Practice of physical knowledge exercises for the public examination, come and try it!
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Group 1
1. The following statement about microwave is correct:
A The frequency of microwave is lower than that of ordinary radio waves
B The moisture content has no effect on the microwave heating effect
C The microwave will be reflected by objects such as glass, plastic and porcelain
D The microwave communication capacity is large, the quality is good, and the transmission distance is long
2. Regarding "Mantis stalks the cicada, oriole is behind", the following statement is wrong:
0 A Cicada, mantis and oriole are all consumers
B The behavior of mantis and oriole is both congenital behavior
C Mantis, cicada and oriole form an ecosystem
D Cicada and mantis belong to arthropod , oriole belongs to bird
3. In order to realize garbage sorting and recycling, garbage bins in many public places have been divided into two categories: "recyclable" and "non-recyclable". The following types of garbage should be placed in the "non-recyclable" sign trash bin ().
① Glass bottle; ② Cans; ③ Fruit peel; ④ Vegetable leaves; ⑤ Non-toxic plastic products; ⑥ Paper packaging bags; ⑦ Leftover food
A. ③④⑥ B. ③④⑦ C. ②③⑥ D. ②④⑥
5 Dragonfly strokes water refers to the action of a dragonfly touching the water surface when flying on the water surface. It is mainly for ().
A. Courting B. Drinking water C. Spawning eggs D. Respiration
4. Common agricultural products such as potatoes, strawberries, sesame seeds and cauliflower, and the corresponding plant organs are ().
A. Root-seed-fruit-stem B. Stem-seed-seed-flower
C. Root - Flower - Fruit - Leaf D. Stem - Fruit - Seed - Flower
Answer analysis:
1.D
Error in item A: Microwave refers to electromagnetic wave with a frequency of 300MHz~300GHz. The microwave frequency is higher than the average radio wave frequency, and is usually called "ultra-high frequency electromagnetic wave".
Error in item B: Water molecules are polar molecules with a large dielectric constant and have a large dielectric loss factor, which has strong absorption capacity for microwaves.
Error in C: For glass, plastic and porcelain, microwaves are almost traveling through without being absorbed.
D is correct: Because the microwave frequency is very high, under a small relative bandwidth, the available frequency band is very wide, reaching hundreds or even over gigahertz, which is incomparable to low-frequency radio waves. This means that the microwave has a large information capacity, so modern multi-channel communication systems, including satellite communication systems, almost without exception, work in the microwave band.
The ABC item is wrong, so the correct answer is item D.
2.Ch
AA The definition of a consumer in nature is a link in the food chain, which means that a creature that cannot produce and can only achieve self-survival by consuming other organisms. Mantis, cicadas, oriole are in line with the concept of consumers. Item A is correct.
B Congenital behavior is an instinct that is born with, determined by genetic material in animals. For example: bees collect honey, ants build nests, spiders weave webs, bird migration, animal predation, etc. Acquired behaviors that are opposite to congenital behaviors are a reflection and habit established through learning in the corresponding environment, which can enable organisms to adapt to the environment better. Item B is correct.
C The biological community in an ecological bad environment must at least include: producers: mainly various green plants, including chemical energy synthetic bacteria and photosynthetic bacteria, which are all autotrophic organisms; decomposition : Mainly various bacteria (parasitic bacteria belong to consumers, saprophytic bacteria are decompositioners) and fungi, and also include dung beetles, earthworms and other saprophytic animals; consumers, see the explanation of item A. Therefore, item C is wrong.
D Mantis and cicadas are arthropods among invertebrates, and are correctly expressed; oriole belongs to birds, and are correctly expressed.
This question is a non-choice question, so the correct answer is C.
3.. (Answer) B. Analysis: Most non-recyclable garbage is garbage that is easy to decompose under natural conditions, such as skin, leftover rice, flowers, plants, leaves, etc. Recyclable garbage is recyclable garbage, mainly including: waste paper, plastic, glass, metal and fabric.
4. (Answer) D.Analysis: The edible part of potatoes is underground tubers; the edible part of strawberries is a fleshy polymerized fruit developed from flower holders; the edible part of sesame is seeds; the edible part of cauliflower is a flower ball made up of flower buds, branches, flower shafts, etc.
