Science Final Exam 7th Grade

Plants use sunlight to make food through a process called photosynthesis. During photosynthesis, plants convert sunlight, water, and carbon dioxide into glucose and oxygen. This process occurs in the chloroplasts of plant cells, specifically in the chlorophyll pigment. The energy from sunlight is captured by chlorophyll and used to convert carbon dioxide and water into glucose, which is then used as a source of energy for the plant. Oxygen is released as a byproduct of photosynthesis. Respiration, fermentation, and mitosis are not involved in the process of using sunlight to make food.

Sand is not made from cells because it is a naturally occurring granular material composed of finely divided rock and mineral particles. Unlike living organisms such as mushrooms, dogs, and leaves, sand does not possess cellular structures or biological components. Sand is formed through processes such as erosion, weathering, and sedimentation, and does not have the characteristic features of living organisms.

Harmful substances that are present in the air, water, or soil are commonly referred to as pollutants. These pollutants can include various substances such as chemicals, toxins, gases, or even solid particles. They are considered harmful as they can have detrimental effects on the environment, human health, and ecosystems. Therefore, pollutants are the correct term used to describe these harmful substances in the given context.

The correct answer is cell wall. The cell wall is a rigid layer that surrounds the cell membrane in plant cells, providing support and protection. Animal cells do not have a cell wall, instead they have a flexible cell membrane that allows for movement and communication. The nucleus and nuclear membrane are present in both plant and animal cells, playing a role in genetic material storage and regulation.

Rain forests are dense forests that receive abundant rainfall throughout the year. These forests are characterized by a high diversity of plant and animal species, as well as a dense canopy that blocks out most sunlight from reaching the forest floor. The constant rainfall creates a moist and humid environment, which supports the growth of a wide variety of plants and provides a habitat for numerous species. Rain forests are typically found in tropical regions near the equator, such as the Amazon rainforest in South America and the Congo rainforest in Central Africa.

The burning of fossil fuels is the main cause of air pollution. When fossil fuels such as coal, oil, and natural gas are burned for energy, they release harmful pollutants into the air, including carbon dioxide, sulfur dioxide, nitrogen oxides, and particulate matter. These pollutants contribute to the formation of smog, acid rain, and the greenhouse effect, leading to various health and environmental problems. Dust and pollen, erupting volcanoes, and acid rain can also contribute to air pollution, but they are not the primary sources like the burning of fossil fuels.

Diffusion is the movement of molecules from an area of greater concentration to an area of lesser concentration. This process occurs spontaneously and does not require any external energy input. It is driven by the random motion of molecules and leads to the equalization of concentration throughout a system. Diffusion is a fundamental process in various biological and physical phenomena, such as the exchange of gases in the lungs, the movement of nutrients across cell membranes, and the mixing of substances in a liquid.

A barometer is used to measure air pressure. It is a device that helps in determining the atmospheric pressure, which is the force exerted by the weight of the air molecules in the atmosphere. By measuring air pressure, a barometer can provide valuable information about weather patterns and changes. It is commonly used in meteorology and also in various industries such as aviation and agriculture, where knowledge of air pressure is important for decision-making and forecasting.

The region between the cell membrane and the nucleus is called the cytoplasm. It is a gel-like substance that fills the cell and contains various organelles, such as mitochondria and ribosomes. The cytoplasm plays a crucial role in cell metabolism, transport of molecules, and providing structural support to the cell. It also serves as a site for many cellular activities, including protein synthesis and cellular respiration.

Climates located farther from the equator tend to have lower temperatures. This is because the angle at which sunlight reaches the Earth's surface decreases as you move away from the equator. As a result, the same amount of sunlight is spread over a larger area, leading to less heat being absorbed by the surface. Additionally, the tilt of the Earth's axis causes the seasons, which further affects temperatures in different regions.

Carbohydrates are the type of organic compound that includes sugar and starches. Carbohydrates are the main source of energy for the body and are made up of carbon, hydrogen, and oxygen atoms. They can be found in foods such as fruits, vegetables, grains, and dairy products. Sugars and starches are both examples of carbohydrates, with sugars being simple carbohydrates and starches being complex carbohydrates. Carbohydrates play a crucial role in providing energy, regulating blood sugar levels, and supporting various bodily functions.

Ribosomes are the correct answer because they are the organelles responsible for protein synthesis in a cell. They are small, grain-like structures found either freely floating in the cytoplasm or attached to the endoplasmic reticulum. Ribosomes read the genetic information from the DNA and use it to assemble amino acids into proteins. They play a crucial role in protein synthesis, which is essential for various cellular functions and processes.

