Mathematics and Science PYQs

The Correct answer is Rose.

Explanation:

Unisexual flowers

• A flower is unisexual if it possesses either stamen (the male reproductive part) or carpels (the female reproductive part) but not both.
• Bisexual flowers contain both these parts.
• Flowers contain only the male or female reproductive organs.
• They reproduce by undergoing cross-pollination.
• Examples: Papaya, White mulberry, and Watermelon. Hence, Option 3 is correct.
• They reproduce by undergoing self-pollination.
• Hibiscus, Rose, and Datura have bisexual flowers because it consists of both stamens and carpel.
• Papaya has unisexual flowers, male flowers, and female flowers are on separate plants.
• A unisexual flower has only one sex organ which is either the stamen or carpel whereas a bisexual flower has both sex organs i.e. stamen as well as carpel.
• The diagram showing the process of germination of pollen grains on the stigma is as follows:

Additional Information

• Corn: Corn (maize) has separate male and female flowers on different parts of the plant. The male flowers produce pollen on tassels, while the female flowers form ears that contain the developing kernels. Since corn has separate male and female flowers, it is an example of a unisexual flower.
• Cucumber: Cucumber plants also have separate male and female flowers. The male flowers produce pollen on long, slender stalks, while the female flowers have a swollen ovary that develops into the fruit. Thus, cucumber is another example of a unisexual flower.
• Papaya: Papaya trees are another example of plants with separate male and female flowers. The male flowers have stamens that produce pollen, while the female flowers have a single ovary and a stigma to receive pollen. Therefore, papaya flowers are also unisexual.
• Rose: Roses are an example of bisexual flowers because they contain both male and female reproductive structures within the same flower. The stamen consists of the anther, which produces pollen, and the pistil consists of the stigma, style, and ovary, where fertilization takes place. Roses are perfect flowers**, making them bisexual.**

The Correct answer is 1.6 sec.

Concept:

• The time taken to complete one oscillation is known as the time period of the pendulum.
• Mathematically, Time Period = Total time taken / Number of Oscillations

Calculation:

Given,

Total time is taken simple pendulum = 64 sec

Number of oscillations = 40

We know that,

Time Period = Total time taken / Number of Oscillations

⇒ Time taken = 64 / 40 = 1.6 sec.

The Correct answer is Toaster.

Explanation:

• Toasters use the property of heating a wire when an electric current flows through it to toast bread slices. Inside a toaster, there are thin, high-resistance wires made of nichrome (an alloy of nickel and chromium). These wires have high electrical resistance, which means they hinder the flow of electricity and convert electrical energy into heat. When you plug in the toaster and turn it on, an electric current flows through these nichrome wires.
• As the current passes through the wires, they heat up rapidly due to their high resistance. The heat generated by the wires is then transferred to the metal grids or slots where you place the bread slices. The heat from the wires toasts the bread by removing moisture and browning the outer layer.
• The toaster usually has a thermostat or timer that controls the heating process, allowing you to adjust the toasting level according to your preference.

Additional Information

Refrigerator:

• A refrigerator is a household appliance used to cool and preserve food and beverages by maintaining a low temperature inside its insulated compartments. The working principle of a refrigerator involves the use of a refrigerant (such as Freon or other environmentally friendly alternatives) that undergoes a continuous cycle of evaporation and condensation.

Vacuum Cleaner:

• A vacuum cleaner is a cleaning device that uses suction to remove dirt, dust, and debris from various surfaces, such as floors, carpets, and upholstery. The basic components of a vacuum cleaner include a motor, a fan, a dust collection bag or container, and various filters.

Water Pump:

• A water pump is a mechanical device used to transport or move water from one location to another. Water pumps are essential for various applications, including supplying water to homes, agricultural irrigation, industrial processes, and maintaining water circulation in cooling systems.

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

Concept:

Mirror

• A mirror is a polished surface that reflects the light incident on it.
• The mirror can be a plane mirror or a spherical mirror.
• The spherical mirror is further classified into a concave and convex mirror
• Concave mirror: The reflecting surface is curved inward.
• Convex mirror: The reflecting surface is curved outward.

Explanation:

Concave mirrors:

• Concave mirrors have a reflective surface that curves inward, towards the center. They are commonly used in dentistry as dentists' mirrors because they produce magnified and virtual images of the patient's teeth. This allows the dentist to view areas that are not directly visible from their line of sight.

Uses of Concave Mirror:

• The concave mirror is used for magnification.
• As a shaving glass.
• As a reflector for the headlights of the vehicle, searchlight.
• An ophthalmoscope examines the eye, ear, and nose by doctors.
• In solar cookers.

