Mathematics and Science PYQs

The Correct answer is ( a ) and (b)

Explanation:

 

• (a) Malleable: This is true. One key property of metals used in jewelry is malleability. Gold is highly malleable, meaning it can be hammered or rolled into very thin sheets without breaking.
• This property allows gold to be shaped into a variety of designs, making it perfect for creating all types of jewelry.
• (b) Resistant to corrosion: This is also true. Gold is notorious for its resistance to corrosion and tarnishing. Even over long periods, it retains its shine and doesn't oxidize in air or water, making it enduring and reliable for jewelry.
• (c) Highly reactive: This is false. Gold is one of the least reactive elements. It doesn't react readily with other elements to form compounds, a quality that contributes to its durability and resistance to tarnish.
• (d) Sonorous: While being sonorous (making a resonant sound when struck) may be a desirable property in certain situations, it's not a key reason for choosing gold for jewelry making. Rather, the visual appeal and durability of gold are far more important considerations.

Therefore, both malleability (a) and resistance to corrosion (b) are reasons why gold is preferred for making jewelry.

The Correct answer is Freezing of ice cream, melting of chocolate, dissolving of candy.

Concept:

Physical changes :

• Properties such as shape, size, color, and state of a substance are called its physical properties.
• A change in which a substance undergoes a change in its physical properties is called a physical change.
• A physical change is generally reversible.
• In such changes, no new substance is formed.
• Examples of physical changes are breaking glass, boiling water, and grinding wheat.
• In the above examples only the physical properties of glass, water, and wheat change.

Explanation:

• Rusting of iron, melting of ice cream, freezing of wax - The rusting of iron is a chemical change as new substances (iron oxide) are formed. The melting of ice cream and freezing of wax are physical changes.
• Freezing of ice cream, melting of chocolate, dissolving of candy - All of these are physical changes. Freezing of ice cream is a change from liquid to solid (a change in state), melting of chocolate is a change from solid to liquid (also a state change), and dissolving candy is a physical change as it can be reversed by removing.
• Cooking food, boiling oil, pounding a herb - Cooking food is a chemical change as new substances are created, boiling of oil can be a physical change but can also break down molecules if the oil is heated enough, and pounding a herb can be considered a physical change.
• Rusting of iron, burning of paper, digestion of food - All of these are chemical changes as they result in new substances being formed.

Therefore, out of the provided options, only option 2 contains exclusively physical changes.

The Correct answer is Both S1 and S2 are correct.

Concept;

• Polyester is a synthetic polymer that is made from repeating units of ester monomers. Specifically, polyester is made by a process called polymerization, where ester linkages are formed between dicarboxylic acids and diols (or polyols).
• The general structure of polyester consists of a long chain of ester functional groups, which are formed by the reaction between a carboxylic acid group (COOH^-) and an alcohol group (OH^-). The ester linkages (-COO^-) connect the repeating units, creating a polymer chain.
• Polyesters can have various properties depending on the specific dicarboxylic acids and diols used in their synthesis. They are known for their durability, wrinkle resistance, and high strength. Polyester is commonly used in textile applications, such as clothing, upholstery, and fabrics, as well as in the production of plastic bottles, films, and other packaging materials.

Explanation:

• S1: Esters are the chemicals that give fruits their smell. This statement is true. Many esters are responsible for the characteristic smells of fruits, perfumes, and other naturally occurring substances.
• For instance, the ester ethyl butyrate carries the smell of pineapples, and the ester methyl salicylate is responsible for the smell of wintergreen.
• S2: Polyester is actually a polymer with repeating units of esters. This statement is also true. Polyesters are polymers that are formed from the reaction between carboxylic acid and alcohol.
• In this reaction, the functional groups on the molecules (the carboxylic acid group on one and the alcohol group on the other) form an ester linkage, creating this class of plastic known as polyesters.

Thus, both S1 and S2 are correct statements regarding esters

The Correct answer is (A) - (ii), (B) - (i), (C) - (iv), (D) - (iii).

Explanation:

• (A) Paraffin wax is used in a variety of applications including candle making, packaging, cosmetics, and ointments.
• (B) Bitumen is a sticky, black, and highly viscous liquid or semi-solid form of petroleum. It's primarily used in road construction, where it serves as the glue or binder mixed with aggregate particles to create asphalt concrete. It is also used in certain types of paints and waterproofing materials for roofs.
• (C) Super phosphate is a fertilizer-grade product, very high in phosphorous and sulfur. It aids the growth of plants by increasing the pH of acidic soil.
• (D) 2,4-D, also known as 2,4-Dichlorophenoxyacetic acid, is a common systemic herbicide used in the control of broadleaf weeds. It's a type of weedicide.

