mankind
1. The human body has 206 bones and more than 600 muscles, and the weight of muscles accounts for 40% of the body weight.
2. Bones have the functions of movement, support and protection. Movable joints between bones are called joints, and all kinds of actions of human body are realized by the contraction and relaxation of muscles to drive bones and joints.
3. The advantages of regular exercise are: improving the flexibility of the body; Enhance myocardial and vital capacity; Muscular; Full of physical strength; Delaying aging; Body symmetry.
4. The main nutrients that people need are: protein, carbohydrate, fat, vitamins and minerals.
The kinds of food we eat every day are: grain, vegetables and fruits, fish eggs, soybean milk, oil, salt and sugar. Eating the most is food. You should eat the least oil, salt and sugar.
6. The main digestive organs of human body are mouth, esophagus, stomach, small intestine, large intestine and anus.
In order to eat safely, vegetables and fruits should be fully soaked and washed, eat more green food and eat less pickled food.
8. Pay attention to the production date and shelf life when buying processed food.
9. No food contains all the nutrients the human body needs, so we should eat food in a diversified and comprehensive way.
10, fruits cannot replace vegetables.
air
1, air is mainly composed of nitrogen, oxygen, a small amount of carbon dioxide, water vapor and other gases. If harmful substances are added to the air, the air will be polluted and the airflow will form wind. The ancients in China invented the Kongming Lantern according to the rising principle of hot air.
2. Combustion must meet three conditions at the same time: combustible, oxygen and a certain temperature.
Air is also the source of life, but human activities are the main cause of air pollution. Some measures to prevent air pollution include planting trees, saving energy, driving less cars, improving car fuel, prohibiting burning straw and using fluorine-free refrigerators.
You can touch it with your hands or put it in a plastic bag to feel the air. Air is a colorless, odorless and tasteless transparent gas.
5. Screw the funnel with rubber stopper on the bottle mouth and pour the water into the funnel. Can water flow into the bottle?
Why? Water can't flow into the bottle, because the space in the bottle is occupied by air, and the rubber plug seals the mouth of the bottle. If the air can't get out, the water in the funnel can't get in. )
6. Use ice cubes to cool food. Should the food be put on the ice or under it? Why? Food should be placed under the ice, because the air around the ice will sink quickly when it is cold, and the sinking air will surround the object to be cooled, so as to achieve the purpose of cooling as soon as possible. )
7. Air is compressible, and compressed air is elastic. Why can't bicycle tires be inflated too much in hot summer? Air has the property of expanding when heated and contracting when cooled. Due to the high temperature in summer, the air in the tire is exposed to high temperature, and the volume will inevitably increase rapidly, resulting in great pressure. When the tire can't bear such a big pressure, it will burst. )
astronomy
1. The position of the sun in the sky can be expressed by its direction and height. The phenomenon that the sun rises and falls day and night is actually formed by the rotation of the earth from west to east. It's just that we live on the earth and take the earth as a reference, so it seems that we are going up and down.
2. The sun is in the east, the shadow is in the west, the sun is in the south, the shadow is in the north, the sun is in the west, and the shadow is in the east. Sun clock is formed according to the changing law of the shadow direction of objects under the sun. Sun clock in the Palace Museum is called the sundial, which belongs to the equatorial sundial and is preserved by Nanjing Purple Mountain Observatory.
The image of the bright part of the moon is called the moon phase.
The new moon refers to the invisible moon in the sky. The moth-eyebrow moon at the beginning of the month means that the sun has just set on the horizon, and the moon phase we see is facing the sun. The moth-eyebrow moon at the end of the month means that when the sun is about to rise, the moon phase you see is also facing the sun.
5. Looking at the moon from the first day to the fifteenth day at sunset, I found that the moth-eyebrow moon is in the west, the first quarter moon is in the south, the convex moon is in the Middle East, and the full moon is in the east. It can be seen that the direction of the moon's revolution around the earth is from west to east.
6. Looking at the moon from 16th to the end of the month at sunrise, I found that the moon on 16th is in the west, the last quarter moon is in the southern sky, the waning moon is in the middle east, and the moth moon is in the east.
7. In a day, the moon rises in the east and sets in the west. This is because the earth rotates from west to east. The moon is the satellite of the earth, and it is a month in the lunar calendar for the moon to go around the earth.
Motion and force
1. When we ride a bicycle, the wheels move in a straight line and rotate.
2. The speed of the truck is related to factors such as self-weight, tension and road surface.
The unit of force is Newton.
4, when using dynamometer, to make the pointer at 0, can't exceed the maximum measuring range.
When an object is subjected to an external force, its shape or volume will change, and it can be restored to its original shape or volume after removing the external force. This property is called elasticity, and this force is called elasticity.
6. Everything on the earth has a vertical downward gravity. This force is due to the gravity of the earth.
7. Judges:
Force can change the motion state of an object. (right)
The elasticity of an object is infinite (wrong)
When an object passes through liquid or air, it also produces friction (pair)
8. Friction can generate heat, and the formation of meteors is related to friction. In hot summer, the car tires on the expressway will be hot; There are many examples of increasing beneficial friction (such as patterns on tires and handlebars) and reducing harmful friction (adding lubricating oil and ball bearings to mechanical moving parts).