A wind vane is used to measure wind direction. It consists of a freely rotating arrow or pointer that aligns itself with the direction of the wind. This allows meteorologists and weather enthusiasts to determine the direction from which the wind is blowing. In contrast, a psychrometer is used to measure humidity, an anemometer is used to measure wind speed, and a thermometer is used to measure temperature. Therefore, the correct answer is wind vane.

A dominant allele is an allele that always expresses its trait in an organism, regardless of whether it is paired with another dominant allele or a recessive allele. This means that even if there is only one copy of the dominant allele present, it will still be able to determine the organism's phenotype. In contrast, a recessive allele only expresses its trait when it is paired with another recessive allele. Therefore, the correct answer is dominant allele.

DNA and RNA are examples of nucleic acids. Nucleic acids are macromolecules that are essential for storing and transmitting genetic information in living organisms. DNA (deoxyribonucleic acid) carries the genetic instructions for the development, functioning, and reproduction of all known organisms. RNA (ribonucleic acid) plays a key role in protein synthesis and gene expression. Both DNA and RNA are composed of nucleotides, which are the building blocks of nucleic acids. Therefore, the correct answer is nucleic acids.

The sun's rays hit least directly in the polar temperature zone. This is because the polar regions are located near the Earth's poles, where the angle of the sun's rays is very low. Due to the curvature of the Earth, the sun's rays have to pass through a larger portion of the atmosphere at the poles, resulting in more scattering and less direct sunlight reaching the surface. As a result, the polar regions experience colder temperatures and less intense sunlight compared to the other temperature zones.

Convection current is the correct answer because it accurately describes the upward movement of warm air and the downward movement of cool air. Convection is the transfer of heat through the movement of fluids (in this case, air) due to differences in temperature. As warm air rises, it creates a low-pressure area, causing cool air to flow in and replace it. This continuous cycle of upward and downward movement is known as a convection current.

Ice cap is the correct answer because it describes a climate where temperatures are always at or below freezing and the land is covered with ice and snow. Ice caps are characterized by extremely cold temperatures and a permanent ice cover, making it impossible for temperatures to rise above freezing. This climate is typically found in polar regions such as Antarctica and Greenland.

Stomata are tiny openings or pores on the surface of plant leaves and stems. They are responsible for the exchange of gases, including carbon dioxide and oxygen, between the plant and its environment. Carbon dioxide enters the plant through these stomata during the process of photosynthesis.

On the Fahrenheit scale, the freezing point of water is -32 degrees. This means that at this temperature, water will freeze and turn into ice. The Fahrenheit scale is commonly used in the United States and a few other countries. It is based on dividing the range between the freezing and boiling points of water into 180 equal intervals. The freezing point of water is marked as 32 degrees on this scale, and since the question asks for the freezing point in negative, the correct answer is -32.

Seismic waves are the waves produced by earthquakes. These waves travel through the Earth's interior and can be detected and measured by seismographs. They are responsible for the shaking and destruction caused by earthquakes. Seismic waves can be classified into two main types: body waves and surface waves. Body waves include P-waves (primary waves) and S-waves (secondary waves), which travel through the Earth's interior. Surface waves, on the other hand, travel along the Earth's surface and are responsible for most of the damage during an earthquake. Therefore, seismic waves is the correct answer to the question.

Nitrogen is the most abundant gas in the universe because it makes up about 78% of Earth's atmosphere. It is also found in the atmospheres of other planets and in the interstellar medium. Nitrogen is an essential element for life and is used by plants and animals in various biological processes. Additionally, nitrogen is a major component of many important compounds such as proteins and nucleic acids.

The phenotype of an organism refers to its physical appearance, which includes observable characteristics such as color, shape, size, and behavior. It is determined by the interaction of the organism's genetic makeup (genotype) with environmental factors. While the genetic makeup and allele combination play a role in determining the phenotype, they alone do not fully define it. Therefore, the correct answer is physical appearance.

Meiosis is the correct answer because it is the process by which the number of chromosomes is reduced by half to form sex cells. During meiosis, the genetic material is shuffled and recombined, resulting in genetic diversity. This process is essential for sexual reproduction and ensures that each offspring receives a unique combination of genes from their parents. Protein synthesis, heredity, and probability are not related to the reduction of chromosome number during the formation of sex cells.

In the Northern Hemisphere, the winds of a cyclone always spin counterclockwise. This is due to the Coriolis effect, which is caused by the rotation of the Earth. As air moves towards the center of the cyclone, it is deflected to the right, causing it to rotate counterclockwise around the center. This rotation pattern is consistent in the Northern Hemisphere.

