Mathematics and Science PYQs

The correct answer is A, B and C.

Concept:

• Cell organelles are specialized structures within cells that perform specific functions essential for the survival, growth, and functioning of the cell.
• Cell organelles are membrane-bound structures that are found in the eukaryotic cells.
• Different types of organelles are responsible for various tasks, and together they contribute to the overall functionality of the cell.

Explanation:

A. Plastids

• Plastids are indeed another type of cell organelles that contain their own DNA.
• Plastids are responsible for various functions in plant cells, including photosynthesis and storage of pigments and starch.
• Plastids is called as autonomous organelle.

B. Mitochondria

• Mitochondria are cell organelles that contain their own DNA.
• They are often referred to as the "powerhouses" of the cell because they are responsible for generating energy through cellular respiration.
• Mitochondria have their own genetic material and replicate independently within the cell.

C. Nucleus

• The nucleus is another cell organelle that contains its own DNA.
• The nucleus houses the cell's genetic material in the form of chromosomes, which carry the instructions for various cellular processes and traits.
• The DNA in the nucleus directs the cell's activities and is essential for cell division, growth, and functioning.

D. Vacuole

• Vacuoles do not contain their own DNA.
• Vacuoles are membrane-bound organelles that primarily function in storage, waste disposal, and maintenance of turgor pressure in plant cells.
• They are not known for containing DNA like mitochondria, plastids, or the nucleus.

Thus, Mitochondria, nucleus, and plastids are cell organelles that contain their own DNA.

The correct answer is Only D.

Explanation:

A. All are microscopic and cannot be seen with the naked eye. (Incorrect)

• Cells are the basic structural and functional units of living organisms.
• They are typically microscopic in size and cannot be seen with the naked eye.
• Most cells are indeed microscopic and cannot be seen with the naked eye. This includes human cells and the cells of other mammals, as well as those of plants, fungi, bacteria, and most other organisms.
• However, there are some exceptions. For example, some single-celled organisms, such as certain species of amoebae and algae, can grow large enough to be visible without a microscope. Additionally, bird and reptile eggs, like those of chicken or ostrich, are single cells and are obviously visible to the naked eye.

B. All have a cell wall. (Incorrect)

• Not all cells have a cell wall.
• While plant cells have a cell wall, animal cells do not.
• Therefore, this statement is not universally true for all cells of living organisms.

C. All have a nuclear membrane. (Incorrect)

• Not all cells have a nuclear membrane.
• Prokaryotic cells, such as bacteria, lack a distinct nucleus with a nuclear membrane.
• Eukaryotic cells, which include plant and animal cells, have a nuclear membrane.

D. All have a cell membrane. (Correct)

• All cells, whether prokaryotic or eukaryotic, have a cell membrane (plasma membrane).
• The cell membrane is a crucial structure that separates the cell's internal environment from its external surroundings.

Thus, the correct option is D.

The correct option is option 2 .

Concept : 

• Waste that comes naturally from plant or animal sources and can be broken down by other living things is referred to as biodegradable waste.
• Green garbage, food waste, paper waste, and biodegradable plastics are examples of biodegradable waste that is typically found in municipal solid waste.
• Ash, soil, dung, and other plant matter are the principal components, along with kitchen waste (spoiled food, trimmings, and inedible bits).
• In contrast to conventional plastic, which can take hundreds of years to completely degrade, biodegradable plastics need only three to six months to do so, according to BBC Science Focus.

Explanation:

1. PET, also known as polyethylene terephthalate, is used to make conventional plastic bottles. It is a lightweight, flexible material that is difficult to breakdown. Decomposition of a PET plastic bottle takes about 450 years.

2.After around four years, silk begins to show signs of deterioration. The process can be sped up and all of the material can disappear in about 12 to 24 months, but because that is so long, it is rarely touted as being biodegradable.

3.COTTON: Especially if it's 100% cotton, cotton is one of the textiles that decomposes the fastest. The particles ought to disappear in the proper compost in a week to five months.

4.A banana peel will take between 1-2 week to completely decompose if left outside. The time period will be shorter in warmer climates. The procedure will be slower in the winter though.

5.Another widely recyclable common home item is paper. Although it can be recycled and made into a new product, it only takes 2 to 6 weeks to degrade.

Hence, The correct option is 2.

The correct answer is Zero.

Explanation:

• The force can be calculated only when there is a rate of change of velocity of a specific mass.
• In the above case, the velocity of the feather while falling remains constant, hence net force is zero.

Here m=10g

Since there is no change in velocity acceleration is zero, a=0

we know force = mass * acceleration

F = m * a

F = m * 0 = 0

So, the net force acting on the feather is zero.

