CBSE Science Grade 10 Practice Questions PDF

Science (Volume 2) | Grade 10 Competency Focused Practice Questions | Science | Grade 10  PREFACE Assessments are an important tool that help gauge learning. They provide valuable feedback about the effectiveness of instructional methods; about what students have actually understood and also...

Science (Volume 2) | Grade 10 Competency Focused Practice Questions | Science | Grade 10  PREFACE Assessments are an important tool that help gauge learning. They provide valuable feedback about the effectiveness of instructional methods; about what students have actually understood and also provide actionable insights. The National Education Policy, 2020 has outlined the importance of competency‐based assessments in classrooms as a means to reform curriculum and pedagogical methodologies. The policy emphasizes on the development of higher order skills such as analysis, critical thinking and problem solving through classroom instructions and aligned assessments. Central Board of Secondary Education (CBSE) has been collaborating with Educational Initiatives (Ei) in the area of assessment. Through resources like the Essential Concepts document and A‐ Question‐ A‐Day (AQAD), high quality questions and concepts critical to learning have been shared with schools and teachers. Continuing with the vision to ensure that every student is learning with understanding, Question Booklets have been created for subjects for Grade 10th and 12th. These booklets contain competency‐based items, designed specifically to test conceptual understanding and application of concepts. Process of creating competency‐based items All items in these booklets are aligned to the NCERT curriculum and have been created keeping in mind the learning outcomes that are important for students to understand and master. Items are a mix of Free Response Questions (FRQs) and Multiple‐Choice Questions (MCQs). In case of MCQs, the options (correct answer and distractors) are specifically created to test for understanding and capturing specific errors/misconceptions that students may harbour. Each incorrect option can thereby inform teachers on specific gaps that may exist in student learning. In case of subjective questions, each question also has a detailed scoring rubric to guide evaluation of students’ responses. Each item has been reviewed by experts, to check for appropriateness of the item, validity of the item, conceptual correctness, language accuracy and other nuances. How can these item booklets be used? There are 187 questions in this booklet. The purpose of these item booklets is to provide samples of high‐quality competency‐based items to teachers. The items can be used to– get an understanding of what good competency‐based questions could look like give exposure to students to competency‐based items assist in classroom teaching and learning get inspiration to create more such competency‐based items Students can also use this document to understand different kinds of questions and practice specific concepts and competencies. There will be further additions in the future to provide competency focused questions on all chapters. The item booklets are aligned with the 2022‐23 curriculum. However, a few questions from topic which got rationalized in 2023‐24 syllabus are also there in the booklet which may be used as a reference for teachers and students. Please write back to us to give your feedback. Team CBSE Competency Focused Practice Questions | Science | Grade 10  CONTENTS 1. ACIDS, BASES AND SALTS................................................................................................... 1 Answer Key & Marking Scheme.......................................................................................... 4 2. CARBON COMPOUNDS...................................................................................................... 6 Answer Key & Marking Scheme.......................................................................................... 7 3. CHEMICAL REACTIONS....................................................................................................... 8 Answer Key & Marking Scheme.......................................................................................... 9 4. CONTROL AND COORDINATION....................................................................................... 10 Answer Key & Marking Scheme........................................................................................ 10 5. ELECTRICITY..................................................................................................................... 11 Answer Key & Marking Scheme........................................................................................ 15 6. HEREDITY AND EVOLUTION.............................................................................................. 16 Answer Key & Marking Scheme........................................................................................ 18 7. HUMAN EYE AND COLOURFUL WORLD............................................................................ 19 Answer Key & Marking Scheme........................................................................................ 20 8. LIFE PROCESSES............................................................................................................... 21 Answer Key & Marking Scheme........................................................................................ 23 9. METALS AND NON-METALS............................................................................................. 24 Answer Key & Marking Scheme........................................................................................ 25 10. OUR ENVIRONMENT........................................................................................................ 26 Answer Key & Marking Scheme........................................................................................ 26 11. PERIODIC CLASSIFICATION............................................................................................... 27 Answer Key & Marking Scheme........................................................................................ 27 12. REFLECTION AND REFRACTION........................................................................................ 28 Answer Key & Marking..................................................................................................... 28 13. REPRODUCTION............................................................................................................... 29 Answer Key & Marking Scheme........................................................................................ 31 14. SOURCES OF ENERGY....................................................................................................... 32 Answer Key & Marking Scheme........................................................................................ 34 15. CHEMICAL SUBSTANCES- NATURE AND BEHAVIOUR........................................................ 35 Answer Key and Marking Scheme.................................................................................... 42 16. WORLD OF LIVING............................................................................................................ 45 Answer Key and Marking Scheme.................................................................................... 63 17. NATURAL PHENOMENA................................................................................................... 