General Science 11 Term Exam Reviewer

Louis Pasteur's swan-neck flask experiment demonstrated that microorganisms do not spontaneously arise from non-living matter, but rather originate from existing microorganisms in the environment. By using flasks with curved necks that allowed air in but trapped particles, Pasteur showed that no microbial growth occurred in sterilized broth unless the neck was broken, exposing it to contaminants. This pivotal experiment provided evidence against spontaneous generation and supported the germ theory of disease, establishing that life comes from pre-existing life.

Aerosol sprays are classified as flammable due to their pressurized contents and volatile solvents, which can ignite easily. Drain cleaners are corrosive as they contain strong acids or bases that can damage tissues and materials. Used batteries pose an environmental hazard when disposed of improperly, as they can leak harmful chemicals into ecosystems. In contrast, baking soda is not toxic and is often used as a safe household product, making it an incorrect match for the toxic hazard category.

The 20-20-20 rule is designed to reduce eye strain caused by prolonged screen time. By looking at an object 20 feet away for 20 seconds, your eyes get a chance to relax and refocus, which helps alleviate discomfort and fatigue. This practice encourages regular breaks from screens, promoting better eye health and comfort during extended periods of digital device usage.

Pasteurization is a process named after Louis Pasteur, who demonstrated that heating liquids can eliminate pathogens. By heating food or beverages to a specific temperature for a set period, harmful microorganisms are destroyed, reducing the risk of foodborne illness. This method not only enhances food safety but also helps to prolong the freshness and shelf life of products, making them safer for consumption and more convenient for storage.

The Department of Environment and Natural Resources (DENR) is the government agency responsible for protecting and managing the country's environment and natural resources. It oversees the enforcement of environmental laws and regulations, including those related to waste management and pollution control. In cases of illegal dumping of chemical waste, DENR is tasked with investigating violations, ensuring compliance with environmental standards, and taking necessary actions to mitigate environmental harm.

The FDA is responsible for ensuring the safety and effectiveness of cosmetics, which includes overseeing product registration and addressing any safety concerns related to cosmetic ingredients. Additionally, the agency investigates reports of adverse reactions, such as allergies, linked to personal care products, ensuring consumer safety. While consumer protection through product labeling is also important, the FDA's primary focus in this context pertains specifically to cosmetics and their safety rather than hazardous waste disposal, which falls under different regulatory agencies.

The chemical in question is categorized as toxic because it poses a significant risk to health when ingested. Toxic substances can cause harmful effects or death even in small amounts. In this scenario, the child's accidental consumption highlights the immediate danger of exposure to harmful chemicals, necessitating proper labeling and storage to prevent such incidents. Flammable, corrosive, and environmental hazards, while serious, do not specifically address the acute health risks associated with ingestion that define a toxic substance.

Germ theory, developed in the 19th century, posits that specific microorganisms, such as bacteria and viruses, are the primary agents responsible for various diseases. This theory revolutionized medicine by establishing a scientific basis for understanding infectious diseases, leading to improved sanitation, hygiene practices, and the development of vaccines and antibiotics. The evidence supporting germ theory includes the identification of pathogens in diseased individuals and the ability to reproduce disease in healthy hosts by introducing these microorganisms. Thus, it is accurate to state that many diseases are caused by microorganisms.

Pasteur's experiment demonstrated that boiling the nutrient broth sterilized it by killing existing microorganisms. The swan-neck design allowed air to enter while trapping airborne microbes in the curved neck, preventing them from contaminating the broth. As a result, the broth remained uncontaminated and did not spoil, providing evidence against the spontaneous generation theory and supporting the idea that microorganisms are responsible for spoilage. This experiment highlighted the importance of both sterilization and the role of microorganisms in contamination.

The motorcycle primarily undergoes translational motion as it moves from one location to another, transporting parcels. Translational motion refers to the movement of an object along a path, which in this case is the route taken from the warehouse to various barangays. Unlike rotational motion, which involves spinning around an axis, or vibrational motion, characterized by oscillations, the rider's movement is linear and directional, making translational motion the most appropriate description of the motorcycle's movement.

LED lights are energy-efficient, consuming significantly less electricity compared to traditional lighting, which reduces energy costs. They have a longer lifespan, often lasting up to 25,000 hours or more, minimizing the need for frequent replacements. Additionally, LED lights generate less heat, enhancing safety and reducing cooling costs in enclosed spaces. These advantages make LEDs a more sustainable and economical lighting choice.

Sonar, which stands for Sound Navigation and Ranging, operates by emitting sound waves into the water. These waves travel until they encounter an object, such as a school of fish, and then bounce back to the vessel as echoes. By analyzing the time it takes for the echoes to return, the sonar system can determine the distance and size of the objects, allowing fishermen to locate schools of fish effectively. This method is particularly suited to underwater environments where sound travels better than electromagnetic waves.

Electromagnetic waves, such as light and radio waves, can propagate through a vacuum, meaning they do not require any material medium (like air or water) to travel. In contrast, sound waves are mechanical waves that rely on the vibration of particles in a medium to transmit energy. This fundamental difference allows electromagnetic waves to travel through space, while sound waves cannot exist without a medium.

According to Archimedes' Principle, a floating object displaces a volume of fluid equal to its own weight. The buoyant force acting on the ship is equal to the weight of the water displaced by it. When this upward buoyant force matches the weight of the ship, it remains afloat. This principle explains why even large ships can float, as their design allows them to displace enough water to counteract their weight, regardless of the materials they are made from.

Pascal's Principle states that when pressure is applied to a confined fluid, it is transmitted undiminished in all directions throughout the fluid. In the case of a hydraulic lift, a small force applied to a small area creates pressure in the hydraulic fluid, which is then transmitted to a larger area, allowing a heavy vehicle to be lifted with that small force. This principle enables the efficient lifting of heavy loads using hydraulic systems.

Archimedes' Principle describes how objects submerged in a fluid experience an upward force due to the pressure difference between the top and bottom of the object. This upward force, known as buoyant force, acts against the weight of the object, allowing it to float or partially submerge in the fluid. The magnitude of the buoyant force is equal to the weight of the fluid displaced by the object, which is why objects with greater displacement experience a stronger buoyant force.

A windmill spins around a fixed central axis, showcasing rotational motion. This type of motion involves an object turning around a point or line, which in this case is the hub of the windmill. As the wind pushes the blades, they rotate around this stationary center, illustrating the principles of rotational dynamics where the position of the center remains unchanged while the rest of the structure moves in a circular path.

The wheels of the cart exhibit rotational motion as they spin around their axes, while the entire cart moves forward through the town, demonstrating translational motion. These two types of motion occur at the same time; the wheels rotate to propel the cart forward, creating a combined effect. Thus, both motions are essential to describe the cart's movement accurately during the parade.