5. The correct answer is C. Analysis:
This question tests scientific and technological knowledge. Because dragonflies' larvae must live in water, in order to reproduce, they must choose to lay eggs in a place with water, and the fertilized eggs must be in water before they can hatch. Therefore, the dragonfly uses the method of sucking water on its tail to discharge the fertilized egg into the water. Therefore, choose option C.
Group 2
1. The following phenomenon belongs to chemical reactions ().
A. The water in spring river warms the ducks. B. The candle turns into ashes and tears dry.
C. The jade cannot become a tool without carving. D. The rope saw the wood and the wood is broken, and the water drops through the stone.
2. Before spring plowing, farmers apply wood ash to the fields mainly to supplement ( ) elements to the crops
A. Potassium B. Nitrogen C. Phosphorus D. Carbon
3. Among many colors, people often have a special liking for red and often use red lights as instructions, such as red lights directing traffic, red lights at the rear of cars, and red lights at the safety doors in public places. This is because the red light is in visible light ( )
A. The longest wavelength and is not easily scattered B. The wavelength is shortest and not easily scattered
C. The longest wavelength and is easily scattered D. The wavelength is shortest and is easily scattered
4. Which of the following uses the principle of thermal expansion and cold contraction ( )
A. The doctor uses a mercury thermometer to measure the patient's body temperature
B. When setting up wires, the wires between the two poles should be slightly drooped
C. Ancient people poured water into cracks of rocks in winter. After the water freezes, it swelled and shattered the rocks
D. In summer, you should not get too much air in bicycle tires
5. Plasma includes various minerals, carbohydrates, lipids, proteins, hormones and vitamins. Among the above substances, the one that causes the blood color to be red is ( )
A. Hormone B. Protein C. Sugar D. Vitamin
Answer analysis:
1. The correct answer is B. Analysis: Candle burns can produce water and carbon dioxide, so term B belongs to a chemical reaction. Item A shows that with the arrival of spring, the weather warms up and the water temperature rises; Item C refers to the appearance and shape of jade carved; Item D also refers to the change in the shape of the object due to external forces. Items A, C, and D are all physical changes. Therefore, choose item B.
2. 【Analysis】A. The main component of wood ash is potassium carbonate (K2CO3). Because wood ash is the ashes after the plant is burned, almost all mineral elements contained in the plant are contained in wood ash. The most abundant content is potassium, which generally contains 6~12% potassium, of which more than 90% is water-soluble and exists in the form of carbonates; followed by phosphorus, which generally contains 1.5~3%; it also contains calcium, magnesium, silicon, sulfur, and trace elements such as iron, manganese, copper, zinc, boron, molybdenum. The main function of sprinkling wood ash in spring is to supplement potassium-like crops. Therefore, item A was elected.
3. 【Analysis】A. Red, the color at the end of the long wave in the visible spectrum, with a wavelength of about 610 to 750 nanometers, is similar to fresh blood, and is one of the three primary colors and psychological primary colors. Among all visible light, the wavelength of red light is the longest, so the penetration power of red light is the strongest. The scattering of light by the atmosphere has one characteristic: light with shorter wavelengths is easily scattered, and light with longer wavelengths is not easily scattered; therefore, red light is not easily scattered, and it can travel far. Therefore, both car taillights and traffic emergency lights use red lights. Item A is correct.
4. [Analysis] C. When examining the principle of thermal expansion and contraction, candidates can often see that options A and options C are in line with common sense in life, but objects in option B will expand when they are heated and shrink when they are cold. This is because the movement of particles (atoms) in the object changes with temperature. When the temperature rises, the vibration amplitude of the particles increases, causing the object to expand; but when the temperature drops, the vibration amplitude of the particles decreases, causing the object to shrink. This is a typical principle of thermal expansion and contraction, but it requires the use of physics knowledge, which requires the highest requirements for candidates, which can be seen as general. Option D clearly states that the water swells after freezing and breaks the rock. This option is caused by the low temperature, which causes the rock to swell and crack. The question examines the obvious cold shrinkage.
