Magis Science Final Exam ( Grade Seven ) 2019 -2020

Explanation
The statement that cytoplasm contains all the DNA of the cell is false. While the cytoplasm does contain some DNA, the majority of the DNA is located within the nucleus of the cell. The nucleus is the control center of the cell and contains the genetic material that determines the cell's characteristics and functions. The cytoplasm, on the other hand, is a gel-like substance that surrounds the nucleus and contains various organelles and molecules necessary for the cell's metabolism and other processes.

Explanation
Migration is a behavioural adaptation because it is a learned behavior that allows certain animals to move from one location to another in response to environmental changes or seasonal variations. This behavior helps animals find better resources, avoid harsh conditions, or reproduce successfully. Migration is not an innate behavior, but rather a response to specific stimuli, making it a clear example of a behavioural adaptation.

Explanation
Kinetic energy is not the energy stored in an object or system, but rather the energy of motion. It is the energy an object possesses due to its motion, and is dependent on the mass and velocity of the object. Therefore, the correct answer is False.

Explanation
The middle layer of the earth is indeed called the mantle. It is located between the outer core and the crust. The mantle is composed of solid rock that is in a semi-fluid state due to high temperatures and pressure. It is responsible for convection currents that drive plate tectonics and volcanic activity.

Explanation
Adaptations are indeed body parts or behaviors that aid in the survival of living organisms. These adaptations can include physical structures like camouflage or specialized organs, as well as behaviors such as migration or hibernation. By possessing these adaptations, organisms are better equipped to cope with their environment, find food, avoid predators, and reproduce successfully. This enables them to increase their chances of survival and pass on their genes to future generations.

Explanation
Glass is transparent because it is made up of a material that allows light to pass through it without significant scattering or absorption. The atomic structure of glass does not have a regular arrangement, which allows light to pass through it easily. This property of transparency makes glass suitable for use in windows, lenses, and other optical devices.

Explanation
Neutralization occurs when an acid and an alkali react with each other, resulting in the formation of a salt and water. The acid donates a hydrogen ion (H+) to the alkali, which accepts it, forming water. This process cancels out the acidic and alkaline properties, leading to a neutral solution. Therefore, the given statement that "Neutralisation is acid and alkali cancel each other" is true.

Explanation
The statement is true because the Milky Way is indeed the galaxy that our solar system belongs to. The Milky Way is a barred spiral galaxy that contains billions of stars, including our Sun. Our solar system is located in one of the spiral arms of the Milky Way, known as the Orion Arm or Local Spur. Therefore, it is correct to say that our solar system belongs to the Milky Way galaxy.

Explanation
The statement is false because asteroids are not spherical bodies. They are irregularly shaped rocky objects that orbit the sun. Unlike planets, asteroids do not have enough mass to form into a spherical shape due to their smaller size.

Explanation
The cell membrane is responsible for regulating the movement of substances in and out of the cell, but it does not direct all the activities of the cell. The cell membrane acts as a boundary, protecting the cell and providing structural support, but the direction of cell activities is primarily controlled by the nucleus, which contains the cell's genetic material and controls the production of proteins. Therefore, the statement that the cell membrane directs all the activities of the cell is false.

Explanation
Physical adaptation refers to the specific body parts or structures that have evolved in plants or animals to help them survive in their environment. These adaptations can include features such as camouflage, sharp teeth, strong limbs, or specialized organs. These physical adaptations enable organisms to better adapt to their surroundings, find food, avoid predators, or reproduce successfully. Therefore, the statement "Physical adaptation is a special body part that helps plants or animals survive" is true.

Explanation
The statement is false because a giraffe's long neck is not an example of behavioral adaptation, but rather a structural adaptation. Behavioral adaptations refer to actions or behaviors that organisms exhibit in response to their environment, while structural adaptations are physical features or characteristics that help organisms survive or thrive in their environment. In the case of giraffes, their long necks are a structural adaptation that allows them to reach high leaves in trees for food.

Explanation
A galaxy is a collection of solar systems orbiting around a central core. This explanation fits the given answer perfectly.

Explanation
The correct answer is "Universe." The question states that it contains billions of galaxies, which implies a vast and expansive entity. Out of the given options, "Universe" is the only one that fits this description. A galaxy is a smaller component of the universe, while a planet and asteroid are even smaller celestial bodies within a galaxy. Therefore, the universe is the most appropriate answer as it encompasses all the other options and is known to contain billions of galaxies.

Explanation
Baking soda is an alkali because it is a basic compound that can neutralize acids. It has a high pH level and can react with acidic substances to form water and a salt. Baking soda is commonly used in baking as a leavening agent, and it can also be used for cleaning and deodorizing due to its alkaline properties.

