Eighth grade (Part 1) final examination paper

Science

(The total score of the examination paper is 120 points, the examination time is 90 minutes)

1. Multiple choice questions (each question has only one correct option, each question is worth 2 points, the total score is 52 points)

1. 220V is most likely ( )

A. A electronic watch The voltage of the battery B, the voltage of a dry cell

C, the voltage of household lighting circuit D, the voltage between clouds during lightning

2. The following biological phenomena are mainly affected by temperature factors Yes ( )

A. Phototaxis of moths B. Seasonal migration of fish

C. Cacti grow leaf thorns D. Ginseng can grow well in dense forests

3. Regarding the statement about water, the wrong statement is ( )

A Pure water has no smell, taste and color

B Natural water is a solution because Water is a good solvent

C Distilled water can usually be regarded as purified water

D Mineral water is sweet and delicious, clean and transparent, and is also a kind of pure water

4. Add white vinegar, edible oil, salt, and alcohol to water respectively. The solution that cannot form is ( )

A White vinegar B Edible oil C Salt D Alcohol

5. The following animals The behavior that has nothing to do with weather changes is ( )

A dragonfly flying low B ant moving C dog sticking out tongue D mantis catching cicada

6. In order to detect one-yuan coins, pencil lead, Regarding the conductivity of rubber and plastic rulers, classmate Xiaoyan designed the circuit as shown on the right (A and B are two metal clips). During operation, insert coins, pencil lead, eraser or plastic ruler between the two metal clips. When the switch is turned on, the small light bulb emits light, and there may be ( ) inserted between the two metal clips

A. Coin or eraser B. Pencil lead or coin

C. Eraser or plastic ruler D. Plastic ruler or pencil lead

7. When the temperature remains unchanged, evaporate part of the solvent from a bottle of saturated sodium chloride solution, and sodium chloride crystals precipitate from the solution, then ( )

A. The solution becomes an unsaturated solution B. The solution remains a saturated solution

C. The solubility of the solute decreases D. The mass of the solvent in the solution remains unchanged

8 , when purifying coarse salt by filtration method, the substance left on the filter paper is ( )

A. Table salt B. Table salt and insoluble impurities C. No substance D. Insoluble impurities

9. It is winter now, and the northwest wind prevails. The following figure correctly represents the direction of the winter wind in my country ( )

A B C D

10. The following description describes the weather ( )

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① Overcast to cloudy ② Warm in winter and cool in summer ③ Clear skies ④ Thunderstorms ⑤ Clear air in autumn ⑥ Gentle breeze and drizzle ⑦ High temperature all year round ⑧ Rain in winter and dry in summer

A, ①②⑦ B, ③⑥⑧ C, ①④⑤ D, ①③④⑥

11. Someone is drunk, walks unsteadily, and stands unsteadily. This indicates which part of the brain has been anesthetized by alcohol ( )

A. Brain B. Brain stem C. , cerebellum D, cranial nerves

12. A intentionally urinates before going to bed, and B intentionally holds back urine before getting up. The center that controls these two behaviors is ( )

A. Spinal cord B. Brain C, cerebellum D, brainstem

13. Xiao Wang, who lives in the countryside, discovered that after the typhoon, the green plants fell down, but the front ends of their stems still maintained an upward trend.

The reason for this phenomenon is ( )

A. Affected by fertilizers, chemotropism B. Affected by sunlight, phototropism

C. Affected by the gravity of the earth , geotropism D. Affected by water, hydrotropism

14. Due to the good sealing performance of the kitchen pressure cooker, the air pressure in the pot can be higher than the standard atmospheric pressure, thus ( )

A. Increase the boiling point of water B. Lower the boiling point of water

C. Increase the specific heat of water D. Reduce the specific heat of water

15. Figure A below This is a schematic diagram of skin blood vessels in a normal temperature environment. When the outside temperature is high, the diameter of human skin blood vessels should be more similar to ( ) in the picture below

A B C D

A B

16. Singing after physical work and playing ball after mental work can eliminate fatigue and improve work efficiency. This is mainly because ( )

A. Each part of the cerebral cortex can get alternate activities and rest

B. Each part of the muscles can get alternate activities and rest

C. It allows various organs of the human body to have opportunities to move, which is good for health

D. It is good for stimulating interest and improving work efficiency

17. The picture on the right is one of the textbooks Please analyze the illustration: The reason why the "Hawker" and the "Olympic" collided was ( )