The Correct answer is By programming our body to produce suitable antibodies.

Explanation:

• Vaccines essentially mimic this natural process. They contain weakened or inactivated forms of the pathogen, or a part of the pathogen (like proteins or sugars) known as antigens. When a vaccine is introduced into the body, it stimulates the immune system to produce a response, including making antibodies.
• Because the vaccine only contains weakened or partial pieces of the pathogen, it doesn't cause the disease in the person being vaccinated. Instead, the immune system "learns" how to respond when faced with the actual pathogen in the future. It stores some of the antibody-producing cells, known as 'memory cells so that if the real pathogen ever invades the body, your immune system can quickly produce more of the same antibodies to counter the invading pathogen and prevent the disease from taking hold.

Additional Information

• "Increasing the number of antigens in our body": Vaccines introduce antigens into our body**, not to increase their amount, but to enable the immune system** to recognize the pathogen and produce a response against it in the future. The quantity of these antigens is generally minimal.
• "Providing antibiotics to our body": Antibiotics are drugs that kill bacteria within the body, but they have no effect on viruses. Vaccines, on the other hand, can protect against both bacterial and viral diseases. Furthermore, vaccines work by stimulating the body's own immune response, not by attacking the pathogens directly.
• "By programming our body to produce anti-inflammatory cells": While anti-inflammatory cells are an important part of the immune response, vaccines primarily work by inducing the production of antibodies specific to the pathogen. Although certain cellular responses may be involved, these are typically coordinated parts of the immune response to the antigen rather than the primary action of the vaccine.

The Correct answer is Plastids are present in plant and animal cells.

Concept:

• Cell organelles are specialized structures within eukaryotic cells that perform specific functions.
• The presence of organelles differs in plant and animal cells.

Plant Cell - 

• A plant cell is bound by a cell wall that is made up of cellulose.
• It contains organelles like the nucleus, mitochondria, vacuoles, Golgi bodies, and endoplasmic reticulum.
• It also contains an additional organelle called a plastid.
• The plastids are of 3 main types:
• Chloroplast - contains chlorophyll and carries out photosynthesis.
• Chromoplast - contains other pigments like xanthophyll, etc. that give color to fruits and flowers.
• Leucoplast - does not contain any pigments and helps in the storage of materials.

Animal Cell - 

• An animal cell lacks a cell wall and is only bound by the cell membrane.
• It contains important organelles like the nucleus, mitochondria, vacuoles, Golgi bodies, and endoplasmic reticulum.
• Plastids are not found in animal cells.
• However, they usually contain lysosomes and centrioles, unlike plant cells.

Explanation:

• prokaryotic and eukaryotic**, have a cell membrane (also known as the plasma membrane).** The cell membrane provides a protective barrier for the cell, controls the passage of substances in and out of the cell, and maintains the cell's osmotic balance.
• "Plastids are present in plant and animal cells." This statement is actually also incorrect; plastids are not found in animal cells. Plastids, which include chloroplasts, are organelles found primarily in plant cells. They are involved in the synthesis and storage of food and contain pigments that capture or reflect light. Animal cells do not possess plastids.
• "Cell membrane is present in both animal and plant cells." This statement is correct. Both animal and plant cells have a cell membrane that controls the movement of substances in and out of the cell. In plant cells, this cell membrane is inside the cell wall.
• "Cell wall is present in plant cell only." This statement is mostly correct. The cell wall is indeed a characterizing feature of plant cells, where it provides structure and support. However, it is worth noting that cell walls are not exclusive to plant cells. They are also present in other organisms such as fungi and bacteria.

The Correct answer is Veins carry deoxygenated blood.

Concept:

Human circulatory system: 

• It is also called the blood-vascular system.
• It consists of a muscular chambered heart, a network of closed branching blood vessels, and blood, the fluid which is circulated.