During DNA replication, adenine pairs with thymine. This is because adenine and thymine are complementary base pairs in DNA. Adenine forms two hydrogen bonds with thymine, creating a stable base pair. This pairing is essential for the accurate replication of DNA, as each strand serves as a template for the synthesis of a new complementary strand. The pairing of adenine with thymine ensures that the genetic information is faithfully copied during DNA replication.

An echo is an example of a reflected wave because it occurs when sound waves bounce off a surface and return to the source. This phenomenon happens when the time it takes for the sound waves to travel to the surface and back is less than the persistence of hearing in the human ear. As a result, we perceive the sound as a distinct repetition. This reflection of sound waves is similar to how a wave reflects off a surface, making an echo a clear example of a reflected wave.

El Nino is a climatic phenomenon that occurs irregularly in the Pacific Ocean. It is characterized by the warming of the ocean surface temperatures, which has significant impacts on weather patterns worldwide. El Nino events typically occur every 2 to 7 years, although the exact frequency can vary. This irregularity is due to various factors such as oceanic and atmospheric conditions. Therefore, the correct answer is 2 to 7 years.

Antinode waves is not a recognized term or category of waves in physics. Transverse waves, surface waves, and longitudinal waves are all well-defined types of waves that exist in various physical systems. Antinodes, on the other hand, are points of maximum amplitude in a standing wave pattern, but they are not considered as a distinct type of wave.

Anton Van Leeuwenhoek is credited as the first scientist to observe and document animalcules, or microscopic organisms. He made significant advancements in the field of microscopy, constructing powerful microscopes that allowed him to observe and describe various microorganisms, including bacteria and protozoa. His discoveries were instrumental in the development of the field of microbiology and our understanding of the microscopic world.

Continental climate typically has cold winters and hot summers. This type of climate is characterized by a large temperature range throughout the year, with cold winters due to its distance from the moderating influence of the ocean, and hot summers due to the lack of maritime influence. Continental climates are often found in the interior regions of large landmasses, away from the moderating effects of nearby bodies of water.

Tornadoes are known to produce the highest winds compared to hurricanes, thunderstorms, and snowstorms. Tornadoes are violent and destructive atmospheric phenomena characterized by a rotating column of air that extends from a thunderstorm cloud to the ground. They can reach wind speeds of over 300 miles per hour, causing significant damage to structures and landscapes in their path. Unlike hurricanes that have a larger size and longer duration, tornadoes are more localized and intense, making them the storms with the highest wind speeds.

The stratosphere is the correct answer because it is the layer of the atmosphere that contains the ozone layer. Ozone is a molecule made up of three oxygen atoms and it acts as a protective shield, absorbing and filtering out harmful ultraviolet (UV) rays from the sun. This is important because excessive UV radiation can cause skin cancer, cataracts, and other harmful effects on both humans and the environment. The presence of ozone in the stratosphere helps to protect the Earth's surface from these harmful UV rays.

Lightning is the correct answer because it refers to the sudden discharge of energy during a storm. Lightning occurs when there is a buildup of electrical charge in the atmosphere, and it is released in the form of a bright flash of light. This discharge of energy can be dangerous and is often accompanied by thunder, which is the sound produced by the rapid expansion of air surrounding the lightning bolt. A storm surge, on the other hand, refers to a rise in sea level during a storm, while a tropical disturbance is a broad term for a weather system that is not yet a tropical cyclone.

Constructive interference occurs when two waves combine to make a wave with a larger amplitude. This happens when the crests of one wave align with the crests of the other wave, and the troughs align with the troughs. As a result, the amplitudes of the individual waves add up, creating a wave with a greater displacement. This phenomenon is commonly observed in various wave systems, such as sound waves, water waves, and electromagnetic waves.

Cumulonimbus clouds are known for their vertical development and are often associated with thunderstorms. These clouds have a large vertical extent, reaching high altitudes and producing intense updrafts. Hailstones form within cumulonimbus clouds when strong updrafts carry raindrops upward into extremely cold regions of the cloud, causing them to freeze and accumulate layers of ice. As the hailstone becomes too heavy for the updrafts to support, it falls to the ground as hail. Therefore, cumulonimbus clouds are the type of cloud in which hailstones form.

Mathias Schleiden is credited with the discovery that all plants are made up of living things. He was a German botanist who, along with Theodor Schwann, formulated the cell theory, which states that all living organisms are composed of cells. Schleiden observed plant tissues under a microscope and concluded that plants are composed of individual cells. This discovery was a significant contribution to our understanding of the structure and function of plants.

As the density of air increases, its pressure decreases. This is because an increase in density means that there are more air molecules in a given volume, resulting in more collisions between the molecules. These collisions exert a force on the walls of the container, causing a decrease in pressure. Therefore, as the density of air increases, the pressure it exerts decreases.