74 Competency Focused Practice Questions | Science | Grade 10  Answer Key and Marking Scheme.................................................................................... 78 18. EFFECTS OF CURRENT...................................................................................................... 81 Answer Key and Marking Scheme.................................................................................... 84 19. NATURAL RESOURCES...................................................................................................... 85 Answer Key and Marking Scheme.................................................................................... 95 Competency Focused Practice Questions | Science | Grade 10 1. ACIDS, BASES AND SALTS Q. No Question Marks Multiple Choice Question Q.1 Hydrangea plants develop blue or pink flowers depending on the availability of 1 aluminium from the soil. When the soil is acidic, aluminium is more available to the roots, resulting in blue flowers. When the soil is alkaline, the availability of aluminium decreases, resulting in pink flowers. The graph below is of the pH of the soil at different sections of a field. In which section of the field will the flowers on ALL the hydrangea plants definitely be blue in colour and in which section will the flowers on ALL the hydrangea plants definitely be pink in colour? Option Blue flowers Pink flowers W Section P and Q Section R and S X Section R and S Section P and Q Y Section P, Q and S Section R Z Section P Section R A. W Competency Focused Practice Questions | Science | Grade 10 1  B. X C. Y D. Z Free Response Question/ Subjective Question Q.2 An excess of carbon dioxide gas is bubbled through lime water. 3 (a) Will the pH of lime water change? If yes, how? Explain your answer. (b) Write the balanced equation for the reaction. Q.3 Tanu takes 500 mL milk each in two bowls P and Q. She adds curd to both the 3 bowls and baking soda only to bowl Q as shown below. (a) Bowl P - 500 mL milk + 1 teaspoon curd (b) Bowl Q - 500 mL milk + 1 teaspoon curd + 1 teaspoon baking soda In which bowl will the milk form into curd faster? Explain your answer. Q.4 A solution P is taken in a flask and two drops of phenolphthalein indicator is 3 added to it. The graph below shows how the pH of the mixture changes as a solution Q is added dropwise to the flask with stirring. (a) Identify the nature of solutions P and Q. (b) What will the colour of the solution in the flask be at points X and Y? (c) Identify the type of reaction taking place in the flask. Q.5 Aditi adds 1 mole of dilute hydrochloric acid to an aqueous solution of 1 mole 5 of sodium carbonate. (a) Write the balanced equation for the reaction that takes place. Competency Focused Practice Questions | Science | Grade 10 2  (b) How will the colour of a red litmus and a blue litmus paper change when dipped in this mixture? Explain why. Q.6 The presence of acidic gases in the air increases the rate of corrosion. 1 Furthermore, an increase in temperature can also increase the rate of corrosion. The graph below is created under 4 different conditions (shown below in the table) of temperature and acidic nature of air. Which of the graphs represents condition 2? (a) P (b) Q (c) R (d) S Competency Focused Practice Questions | Science | Grade 10 3  Answer Key & Marking Scheme Q. No Answers Marks Q.1 D. Z 1 Q.2 (a) 3 - The pH of lime water will decrease. [0.5 marks] - Carbon dioxide, being an acidic oxide, will neutralise lime water which is basic. [1 mark] OR -The products formed, namely, calcium carbonate and Calcium hydrogen carbonate are basic salts but less basic than Calcium hydroxide so pH decreases. (b) 0.5 marks each for writing the formula of lime water and the product calcium bicarbonate; 0.5 marks for balancing the equation: Ca(OH)2 + 2 CO2 ---> Ca(HCO3)2 OR Ca(OH)2 + CO2 ---> CaCO3 + H2O CaCO3 + CO2 + H2O ---> Ca(HCO3)2 Q.3 The milk will form into curd faster in bowl P. 3 - Curdling of milk takes place due to formation of lactic acid by bacteria. [1 mark] - In bowl Q, the lactic acid formed by bacteria has to first neutralise the baking soda, which is basic in nature, before the milk starts curdling. [1 mark] Q.4 (a) 0.5 marks each for the following: 3 - solution P: acidic - solution Q: basic (b) 0.5 marks for each of the following: - colour of solution at X: colourless - colour of solution at Y: pink (c) neutralisation Q.5 (a) 0.5 marks each for writing the formula of each reactant and product: 5 HCl + Na2CO3 ---> NaCl + NaHCO3 (b) - Red litmus paper will turn blue. [0.5 marks] - There will be no effect on blue litmus paper. [0.5 marks] Competency Focused Practice Questions | Science | Grade 10 4  - The complete neutralisation of 1 mole of sodium carbonate requires 2 moles of hydrochloric acid. [1 mark] - Since only 1 mole of HCl is used, neutralisation is incomplete and the mixture will be basic. [1 mark] Q.6 Graph P 1 Competency Focused Practice Questions | Science | Grade 10 5 2. CARBON COMPOUNDS Q. No Question Marks Free Response Question/ Subjective Question Q.7 Combustion analysis of compound X revealed the ratio of its elements in a 2 molecule to be carbon:hydrogen:oxygen::3:6:2. The compound undergoes esterification to yield an ester and water. (a) Identify the compound X. Write its chemical formula. (b) Write the balanced equation for the combustion of compound X. Q.8 Bonding of oxygen with carbon and with hydrogen are highly exothermic 3 processes. Compare the amount of energy released on combustion of methane and propane. (a) Which compound will yield more energy per mole on combustion? Justify your answer. (b) Write the balanced chemical equations for complete combustion of propane and methane. Q.9 One mole of an alkane P is burned in an excess of oxygen to yield 6 moles of 3 carbon dioxide and 14 moles of water. (a) Write the chemical formula and chemical name of the compound. (b) Will this compound produce a clear or sooty flame on burning? Justify your answer. Competency Focused Practice Questions | Science | Grade 10 6  Answer Key & Marking Scheme Q. No Answers Marks Q.7 (a) Propionic acid / Propanoic acid [0.5 marks] 2 C2H5COOH [0.5 marks] (c) 2C2H5COOH + 7O2 --> 6CO2 + 6H2O + energy Q.8 (a) Energy released per mole will be more in propane since it has more number 3 of carbon atoms. (b) 1 mark for each correct equation: CH4 + 2O2 --> CO2 + 2H2O C3H8 + 5O2 --> 3CO2 + 4H2O Q.9 (a) 1 mark each for the correct name and formula: 3 chemical name - Hexane chemical formula - C6H14 (b) It will burn with a clear flame since it is a saturated hydrocarbon. Competency Focused Practice Questions | Science | Grade 10 7 3. CHEMICAL REACTIONS Q. No Question Marks Free Response Question/ Subjective Question Q.10 Photographic film consists of a gelatin emulsion with silver halide grains layered 1 onto a film base. The halides that are used are silver chloride, bromide or iodide. The photographic film is usually stored in metal containers to protect it from light. Write the chemical equation for the possible chemical reaction that this method of storing photographic film is preventing. Q.11 Trupti mixed one teaspoon of baking soda in 500 g of cake mixture. She kept 3 the mixture aside for 5 minutes. Geeta mixed one teaspoon of baking powder in 500 g of the same cake mixture. She also kept the mixture aside for 5 minutes. She then baked the two cakes together in the same oven. Whose cake is likely to rise higher? Justify your answer. Q.12 