Explanation:

• The human heart is a four-chambered muscular organ responsible for pumping blood throughout the body. It consists of two upper chambers called atria (singular: atrium) and two lower chambers called ventricles.
• The heartbeat is the result of rhythmic contraction (systole) and relaxation (diastole) of the heart's muscles. During systole, the heart contracts, pumping blood into the arteries. During diastole, the heart relaxes, allowing the chambers to fill with
• The upper two chambers are called the atria, and the lower two chambers are called the ventricles. The atria receive blood from various parts of the body and pump it into the ventricles. The ventricles then contract to pump blood out of the heart to the lungs (right ventricle) and the rest of the body (left ventricle).

 Additional Information

• Veins have thick walls and no valves present." This is incorrect. Veins have relatively thinner walls in comparison to arteries. This is because the pressure in veins is much lower than in arteries, so they do not need to be as strong. Additionally, veins do possess valves. These one-way valves support the return of blood to the heart by preventing backflow, which is crucial considering the blood in veins is under lower pressure and might not otherwise flow 'upward' against gravity (from the lower limbs, for instance).
• "Deoxygenated blood is blue in color." This statement is incorrect. Deoxygenated blood is not blue; it is actually a dark red color. The idea that it seems blue is due to the way that skin and tissues absorb and reflect different wavelengths of light.
• "Dark clot formed over a cut is due to white blood cells." This is also incorrect. The dark clot or "scab" that forms over a cut is not primarily due to white blood cells but rather the action of platelets and a protein called fibrin. Following an injury, platelets in your blood stick together to form a plug, while fibrin forms a mesh that hardens, creating a clot that prevents further bleeding. While white blood cells are part of the immune system's response to a wound, their main job is to combat infection, not to form clots.

 Important Points Blood Vessels:

• There are different types of blood vessels in our body each carrying out specialized functions.
• Three types of blood vessels are Arteries, Veins, and Capillaries.

Arteries:

• These are thick-walled blood vessels that carry oxygenated blood from the heart to different organs.
• Pulmonary arteries are exceptions because they carry deoxygenated blood from the heart to the lungs, where the oxygenation of blood takes place.

Veins:

• These are thin-walled blood vessels that carry deoxygenated blood from different organs to the heart.
• Pulmonary veins are exceptions because they carry oxygenated blood from the lungs to the heart.
• Valves are present in veins to prevent back-flow of blood.

Capillaries: These are the blood vessels that have single-celled walls.

The Correct answer is A - Air, B - Water, C - Mosquito, D - Insect.

Explanation:

• A) Citrus canker, caused by bacteria, is generally transmitted through air. This disease affects citrus plants resulting in raised corky outgrowths. Wind and rain can carry the pathogen from infected plants and contaminate healthy ones.
• B) Hepatitis B is caused by a virus and it is mainly transmitted through exposure to infected body fluids such as blood and semen. This can happen through unprotected sex, sharing of needles, from mother to child during childbirth, or by transfusion of unscreened blood and blood products. It could also be transmitted in settings where unsterile equipment is used. Therefore, the categorization of Hepatitis B under bacteria is inaccurate.
• For the context given here, the transmission would be through 'Water', but it's important to note that it's not the most common mode of transmission.
• C) Malaria is caused by a protozoan parasite that belongs to the genus Plasmodium. The mode of transmission of the parasite is via the bite of a female Anopheles mosquito, which acts as a vector.
• D) Yellow vein mosaic disease of okra (lady's finger) is caused by a virus. This is typically transmitted through insects, specifically whiteflies. Insect vectors acquire the virus by feeding on infected plants and can transmit it to healthy plants.

The Correct answer is (A) - viviparous, (B) - oviparous, (C) - zygote, (D) - metamorphosis.

Explanation:

• (A) Animals that give birth to young ones are called viviparous. This term refers to the animals that bear live offspring, such as most mammals, where the embryo develops inside the body of the mother, as opposed to laying eggs which then independently develop.
• (B) Animals that lay eggs are called oviparous. This term refers to animals that lay eggs, with little or no other embryonic development within the mother. This is common in birds, reptiles, and some mammals like monotremes.
• (C) The term that describes the form that results from the fusion of the egg and sperm is a zygote. A zygote is the initial cell formed when two gamete cells (sperm and ovum) fuse. A zygote is always diploid, meaning it contains two sets of chromosomes, one each from the sperm and ovum.
• (D) The transformation of a larva to an adult through drastic change is called metamorphosis. This is a biological process that involves obvious morphological changes after birth or hatching. Examples of organisms that undergo metamorphosis include insects (like butterflies), amphibians, and some species of fish.