Tornadoes form in cumulonimbus clouds. Cumulonimbus clouds are large, towering clouds that are associated with thunderstorms. These clouds have strong updrafts and can reach great heights in the atmosphere. Tornadoes typically form in the lower portion of cumulonimbus clouds, where there is a strong rotation of air. The combination of the updrafts and the rotation creates the conditions necessary for a tornado to develop.

A mutation that causes disease resistance in potatoes is considered a helpful mutation because it provides an advantage to the organism. In this case, the mutation allows the potatoes to resist diseases, which can improve their chances of survival and productivity. This beneficial trait can be passed on to future generations, leading to a population of potatoes with enhanced disease resistance.

A thin tree ring indicates that the year was cool or dry. Tree rings are formed by the growth of a tree during each year, with wider rings indicating favorable growth conditions. In contrast, a thin tree ring suggests that the tree experienced limited growth due to unfavorable conditions such as low temperatures or lack of moisture. Both cool and dry conditions can hinder tree growth, resulting in thin rings. Therefore, a thin tree ring is indicative of a cool or dry year.

Mutations are changes in the DNA sequence that can lead to the development of cancer. These changes can occur spontaneously or be caused by exposure to certain chemicals, toxins, or viruses. Mutations can disrupt the normal functioning of genes involved in cell growth and division, leading to uncontrolled cell growth and the formation of tumors. While radiation, tumors, and drugs can be factors that contribute to the development of cancer in some cases, mutations are the primary cause.

The cytoplasm is the part of the cell where proteins are made. This is because it contains various organelles, such as ribosomes, which are responsible for protein synthesis. Proteins are essential for various cellular functions and are involved in processes like cell signaling, enzyme activity, and structural support. Therefore, the cytoplasm plays a crucial role in protein production within the cell.

Cytokinesis is the correct answer because it is the final stage of the cell cycle. During cytokinesis, the cytoplasm of the cell divides, resulting in the formation of two daughter cells. This process completes the cell cycle and is essential for the growth and development of organisms. Interphase is not the final stage, but rather the stage where the cell prepares for division. Mitosis is a stage that occurs before cytokinesis, where the nucleus of the cell divides. Telophase is a substage of mitosis, not the final stage of the cell cycle.

During meiosis, sex cells, also known as gametes, are formed through a process called chromosome separation. This occurs during the second division of meiosis, known as meiosis II. In this phase, the replicated chromosomes line up at the center of the cell and are pulled apart, or separated, to opposite poles of the cell. This ensures that each gamete receives only one copy of each chromosome, resulting in the formation of haploid cells that are genetically distinct from each other. Therefore, the correct answer is "separated."

Primary, Secondary, and Surface waves are all types of seismic waves. Seismic waves are waves of energy that travel through the Earth's layers, especially during earthquakes or other seismic events. Primary waves (P-waves) are the fastest and can travel through solids, liquids, and gases. Secondary waves (S-waves) are slower and can only travel through solids. Surface waves are the slowest and cause the most damage, as they travel along the Earth's surface. Therefore, seismic waves is the correct answer as it encompasses all three types of waves mentioned in the question.

Gregor Mendel's work was the foundation for understanding why offspring have traits similar to those of their parents. Through his experiments with pea plants, Mendel discovered the principles of inheritance and established the concept of dominant and recessive traits. He observed that certain traits were consistently passed down from parents to offspring, and he developed the laws of segregation and independent assortment to explain how these traits are inherited. Mendel's work laid the groundwork for the field of genetics and provided a scientific explanation for why offspring resemble their parents in terms of inherited traits.

During prophase, chromatin condenses and forms rod-like structures called chromosomes. This is an important step in cell division, as the condensed chromosomes allow for easier separation and distribution of genetic material to daughter cells. In anaphase, the chromosomes are already separated and moving towards opposite poles of the cell. In telophase, the chromosomes decondense and form chromatin again. In interphase, the cell is in a resting phase and the chromatin is not condensed. Therefore, the correct answer is prophase.

Radiation is the correct answer because it refers to the direct transfer of electromagnetic waves. Unlike conduction, which involves the transfer of heat through direct contact, or convection, which involves the transfer of heat through the movement of fluids, radiation does not require a medium. It can occur through empty space and is responsible for the transfer of heat from the Sun to the Earth.

In December, the south end of Earth's axis is tilted towards the sun. This is because December is the start of the southern hemisphere's summer and the northern hemisphere's winter. During this time, the southern hemisphere experiences longer days and shorter nights because the tilt of Earth's axis causes the sun's rays to be more direct in the southern region. This tilt towards the sun in December leads to warmer temperatures and the peak of the summer season in the southern hemisphere.