While cooking in an aluminum vessel, Sudeshna burned some food till all that 2 was left was a completely charred and black residue. She just left the blackened vessel heating on the stove. After an hour she found that the vessel was completely clean, with no trace of any blackness. (a) Write a chemical equation to explain what happened to the charred, black residue that made it disappear. (b) Name the type of reaction referred to in (a). Competency Focused Practice Questions | Science | Grade 10 8  Answer Key & Marking Scheme Q. No Answers Marks Q.10 1 Q.11 Trupti's cake will rise more. [1 mark] 3 Baking powder is a mixture of sodium bicarbonate and tartaric acid. [1 mark] - Baking soda is pure sodium bicarbonate. Hence one teaspoon of baking soda contains more bicarbonate than baking powder and releases more carbon dioxide than baking powder.. [1 marks] Q.12 (a) 0.5 marks each for writing the reactants and product: 2 C + O2 ---> CO2 (b) 0.5 marks for any of the following: - combustion - oxidation - combination Competency Focused Practice Questions | Science | Grade 10 9 4. CONTROL AND COORDINATION Q. No Question Marks Multiple Choice Question Q.13 Two statements are given below - one labelled Assertion (A) and the other 1 labelled Reason (R). Read the statements carefully and choose the option that correctly describes statements (A) and (R). Assertion (A): All reflex actions are involuntary actions but only some involuntary actions are reflex actions. Reason (R): Reflex actions take the shortest route from the receptor (detector of stimulus) to the effector (producer of response). Which of the following is correct? A. Both (A) and (R) are true and (R) is correct explanation of the assertion. B. Both (A) and (R) are true but (R) is not the correct explanation of the assertion. C. (A) is true but (R) is false. D. (A) is false but (R) is true. Answer Key & Marking Scheme Q.No Answers Marks Q.13 B. Both (A) and (R) are true but (R) is not the correct explanation of the 1 assertion. Competency Focused Practice Questions | Science | Grade 10 10 5. ELECTRICITY Q. No Question Marks Multiple Choice Question Q.14 The graph below shows the variation of resistivity of copper with temperature. 1 Kishore constructs a simple circuit as shown below. The resistor is made of copper. He then heats the copper resistor. What will happen to the current flowing through the circuit? Why? A. The current will increase because the resistance of copper increases with an increase in temperature. B. The current will increase because the resistance of copper decreases with an increase in temperature. C. The current will decrease because the resistance of copper increases with an increase in temperature. D. The current will decrease because the resistance of copper decreases with an increase in temperature. Q.15 Priya has three resistors each of resistance 2 Ω. 1 Competency Focused Practice Questions | Science | Grade 10 11  Which of the following resistances will she NOT be able to get by combining these resistors is different combinations? A. 0.67 Ω B. 0.75 Ω C. 3 Ω D. 6 Ω Q.16 A cylindrical copper wire X of length l and radius r has a resistance R and 1 resistivity ρ. Another copper wire Y has a length 2l and a radius 2r. Which of the following rows in the table shows the correct resistance and resistivity of the copper wire Y? Resistance Resistivity I R/2 ρ I R ρ I I R/2 ρ/2 I I I R ρ/2 V A. I B. II C. III D. IV Q.17 The variable resistor R is connected in a circuit, as shown below. A variable 1 resistor is one whose resistance can be changed. Competency Focused Practice Questions | Science | Grade 10 12  The resistance of R is increased. What will happen to the voltmeter readings V1 and V2? A. V1 increases; V2 increases B. V1 increases; V2 decreases C. V1 decreases; V2 increases D. V1 decreases; V2 decreases Q.18 Kishore connects two resistors in parallel. He wants to measure the total 1 current through the two resistors. Which of the following shows the correct arrangement to measure the current through Ammeter ‘A’? A. B. Competency Focused Practice Questions | Science | Grade 10 13  C. D. Competency Focused Practice Questions | Science | Grade 10 14  Answer Key & Marking Scheme Q. No Answers Marks Q.14 C. The current will decrease because the resistance of copper increases with 1 an increase in temperature. Q.15 B. 0.75 Ω 1 Q.16 A. I 1 Q.17 C. V1 decreases; V2 increases 1 Q.18 1 B. Competency Focused Practice Questions | Science | Grade 10 15 6. HEREDITY AND EVOLUTION Q. No Question Marks Multiple Choice Question Q.19 Manisha is an Indian actress. She was born in Delhi to a homemaker mother 1 and an engineer father. She is around 5 feet tall. She has naturally curly hair. She has trained in contemporary and ballet dancing. Which of these is MOST LIKELY to be true about her children? A. They may dance well. B. They may grow up to have curly hair. C. They may be born to an engineer father. D. They may become famous actors one day. Q.20 Study the diagrams given below that depict the analogy/homology of organs 1 and answer the questions that follow. Which diagram represents evolution of homologous organs? A. only P B. only Q C. both - P and Q D. neither - P nor Q Free Response Question/ Subjective Question Q.21 The farmer concludes that the allele for green seeds shows dominance over 1 that of yellow seeds. Is he right? Justify your answer. Q.22 What is the genetic basis of the increase in number of the black peppered 1 moth after the Industrial Revolution? Q.23 The picture below is of the chromosome pairs present in a cell of a person. 2 Competency Focused Practice Questions | Science | Grade 10 16  (a) Identify the sex of the person. Give reasons for your answer. (b) State the number of chromosomes present in a male or female gamete. Competency Focused Practice Questions | Science | Grade 10 17  Answer Key & Marking Scheme Q. No Answers Marks Q.19 B. They may grow up to have curly hair. 1 Q.20 A. only P 1 Q.21 Yes, he is right. [0.5 marks] 1 Since the offspring pod has all green seeds, the allele for green seeds is dominant even if present in heterozygous state. [0.5 marks] Q.22 During sexual reproduction, the genes determining darker colour of moths get 1 selected and their frequency increased in the population. Q.23 (a) male. 23rd pair has X and Y chromosomes. 2 (b) 23 Competency Focused Practice Questions | Science | Grade 10 18 7. HUMAN EYE AND COLOURFUL WORLD Q. No Question Marks Free Response Question/ Subjective Question Q.24 An autorefractor, which is used to automatically measure the refractive errors 3 in a person's eye, makes use of the Scheiner principle explained below. Parallel rays of light from a distant object are limited to two parallel bundles of light using a disc with two pinholes. For an eye with no refractive error, the rays would be focused on the retina, where only one spot can be observed. (a) For a myopic eye, how many spots will be observed on the retina? (b) Draw a diagram showing how the light rays fall on the retina of a myopic eye? (c) What could be the reason for the observation? Competency Focused Practice Questions | Science | Grade 10 19  Answer Key & Marking Scheme Q. No Answers Marks Q.24 (a) 2 spots 3 (b) (c) 1 mark for any one of the following: -elongation of the eyeball -excessive curvature of the eye lens Competency Focused Practice Questions | Science | Grade 10 20 8. LIFE PROCESSES Q. No Question Marks Multiple Choice Question Answer the questions based on the following information. 