Additional Information Viviparous and Oviparous Animals: 

• Oviparous and viviparous animals are two different groups of animals, which are classified on the basis of fertilization.
• The main difference between oviparous and viviparous animals is listed below.

The Correct answer is Desert.

Explanation:

• Thick Stem: A thick stem provides storage for water, which is scarce in desert environments. In many desert plants, the stem performs the function of leaves (which are often small or nonexistent to prevent water loss by transpiration).
• Waxy Layers: The waxy layer on the stem is a protective covering that helps to prevent water loss through transpiration. This is very important in a water-starved ecosystem like a desert where every drop counts.
• Deep Roots: Desert plants often have deep roots that can reach far down into the soil to access any available water.

Some desert plants' root systems can reach more than 20 feet into the ground in search of water.

• Meanwhile, the other three habitats - mountain, water, and grassland - don't generally require these specific adaptations. In water habitats, for instance, the struggle would not be for conserving water, but rather for obtaining sunlight. Grassland and mountain habitats have their own sets of challenges that require different sets of adaptations.

Science is a systematic enterprise that builds and organizes knowledge in the form of testable explanations and predictions about the universe.

Key Points

• In science, laws, and theories serve different purposes and one doesn't graduate into the other.
• Laws describe the relationships under certain conditions in nature, while theories explain why those relationships exist.
• Many scientific discoveries have been made through other means, such as observation and correlation.
• Scientific ideas are always subject to modification or rejection based on new evidence. This is a fundamental principle of the scientific method.
• Science requires creativity and imagination to form hypotheses, design experiments, and interpret results.

Hence, we can conclude that statements (a) and (b) are false about science.

Concept mapping is a graphical tool that involves creating diagrams or networks that depict the relationships between different concepts.

Key Points

• Eliciting Ideas of Learners: Concept mapping is a great way to understand the ideas, understanding, and misconceptions that students may have about a particular topic.
• Lesson Planning: Educators can use concept mapping to plan lessons, helping to outline the key ideas, connections between those ideas, and the sequence in which those ideas might be taught.
• Assessment: Concept maps can be used as a form of assessment, allowing teachers to evaluate a student's understanding of a topic.
• Mapping Student's Progress: Concept mapping can provide snapshots of a student's understanding at different points in time, it is not typically used as a tool for tracking or mapping a student's progress over a more extended period, such as a semester or an entire course.

Hence, we can conclude that Concept mapping is not used as a tool for mapping student's progress.

Activity-based teaching is an instructional approach that emphasizes engaging students in hands-on, real-world activities to deepen their understanding of academic subjects.

Key Points

• By comparing past and present sewage disposal systems, students can understand technological and societal changes that have occurred.
• Educators typically seek to foster critical thinking rather than judgment, and gratitude for advancements might not be a primary learning goal.
• Though engaging with community members may be more enjoyable than traditional classroom work, the primary aim of the activity isn't merely to have fun but to enrich learning.
• The process of formulating and asking questions, engaging in dialogue, and gathering information from primary sources are important skills that the activity is designed to foster.
• Engaging with primary sources, such as personal testimonies from community members, broadens students' understanding of how knowledge is generated and allows them to see that learning can come from many different sources.

Hence, we can conclude that statements (a), (d), and (e) are correct regarding the purpose of such kind of activities.

The National Curriculum Framework (NCF) 2005 laid down several principles and recommendations to guide the development and implementation of curricula, syllabi, and textbooks, with an aim to make learning more child-centered and effective.

Key Points

• NCF 2005 emphasizes making learning relevant to the lives of children, focusing on their experiences and real-world contexts. This makes the material more engaging and relatable.
• A core principle of NCF 2005 is the idea that children should be encouraged to think critically, ask questions, and actively construct their own understanding.
• Vocational education is mentioned in NCF 2005, it is not specifically emphasized for integration with science at the upper primary level.
• NCF 2005 actually encourages a more interdisciplinary approach, connecting concepts across different subjects, rather than a strict disciplinary approach.

Hence, we can conclude that statements (A) and (B) are recommendations of NCF 2005 for upper primary science teaching a learning.

The deductive approach in teaching and learning refers to a method where the teaching starts with a general principle or concept and then moves towards specific examples or applications.