Explanation
We live on the crust of the Earth. The Earth's crust is the outermost layer, and it is the thinnest layer compared to the mantle and core. It is made up of solid rocks, soil, and minerals. The crust is where all life on Earth exists, including humans, animals, and plants. It is the layer that we directly interact with and where most geological processes, such as earthquakes and volcanic activity, occur.

Explanation
During neutralization, an acid reacts with a base to form a salt and water. The pH of an acid is typically below 7, indicating its acidic nature. As the acid reacts with the base, the concentration of hydrogen ions (H+) decreases, resulting in a decrease in acidity. This causes the pH of the acid to move up towards pH 7, which is considered neutral. Therefore, the correct answer is that the pH of the acid moves up towards pH 7 during neutralization.

Explanation
When an acid and alkali react together in equal amounts, they undergo a neutralization reaction. This reaction results in the formation of salt and water. The acid and alkali molecules combine to form a salt, while the hydrogen ions from the acid and hydroxide ions from the alkali combine to form water. Therefore, the correct answer is salt and water.

Explanation
The correct answer is 13.7 billion years ago. This is based on scientific evidence and theories such as the Big Bang theory, which suggests that the universe began expanding from a single point approximately 13.7 billion years ago. This age is determined through various methods, including the measurement of cosmic microwave background radiation and the observations of the rate of expansion of the universe.

Explanation
Stomach acid, with a pH of 2, is the strongest acid among the given substances. The pH scale ranges from 0 to 14, with lower values indicating higher acidity. Stomach acid has a lower pH compared to soda, coffee, and tomatoes, indicating a higher concentration of hydrogen ions and stronger acidity.

Explanation
Kinetic energy is the energy possessed by an object due to its motion. It is directly related to the object's mass and velocity. When an object is in motion, it has the ability to do work and transfer energy. Therefore, the correct answer is Kinetic energy.

Explanation
According to the kinetic energy equation, kinetic energy is directly proportional to the square of the velocity. As velocity increases, the kinetic energy increases exponentially. Therefore, the faster an object moves, the more kinetic energy it has.

Explanation
Potential energy is stored energy that an object possesses due to its position or condition. It is the energy that can be converted into other forms of energy, such as kinetic energy, when the object is in motion. Therefore, potential energy is the correct answer as it refers to the stored energy.

Explanation
Cotton and wool are suitable materials for making clothes because they are both natural fibers that have properties ideal for clothing. Cotton is lightweight, breathable, and absorbs moisture, making it comfortable to wear in warm weather. Wool, on the other hand, is warm, insulating, and moisture-wicking, making it suitable for colder climates. These materials are also easy to dye and manipulate, allowing for a wide range of clothing designs and styles.

Explanation
Metals are a better conductor of electricity compared to wood, plastic, and cloth. This is because metals have free electrons that can easily move through the material, allowing electric current to flow with minimal resistance. In contrast, wood, plastic, and cloth are insulators and do not have free electrons, so they impede the flow of electric current.

Explanation
The Geocentric Model is an ancient astronomical model that places the Earth at the center of the universe, with all other celestial bodies, including the Sun, Mars, and Neptune, revolving around it. Therefore, the correct answer is Earth, as it is the central object in this model.

Explanation
Copernicus is the correct answer because he was the first person to propose the Heliocentric Model, which states that the Earth and other planets revolve around the Sun. This model challenged the prevailing belief at the time that the Earth was the center of the universe. Copernicus' work was published in his book "De Revolutionibus Orbium Coelestium" in 1543, and it laid the foundation for modern astronomy.

Explanation
This model represents the heliocentric model, which states that the Sun is at the center of the solar system and all the planets, including Earth, revolve around it. This model was proposed by Nicolaus Copernicus in the 16th century and replaced the geocentric model, which believed that Earth was at the center of the universe. The heliocentric model is widely accepted in modern astronomy and has been supported by various scientific observations and evidence.

Explanation
The correct answer is strong, waterproof, transparent, heat conductor, and hard. These material properties are being listed.

Explanation
The materials that can be ticked from the given options are Wood, Metal, Glass, Plastic, and Ceramic. These materials are ticked because they are all commonly used in various applications due to their specific properties and characteristics. Wood is a natural material that is often used for construction and furniture due to its strength and durability. Metal is a good conductor of heat and electricity, making it useful in many industrial and electrical applications. Glass is transparent and can be molded into various shapes, making it suitable for windows, bottles, and other products. Plastic is a versatile material that is lightweight, durable, and can be easily molded into different forms. Ceramic is a hard and heat-resistant material that is commonly used for tiles, pottery, and other decorative and functional items.