1 William Harvey (1578–1657) was one of the early biologists who studied the bodies of humans and animals. He even dissected the bodies and did experiments with the heart and blood vessels. He concluded from his experiments that the blood leaves the heart through the arteries and returns via the veins. However, he could not explain how blood left the arteries to enter the veins. He said there must be some structure between arteries and veins but he could not find them. Marcello Malphigi (1628–1694) later discovered these structures while studying a dead frog's lungs under a microscope. Q.25 Which of the following structures did Malphigi find in the frog? 1 A. cells B. capillaries C. heart chambers D. small air sacs in lungs Q.26 What is the MOST LIKELY reason why Harvey could NOT find these structures? 1 A. These structures are not found in humans. B. These structures are found only in the lungs. C. These structures become visible only in dead animals. D. These structures were too small to be seen by the naked eye. Q.27 Which of the following statements about arteries and veins is TRUE? 1 A. Arteries have thicker walls than veins. B. Veins have thicker walls than arteries. C. All arteries carry only oxygenated blood. D. All veins carry only deoxygenated blood. Q.28 Which two chambers of the human heart have arteries connected to them? 1 A. left atrium and left ventricle B. right atrium and right ventricle C. left atrium and right atrium Competency Focused Practice Questions | Science | Grade 10 21  D. left ventricle and right ventricle Free Response Question/ Subjective Question Q.29 Aerobic respiration requires intake of oxygen to breakdown food to release 5 energy. (a) Name the structures through which gaseous exchange takes place in plants and human beings. (b) Name the structure that controls the size of the chest cavity in humans to facilitate exchange of gases. (c) What is the process by which gas exchange occurs in plants? (d) Why is the process named in (c) not sufficient to carry oxygen throughout human body? How is this complemented in humans to ensure that oxygen is carried to all parts of the body? (e) Reactions in living systems can absorb heat or release heat. State whether the heat energy is absorbed/ released during digestion. Also write the scientific term to denote the same. Q.30 Given below is an image of an experiment conducted by a student to 3 understand the process of respiration. He blows into a clear solution present in the test tube and sees that it turns cloudy. (a) What is the most likely substance present in the test tube? (b) What could be the aim of his experiment? (c) What kind of respiration is shown in the experiment? Justify your answer. Competency Focused Practice Questions | Science | Grade 10 22  Answer Key & Marking Scheme Q. No Answers Marks Q.25 B. capillaries 1 Q.26 D. These structures were too small to be seen by the naked eye. 1 Q.27 A. Arteries have thicker walls than veins. 1 Q.28 D. left ventricle and right ventricle 1 Q.29 (a) 0.5 marks for each correct answer: 5 Plants: stomata/guard cells Human beings: alveoli/ lungs (b) diaphragm (c) diffusion (d) 1 mark for each correct point: - because diffusion is a slow process and human beings have complex tissues that might not allow diffusion to happen effectively and easily - carried by the blood/ haemoglobin in the blood (e) 0.5 marks for each correct answer: - use up heat - endothermic Q.30 (a) lime water / dilute aqueous solution of calcium hydroxide/ Ca(OH)2 3 (b) To prove that carbon dioxide is released during respiration. (c) - aerobic respiration [0.5 marks] - CO2 is a product of either aerobic respiration or fermentation [0.5 marks] - fermentation does not take place in human cells. [0.5 marks] Competency Focused Practice Questions | Science | Grade 10 23 9. METALS AND NON-METALS Q. No Question Marks Multiple Choice Question Q.31 In which of the following forms do electrovalent compounds conduct 1 electricity? A. only in solid form B. both in solid form and in aqueous solution C. both in aqueous solution and in molten form D. in solid form, molten form and in aqueous solution Free Response Question/ Subjective Question Q.32 1 Many chemical reactions like the one shown below, are carried out in glass- lined, iron chemical reactors instead of directly in iron reactors. State one advantage of carrying out the reaction in a glass-lined reactor instead of directly in an iron reactor. Competency Focused Practice Questions | Science | Grade 10 24  Answer Key & Marking Scheme Q. No Answers Marks Q.31 C. both in aqueous solution and in molten form 1 Q.32 1 mark for any one of the following: 1 - no corrosion of the reactor - no contamination of the product with metal / metal salts Competency Focused Practice Questions | Science | Grade 10 25 10. OUR ENVIRONMENT Q. No Question Marks Free Response Question/ Subjective Question Q.33 Fishes like swordfish and king mackerel are tertiary consumers. Fishes like 1 tilapia and salmon are secondary consumers. The habitat of these fishes are usually contaminated with heavy metals like mercury. Scientists suggest consuming these fishes according to the table given below: Best to avoid Good to eat (1 serving/ (2-3 month) servings/week) King mackerel Tilapia Swordfish Pollock What phenomenon is likely to have led the scientists to give such an advisory to the people who consume fish? Answer Key & Marking Scheme Q. No Answers Marks Q.33 biomagnification of toxic substances in higher trophic levels 1 Competency Focused Practice Questions | Science | Grade 10 26 11. PERIODIC CLASSIFICATION Q. No Question Marks Multiple Choice Question Q.34 Elements X and Y are in the same period of the periodic table and have the same 1 valency. The force of attraction between the valence electrons and the nucleus is greater in element X than in element Y. Which of the following is also likely to be true about elements X and Y? A. Y is more electronegative than X. B. X has a greater atomic radius than Y. C. Y has more metallic character than X. D. X forms covalent bonds and Y forms ionic bonds. Answer Key & Marking Scheme Q. No Answers Marks Q.34 C. Y has more metallic character than X. 1 Competency Focused Practice Questions | Science | Grade 10 27 12. REFLECTION AND REFRACTION Q. No Question Marks Multiple Choice Question Q.35 Which of the following characteristics of a spherical mirror is given by the ratio 1 of the size of the image to the size of the object? A. aperture B. magnification C. focal length D. radius of curvature Q.36 Which of the following does the negative sign in the power -3D signify? 1 A. The focus is on the same side of the lens as the object. B. The focus is on the opposite side of the lens as the object. C. The principal focus is situated outside the principal axis. D. The focal length on one side of the lens is smaller than that on the other. Q.37 Which among the two lenses with power- 3D AND 4D respectively can form a 1 real image? A. only the lens with power -3 D B. only the lens with power 4 D C. both the lenses D. neither of the lenses Answer Key & Marking Q.No Answers Marks Q.35 B. magnification 1 Q.36 A. The focus is on the same side of the lens as the object. 1 Q.37 B. only the lens with power 4 D 1 Competency Focused Practice Questions | Science | Grade 10 28 13. REPRODUCTION Q. No Question Marks Multiple Choice Question Q.38 Contraceptives help in preventing pregnancies. 