The correct option is option 4 .

Concept :

• The father of atoms and the atomic theory is John Dalton.
• Protons, neutrons, and electrons are the fundamental three components of an atom.
• Protons, which have a positive charge, and neutrons, which have no charge, make up the atom's nucleus.
• The electron shell, where the electrons are located, is the region closest to the surface.

 

Explanation:

• Atomic no= No of protons =no of electrons.

That is atomic no =13 ,so the protons =13 and the electrons = 13

• But for X³⁺ represents that the X acquire positive charge by loosing 3 electrons .

        so the overall count is = 13- 3 = 10 electrons.

• No of Neutrons = Atomic mass - Atomic number

        that is 27- 13 = 14 .

• Hence , No of protons = 13 , No of electrons = 10 , No of    Neutrons  = 14. The correct option is 4.

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The correct answer is Mustard, Rose, Petunia.

Concept:

• Plants have two types of flowers: unisexual and bisexual flowers.
• Unisexual flowers are those that contain male and female reproductive structures in separate flowers.
• Bisexual flowers are those that contain both male and female reproductive structures within the same flower.

Explanation:

A. Cucumber, Papaya, Rose

• Cucumber: Cucumbers produce unisexual flowers, i.e., they have separate male and female flowers on the same plant (monoecious).
• Papaya: Papayas also produce unisexual flowers, i.e., they are dioecious, meaning individual plants have either male or female flowers.
• Rose: Roses are bisexual flowers, i.e., they contain both male (stamens) and female (pistils) reproductive structures within the same flower.

B. Mustard, Rose, Petunia

• Mustard: Mustard plants produce bisexual flowers, i.e., they have both male (stamens) and female (pistils) reproductive structures within the same flower.
• Rose: As mentioned earlier, roses are bisexual flowers.
• Petunia: Petunias produce bisexual flowers with both male and female reproductive structures within the same flower.

C. Corn, Cucumber, Petunia

• Corn: Corn is an example of a plant with separate male and female flowers on the same plant (monoecious), rather than within the same flower.
• Cucumber: Cucumbers, as discussed earlier, produce unisexual flowers.
• Petunia: Petunias, as mentioned earlier, produce bisexual flowers.

D. Corn, Papaya, Mustard

• Corn: As explained, corn produces separate male and female flowers on the same plant.
• Papaya: Papayas produce unisexual flowers.
• Mustard: Mustard plants produce bisexual flowers.

Thus, Mustard, rose, petunia are those plants that produce bisexual flowers.

The correct answer is Option 1 (Clayey soil is better aerated than loamy soil.).

Concept:

Soil is of different types: clayey, loamy, and sandy.

The soil is classified on the basis of the proportion of particles of various sizes.

• Sandy soil:
• If soil contains a greater proportion of big particles it is called sandy soil.
• The percolation rate of water is highest in the sandy soil.
• Clayey soil:
• If the proportion of fine particles is relatively higher, then it is called clayey soil.
• The percolation rate of water is lowest in the clayey soil.
• loamy soil:
• If the amount of large and fine particles is about the same, then the soil is called loamy.
• The percolation rate of water is slow to medium in the clayey soil.

Explanation:

Clayey soil is better aerated than loamy soil. (Incorrect)

• Loamy soil typically has better aeration than clayey soil.
• Loamy soil is made up of roughly equal parts clay, sand, and silt. Thus, the aeration in loamy soil is moderate.
• Clay particles, being much smaller, pack tightly together, leaving little space for air. Thus, the aeration in clayey soil is poor.

Water retention capacity of clayey soil is better than that of loamy soil. (Correct) 

• Clayey soil does indeed have better water retention capacity compared to loamy soil.
• The smaller particles in clayey soil have a higher surface area, allowing them to hold onto water molecules more effectively.
• The water retention capacity of loamy soil is moderate.

The particle size of clayey soil is much smaller than that of loamy soil. (Correct)

• Clayey soil has smaller particle sizes than loamy soil.
• The particle sizes in soil are typically categorized as sand, silt, and clay.
• Sand particles are the largest, followed by silt particles, and clay particles are the smallest.

The correct answer is Red phosphorus and glass powder.

Explanation:

• The rubbing surface of a matchbox typically contains a mixture of red phosphorus and glass powder.
• When the match is struck against the rubbing surface, some red phosphorus gets converted into white phosphorus.
• The friction between the matchstick and the rubbing surface generates enough heat to initiate the chemical reaction between the red phosphorus and the potassium chlorate in the match head, resulting in a flame.
• This heat causes a small amount of white phosphorus to vaporize and become gaseous.