Key Points

• The approach described here starts with general principles and concepts about acids and bases, including their properties, occurrence in everyday life, pH, and indicators.
• After teaching these principles, the teacher then moves on to specific verification activities to apply and test the concepts.
• This progression from general principles to specific applications is characteristic of the deductive method.

Hence, we can conclude that the approach to sequencing of teaching-learning activity will be termed a Deductive approach.

Open-book assessments are designed to allow students to refer to their textbooks or notes during an examination. 

Key Points

• It reduces the fear of assessment in students as it can alleviate anxiety related to memorization and allow students to focus on understanding and applying concepts.
• It gives full opportunity to students to explore the book, as open book questions encourage students to engage with their materials and use them as resources during the assessment.
• Open-book questions reduce the burden of memorization, saying it's unfair to bright students is subjective and not aligned with the general philosophy of open-book assessments.
• It helps to gauge the conceptual understanding of the student, as open book questions are typically designed to assess deeper understanding and application of concepts rather than mere recall of facts.

Hence, we can conclude that statements (a), (b), and (d) are aligned with the spirit of open-book questions.

Divergent questions are those that allow for multiple correct answers or perspectives. They encourage students to think creatively, explore different possibilities, and engage in critical thinking. 

Key Points

(a) Develop multiple views: True, as divergent questions encourage students to explore different angles and perspectives.

(b) Improve their thinking strategies: True, as these questions promote critical thinking and problem-solving skills by requiring students to think beyond single, straightforward answers.

(c) Engage in classroom discussions: True, as the open-ended nature of divergent questions can foster lively classroom debates and discussions where students share and defend various viewpoints.

(d) Arrive at one answer: False, as the very nature of divergent questions is that they allow for multiple possible answers, rather than converging on a single correct response.

Hence, we can conclude that statements (a), (b), and (c) are correct.

Discrepant events in the science classroom refer to demonstrations or activities that produce unexpected results, contradicting students' preconceived ideas or intuitions.

Key Points

• It helps teachers to elicit misconceptions in students: True, as discrepant events can reveal students' misunderstandings by presenting them with unexpected outcomes.
• It helps to create cognitive conflict in students: True, as these events provoke cognitive dissonance by conflicting with prior beliefs or expectations, encouraging students to reconsider and refine their understanding.
• It helps the student to view their ideas differently: True, as the surprise or confusion elicited by a discrepant event can prompt students to think more deeply about a concept, exploring different perspectives and interpretations.
• It helps weak students to perform well in assessment: This statement is not typically an objective of using discrepant events. While they can enhance understanding and encourage critical thinking, discrepant events are not specifically designed to improve the performance of weak students in assessments.
• Their primary focus is on challenging preconceptions and stimulating deeper thinking rather than directly boosting assessment performance.

Hence, we can conclude that "It helps weak students to perform well in assessment" is not an objective of using discrepant events in science classrooms.

The inclusion of historical stories, like that of William Harvey's discovery of blood circulation and the initial ridicule he faced, serves several purposes in science education.

Key Points

(a) To develop a historical perspective for the development of a concept: True, as including historical accounts helps students understand how scientific concepts have evolved over time.

(b) To develop a sense that new ideas take time to be accepted: True, as the example of William Harvey shows how novel and groundbreaking ideas can be met with skepticism or resistance before becoming widely accepted.

(c) To develop open-mindedness in science: True, as these stories can illustrate the importance of keeping an open mind to new ideas and being willing to question prevailing beliefs, which is fundamental to the scientific method.

(d) To include a fun element in science that is not for testing: The story serves more of an educational purpose in teaching about the development of scientific ideas and the importance of open-mindedness, rather than merely adding a "fun element."

Hence, we can conclude that statements (a), (b), and (c) are correct.

A scientific fact is something that has been confirmed to such an extent that reasonable people can agree on its truth.

Key Points

• Assertion: "The facts of science serve as the foundation for concepts, principles, and theories."
• This statement is true. In science, facts are observed and measured phenomena that are used as the basis for building more complex ideas, concepts, principles, and theories.
• Reason: "Facts in science are static and do not change."
• This statement is false. While a fact is an observation that has been repeatedly confirmed, our understanding of those facts can change with new information or technology.
• Scientific knowledge is continually evolving, and what is considered a fact can be refined or revised in light of new evidence.

Hence, we can conclude that assertion is true but reason is false.