1 What function would a contraceptive loop inserted at T serve? A. Stopping sperms from reaching and fertilizing eggs B. Stopping release of sperms C. Blocking the release of eggs D. Stopping egg creation Free Response Question/ Subjective Question Q.39 Bindu wants to produce a hybrid variety of tomatoes. She has tomato plants X 1 and Y belonging to two different varieties, one with smooth, long fruits and the other one with wrinkled, round fruits. Tomatoes have bisexual flowers. Bindu carries out the following steps carefully to cross pollinate the flowers of plants X and Y: 1. She removes a part of the flowers of tomato plant X just before the flowers bloom. 2. She manually pollinates the flowers of tomato plant X using pollen from the flowers of tomato plant Y. 3. She ties small plastic bags around the pollinated flowers of tomato plant X. The plastic bags are removed after a couple of days. What could be reason for covering the pollinated flowers of plant X? Q.40 Water hyacinths reproduce both sexually and asexually. They reproduce 4 sexually by producing seeds through flowers, and asexually by bud formation or fragmentation. It undergoes reproduction through either of the methods depending on environmental conditions. Water hyacinths bloom freely in water-rich conditions whereas, reproduction for survival is more effort- intensive in water-scarce conditions. (a) Explain why this variation in reproduction is required in water hyacinths. (b) Which mode of reproduction is likely to occur in the following conditions? Justify: Competency Focused Practice Questions | Science | Grade 10 29  (i) abundance of water (ii) scarcity of water Q.41 Compare the reproductive parts of flowers and humans and answer the 3 questions below: (a) Which part of the human female reproductive system has a similar function as the stigma in a flower? Give a reason to support your answer. (b) Testes in the male reproductive system would correspond to which part of the male reproductive system in a flower? Justify. (c) The style of a flower and the fallopian tube in humans correspond functionally with each other. Is this statement true? Justify your answer. Competency Focused Practice Questions | Science | Grade 10 30  Answer Key & Marking Scheme Q. No Answers Marks Q.38 A. Stopping sperms from reaching and fertilizing eggs 1 Q.39 to prevent pollen from other plants from reaching the stigma 1 Q.40 (a) 1 mark for each point: 4 - The population of each species thrives in its specific habitat/niche, having particular environmental conditions which can change due to reasons beyond the organisms' control - Having variation ensures greater chances of survival through such changes. [Accept any other valid answer] (b) 0.5 marks each for the following points: (i) - asexual reproduction - In its natural environment, the organism is likely to undergo an energy- efficient method of reproduction such as asexual reproduction. (ii) - sexual reproduction - In a stressed environment, the organism is likely to opt for the effort-intensive method for survival. [Accept any other valid answer] Q.41 (a) 0.5 marks for identifying the part and 0.5 marks for the reason: 3 - Part - Cervix/Vagina - Reason - The stigma of the flower serves as the point of entry of the male gametes/pollen grains, similarly, the cervix serves as the point of entry of the male gametes/sperm in humans/ vagina receives the male gametes in humans. (b) 0.5 marks for identifying the part and 0.5 marks for the reason: - Part - anther - Function - produces male gametes in form of pollen, just like testes which produce sperms (c) 0.5 for stating true/false and 0.5 marks for the reason: - False - Reason - the main function of the fallopian tube is to serve as the point of fertilisation, which is not the function of the style in flowers. [Accept any other valid answer] Competency Focused Practice Questions | Science | Grade 10 31 14. SOURCES OF ENERGY Q. No Question Marks Multiple Choice Question Q.42 Place X is a metropolitan city with many high-rise buildings and parks. Place Y is 1 an elevated location with cottages and large open spaces. Which of the two places would be LESS SUITABLE to set up a wind energy farm and why? A. Place X, as there are parks. B. Place Y, as it is at an elevation. C. Place Y, as it has large open spaces. D. Place X, as there are high-rise buildings. Q.43 Mohan owns a large livestock farm near a pond. The farm is on an elevation. It 1 receives a steady wind speed of 10 km/h. The area is sunny for the greater part of the day on most days. Which of the following could be the sources of energy on his farm? P) hydro-electricity Q) biomass R) wind S) solar A. only P and S B. only Q and S C. only Q and R D. only P and R Q.44 The best source of energy to power satellites in space is solar energy. 1 Select the reasons that justify the above statement. P) It is easily available. Q) It is the only inexhaustible form of energy. R) It does not need to be transported as a source of fuel. A. only P and Q B. only Q and R C. only P and R Competency Focused Practice Questions | Science | Grade 10 32  D. all- P, Q and R Free Response Question/ Subjective Question Q.45 Although wind is present everywhere, wind energy devices are not commonly 2 found in residential areas. State any TWO reasons why harnessing wind energy is NOT a common practice in residential areas. Q.46 Hydropower plants are used to generate electricity, commonly, from waterfalls. 2 In the absence of waterfalls, (a) What kind of setup has to be made to enable a flowing water source to generate electricity? (b) How does the setup mentioned in (a) help to generate electricity? Q.47 A region 'X' along the coast, with large vacant space experiences a wind speed 5 of 32 km/h for most of the year. (a) Describe, briefly, the setup and the process involved in generating electricity using the given wind speed. (b) State TWO factors that make region X a suitable location to set up a wind energy farm. (c) Apart from wind energy, identify TWO forms of energy that can be generated using renewable sources in region X. Justify your answer. Competency Focused Practice Questions | Science | Grade 10 33  Answer Key & Marking Scheme Q. No Answers Marks Q.42 D. Place X, as there are high-rise buildings. 1 Q.43 B. only Q and S 1 Q.44 C. only P and R 1 Q.45 1 mark each for any two reasons such as: 2 - Devices that harness wind energy require large areas of land which is generally scarce in residential areas. - Buildings in residential areas may block the wind reducing its speed to below 15 m/s required to run a turbine. (Accept any other valid answer.) Q.46 (a) High-rise dams can be constructed on the river to obstruct the flow and 2 collect water in the reservoirs. (b) Water falling from the high level of the reservoir turns the turbines at the bottom of the dam, converting the potential energy of the falling water into electricity. Q.47 (a) 0.5 marks for each of the following: 5 - A wind energy farm OR windmill has to be set up in the open space available near the coast. - The kinetic energy of the wind causes the windmill to rotate. - The rotating windmill turns the turbine of an electric generator thereby generating electricity. (b) 1 mark for each of the following: - High wind speed that can be used to harness more energy. - availability of large open spaces to set up a windmill/ wind energy farm (c) 0.5 marks each for identifying the two forms of energy and 0.5 marks for the justification: - wave energy - tidal energy - Justification: Since the region is located along