processes in the horse’s body during its transition from walking to galloping. During this transition, the horse has cardiac output values of [[fill_choice_big-356]].","widgets":{"fill_choice_big-356":{"type":"fill_choice_big","options":["increased","decreased","have not changed"],"answer":0}},"explanation":"Cardiac output increases as blood circulation increases during exercise."},{"content":"The experimenter observed the biological processes in the horse’s body during its transition from walking to galloping. During this transition, the horse has a nerve impulse conduction speed of [[fill_choice_big-389]].","widgets":{"fill_choice_big-389":{"type":"fill_choice_big","options":["has not changed","increased","decreased"],"answer":0}},"explanation":"The speed of nerve impulse conduction does not change, since this is a biophysical property of nervous tissue."},{"content":"In the study, the scientist measured the parameters of human skin under different lighting conditions. With increasing time spent in the sun, the thickness of the epidermis is [[fill_choice_big-605]].","widgets":{"fill_choice_big-605":{"type":"fill_choice_big","options":["has not changed","increased","decreased"],"answer":0}},"explanation":"Melanocytes are activated, but the structural thickness of the epidermis remains approximately the same with moderate sun exposure."},{"content":"In the study, the scientist measured the parameters of human skin under different lighting conditions. With increasing time spent in the sun, the amount of melanin in it is [[fill_choice_big-564]].","widgets":{"fill_choice_big-564":{"type":"fill_choice_big","options":["increased","decreased","has not changed"],"answer":0}},"explanation":"In active sunlight, the synthesis of melanin in melanocytes increases (this is why the skin darkens - tanning) as a protective reaction of the skin to UV radiation."},{"content":"In the experiment, the researcher determined the content of gases in human blood as it moves through the vessels of the systemic circulation. Oxygen content in venous blood relative to arterial blood [[fill_choice_big-867]].","widgets":{"fill_choice_big-867":{"type":"fill_choice_big","options":["decreased","increased","has not changed"],"answer":0}},"explanation":"Arterial blood (after the lungs) is rich in oxygen, which is given to the tissues as it moves in a large circle. Consequently, there is less of it in the venous blood."},{"content":"In the experiment, the researcher determined the content of gases in human blood as it moves through the vessels of the systemic circulation. Carbon dioxide content in venous blood relative to arterial blood [[fill_choice_big-806]].","widgets":{"fill_choice_big-806":{"type":"fill_choice_big","options":["increased","decreased","has not changed"],"answer":0}},"explanation":"Carbon dioxide is formed in tissues as a metabolic product. It accumulates in the blood, passing from tissues to capillaries, so there is more carbon dioxide in venous blood than in arterial blood."},{"content":"The experimenter placed a chicken bone in a 3% solution of hydrochloric acid for several days. The amount of proteins in the bone during this time is [[fill_choice_big-1091]].","widgets":{"fill_choice_big-1091":{"type":"fill_choice_big","options":["has not changed","increased","decreased"],"answer":0}},"explanation":"The main protein component of bone is collagen, which is part of the organic matrix. Hydrochloric acid dissolves mineral salts, but does not destroy proteins. Therefore, the amount of proteins does not change."},{"content":"The experimenter placed a chicken bone in a 3% solution of hydrochloric acid for several days. The amount of calcium salts in the bone during this time is [[fill_choice_big-1162]].","widgets":{"fill_choice_big-1162":{"type":"fill_choice_big","options":["decreased","has not changed","increased"],"answer":0}},"explanation":"Hydrochloric acid actively displaces calcium ions from bone tissue, destroying the mineral component (hydroxyapatite). This makes the bone soft and flexible, hence the amount of calcium salts is reduced."},{"content":"An experimenter studied the effect of medications, based on the placebo effect (a person's belief that he is taking a real medicine), on heart function. Heart rate in a dog when taking one single dose of the medicine [[fill_choice_big-1532]].","widgets":{"fill_choice_big-1532":{"type":"fill_choice_big","options":["has not changed","increased","decreased"],"answer":0}},"explanation":"Placebo acts through the psyche and belief, and dogs do not have a conscious expectation of the effect. Consequently, neither single nor multiple doses have a real physiological effect. The physiology of the heart (in particular, heart rate) does not change, because there is no pharmacological effect and psychological attitude, like in humans."},{"content":"An experimenter studied the effect of medications, based on the placebo effect (a person's belief that he is taking a real medicine), on heart function. Heart rate in a dog after repeated doses of the medication [[fill_choice_big-1403]].","widgets":{"fill_choice_big-1403":{"type":"fill_choice_big","options":["has not changed","decreased","increased"],"answer":0}},"explanation":"Placebo acts through the psyche and belief, and dogs do not have a conscious expectation of the effect. Consequently, neither single nor multiple doses have a real physiological effect. The physiology of the heart (in particular, heart rate) does not change, because there is no pharmacological effect and psychological attitude, like in humans."},{"content":"In the experiment, the researcher determined the most important physical parameters of blood moving through the vessels of the systemic circulation in humans. Blood pressure when moving from the capillaries of skeletal muscles to the right atrium [[fill_choice_big-1808]].","widgets":{"fill_choice_big-1808":{"type":"fill_choice_big","options":["decreased","increased","has not changed"],"answer":0}},"explanation":"The pressure in the capillaries is still relatively high. As you move toward the venules, veins, and finally the right atrium, the pressure gradually decreases, reaching a minimum at the point of entry into the heart."