A. The flow velocity at A is smaller than that at B and C, but the pressure is higher

B. The flow rate at A is smaller than that at B and C, and the pressure is also relatively small

C. The flow rate at A is greater than that at B and C, but the pressure is relatively high

D , The flow velocity at A is greater than that at B and C, and the pressure is also smaller

18. There is often a cool breeze blowing on the beach under the scorching sun. The direct cause of the cool breeze is ( )

A. The specific heat of water is large and the water temperature changes little

B. The sea water is hot, the sea surface air expands, and the surrounding cold air is supplemented to form wind

C. The beach is hot. The air expands and rises, and the cold air on the sea surface is supplemented to form wind

D. The specific heat of sand is small and the temperature changes greatly

19. Add equal amounts to four identical beakers For water with a large temperature difference, cover the mouth of the cup with the same piece of glass at the same time. After a while, you will see the phenomenon as shown in the picture, then the water with the highest temperature is ( )

A B C D

20. Xiao Ke participated in a summer camp to conduct an ecological inspection in the Jiuzhaigou area, which is nearly 4,000 meters above sea level. He encountered the following phenomena. Three of them had the same cause, and only one had a different cause. This phenomenon is ( )

A. The sealed "Egg Yolk Pie" bag swelled as hard as a stone

B. I drank most of the pure water bottle at the top of the mountain, closed it and took it down the mountain, and it deflated

C. When riding up the mountain by car, people kept releasing "intestinal gas"

D. The dawn time was about an hour later than in hometown

21. As shown in the picture In the circuit shown, what may cause damage to both the power supply and the ammeter is ( )

A B C D

22. Lamps L1 and L2 form the circuit shown in Figure 1. In the following statement The correct one is ( )

A. Close switch S and both lights will light up. Remove wire a and connect the two lights in series

B. Close the switch S, both lights will not light up, remove the wire b, and connect the two lights in series

C. Close the switch S and both lights will light up. Remove the wire b and connect the two lights in series

D. Close switch S, both lights will not light up, remove wire a, and connect the two lights in series

23. As shown in the figure, A, B, C, and D show the structure and connection of the sliding wire varistor. Schematic diagram of the circuit. When the slider slides to the right, the resistance connected to the circuit becomes smaller ( )

A B C D

24. Use an ammeter to measure the current when two lamps are connected in series. When the switch is closed, it is found that the two lights are on and off, and the ammeter swings back and forth.

The possible reasons for this phenomenon are ( )

A. The filament of a certain lamp is broken

B. The filament of a certain lamp is short-circuited

C. The ammeter is damaged And open circuit

D. The light bulb and the filament are not in good contact, and they are on and off

25. There are four fluorescent lamps in the classroom and only one switch on the wall. Turn the switch on and all the lights will be on; turn off the switch and all the lights will go off. When the lamp tube of a lamp turns black and the switch is turned on, the lamp will not light up but the other lights will still light up. Regarding the connection between lights and switches, the correct judgment is ( )

A. Four lights are connected in series

B. Four lights may be connected in series or in parallel

C , Four lights are connected in parallel, and the switch is connected to the main road

D. Four lights are connected in parallel, and the switch is connected to one of the branch roads

26. Scientists conducted an experiment in the 1970s , arrange many white squares in a long row on the grass, and then put sugar on squares 1, 2, 4, 6, 8... in sequence. When the scientist finished placing the 10th block and came to the 12th block, the bees were already waiting there. The stimulated scientist ran to the 14th block to see that there were also bees waiting there. He put down the thing in his hand in frustration and said angrily: "Who knows whether I am training them or they are training me!" This "intelligent" behavior of bees belongs to ( )

A. Innate behavior B. Instinct C. Learned behavior D. Random behavior

2. Fill-in-the-blank questions (2 points for each blank, ***28 blanks, 6 of which are additional points. The total score for this question cannot exceed 50 points)

27. As shown in the figure, after direct current is passed through the water, a gas that can re-ignite the wooden strips with sparks is produced on the electrode connected to the positive electrode of the power supply ( Oxygen); the gas produced at the other pole can be ignited with a match (hydrogen). This experiment can show that water is composed of and . (2 points for this question)

28. As shown in the picture below, the altitude of the top of the mountain is 2500 meters. The arrow indicates the direction of air flow. Compare the two places A and B

. The temperature in the place is higher. Comparatively In places B and C, there is a lot of precipitation.