the coast, it allows for the generation of electricity using tides and wave speed/size of marine water. Competency Focused Practice Questions | Science | Grade 10 34 15. CHEMICAL SUBSTANCES- NATURE AND BEHAVIOUR Q. No Question Marks Multiple Choice Question Q.48 Manav found an unknown solid substance on a riverbank. To check its nature, 1 he carried out some tests on the substance and recorded his observations in the table shown below. Test Observation Effect of heat melts on heating Ductility can be stretched into a thin strand Malleability can be beaten into a thin sheet Electrical conductivity does not conduct electricity Which of the following could the substance be? A. It is a polymer. B. It is a metal. C. It is glass. D. It is wax. Q.49 Trupti has given the following reasons for Gold being the most abundantly used 1 metal for jewellery: (i) It has high ductility. (ii) It has high malleability. (iii) It shines more than other metals. (iv) It reacts quickly with oxygen to form a protective layer of oxide. (v) It does not react with water & oxygen even at high temperatures. Which of the reasons given is/are INCORRECT? A. only (iii) B. only (iv) C. only (iv) & (v) D. only (i), (ii) & (iii) Competency Focused Practice Questions | Science | Grade 10 35  Q.50 Sheetal has two test tubes, one containing dilute hydrochloric acid and the 1 other dilute sulphuric acid but they are not labelled. Adding which of the following to the test tubes will help her to find out which test tube contains hydrochloric acid and which contains sulphuric acid? A. Blue litmus paper B. Zinc metal strips C. Sodium carbonate D. Barium carbonate Q.51 Two statements are given - one labelled Assertion (A) and the other labelled 1 Reason (R). Read the statements carefully and choose the option that correctly describes statements A and R. Assertion (A): An alloy may be a compound consisting of a metal and a non- metal. Reason (R): An alloy is made by melting a metal and then dissolving other elements in it in definite proportions. A. Both A and R are true and R is the correct explanation for A. B. Both A and R are true but R is not the correct explanation for A. C. A is true but R is false. D. A is false but R is true. Q.52 Freshly cut pieces of iron are stored in three closed containers P, Q and R 1 containing dry air, oxygen and nitrogen respectively. In which of the containers is the Iron likely to rust? A. Only P B. Only P and Q C. All - P, Q and R D. In none of them Q.53 Gautam has to courier a sample of silver bromide powder to a laboratory for 1 analysis. Which of the following containers can he use to pack the sample? P) Transparent glass bottle Q) Opaque plastic bottle R) Black paper packet A. Only P B. Only P or Q Competency Focused Practice Questions | Science | Grade 10 36  C. Only Q or R D. Any of P, Q or R Q.54 Two statements are given - one labelled Assertion (A) and the other labelled 1 Reason (R). Read the statements carefully and choose the option that correctly describes statements A and R. Assertion (A): Potassium metal burns and produces a flame when thrown in water.. Reason (R): The reaction of potassium with water is highly exothermic and violent. A. Both A and R are true and R is the correct explanation for A. B. Both A and R are true but R is not the correct explanation for A. C. A is true but R is false. D. A is false but R is true. Q.55 Doing which of the following will break the bonds in a crystal of sodium 1 chloride? A. Passing an electric current through it B. Crushing it into a fine powder C. Mixing it with kerosene D. Mixing it with water Q.56 In the list given below, a metal to the right is more reactive than a metal that is 1 to its left. Copper Tin Nickel Cobalt Iron Zinc The table below gives the colour of the metal sulphate salt solutions. Colour of aqueous metal salt Metal salt solution solution Copper sulphate blue Tin sulphate yellow Nickel sulphate green Cobalt sulphate pink Iron sulphate green Zinc sulphate colourless Competency Focused Practice Questions | Science | Grade 10 37  Adding nickel and iron metal to which of the following solutions will show that iron is more reactive than nickel? A. Copper sulphate B. Tin sulphate C. Cobalt sulphate D. Zinc sulphate Q.57 Carbon compounds undergo combustion in oxygen to give carbon dioxide along 1 with heat and light. The same number of molecules of each of the following carbon compounds undergo complete combustion. P) CH3COOH Q) CH3CH2COOH R) CH3CH=CH2 S) CH3CH2CH2OH Which of them will produce the same amount of carbon dioxide? A. Only P and Q B. Only Q and S C. Only P, Q and R D. Only Q, R and S Free response question/Subjective Question Q.58 A redox reaction is defined as a type of chemical reaction that involves transfer 4 of electrons between reacting atoms, molecules or ions - one gains and the other loses electrons. Study the equation given below that shows the reaction between zinc oxide and hydrochloric acid. ZnO + 2 HCl → ZnCl2 + H2O (a) Is this a double displacement reaction? Justify your answer. (b) Is this a redox reaction? Justify your answer. (c) Name another type of reaction that this is an example of. Q.59 A metal oxide XO on being heated with carbon does NOT produce carbon 1 dioxide. Competency Focused Practice Questions | Science | Grade 10 38  Give a possible explanation for this behaviour of the metal oxide. Q.60 Farida checks the pH of a bottle of milk at 10:00 AM and finds it to be 6.0. She 2 leaves the milk bottle on the table at room temperature (30 °C). She checks the pH of the milk again at 4:00 PM. How is the pH of the milk at 4:00 PM likely to compare with the pH of milk at 10:00 AM? Justify your answer. Q.61 On opening a bottle of soda, Nishchal observed that there was a lot of 2 effervescence and some of the soda water bubbled out of the bottle. (a) Write the equation for the chemical reaction taking place. (b) Identify the type of reaction. Q.62 The molecular formulae of three carbon compounds are: 2 CH2O, C2H4O, C3H6O (a) Identify the compound that can exist as two isomers having different functional groups. (b) Write the structures of the two isomers. Q.63 Uzma peeled and cut some potatoes and left them in an open bowl. After a few 1 minutes, she observed that the cut potato pieces had turned brown. Radhika also peeled and cut some potatoes. She kept the cut potato pieces immersed in a bowl of water. The potato pieces in water did NOT turn brown. Explain the difference in the reaction of the cut potato pieces in the two cases. Q.64 The densities of water and magnesium metal at different temperatures are 1 given in the table below. Density of Density of Temperature magnesium metal water 25 °C (room temperature) 1.738 0.99 100 °C (boiling point of - 0.958 water) 650 °C (melting point of 1.64 - magnesium) 'Magnesium floats in boiling water because its density decreases on heating.' Is the statement above true or false? If true, give a reason. If false, correct it. Q.65 Bala was monitoring the pH of the reaction mixture of ethanoic acid and ethanol 2 in the presence of an acid. Competency Focused Practice Questions | Science | Grade 10 39  What change is he likely to observe in the pH of the mixture as the reaction proceeds? Explain why. Q.66 A red litmus paper and a blue litmus paper are added to distilled water in a test 2 tube. A small piece of calcium metal is now added to the water. What will be the change in the colour of the litmus papers? Justify your answer. Q.67 Sugar free chewing gum, as shown below, have baking soda as one of their key 1 ingredients and are considered to be good to keep teeth healthy. What is likely to be the function of baking soda in the chewing gum? Q.68 Study the compounds displayed below: 4 (a) Identify all the compounds that are the first members of their respective homologous series. (b) Which of the above compounds are likely to undergo non-catalytic hydrogenation reaction? (c) Which TWO compounds will combine to form an ester? Justify with an equation for the reaction. Q.69 The reactants of two reactions are given below. 