Convex mirrors:

• Convex mirrors have a reflective surface that curves outward, away from the center. They are used as side mirrors in vehicles because they provide a wider field of view, allowing the driver to see objects and vehicles behind and beside them. The image formed in a convex mirror is smaller than the actual object but provides a broader perspective**, making it suitable for use in side mirrors.**

Use of Convex Mirrors:

• The convex mirror gives virtual, erect, and diminished images of the objects.
• The mirror gives a wider view of the image formed in it.
• That's why, it is used in cars, and bikes to see any object behind, or any vehicles coming.
• Also, it is used in CCTV Cameras for a wider view.

Convex lens:

• ​Convex lenses are thick in the middle and thinner at the edges.
• A convex lens is also known as a converging lens as the light rays bend inwards and converge at a point which is known as focal length.
• The image formed in a convex lens could be enlarged and erect.

Concave lens:

• Concave lenses have a thinner center and are thicker at the edges, curving inward.
• They are commonly used in flashlights to spread out the light beam and make it broader and less focused.
• The use of a concave lens in a flashlight helps in creating a more uniform and wider illumination.

Conclusion:

The Correct answer is Muscular Force.

Concept:

Force

• A push or a pull on an object is called a force.
• The SI unit of force is the newton which is represented by N.
• The forces in nature can be classified according to whether they act on the body by coming into physical contact with it or not.
• On the basis of this, the forces are of two types -contact forces and non-contact forces.

Contact force: 

The force exerted by one object on another by physical contact.

• There is no field required for contact force.
• Examples: friction, air resistance, etc.

Non-contact force:  

Force exerted by one object on another from a distance or without any physical contact.

• There is always a field required for non-contact force.
• ​Examples: Gravitational, magnetic, electrostatic, etc.

Explanation:

• There are many types of force divided into two groups contact force and Non-contact (distance) force.

From the above table, we know that the force of friction is the contact force.

The force of friction:

• Friction is the force that resists motion when the surface of one object comes into contact with the surface of another.
• The frictional force also depends on the shape of the object and the nature of the fluid.

Additional Information 

The force of gravitational:

• The gravitational force is the force of attraction that exists between all objects in the universe that have mass.
• The force of gravity decreases with altitude.
• It also varies on the surface of the earth, decreasing from the poles to the equator.

Magnetic force:

• ​The magnetic force between two moving charges can be described as the effect exerted on either charge by a magnetic field created by the other.
• Magnetic force is another type of attractive or repulsive force that exists between two objects.
• Due to the magnetic force, the attraction or repulsion depends upon the polarity of the objects.

Electrostatic force: 

• The electrostatic force between particles is an attracting or repulsive force caused by the electric charges on their surfaces.
• The electrostatic force is the electric force that exists between two stationary charged bodies.

The Correct answer is Operation of moving parts of a machine.

concept:

Force

• A push or a pull on an object is called a force.
• The SI unit of force is the newton which is represented by N.
• The forces in nature can be classified according to whether they act on the body by coming into physical contact with it or not.
• On the basis of this, the forces are of two types -contact forces and non-contact forces.
• Contact force: 
• The force exerted by one object on another by physical contact.
• There is no field required for contact force.
• Examples: friction, air resistance, etc.

Explanation:

• Friction is a force that opposes the relative motion or tendency of such motion between two surfaces in contact. While friction has several beneficial applications, such as providing traction for walking, writing, or holding objects, there are cases where friction can be undesirable, particularly during the operation of moving parts in a machine.
• In machines, moving parts often rub against each other due to friction. This friction generates heat and causes wear and tear on the machine's components. Over time, excessive friction can lead to mechanical failures, increased energy consumption, and a decrease in the efficiency of the machine.

Additional Information Undesirable friction in machines can result in:

• Energy Loss: Friction between moving parts converts some of the mechanical energy into heat energy. This energy loss can reduce the overall efficiency of the machine, making it less economical to operate.
• Increased Wear and Tear: Friction between components causes abrasion and wear on the machine's surfaces. This can lead to the need for frequent maintenance and replacement of parts, increasing operating costs.
• Reduced Lifespan: Excessive friction can accelerate the deterioration of moving parts, shortening the machine's overall lifespan.
• To mitigate the undesirable effects of friction in machines, various techniques are employed, such as:
• a) Lubrication: Using lubricants like oils, greases, or solid lubricants between moving parts reduces direct surface-to-surface contact, minimizing friction and wear.
• b) Bearings: Properly designed bearings reduce friction by providing smooth rolling or sliding surfaces between moving parts.
• c) Surface Coatings: Coating surfaces with low-friction materials or reducing surface roughness can reduce friction and increase the lifespan of the components.