Thus, Red phosphorus and glass powder substances are present on the rubbing surface of a matchbox.

The correct answer is Thyroid, Adrenal glands, Pituitary.

Concept:

• In the human body, glands are of two types endocrine and exocrine glands.
• Endocrine gland:
• Endocrine glands are ductless glands, which means they lack ducts.
• Examples: Pineal gland, Adrenal gland, Thyroid gland, Thymus, Pancreas, etc.
• Exocrine gland:
• The glands that have ducts are known as the exocrine glands.
• They secrete their secretions into the ducts.
• Examples: Salivary gland, digestive gland, sweat gland, etc.

Explanation:

• A (Thyroid) and B (Adrenal glands) are endocrine glands that secrete hormones.
• The thyroid gland is also known to be the largest endocrine gland.
• C (Pituitary) is a master gland in the brain that controls and regulates the activity of various other endocrine glands, including the thyroid and adrenal glands.
• It sends orders to these glands to secrete hormones as needed.

Thus, Thyroid and Adrenal glands secrete their hormones when they receive orders from the Pituitary gland.

The correct answer is Light travels in a straight line.

Concept:

• A pinhole camera is a simple camera that does not have any lens.
• Light is made to pass through a very small pin-sized hole which is made light roof by proper covering around it.
• A real and inverted image is formed on the screen.
• There is rectilinear propagation of light which means light travels in a straight line.
• The size of the image may change on the distance of the object from the camera.

Explanation:

• The image formed by a pin-hole camera is real because in a pinhole camera light travels in a straight line.

• We can see in giving the following diagram, that the light from the top of the object passes through the pinhole and reaches the bottom of the camera screen, and light from the bottom of the object will pass through the pinhole and reach the top of the screen.

• Thus, the light passes straight through the hole and forms images.

• This will cause an inverted image.

Thus, the image formed by a pin-hole camera is real because in a pinhole camera light travels in a straight line.

A question is a sentence or expression used to inquire, seek information, or prompt thought, often inviting a response or explanation from someone else. It serves as a tool for communication, learning, and exploration.

Key Points Open-ended questions are designed to stimulate thoughtful and comprehensive responses, fostering critical thinking, diverse perspectives, and meaningful interactions in various contexts. The characteristics of open-ended questions:

• Depth and Exploration: Open-ended questions delve beyond simple yes/no responses, encouraging respondents to explore their thoughts, opinions, and experiences in greater depth.
• Diverse Responses: These questions allow for a wide range of answers, acknowledging individual perspectives and fostering diverse discussions or insights.
• Critical Thinking: Respondents need to think critically to provide well-reasoned and meaningful answers, making open-ended questions effective tools for promoting analytical skills.
• Encourages Elaboration: These questions typically begin with phrases like "How," "What," "Why," or "Tell me about," prompting individuals to elaborate and share comprehensive responses rather than providing simple yes or no answers.
• Enhances Communication: By encouraging detailed responses, open-ended questions promote meaningful communication, active listening, and an exchange of ideas, making them valuable tools in learning, problem-solving, and qualitative research.
• The question "What would happen if humans could digest cellulose?" opens up a broad field of inquiry and encourages speculative thinking about biological, nutritional, environmental, economic, and ecological impacts.
• It requires considering various facets and how they interconnect, leading to complex and nuanced answers.

Thus, it can be concluded that What would happen if humans could digest cellulose? is an open-ended question.

Curricular refers to everything related to a formal educational curriculum, including courses, subjects, materials, and activities that are designed to be taught and learned in an educational setting.

Key Points

Thus, it can be concluded that the curricular practice currently being followed in schools is Physics, Chemistry, and Biology are being taught integrated as 'Science' in secondary classes, and Science and Social Science are being taught integrated as 'EVS' in primary classes are true.

A group of students refers to a collection of individuals who come together for learning, social interaction, and collaborative activities within an educational setting, like a classroom or school. They share experiences, and ideas, and engage in various educational pursuits as part of a collective learning community.

Key Points

 Suitable indicator to assess students on task:

• Pay due attention to the least count of the thermometer: This means they need to notice the smallest unit the thermometer can measure. If they ignore this, their measurement might not be accurate.
• Ensure that the thermometer does not touch the walls of the beaker: If the thermometer touches the beaker's walls, it might not measure the water's temperature correctly because the beaker's heat can affect it.
• Measure the boiling temperature as 100°C: This is not suitable because ordinary tap water doesn't always boil exactly at 100°C. The boiling point can change due to factors like altitude and impurities in the water.
• Use a stand to suspend the thermometer: This means they should use something to hold the thermometer upright. If they don't use a stand, the thermometer might not be positioned properly in the water, giving wrong readings.