3 Competency Focused Practice Questions | Science | Grade 10 40  1) Ca + 2 H2O ------> 2) CaO + H2O ------ > (a) Write the chemical formula of the common product formed in the two reactions. (b) Identify the type of reaction that will occur in (1) and (2) Q.70 Excess carbon dioxide gas is continuously bubbled through a solution of slaked 5 lime. (a) Describe how the appearance of the solution will change. (b) Write balanced chemical equations to explain the change described in the answer to part (a). Also mention the states of the reactants and products for each reaction. Q.71 The list given here is known as the Electrochemical Series of metals. A metal to 2 the right is more reactive than a metal that is to its left in the list. Copper Tin Nickel Cobalt Iron Zinc The table below gives the colour of a few metal sulphate salt solutions. Metal salt solution Colour of aqueous metal salt solution Copper sulphate blue Tin sulphate yellow Nickel sulphate green Cobalt sulphate pink Iron sulphate green Zinc sulphate colourless To show that iron is more reactive than nickel, Smita adds nickel metal and iron metal to copper sulphate solution in separate test tubes. Will her test show which is more reactive? Justify your answer. Q.72 To compare the reactivity of magnesium and aluminium two friends carried out 3 the following tests. - Shardul reacted the metals with hydrochloric acid. - Ashwin reacted the metals with boiling water. Whose test will differentiate between the two metals based on their reactivity? Explain why. Competency Focused Practice Questions | Science | Grade 10 41  Answer Key and Marking Scheme Q.No Answers Marks Q.48 A. It is a polymer. 1 Q.49 B. Only (iv) 1 Q.50 D. BArium carbonate 1 Q.51 D. A is false but R is true. 1 Q.52 D. (in none of them) 1 Q.53 C. Only Q or R 1 Q.54 D. A is false but R is true. 1 Q.55 D. mixing it with water 1 Q.56 C. Cobalt sulphate 1 Q.57 D. Only Q, R and S 1 Q.58 (a) Yes, it is. [0.5 marks] 4 Since there is an exchange of ions between the reactants. [1 mark] (No marks to be given if justification not given.) (b) No, it is not. [0.5 marks] Since none of the reactants have gained or lost an electron. [1 mark] (No marks to be given if justification not given.) (c) neutralisation reaction Q.59 (a) The metal is more reactive than carbon. 1 Q.60 - The pH will be below 6.0. [1 mark] 2 - The bacteria in the milk will change the lactose in the milk to lactic acid. [1 mark] (no marks to ge given without justification.) Q.61 (a) H2CO3 -----> H2O + CO2 2 (b) decomposition reaction Q.62 (a) C3H6O 2 (b) CH3 - CO - CH3 [0.5 marks] CH3 - CH2 - CHO [0.5 marks] Competency Focused Practice Questions | Science | Grade 10 42  Q.63 The browning of the potato pieces kept in the open bowl is likely to be due to an 1 oxidation reaction between the potato and air. The oxidation is prevented by keeping the potato under water as it is not in contact with air. Q.64 - False. 1 - Magnesium floats when placed in boiling water because of the bubbles of hydrogen gas forming on its surface as it reacts with hot water. Q.65 - He will observe an increase in the pH of the reaction mixture. [1 mark] 2 - The amount of acid in the reaction mixture keeps decreasing as ethanoic acid gets converted to the ester. [1 mark] Q.66 - The red litmus paper will turn blue. [0.5 marks] 2 - The blue litmus paper will remain blue. [0.5 marks] - Calcium reacts with water to form calcium hydroxide which is basic in nature. [1 mark] (no marks to be given if justification is not given or is incorrect) Q.67 The baking soda neutralises the acids that form in the plaque between the teeth. 1 Q.68 (a) A,D,E 4 (1 mark for all three correct answers, 0.5 marks for any two correct answers.) (b) 0.5 marks each for both correct names: compound A and compound F (c) compound E and compound C [0.5 marks each] HCOOH + CH3CH2OH --> CH3CH2OCOH + H2O [1 mark] Q.69 (a) Ca(OH)2 3 (b) 1 mark each for the following: - (1) displacement reaction - (2) combination reaction (Accept any other correct answer.) Q.70 (a) The clear solution of slaked lime will first turn milky (whitish in colour), due 5 to the formation of a precipitate of calcium carbonate. [1 mark] On passing excess carbon dioxide, the solution will slowly become clear again due to formation of calcium bicarbonate which is water soluble. [1 mark] (b) 1 mark for each balanced equation, and 0.5 marks for writing the states of the substances in each equation. Ca(OH)2(aq) + CO2 (g) --> CaCO3(s) + H2O (l) [1.5 marks] CaCO3 (s) + H2O (l) + CO2 (g) --> Ca(HCO3)2 (aq) [1.5 marks] Competency Focused Practice Questions | Science | Grade 10 43  Q.71 The test will not be able to tell which is more reactive. 2 Both nickel and iron are more reactive than copper and will displace copper from the copper sulphate solution turning it green in colour. Q.72 Only Ashwin's test 3 1 mark each for the following: - Only magnesium reacts with boiling water releasing hydrogen gas. Aluminium does not react with boiling water, but reacts only with steam. [1 mark] Mg + 2 H2O (l)--------- > Mg(OH)2 + H2 Al + H2O (l) --- > no reaction - Both magnesium and aluminium react with hydrochloric acid producing salt and hydrogen gas. [1 mark] Mg + 2 HCl ---> MgCl2 + H2 2 Al + 6 HCl- > 2 AlCl3 + 3 H2 Competency Focused Practice Questions | Science | Grade 10 44 16. WORLD OF LIVING Q.No Question Marks Multiple Choice Question Q.73 Study the diagrams given below that depict the analogy/homology of organs 1 and answer the question that follow. In cactus, leaves are modified into spines. In Venus flytrap, leaves are modified into jaws. Which diagram are the spines in the cactus and the jaws in the venus flytrap an example of? A. Only P B. Only Q C. Both - P and Q D. Neither - P nor Q Q.74 Which of the following would be true about the wings of a bat and wings of a 1 bird? A. They are analogous organs with same functions. B. They are analogous organs with different function. C. They are homologous organs with same function. Competency Focused Practice Questions | Science | Grade 10 45  D. They are homologous organs with different functions. Q.75 Two statements are given - one labelled Assertion (A) and the other labelled 1 Reason (R). Read the statements carefully and choose the option that correctly describes statements A and R. Assertion (A): Desert plants take in carbon dioxide for photosynthesis during the night. Reason (R): In desert plants, the stomata are closed during the day to conserve water by reducing transpiration. A. Both A and R are true and R is the correct explanation of A. B. Both A and R are true but R is not the correct explanation of A. C. A is true but R is false. D. A is false but R is true Q.76 Given below are some biotic and abiotic components of an ecosystem. 1 rock, rainfall, sunlight, mango tree, rabbit Which of these components can continue to exist in the absence of the other component/s? A. Only sunlight B. Only rock and sunlight C. Only mango tree and rabbit D. Only rock, sunlight and rainfall Q.77 Shown below are the trophic levels of an ecosystem. 