The Correct answer is We don't feel atmospheric pressure as it is negligible in quantity.

Concept:

Pressure: 

• The pressure is the physical quantity which is defined as the force acting per unit of area. 
• \(P = \frac{F}{A}\)
• P is pressure, F is force, and A is an area.
• The SI unit of Pressure is Pascal.

Pressure by Liquid

• The liquid exerts pressure on the walls of its container.
• Equal pressure is applied at equal height in all directions by the liquid.

Pascal's Law:

• Pascal's principle states that pressure applied to fluids is equally transmitted in all directions, to all parts of the fluid, and to all parts of a container.
• The increase in pressure at one point of the enclosed liquid in an equilibrium of rest is transmitted equally to all other points of the liquid and also to the walls of the container, provided the effect of gravity is neglected.

Explanation:

• The smaller the area, the larger the pressure on a surface for the same force: This statement is correct. Pressure is defined as force per unit area. If the same force is applied to a smaller area, the pressure on that surface will be larger because the force is distributed over a smaller area.
• Liquids exert pressure on the walls of the container: This statement is correct. Liquids are fluid substances, and they exert pressure on the walls of the container that contains them. This pressure is due to the weight of the liquid pressing down on the bottom and sides of the container.
• In a static situation, the pressure at any point in a liquid is the same in all directions and is proportional to the depth of the liquid. This phenomenon is the basis for hydraulic systems and the functioning of liquid-filled manometers.
• Air exerts atmospheric pressure on us: This statement is correct. The Earth's atmosphere exerts pressure on all objects and surfaces at or near the Earth's surface. This pressure is known as atmospheric pressure. The atmospheric pressure is caused by the weight of the air above us, and it decreases with increasing altitude.
• We don't feel atmospheric pressure as it is negligible in quantity: This statement is incorrect. We do feel atmospheric pressure. Atmospheric pressure is not negligible; it is significant and has observable effects on our environment and our bodies. Our bodies are in equilibrium with the atmospheric pressure because we live in an environment where the air pressure is significant.
• Changes in atmospheric pressure, such as during weather changes or when ascending or descending in an airplane, can be felt, especially in the ears. These changes in pressure are relatively small compared to the overall atmospheric pressure but can still cause noticeable effects on our bodies.

The Correct answer is  (A), (C), (D).

Concept:

Sound:

• ​A sound wave is a pattern of disturbance caused by the movement of energy traveling through a medium (such as air, water, or any other liquid or solid matter) as it propagates away from the source of the sound.
• Sound waves are created by object vibrations and produce pressure waves, for example, a ringing cellphone.
• Sound propagates through the air or other mediums as a longitudinal wave, in which the mechanical vibration constituting the wave occurs along the direction of propagation of the wave.

​The loudness of the sound:

• The loudness of a sound relates the intensity of any given sound to the intensity at the threshold of hearing.
• It is measured in decibels (dB).

Explanation:

• (A) Sound is produced by vibrating objects: Sound is a form of energy that travels in the form of waves. It is produced when an object vibrates, causing the surrounding air molecules to vibrate as well. These vibrations create changes in air pressure, which propagate as sound waves through the air. When these sound waves reach our ears, they are detected by the ear's sensory organs, and we perceive them as sound.
• (B) "Sound does not require a medium to travel:  This statement is incorrect. Sound does require a medium to travel. Sound waves are mechanical waves that need a material medium (such as air, water, or solids) to propagate. When an object vibrates, it displaces the particles of the surrounding medium, and these particles then transfer the vibration to adjacent particles, causing the sound waves to propagate. In the absence of a medium, like in a vacuum, sound cannot travel.
• (C) In humans, the vibration of the vocal cords produces sound: In humans and many other animals, sound production occurs through the vibration of specialized structures, such as the vocal cords in the larynx (voice box). When we speak or sing, air from the lungs is forced past the vocal cords, causing them to vibrate.
• The vibration of the vocal cords produces sound waves, which then resonate in the cavities of the throat, mouth, and nasal passages, shaping the sound into specific tones and pitches. This is how we produce speech and communicate with each other.
• (D) Plantation on the roadside can reduce noise pollution: Planting trees and creating greenery along the roadside can indeed help reduce noise pollution. Trees and vegetation act as natural sound barriers that absorb and scatter sound waves, reducing their intensity and reflection. When sound waves encounter vegetation, they get dispersed and absorbed by the leaves, branches, and other plant parts, preventing them from bouncing off hard surfaces and causing echoes or amplification of noise.

