Class 7 Half Yearly Question Paper 2019 Science

Science is an essential subject that helps students understand the natural world. For Class 7 students, half-yearly exams test fundamental concepts, critical thinking, and application of knowledge. Here are detailed questions and answers for the Class 7 half-yearly science exam, covering all essential topics and question formats.

Physics Questions

Question: What is speed, and how is it calculated?

Answer: Speed is the distance covered by an object in a unit time. It is calculated using the formula: Speed = Distance/Time.

Question: Define force and give two examples.

Answer: Force is a push or pull on an object. Examples: Pushing a door and pulling a rope.

Question: What is the difference between mass and weight?

Answer: Mass is the amount of matter in an object, measured in kilograms, while weight is the force of gravity acting on an object, measured in newtons.

Question: Explain Newton’s First Law of Motion.

Answer: Newton’s First Law states that an object remains at rest or in uniform motion unless acted upon by an external force.

Question: What is gravitational force?

Answer: Gravitational force is the force of attraction between any two masses. It is responsible for objects falling to the ground.

Question: How does friction affect motion?

Answer: Friction opposes the motion of objects, slowing them down or stopping them.

Question: Define energy and its types.

Answer: Energy is the capacity to do work. Types include kinetic energy, potential energy, thermal energy, and electrical energy.

Question: What is the role of simple machines?

Answer: Simple machines make work easier by reducing the effort needed to perform tasks. Examples: levers, pulleys.

Question: What is a lever, and give an example?

Answer: A lever is a rigid bar that rotates around a fixed point called a fulcrum. Example: See-saw.

Question: State the difference between renewable and non-renewable energy sources.

Answer: Renewable sources can be replenished, like solar and wind energy. Non-renewable sources, like coal and oil, are finite.

Question: What are conductors and insulators?

Answer: Conductors allow electricity to pass through them, like metals. Insulators do not, like rubber and wood.

Question: Explain the working of a simple electric circuit.

Answer: A simple electric circuit consists of a power source, a conductor, and a load. Current flows through the conductor, powering the load.

Question: What is reflection of light?

Answer: Reflection of light is the bouncing back of light rays when they hit a smooth surface.

Question: Differentiate between concave and convex lenses.

Answer: Concave lenses are thinner at the center and diverge light. Convex lenses are thicker at the center and converge light.

Question: Define sound and its propagation.

Answer: Sound is a form of energy produced by vibrating objects. It propagates through mediums like air, water, and solids.

Question: What are echoes?

Answer: Echoes are reflected sound waves heard after the original sound.

Question: Explain the role of a prism in light dispersion.

Answer: A prism disperses white light into its component colors, forming a spectrum.

Question: What is the importance of the ozone layer?

Answer: The ozone layer protects Earth from harmful ultraviolet radiation.

Question: Define static electricity and give an example.

Answer: Static electricity is the accumulation of electric charges on a surface. Example: Rubbing a balloon on hair.

Biology Questions

Question: What are the main components of a plant cell?

Answer: The main components are the cell wall, cell membrane, nucleus, chloroplasts, and vacuole.

Question: What is photosynthesis?

Answer: Photosynthesis is the process by which plants make food using sunlight, carbon dioxide, and water.

Question: What are the functions of the human skeleton?

Answer: The skeleton provides structure, supports the body, protects organs, and facilitates movement.

Question: What are the main types of nutrients?

Answer: The main types are carbohydrates, proteins, fats, vitamins, and minerals.

Question: Explain the process of digestion in humans.

Answer: Digestion involves breaking down food into simpler substances in the mouth, stomach, and intestines, absorbed by the body.

Question: What are stomata, and what is their function?

Answer: Stomata are tiny pores on leaves that facilitate gas exchange and transpiration.

Question: What is the role of the respiratory system?

Answer: The respiratory system exchanges oxygen and carbon dioxide in the body, enabling cellular respiration.

Question: Define ecosystems and their components.

Answer: An ecosystem is a community of living and non-living things interacting in an environment. Components: biotic and abiotic.

Question: What are food chains and food webs?

Answer: A food chain is a linear sequence of energy transfer. A food web is interconnected food chains.

Question: What is the function of the circulatory system?

Answer: The circulatory system transports oxygen, nutrients, and waste throughout the body.

Question: What is excretion, and why is it important?

Answer: Excretion is the removal of waste from the body, crucial for maintaining health and preventing toxin buildup.

Question: What is the role of xylem and phloem in plants?

Answer: Xylem transports water, and phloem transports food in plants.

Question: Explain the nitrogen cycle.

Answer: The nitrogen cycle involves the conversion of nitrogen into usable forms, cycling through the atmosphere, soil, and organisms.

Question: What are the differences between aerobic and anaerobic respiration?

Answer: Aerobic respiration uses oxygen; anaerobic respiration does not.

Question: What are microorganisms?

Answer: Microorganisms are tiny living organisms, like bacteria and viruses, invisible to the naked eye.

Question: What are the effects of deforestation?

Answer: Deforestation leads to loss of habitat, soil erosion, and climate change.

Question: What are renewable and non-renewable natural resources?

Answer: Renewable resources are replenishable, like sunlight. Non-renewable resources are finite, like coal.

Question: What is the role of decomposers?

Answer: Decomposers break down organic matter, recycling nutrients in the ecosystem.

Question: How do vaccines work?

Answer: Vaccines stimulate the immune system to recognize and fight specific pathogens.

Chemistry Questions

Question: Define matter and its states.

Answer: Matter is anything that occupies space and has mass. States: solid, liquid, gas.

Question: What is an atom?

Answer: An atom is the smallest unit of an element, consisting of protons, neutrons, and electrons.

Question: Define elements and compounds.

Answer: Elements are pure substances with one type of atom. Compounds are substances formed by combining elements.

Question: What is a chemical reaction?

Answer: A chemical reaction is a process where substances change to form new substances.

Question: What is the difference between acids and bases?

Answer: Acids release hydrogen ions; bases release hydroxide ions.

Question: What is the periodic table?

Answer: The periodic table organizes elements based on their properties and atomic numbers.

Question: Define physical and chemical changes.

Answer: Physical changes do not alter substance composition. Chemical changes form new substances.

Question: What are mixtures and solutions?

Answer: Mixtures combine substances without chemical bonding. Solutions are uniform mixtures.

Question: What is the water cycle?

Answer: The water cycle involves evaporation, condensation, precipitation, and collection.

Question: Explain the importance of water conservation.

Answer: Water conservation ensures sustainable use and availability for future generations.

Question: What are metals and non-metals?

Answer: Metals are good conductors of heat and electricity. Non-metals are poor conductors.

Question: What is rusting, and how can it be prevented?

Answer: Rusting is the corrosion of iron. Prevention: painting, galvanizing.

Question: Define pH scale.

Answer: The pH scale measures the acidity or basicity of a substance, ranging from 0 to 14.

Question: What are alloys?

Answer: Alloys are mixtures of metals or metals with non-metals. Example: Steel.

Question: What is crystallization?

Answer: Crystallization is the process of forming solid crystals from a solution.

Question: What are fossil fuels?

Answer: Fossil fuels are natural fuels like coal and oil, formed from ancient organic matter.

Question: What is the greenhouse effect?

Answer: The greenhouse effect is the trapping of heat by greenhouse gases, warming the Earth.

Question: Explain the process of sublimation.

Answer: Sublimation is the change of a solid directly into a gas without becoming liquid.

Understanding and practicing science questions is vital for building a strong foundation in Class 7. These detailed questions and answers prepare students for exams while promoting analytical thinking and practical knowledge application.