7th Grade Science Quiz Questions And Answers

A thermometer is used to check the temperature. It is a device that measures the temperature of a substance or an environment. It consists of a glass tube filled with a liquid, usually mercury or alcohol, that expands or contracts with temperature changes. The expansion or contraction of the liquid is indicated by a scale on the thermometer, allowing the user to read the temperature. Thermometers are commonly used in various settings, such as in homes, laboratories, and medical facilities, to monitor and control temperature.

The main source of energy for the Earth is the Sun. The Sun's energy is primarily produced through nuclear fusion, where hydrogen atoms combine to form helium, releasing enormous amounts of energy. This energy travels through space in the form of electromagnetic radiation, including visible light, ultraviolet, and infrared radiation. Earth absorbs this energy, which drives weather patterns, supports plant growth through photosynthesis, and powers the water cycle. The Moon, Earth’s core, and the wind all play significant roles, but none provide the amount of energy that the Sun does, which is crucial for sustaining life.

The process by which liquid water changes into vapor is known as evaporation. Evaporation occurs when molecules in the liquid state gain enough energy, often from heat, to overcome intermolecular forces and enter the gaseous state. This process occurs at the surface of the liquid and increases with higher temperatures and greater surface area. The rate of evaporation can be calculated using the formula for heat required to change the phase of the liquid. While condensation and precipitation are related to water vapor, evaporation specifically refers to the transition from liquid to gas, essential for the water cycle.

Acids are known to have a sour taste. This is a common characteristic of acidic substances, such as lemon juice and vinegar, which contain citric acid and acetic acid, respectively. This sourness is a typical property used to describe acids. Therefore, the statement "Acids taste sour" is true.

Chlorophyll is a vital pigment found in the chloroplasts of green plants and is crucial for photosynthesis, the process by which plants convert light energy into chemical energy. This green pigment absorbs sunlight, specifically capturing light in the blue and red wavelengths most effectively, while reflecting green light, which is why plants appear green. The absorbed light energy is then used to convert carbon dioxide (CO2) from the air and water (H2O) from the soil into glucose and oxygen.

During photosynthesis, plants primarily absorb carbon dioxide (CO2) from the atmosphere. This process takes place in the leaves, where chlorophyll absorbs sunlight and uses its energy to convert carbon dioxide and water into glucose and oxygen. The plants absorb CO2 through tiny pores called stomata on their leaves. This is essential because carbon atoms from CO2 are used to form glucose, a crucial energy source for plants. Nitrogen, oxygen, and hydrogen are important for other biological processes, but carbon dioxide is the primary molecule required for photosynthesis and the creation of energy-rich sugars.

A merry-go-round is an example of circular motion. It involves objects moving in a circular path around a central axis or point, typically in a circular and repetitive manner. Straight motion does not describe a merry-go-round because this ride does not move in a straight line.

Leaves are primarily responsible for photosynthesis, not for absorbing water and minerals. The stem transports water and nutrients within the plant but is not the main site of absorption. Roots have specialized structures, such as root hairs, for absorbing water and minerals from the soil. Flowers are involved in reproduction and do not play a significant role in absorbing water and minerals.

The standard international unit of speed is meters per second (m/s), not seconds per meter (s/m). Speed is defined as the distance traveled per unit of time, and meters per second accurately represent this measurement. The confusion with s/m arises from the incorrect representation of speed, which should be a ratio of distance to time.

Photosynthesis is the process by which green plants, algae, and some bacteria use sunlight to synthesize foods with the help of chlorophyll pigment. During photosynthesis, carbon dioxide and water are converted into glucose (a form of sugar) and oxygen. This process is fundamental to the survival of most life forms on Earth, as it produces food and oxygen, both of which are essential for life. Respiration is a different biological process involving the release of energy from food/sugar, fermentation is a metabolic process that doesn't involve sunlight, and germination is the process of a seed sprouting into a plant.

Mitochondria are often referred to as the powerhouses of the cell. They are specialized organelles within animal cells that play a critical role in converting the energy stored in glucose into ATP (adenosine triphosphate) through a process known as cellular respiration. ATP is the main energy currency of cells, used to power various biological processes such as muscle contraction, nerve impulse propagation, and chemical synthesis.

The Earth's structure is divided into several layers: the crust, mantle, outer core, and inner core. The crust is the outermost layer of the Earth and is composed primarily of solid rock. It includes both continental crust (which forms the continents) and oceanic crust (which forms the ocean floors). The crust is relatively thin compared to the other layers, averaging about 30 kilometers thick under continents and about 5-10 kilometers thick under oceans. It is where we live, and it contains the rocks, minerals, and soils that make up the Earth's surface. The mantle, which lies beneath the crust, is made of semi-solid rock, while the outer core is liquid, and the inner core is solid but composed of metal rather than rock.

Convex mirrors are used for side view in vehicles because they have a wider field of view and provide a larger image compared to concave mirrors. This allows the driver to see a larger area and objects that may be in their blind spot. The convex shape of the mirror causes light rays to diverge, resulting in a wider view. Additionally, convex mirrors also help to reduce the distortion of the image, making it easier for the driver to judge the distance and size of objects.

During anaerobic respiration in yeast, glucose is broken down into alcohol (usually ethanol/ethyl alcohol) and carbon dioxide. This process, known as fermentation, occurs when there is a lack of oxygen or oxygen is not present. The yeast cells use glucose as a source of energy. The glucose is broken down into alcohol and carbon dioxide. A related process known as fermentation is a common process in the production of alcoholic beverages such as beer and wine.

The odometer is a device that records the distance traveled by a vehicle. It is typically located on the dashboard on the driver’s side of the car and displays the total number of miles or kilometers that the vehicle has traveled since it was first put into use. The odometer is an important tool for keeping track of the mileage on a vehicle, which can be useful for maintenance purposes, determining fuel efficiency, and calculating depreciation. It is different from a speedometer, which measures the current speed of the vehicle, and from a manometer and moto meter, which are not related to measuring distance traveled.