The Correct answer is A glass rod becomes negative charged when it is rubbed with silk.

Concept:

• Charging: Charging means gaining or losing an electron. Matters can be charged in three ways, charging by friction, charging by contact, and charging by induction.

• Charging by friction: When you rub one material against another, they are charged by friction. Material losing electrons is positively charged and material gaining electrons is negatively charged. The amount of gained and the lost electron is equal to each other.

• Charging by contact: There are equal numbers of electrons and protons in a neutral matter. If something changes this balance we can say it is charged.

• ‘A’ charged body (e.g.; positively charged metal can) is brought in contact with uncharged body ‘B’. When in contact, negative charges from the uncharged body are attracted by the positive charges of the metal can. Finally, body B will remain with a net positive charge. Therefore, body B has been charged with positive charges.

Explanation:

• When two objects are rubbed together, they can transfer electrons between them. Electrons are negatively charged particles. If one object gains electrons, it becomes negatively charged, and the other object loses electrons, becoming positively charged.
• In the case of rubbing a glass rod with silk, the glass rod has a higher affinity for electrons than silk. So, during the rubbing process, electrons are transferred from the silk to the glass rod. As a result, the glass rod gains electrons and becomes positively charged, while the silk loses electrons and becomes negatively charged.

The Correct answer is Al > Zn > Fe > Cu.

Explanation:

• The Reactivity series of metals refers to the arrangement of metals in the descending order of their reactivities.
• ​Features of the Reactivity series:
• The metals at the top of the reactivity series are powerful reducing agents since they are easily oxidized and get corroded very easily.
• The reducing ability of the metals grows weaker while traversing down the series.
• The electro-positivity of the elements also reduces while moving down the reactivity series of metals.
• All metals that are found above hydrogen in the activity series liberate H2 gas upon reacting with dilute HCl or dilute H2SO4.
• Metals that are placed higher on the reactivity series have the ability to displace metals that are placed lower from their salt solutions.

So, the correct representation of metals in decreasing order of reactivity is Al > Zn > Fe > Cu.

Scientific knowledge is based on empirical evidence and is produced through the systematic application of the scientific method.

Key Points

• Scientific knowledge is tentative: It's subject to change in light of new evidence or reinterpretation of existing evidence.
• Scientific knowledge is objective: It aims to describe and understand the natural world independently of individual biases or beliefs.
• Scientific knowledge is influenced by society: The questions scientists ask and how they approach their investigations can be influenced by societal factors, including values, needs, and interests.
• The process of scientific investigation is not strictly linear and does not follow just one method. Different fields and different investigations may require different methods, techniques, and approaches.

Hence, we can conclude that 'Scientists use the one scientific method to discover new knowledge' is incorrect about scientists and scientific knowledge.

The "purpose of science education" refers to the intended outcomes or goals of teaching science in schools. These are the reasons why we teach science to students, and what we hope they will gain from their science education.

Key Points

• Developing Scientific Literacy: This refers to the ability to understand and interpret scientific information, to distinguish between sound science and pseudoscience, and to make informed decisions about scientific issues.
• Promoting Understanding of the Natural World: Science education helps students understand natural phenomena, from biological processes to physical laws to chemical reactions.
• Fostering Critical Thinking and Problem-Solving Skills: Science, with its emphasis on evidence-based reasoning and systematic investigation, is a powerful tool for developing these skills.
• Encouraging Curiosity and Inquiry: Science is fundamentally about asking questions and seeking answers. Good science education encourages this spirit of inquiry.

Hence, we can conclude that 'To become a scientifically literate citizen of society' should be the purpose of science education at the elementary school level.

The main purpose of asking "what will happen next?" during a science demonstration is to sustain the interest of students in the class.

Key Points

• It engages students in the demonstration and encourages them to think about what is happening.
• It also helps to keep students' attention focused on the demonstration.
• The teacher might ask "What will happen next?" during a demonstration:
• To check students' prior knowledge of the concept being demonstrated.
• To help students to make predictions about what will happen.
• To encourage students to think critically about the demonstration.
• To make the demonstration more engaging and interactive.

Hence, we can conclude that 'To sustain the interest of students in the class' is the main purpose of asking such questions during the demonstration.

A science curriculum is a set of learning goals, content, and assessments that are designed to help students learn about science. The important feature of the science curriculum is Activity-based teaching.