Thus, it is concluded that a group of students is engaged in an activity in which they are measuring the boiling temperature of ordinary tap water in a beaker. Measuring the boiling temperature as 100°C is not a suitable indicator to assess them on this task.

Hint

• The boiling temperature of water is not always 100°C.
• The boiling temperature of water depends on the atmospheric pressure.
• At sea level, the boiling temperature of water is 100°C.
• However, at higher altitudes, the boiling temperature of water is lower.
• For example, at an altitude of 2,000 meters, the boiling temperature of water is 95°C

Science curricula refer to the planned and organized educational content, including topics, concepts, and learning objectives, designed to teach scientific knowledge and skills to students at different grade levels.

Key Points Socio-scientific issues (SSIs) are complex and controversial issues that involve science, technology, and society. Including SSIs in the school science curriculum can help students develop a number of important skills and understandings, such as:

• SSIs should not be used to teach students that science is a definitive discipline: Science is a process of inquiry, and there is always room for uncertainty and ambiguity.
• Argumentation skills: SSIs require students to be able to think critically about scientific evidence and to construct arguments that support their positions.
• Understanding of the nature of science: SSIs can help students understand that science is a process of inquiry and that scientific knowledge is always evolving.
• Capacity to engage in evidence-based reasoning: SSIs can help students develop the skills to evaluate scientific evidence and to make informed decisions.

Thus, it is concluded that the helpful appreciation of science as a definitive discipline cannot be considered a valid reason for including socio-scientific issues (such as GM food) in the school science curricula.

Additional Information Some additional points about including SSIs in the school science curriculum:

• SSIs can help students to develop critical thinking skills and to become more engaged in the world around them.
• SSIs can help students to understand the role of science in society and to make informed decisions about important issues.

A teacher is an educator who imparts knowledge, skills, and guidance to students, facilitating their learning and personal development within a structured educational environment.

Key Points

• Predicting is an important process skill in science because it allows students to make informed decisions about the natural world.
• It also helps students to develop their critical thinking skills and to become more independent learners.
• The teacher is asking the students to use what they've learned about respiration (how living things breathe) to guess which test tube will have the most carbon dioxide (CO2).
• By looking at the setups (snail, water plant, both), the students are using their knowledge to predict which situation will produce the most CO2.
• This skill helps them apply what they've learned to figure out the outcome before actually observing it. It's like making a smart guess based on what they know.
• To make their prediction, the students must consider the following factors:

Based on these factors, the students can predict that test tube C will have the highest concentration of CO2. This is because test tube C has both a snail and a plant, and the snail is respiring more than the plant is photosynthesizing.

Thus, it is concluded that the Predicting process skill is the teacher's emphasis in this case.

Additional Information

Textbooks are educational resources containing structured content, explanations, and exercises designed to teach specific subjects or topics to students in a classroom setting.

Key Points Extended learning activities are generally more about encouraging independent learning and exploration rather than being a primary basis for evaluation. The activities suggested as part of 'Extended learning' in textbooks are:

• These are important value-additions to children's repertoire of knowledge and skills: Extended learning activities can help students to develop new skills and knowledge, and to apply what they have learned in new and creative ways.
• Some of these require students to collect information of various kinds and draw conclusions on their own: This can help students to develop critical thinking skills and to become more independent learners.
• Some of these enhance children's interaction with experts, teachers, and society at large: This can help students to learn from others and to gain a broader perspective on the world.
• These form an important basis for students' evaluation: This is not always true. Extended learning activities are meant to help you learn more, but they might not always be used for grading or evaluating how well you're doing in class.

Thus, it is concluded that these form an important basis for students' evaluation is not correct with respect to the activities suggested as part of 'Extended learning' in textbooks.

Additional Information Some additional points about extended learning activities:

• They can be used to supplement the regular curriculum.
• They can be used to give students more opportunities to explore their interests.
• They can be used to help students develop problem-solving skills.

Science curriculum outlines the scope and sequence of scientific concepts, experiments, and skills to be taught at different educational levels, fostering scientific understanding and inquiry-based learning.

Key Points Content validity is the extent to which the content of a test is a representative sample of the content that is being measured.

• In the context of the science curriculum, content validity refers to the extent to which the content of the curriculum is a representative sample of the science content that students need to know.
• It means that the content of the science curriculum is relevant, important, and representative of the science that students need to know.

Thus, it is concluded that the content is updated, and concepts accurately represented are ordinarily implied in the context of the 'Content validity' of the Science curriculum.