29. The picture on the right is an "isobar diagram" that reflects the level of air pressure near the ground. It often appears on "Weather Maps" on television weather programs. Try to judge based on the air pressure data on the map: Place A is controlled by (optional: "high pressure area" or "low pressure area"), and the weather is (optional: "rainy" or "sunny").

30. If the sole of your foot accidentally touches a sharp stone, your foot will retract immediately. This process is called ___________.

31. When a student was doing an experiment to determine the density of wax, he took the following steps:

⑴Measure the mass of the wax on the adjusted balance, as shown in Figure A below.

⑵Tie the wax block with a thin thread, and then tie a small iron block under the wax block, as shown in Figure B;

⑶Use a measuring cylinder to measure the wax The volume of the block, as shown in Figures C, D, and E:

Please record the experimental data in the spaces in the table below, and calculate the density of the wax based on the data:

The wax block Mass (g) Volume of the wax block (cm3) Density of the wax block (kg/m3)

32. The area of ??a certain roof is 100 m2, at standard atmospheric pressure (roughly taken as 100 kPa) Below, the pressure of the atmosphere on the roof is ______N. When a tornado occurs, the air pressure outside the house drops sharply to 90 kPa. At that time, the doors and windows are closed. At this time, the pressure difference between the inside and outside of the roof is ______N. The sharp drop in air pressure outside the house is related to the _______ of the air being too large.

33. As shown in Figure A on the right, the fact that the drink can rise along the straw into the mouth is the result of __________. As shown in Figure B, A and B are two identical small balloons. Ball A is placed under a large funnel, and ball B is placed under a thin glass tube. The funnel and glass tube contain the same water mass, then _______ _The ball is more likely to break.

Picture A and Picture B

34. In order to explore whether the buoyancy force on an object floating on the water follows Archimedes' principle, a student conducted an experiment as shown in the figure. . A black grid or a white grid on the spring dynamometer used in the experiment represents 0.5 N. Please answer the following questions:

(1) From the measurement of a in the figure, it can be seen that the magnitude of the gravity exerted by the wooden block is 0.5 N; according to the principle of two-force balance, it can be seen that the wooden block in the figure d is floated by the buoyancy force ________ _ox.

(2) The readings in the two pictures b and e are _________cow and _________cow respectively. The purpose of the two measurements is to determine the size of _______________________________.

(3) Analyzing the above experiments, we can draw a preliminary conclusion: the buoyancy force on an object floating on the water is __________ Archimedes' principle (optional "comply" or "disobey").

35. Xiaoyan traveled by plane. When she took off, the sky was overcast and it was drizzling. As the plane ascended, she felt a little pain in her ears. This was because the air pressure gradually _______ as the altitude increased. After a while, suddenly, the sun was shining brightly outside the window, the sky was blue, and the white clouds were under her feet, making it look like an endless snowfield! At this time, the screen in the cabin showed: altitude 10,800 meters. It's rainy on the ground, but the sun is shining brightly in the sky. This is because ____________________________________. The screen also shows that the outside temperature is -15°C. What other equipment do you think should be on the plane for the comfort of passengers in the cabin? ____________________________. From a sports perspective, flying the plane so high is beneficial to reducing ____________________.

36. To prepare physiological saline for injection, dissolve 18 grams of sodium chloride in 1982 grams of distilled water. The mass fraction of the solute in the physiological saline is

37. There is such a way Question: When a voltage of 4V is applied to both ends of the conductor, the current passing through is 500mA. What is the resistance of the conductor? When 12V is applied to both ends, what is the resistance of the conductor?

Xiao Ke’s answer is as follows: the first time R=U / I=4V / 0.5A=8Ω; the second time R=U / I=12V / 0.5A=24Ω.

Classmate Xiaoyan said that this is wrong because the resistance is determined by factors in the conductor itself, and the resistance should remain unchanged the second time. Xiao Ke thinks what she said makes sense, but he is still a little confused: the second time was also calculated based on R=U/I!

Do you think the formula R=U/I is still applicable the second time? _______________. What was wrong with Xiao Ke's second calculation? ____________________________.

38. Put the broad bean seedlings cultivated in the culture medium into four dark boxes for a period of time. The dark box C has a hole on the side to allow light to enter, then

A, B, C

⑴ Select two ________ devices for experiments to understand the relationship between the growth of broad bean stems and light.

⑵ Select two ________ devices for experiments to understand the relationship between the growth of broad bean stems and roots and gravity.