Key Points

• Activity-based teaching is a student-centered approach to learning that engages students in hands-on activities.
• This type of teaching allows students to learn by doing, which helps them to understand concepts more deeply.
• Activity-based teaching is also more engaging and motivating for students than traditional lecture-based teaching.
• Here are some of the benefits of activity-based teaching:
• Students learn by doing. This helps them to understand concepts more deeply and to develop problem-solving skills.
• Students are more engaged and motivated. This leads to better learning outcomes.
• Students develop critical thinking skills. This is because they have to think about how to apply the concepts they are learning to real-world situations.
• Students develop teamwork skills. This is because they often have to work together to complete activities.

Hence, we can conclude that Activity based teaching is an important feature of science curriculum.

Scientific knowledge is based on empirical evidence and is produced through the systematic application of the scientific method.

Key Points

Statement (A) is true because scientists use a variety of methods to approach any investigation. These methods include:

• Observation: Scientists observe the natural world and make careful records of what they see.
• Experimentation: Scientists design experiments to test their observations and to gather new evidence.
• Modeling: Scientists use models to represent the natural world and to make predictions about how it works.
• These methods are not mutually exclusive, and scientists often use a combination of methods to approach an investigation.

Statement (B) is false because the development of scientific knowledge is not linear and hierarchical from observations to laws.

• Scientific knowledge is often developed through a process of trial and error, and it can be revised or even discarded as new evidence is gathered.

Hence, we can conclude that the statement (A) is true and (B) is false.

Scientific literacy is the ability to understand and use scientific concepts and information to make informed decisions about the world around us.

Key Points

• A more scientifically literate society would actually increase the need for scientists and technologists, as these individuals would be responsible for generating and disseminating scientific knowledge.
• Scientists and technologists are also essential for developing new technologies that can improve our lives.
• The knowledge and understanding of scientific concepts and processes is required for personal decision-making.
• Understanding scientific concepts improves participation in civic and cultural affairs of society.
• The use of scientific knowledge helps in building the economic productivity of the society.

Hence, we can conclude that "More scientifically literate society decreases the need for scientists and technologists in society" is incorrect about scientific literacy.

Problem-posing questions are questions that ask students to come up with their own solutions to a problem. 

Key Points

• The question "Can you figure out a way to measure the height of a tree?" is a problem-posing question.
• These questions can be used to assess students' critical thinking skills and their ability to apply their knowledge to new situations.
• Problem-posing questions can be used in a variety of settings, including the classroom, the workplace, and the community.
• They can be used to stimulate creativity, to encourage critical thinking, and to solve problems.

Hence, we can conclude that it is a type of problem-posing question.

The least desirable assessment tool to assess learners' experiences of a field trip in science is multiple choice questions.

Key Points

Here are some of the reasons why:

• Multiple-choice questions do not allow for much creativity or critical thinking.
• Multiple-choice questions can be easily memorized, which does not assess the learner's true understanding of the concepts.
• Multiple-choice questions do not allow for the learner to explain their reasoning, which can be important for assessing their understanding.

Hence, we can conclude that Multiple-choice questions are least desirable to assessing learners' experiences of a field trip in science.

Formative assessment is an ongoing process that helps students learn and improve their understanding of the material. Summative assessment is a more formal assessment that is used to measure student learning at the end of a unit or course.

Key Points

• Statement (A) states that assessment is an ongoing and continuous process, which is a key characteristic of both formative and summative assessment.
• Statement (B) states that the purpose of assessment is the assessment of learning, which means that the goal of assessment is to measure student learning. This is a characteristic of summative assessment.
• Statement (C) states that another purpose of assessment is assessment for learning, which means that the goal of assessment is to help students learn. This is a characteristic of formative assessment.
• Statement (D) states that assessment is done at the term end to evaluate objectives achieved. This is a characteristic of summative assessment.

Hence, we can conclude that the correct grouping of statements is Formative Assessment - (A) and (C) and Summative Assessment - (B) and (D).

An instructional objective is a statement that describes what a student will be able to do after completing a learning activity. It should be clear, concise, and measurable.

Key PointsThe instructional objective is well-written and has all three components: performance, condition, and criterion.

• Performance: The performance component of the instructional objective is what the students will be able to do. In this case, the students will be able to label key types of energy transfer.
• Condition: The condition component of the instructional objective is the context in which the performance will occur. In this case, the students will be able to label the key types of energy transfer given a set of pictures.
• Criterion: The criterion component of the instructional objective is the standard that will be used to judge the performance. In this case, the students will be able to label the key types of energy transfer as conduction, convection, and radiation.

Hence, we can conclude that the correct match is (i) - (B), (ii) - (C), (iii) - (A).