5. [Analysis] B. This question examines common medical knowledge.The protein is the red color of the blood.
Group 3
1. The scientific principle on which the tools or applications in the following options are based are different from the other three items ( )
A. Thermometer B. Hot air balloon C. Thermal relay D. Tide power generation
2. When matter undergoes energy conversion, there are usually a series of physical or chemical reactions. The following energy conversion process has chemical reactions ( )
A. Wind power generation B. Burn coal for heating C. Ice and snow melt D. Alcohol volatile
3. Sound can propagate in solid, liquid and gaseous media, and the speed of propagation is related to the molecular spacing of the medium. The smaller the molecular spacing, the faster the sound propagates. Among the following media, the fastest sound propagating speed is ( )
A. Iron rod B. Bamboo pole C. Salt water D. Liquid mercury
4. In nature, we see that most plants have green leaves, and the correct explanation for this is ( )
A. The leaves undergo photosynthesis and absorb green light B. The leaves are photosynthesised and emit green light
C. The leaves reflect green light from the sun's light D. The leaf skin is covered with a layer of green substance
5. Red blood cells is the most numerous blood cell in the blood. Its main function in the human body is:
A. Transport oxygen from the lungs to various tissues of the body
B. As part of the immune system, help the body fight against infectious diseases and foreign infections
C. Promote biochemical reactions in the blood and assist the metabolism of organisms
D. When the blood vessels rupture, they gather in large quantities, which plays a role in coagulation
Answer analysis:
1. 【Analysis】A. The principle of a thermometer is due to the heat rise and contraction of mercury. Hot air balloons use heated air or certain gases such as hydrogen or helium, whose density is lower than the air density outside the balloon to generate buoyancy flight, and internal energy is converted into kinetic energy and gravitational potential energy. Thermal relay is a protective appliance that uses the thermal effect of current to cut off the circuit, and the electromagnetic energy is converted into internal energy and then converted into kinetic energy. Tidal power generation is similar to ordinary hydropower generation. Through the reservoir, seawater is stored in the reservoir at high tide, and the potential energy of the water drives the generator to generate electricity. Only A is thermal expansion and contraction, while B, C, and D are all energy conversion. Therefore, choose option A.
2. 【Analysis】B. Physical changes refer to changes that do not generate other substances, such as wind power generation, volatilization of alcohol, melting ice and snow, and light bulbs shining. Chemical changes are changes that generate other substances during changes, such as burning of wood strips, rusting of iron, and rotting of food. Chemical changes not only generate other substances, but also accompany energy changes, which are often manifested as heat absorption, exothermic, luminescence, etc. A, C, and D are all physical changes, so choose B.
3. 【Analysis】A. Sound propagates by vibration of the medium, and its speed is related to the density of the medium. The higher the density, the faster the propagation: sound travels the fastest in solids, the slowest in gas, and liquid is in between. The density of the iron rod is greater than that of the bamboo rod, so the sound spreads faster through the iron rod. Therefore, BCD is excluded and item A is elected.
4. 【Analysis】C. The color of an opaque object is determined by the color of the light it reflects. When the sun shines on the leaves, the colorful colors of the sun are absorbed by the leaves, and only the green light is reflected. Therefore, most of the leaves of plants are green. The other options are wrong, so choose option C.
5. A. [Analysis] This question is an examination of biology and medical knowledge. Red blood cells, also known as red blood cells, are the most numerous blood cells in the blood and are also the main medium for vertebrates to transport oxygen through the blood. 90% of red blood cells are composed of hemoglobin. Hemoglobin is a red blood cell-related compound that stores oxygen in muscle cells and can temporarily bind to oxygen molecules in the lungs or gills. When the oxygen partial pressure is low, it dissociates from oxygen, and oxygen is released from the tissues of the body, becoming the reduction of hemoglobin, thereby realizing the function of transporting oxygen. Option B is the role of white blood cells in the blood, and option D is the main role of platelets. So select option A.
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Thank you for your reading and collection. Today's real questions mainly practice physics-related knowledge. I hope this article can help you enrich your knowledge system and make daily accumulation!