3. Analysis and calculation questions (38 questions are 7 points, 39 questions are 12 points, and 40 questions are 3 points, of which 4 are additional points. The total score for this major question shall not exceed 18 points)

39. (7 points) There are some circuit components in the picture below. The power supply is two dry batteries. The resistance of the two light bulbs is 12Ω.

(1) Please use pencils instead of wires to connect the circuit components, and please write the calculation process for determining the ammeter range in the right box. Requirements: The switch controls two lights at the same time, the ammeter measures the current of L2, and the wires do not cross.

(2) Draw the circuit diagram corresponding to the above physical diagram.

40. (12 points) In the experiment of "Measuring fixed value resistance with voltmeter and ammeter",

(1) When connecting the experimental circuit, the switch should be . Before closing the switch S, the slider of the sliding rheostat should slide to the end (fill in "left" or "right");

(2) When a student connected the physical objects according to the circuit diagram and started the experiment, he discovered that the voltmeter The situation shown in the picture above occurs. What problems can be found?

Student A

Number of experiments Voltage (V) Current (A)

1 1.50 0.56

2 2. 00 0.51

3 2.50 0.44

Student B

Number of experiments Voltage (V) Current (A)

1 1.50 0.31

2 2.00 0.41

3 2.50 0.52

(3) In the experiment, there are The experimental equipment of groups A and B are in good condition, and their respective readings are accurate. The three sets of data they measured are recorded in the following two tables. After looking at the two sets of data, the teacher thought that the experimental circuit of one group of students was connected wrongly.

① What do you think the line is connected wrong is ;

② Your judgment is based on .

③According to the three sets of data measured by the correctly connected students, calculate the resistance of the fixed-value resistor as ohms

(keep one decimal place).

41. (3 points) A student conducted the following research experiment:

①Take two water tanks of the same size and organize them into two groups, A and B, with equal amounts of water inside. Using the same kind of river water, put equal amounts of tadpoles of similar size and development status into the two tanks.

② Feed the tadpoles of Group A with feed containing thyroid preparations, and feed the tadpoles of Group B with feed that does not contain thyroid preparations. Other culture conditions are the same.

③ Feed continuously for a period of time and observe and record. The completed recording results are as follows.

Average time for hind limbs to grow

Average time for fore limbs to grow

Average time for tail to fall off

Average Time (days) Average tail loss

Body length (cm)

A 4 7 26 0.7

B 5 9 37 1.3

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⑴The purpose of this research experiment is_______________________________________________.

⑵The purpose of designing Group B experiments is to _______________________.

⑶The conclusion obtained from this experiment is_________________________________________.

Reference answers to the 2004 academic year eighth grade (first) science final test questions

1. Multiple choice questions (each question has only one correct option, each question is worth 2 points, and the total score is 52 points)

1, C 2, B 3, D 4, B 5, D 6, B 7, B 8, D

9, B 10, D 11, C 12, B 13, C 14, A 15, D 16, A

17, D 18, C 19, A 20, D 21, A 22, B 23, A 24, D

25. C 26. C

2. Fill-in-the-blank questions (2 points for each blank, ***28 blanks, 6 of which are extra points.

The total score for this major question shall not exceed 50 points)

27. Hydrogen and oxygen 28, A B

29. High pressure area is clear

30. Reflection

31, 18.1 20 0.905╳102

32, 10 7 106 Flow rate (speed)

33. Atmospheric pressure B

34, 0.5 1.0 1.5 The gravity of the discharged water

35. Reduce the aircraft has entered the stratosphere, while clouds, rain, snow, etc. generally only appear in the troposphere or at an altitude of 10,000 meters. The air is very thin (reasonable distribution). ) Resistance or bumps of the equipment that adjusts the temperature (reasonable equalization)

36. 0.9℅

37. When the applicable voltage is 12V, the current is no longer 0.5A

38. B, C, A and B

3. Analysis and calculation questions (38 questions are worth 7 points, 39 questions are worth 12 points, and 40 questions are worth 3 points, of which 4 points are additional points. The total score for this major question is No more than 18 points)

39. (1) 3 points for correct calculation process to determine ammeter range, 2 points for correct circuit connection

(2) 2 points for correct circuit diagram

40. (1) Disconnect the right

(2) Improper voltmeter range (too small)

(3) The current of A (within the allowable error range) should be the same as Voltage is proportional to 4.8 (2 points for each space)

41. (1) What effect does thyroxine have on the growth and development of animals?

(2) Control (3) Thyroid hormone promotes the growth and development of animals