9. The shape of an object is related to the friction it receives. For example, the descending speed of a parachute is related to the size of its canopy.
water
1, water is the source of life, water is a colorless, odorless and tasteless transparent liquid. Water has three states: solid, liquid and gas. Clouds, fog, rain, dew and frost are all condensed by water in the air.
2. The common ways to know objects are to look, smell with the nose, taste with the tongue and touch with the hands. Don't smell or taste what you don't know. What is the way to identify water, salt water, sugar water, milk and white vinegar in a cup?
Water has the force to make its surface as small as possible, which is called the surface tension of water.
4. Iron will sink in the water, but why can steel boats float on the water? Because the steel ship has a large space and is lighter than the same volume of water, it floats on the water. )
Most of the water on the earth is salt water in the ocean, only a small amount of fresh water. Most fresh water is only stored in glaciers in Antarctica and the Arctic. There is a small amount of invisible water vapor in the atmosphere, and only the water in rivers, lakes and shallow strata can be used by human beings. And this little fresh water available for human use has been polluted to varying degrees. If human beings do not pay attention to protecting water resources, there will be no clean water available on the earth.
6. Solids have certain shapes. The separation of solids, such as beans and rice, coarse sand and fine sand, will reduce the volume of two different solids after mixing. For example, when soybeans and rice are mixed together, the volume becomes smaller, but the weight remains the same. Liquid is mixed with water, some are soluble in water, and some are insoluble in water. Some float on the water and some sink under the water, but this is not absolute. Under changing conditions, water-insoluble liquids may also be soluble in water.
biology
1. Seed structure: cotyledon, radicle and embryo. The germ will grow into stems and leaves, and the radicle will grow into roots.
2, plant growth needs: sunshine, water, air, soil, suitable temperature, nutrients.
3. A flower, such as rape, has petals, sepals, pistils and stamens.
Bees and some insects can pollinate some flowers There are seeds in the fruit. "Seedless melon" is cultivated artificially. It is still a fruit, and radish is not a fruit.
4. The main components of soil are: sand, clay, humus, etc.
5. Silkworms, dragonflies, ants and crickets. Are all insects. Their adult bodies are divided into three parts: head, chest and abdomen. There are a pair of tentacles in the head and three feet in the chest. The antenna of silkworm moth is pinnate. Insects go through metamorphosis all their lives, and silkworms go through four stages: egg, silkworm, pupa and moth. China is the first country in the world to plant mulberry, raise silkworms and produce silk products.
6. Fish live in water all their lives. Fish have various shapes, and the surface of fish has scales. Some fish, such as eels and sticky fish, have no scales. Fish scales have patterns like rings. Fish also have ears, but they are hidden in the skull. Fish use gills to get oxygen from water. Fish can change their volume by adjusting the amount of gas in the swim bladder, so as to adjust their specific gravity and get different buoyancy. Fast-moving sharks have no swim bladders. Fish move forward by tail, and slowly move forward by ventral fins or gills to drain water. The pectoral fin can stop the swimming fish, and the lateral line can determine the direction and sense the water temperature.
7. Be kind to animals, love animals and protect animals closely related to our lives. Such as cattle, bees and insect-eating birds. Protect rare animals. Where can we start? For us middle schools who have lived in urban areas for a long time, we should love the environment where birds, trees and small animals live. In order to protect the animals in the water, we must protect the water source. In the breeding season of birds, we should work with our parents to make "artificial nests" for birds. In the zoo, we should also be civilized spectators and care for all kinds of animals. )
8. Animals have different living habits. Most birds move during the day, while owls mainly prey on mice. Mice like to move at night, so owls also move at night. It's sleeping time from morning to afternoon. Snails like to live in a dark and humid environment, and their activity time is also at night.
thermology
1, the degree of heat and cold of an object is called temperature. Heat is always transferred from high to low.
2. The main heat transfer mode of solid is conduction, and the main heat transfer mode of liquid and gas is convection, and the heat from the sun radiates to the earth.
When most objects are heated, their volume will expand, but when they are cooled, their volume will shrink. This property is called thermal expansion and cold contraction.
Because dark objects absorb radiant heat more easily than light objects, we like to wear light clothes in summer and dark clothes in winter.
5. What effect will temperature change have on objects? The wires are stretched in summer, and the water pipes are frozen and cracked in cold winter. )
6. The application of heating and cooling objects in life? (Sometimes the pickle bottle cap can't be unscrewed. You can wrap the bottle cap with a hot towel, and the bottle cap can be easily unscrewed when heated and expanded. And the connection of plastic water pipes, steelmaking, making popsicles and candles. )
7. Why is the pot handle plastic? Is the pot made of metal? Plastic is not good at heat transfer, so the handle made of plastic won't burn. Because metal conducts heat well, the pot body is made of metal. )
8. Draw the heat transfer diagram in the kettle. (omitted)
sound
1, sound is produced by object vibration. Any sound that people don't need is noise. Noise harms people's physical and mental health and is one of the four major public hazards in today's society.
2. Human ear structure: auricle, external auditory canal, tympanic membrane, ossicular bone, cochlea and auditory nerve.
3. Sound can't travel in vacuum.
This exam is very important for junior high school study ~ Be sure to cheer up ~ ~