},{"content":"In the experiment, the researcher determined the most important physical parameters of blood moving through the vessels of the systemic circulation in humans. Linear blood velocity when moving from the capillaries of skeletal muscles to the right atrium [[fill_choice_big-1899]].","widgets":{"fill_choice_big-1899":{"type":"fill_choice_big","options":["increased","decreased","has not changed"],"answer":0}},"explanation":"Blood flows slowly in capillaries - this provides time for metabolism. In venules and veins, the muscle pump and the valve apparatus of the veins are activated. The total diameter of the vessels decreases and the speed increases."},{"content":"The experimenter added an additional amount of glucose to the nutrient medium on which yeast was grown under anaerobic conditions. In the nutrient medium, the volume of carbon dioxide is [[fill_choice_big-1]].","widgets":{"fill_choice_big-1":{"type":"fill_choice_big","options":["will increase","will decrease","will not change"],"answer":0}},"explanation":"Anaerobic fermentation in yeast is alcoholic fermentation. When glucose is added, its intensity increases, which means more carbon dioxide is released."},{"content":"The experimenter added an additional amount of glucose to the nutrient medium on which yeast was grown under anaerobic conditions. In the nutrient medium, the number of yeast cells is [[fill_choice_big-2]].","widgets":{"fill_choice_big-2":{"type":"fill_choice_big","options":["will increase","will not change","will decrease"],"answer":0}},"explanation":"Although yeast multiply more slowly under anaerobic conditions than under aerobic conditions, additional glucose is an additional resource for growth, which means the number of cells will increase."},{"content":"The experimenter placed a colony of bacteria in a flask with a nutrient medium and placed it in a thermostat at a temperature of 37°C for a day. Number of bacteria [[fill_choice_big-38]].","widgets":{"fill_choice_big-38":{"type":"fill_choice_big","options":["will increase","will decrease","will not change"],"answer":0}},"explanation":"Temperature 37°C is optimal for the growth of most bacteria, especially pathogenic and intestinal ones. During the day, bacteria actively divide, especially in a rich nutrient medium."},{"content":"The experimenter placed a colony of bacteria in a flask with a nutrient medium and placed it in a thermostat at a temperature of 37°C for a day. Volume of medium in flask [[fill_choice_big-27]].","widgets":{"fill_choice_big-27":{"type":"fill_choice_big","options":["will not change","will increase","will decrease"],"answer":0}},"explanation":"The nutrient medium does not disappear physically: bacteria absorb nutrients, but do not “eat” the volume of the medium in the sense of liquid, releasing metabolic products."},{"content":"The experimenter placed the Euglena culture in a nutrient medium in the dark for 10 days. Oxygen concentration in the [[fill_choice_big-99]] environment.","widgets":{"fill_choice_big-99":{"type":"fill_choice_big","options":["decreased","increased","has not changed"],"answer":0}},"explanation":"Euglena is a unicellular photosynthetic creature capable of autotrophic nutrition in the light.<br />Oxygen is a product of photosynthesis. In the dark, photosynthesis stops and oxygen ceases to be released; moreover, cells continue to breathe, consuming oxygen."},{"content":"The experimenter placed the Euglena culture in a nutrient medium in the dark for 10 days. Chlorophyll content in [[fill_choice_big-124]] cells.","widgets":{"fill_choice_big-124":{"type":"fill_choice_big","options":["increased","decreased","has not changed"],"answer":1}},"explanation":"Euglena is a unicellular photosynthetic creature capable of autotrophic nutrition in the light.<br />Without light, chlorophyll is not used. It begins to break down so that cells can use its components to survive."},{"content":"Agricultural scientists added a preparation containing nodule bacteria to the soil of an experimental plot. The concentration of ammonium salts in the soil cultivated on the experimental plot is [[fill_choice_big-263]].","widgets":{"fill_choice_big-263":{"type":"fill_choice_big","options":["will not change","will increase","will decrease"],"answer":1}},"explanation":"Nodule bacteria (for example, Rhizobium) are nitrogen-fixing bacteria that live in symbiosis with legumes (including soybeans).<br />Nodule bacteria fix atmospheric nitrogen (N₂) and convert it into ammonium compounds (NH₄). This means that the concentration of ammonium salts in the soil increases."},{"content":"Agricultural scientists added a preparation containing nodule bacteria to the soil of an experimental plot. The yield of soybeans cultivated on an experimental plot is [[fill_choice_big-232]].","widgets":{"fill_choice_big-232":{"type":"fill_choice_big","options":["will increase","will decrease","will not change"],"answer":0}},"explanation":"Nodule bacteria (for example, Rhizobium) are nitrogen-fixing bacteria that live in symbiosis with legumes (including soybeans).<br />With an increase in available nitrogen (in the form of ammonium salts), the plant grows and develops more actively. Accordingly, productivity increases."},{"content":"The experimenter populated a nutrient medium with a colony of Escherichia coli bacteria with the mold fungus penicillium. Colony size of E. coli bacteria [[fill_choice_big-439]].","widgets":{"fill_choice_big-439":{"type":"fill_choice_big","options":["will decrease","will increase","will not change"],"answer":0}},"explanation":"Penicillium is a fungus that produces penicillin, an antibiotic. Penicillin inhibits the growth of gram-positive and gram-negative bacteria, including E. coli.<br />Under the influence of penicillin, bacterial growth slows down or stops."},{"content":"The experimenter colonized a nutrient medium with a colony of Escherichia coli bacteria and colonized the mold fungus penicillium. Penicillium mycelium area [[fill_choice_big-398]].","widgets":{"fill_choice_big-398":{"type":"fill_choice_big","options":["will increase","will not change","will decrease"],"answer":0}},"explanation":"Penicillium is a fungus that produces penicillin, an antibiotic. Penicillin inhibits the growth of gram-positive and gram-negative bacteria, including E. coli.<br />Penicillium has no competition for nutrients - E. coli is suppressed. The mold continues to grow, the mycelium expands."}]}