Additional Information Some additional points about content validity:

• It is important because it ensures that the curriculum is measuring what it is supposed to measure.
• It can be assessed by using a variety of methods, such as expert review, focus groups, and student surveys.

Teaching is the process of imparting knowledge, skills, and information to learners through various instructional methods and interactions, fostering their learning and understanding in a structured educational setting.

Key Points Team teaching can be a great way to provide students with a high-quality education. The benefits of the students with diverse expertise can be considered as the most suitable rationale for team teaching:

• Different perspectives: When two or more teachers with different expertise teach together, they can share their different perspectives on the subject matter. This can help students to see the subject from different angles and to develop a deeper understanding.
• Variety of teaching methods: Teachers with different expertise may have different teaching methods. This can allow teachers to tailor their instruction to the needs of different students.
• More individualized attention: When two or more teachers are teaching together, they can provide more individualized attention to students. This can be especially beneficial for students who need extra help.
• Enhanced Problem-Solving: Collaborating with peers who possess different expertise fosters innovative problem-solving.
• Shared responsibility: When two or more teachers are teaching together, they share the responsibility for student learning. This can be a great way to reduce stress and workload for teachers.

Thus, it is concluded that the benefits of the students with diverse expertise can be considered as the most suitable rationale for team teaching.

Additional Information Some additional benefits of team teaching:

• Increased creativity: When two or more teachers collaborate, they can come up with more creative and innovative teaching ideas.
• Improved communication: Team teaching can help teachers to improve their communication skills. This can be beneficial for both teachers and students.

Spherical mirrors are curved reflective surfaces that either converge (concave) or diverge (convex) light rays, forming real or virtual images, essential in optics and applications like mirrors and optical devices.

Key Points The most suitable activity to introduce the concept of image formation in spherical mirrors to Class VII students:

• Students are asked to play with shiny, steel spoons and observe their images in them: This activity is closer to the concept of image formation. Shiny spoons can act like curved mirrors, showing students how their reflections change when they move the spoon.
• Students are asked to observe their images at various positions in a plane mirror: This activity might help students understand how reflections work, but it's not directly related to the concept of image formation in spherical mirrors. It's better suited to introduce the concept of reflections.
• Students have explained the laws of reflection: This is an important concept to understand, but it is not sufficient to introduce the concept of image formation in spherical mirrors.
• Students have explained the process of drawing ray diagrams in curved mirrors: This might be a bit advanced for Class VII students. Ray diagrams involve tracing light rays to understand how they reflect off mirrors. While it's important later, it might be too complex to introduce this concept at this stage.

Thus, it is concluded that the students are asked to play with shiny, steel spoons and observe their images in them would be the most suitable activity to introduce the concept of image formation in spherical mirrors to Class VII students.

Additional Information Additional tips for introducing the concept of image formation in spherical mirrors:

• Use a variety of objects to create different types of images. This will help students to see the different ways that images can be formed.
• Use a flashlight to shine light on the objects. This will make it easier to see the images.
• Draw ray diagrams to show how the images are formed. This will help students to visualize the process of image formation.

Science education refers to the process of teaching and learning about the natural world, scientific principles, and methodologies, fostering critical thinking, inquiry, and an understanding of the empirical foundations that shape our understanding of the universe.

Key Points Science education isn't only about textbooks and classrooms; it's about fostering a sense of wonder, nurturing curiosity, and equipping students with tools to explore and understand the world around them. It includes:

• Science education should help students acquire the processes of science: This means that students should learn how to ask questions, gather evidence, and evaluate evidence. They should also learn how to use the scientific method to test hypotheses and to make conclusions.
• Science education should build a link between the child and his/her environment:  This means that students should learn about the natural world and how it works. They should also learn how to apply scientific knowledge to solve problems in their own lives.
• Science classroom practices should be developmentally appropriate: This means that the teaching methods and materials should be appropriate for the student's age and level of understanding.
• Learning How Science Works: Science education is about teaching students not just facts, but how science works. It helps them understand how scientists ask questions, make observations, conduct experiments, and draw conclusions to uncover the mysteries of the world around us.
• Hands-On Exploration: Science education encourages students to explore through hands-on activities. They might conduct simple experiments, make observations, or even go on nature walks.
• Curiosity and Critical Thinking:  It nurtures curiosity by encouraging students to ask questions and seek answers. Science education also develops critical thinking skills, helping students evaluate information, make informed decisions, and solve problems.

Thus, it is concluded that Science education should train the students to remain disciplined in school is not implied by the statement 'Good science education is true to the child, true to life and true to the discipline'.