1 In which of the levels can an omnivore be present? A. Only secondary consumers B. Only secondary and tertiary consumers C. Only primary and secondary consumers Competency Focused Practice Questions | Science | Grade 10 46  D. Only primary, secondary and tertiary consumers Q.78 If the total energy at the trophic level of producers in an ecosystem is 'E', then 1 which of the following corresponds to the energy available to the tertiary consumers? A. E/10 B. 10 x E C. E/1000 D. 1000 x E Q.79 Two statements are given - one labelled Assertion (A) and the other labelled 1 Reason (R). Assertion (A): Plants that can reproduce asexually cannot reproduce sexually. Reason (R): Asexual reproduction does not involve the production of gametes. Which of the following correctly describes statements A and R? A. (A) and (R) are true and (R) is the reason for (A). B. (A) and (R) are true, but (R) is not the reason for (A). C. (A) is false, but (R) is true D. (A) is true, but (R) is false. Q.80 Biological magnification is the increase in concentration of certain substances 1 in the tissues of organisms at successively higher levels in a food chain. Which of the following could the increase be a result of? P) Inability of environmental processes to break down the substance. Q) High rate of excretion of the substance by the organism. R) Low rate of internal degradation of the substance by organisms. A. Only P B. Only P and R C. Only Q and R D. All - P, Q and R Q.81 Two statements are given below - one labelled Assertion (A) and the other 1 labelled Reason (R). Assertion (A): Blood cells do not receive or pass information to the rest of the human body. Reason (R): Blood cells are not directly connected with neurons. Competency Focused Practice Questions | Science | Grade 10 47  Which of the following is CORRECT? A. Both A and R are true, and R is the correct explanation for A. B. Both A and R are true, but R is not the correct explanation for A. C. A is true, but R is false. D. A is false, but R is true. Q.82 If a tall pea plant bearing red flowers (TTRr) is crossed with another pea plant 1 that is short and has white flowers (ttrr), what percentage of GAMETES will have both alleles for short and white flowers? A. 0% B. 25% C. 50% D. 75% Rett syndrome is a condition caused due to the mutation of a gene located on the X chromosome such that if an individual carries even a check of the mutated gene they show symptoms of the condition. Consider two cases: Case I: The father is affected (XRY) but the mother is not (XX). Case II: The father is not affected (XY) but the mother is (XRX). Answer Q.83 and Q.84 based on the facts given above. Q.83 What is the probability of the sons showing symptoms of the disease in Case I? 1 A. 0% B. 50% C. 75% D. 100% Q.84 What percentage of daughters will be affected in Case II? 1 A. 0% B. 25% C. 50% D. 100% Q.85 A person views an object placed at a certain distance from him. Under which 1 of the following scenarios will the ciliary muscles contract to make the eye lens thicker? A. Amount of light falling on the object is increased B. Amount of light falling on the object is decreased C. Object is moved closer to the eye Competency Focused Practice Questions | Science | Grade 10 48  D. Object is moved away from the eye Q.86 Which of the following is/are TRUE about traits that have NOT been naturally 1 selected? X) They were always detrimental to the life of the organism. Y) Their frequency reduces in subsequent generations. Z) Organisms carrying these traits cannot reproduce at all. A. Only X B. Only Y C. Only Y and Z D. Only X and Z Q.87 Gautam notices that Geeta wears spectacles that contain concave lens. Which 1 of the following conditions could she be suffering from? A. Myopia B. Hypermetropia C. Presbyopia D. Night blindness Q.88 In their natural habitats, and in normal conditions, in which of the following 1 organisms does the offspring exhibit genetic differences from their parents? A. Cyanobacteria B. Amoeba C. Planaria D. Ant Q.89 Two statements are given below - one labelled Assertion (A) and the other 1 labelled Reason (R). Assertion (A): An organism with 24 chromosomes undergoes binary fission to give rise to daughter cells with 12 chromosomes each. Reason (R): Binary fission gives rise to two identical daughter cells. Which of the following is correct? A. Both A and R are true, and R is the correct explanation for A. B. Both A and R are true, but R is not the correct explanation for A. C. A is true, but R is false D. A is false, but R is true. Q.90 Which of the following actions helps the eye in focusing on distant objects? 1 Competency Focused Practice Questions | Science | Grade 10 49  A. Pupil dilation B. Thickening of the eye lens C. Relaxation of the ciliary muscles D. Contraction of the ciliary muscles Q.91 A certain class of herbicides does not allow pollen tube formation. Which of the 1 following processes does it inhibit? A. Cross-pollination B. Self-pollination C. Seed dispersal D. Fertilisation Study the diagrams given below that depict the analogy/homology of organs and answer the question that follow. Q.92 Sweet potato is a root that stores food. Potato is a stem that stores food. 1 Which diagram(s) is/are the example/s above related to? A. Only P B. Only Q C. Both - P and Q D. Neither - P nor Q Q.93 Here is an image of a pea plant climber. The tendrils at the tip of the plant tend 1 to circle around an object or a surface. When are tendrils likely to grow rapidly? Competency Focused Practice Questions | Science | Grade 10 50  A. When the plant is kept warm B. When the plant is well watered C. When the tendril is exposed to light D. When the tendril is in contact with a surface Q.94 Pneumatophores are a special type of root found in mangrove trees. They help 1 the trees by absorbing oxygen needed for the process of respiration in the roots. Choose the statement/s that is/are TRUE about the movement exhibited by pneumatophores. P) They show negative geotropism as they grow against gravity. Q) They show positive phototropism to absorb sunlight. R) They show positive geotropism as the roots grow below the ground. A. Only P B. Only Q C. Both P & Q D. Both Q & R Q.95 Identify the example that BEST describes a response to a stimulus. 1 A. Absorption of sunlight by chloroplast B. Germination of pollen grains on the stigma C. Absorption of nutrients from the soil through root hairs D. Transportation of water and nutrients through the xylem Q.96 Person X met with an accident and injured a part of the hindbrain. 1 Identify the function that is most likely to be affected due to the injury. A. Display of emotions B. Walking in a straight line C. Regulation of blood pressure D. Maintenance of body temperature Competency Focused Practice Questions | Science | Grade 10 51  Q.97 A plant 'X' is placed in a closed box and is left unwatered for 15 days. 1 Identify the plant hormone that is MOST LIKELY to be released and the reason for it. A. Auxins are released in response to the absence of light. B. Cytokinins are released to enhance the growth of the shoot. C. Abscisic acid is released in response to the scarcity of water. D. Gibberellins are produced in response to the absence of water. Free response question/Subjective Question Q.98 There are different nutrients required by the human body. These are in 3 major 3 categories of carbohydrates, fats and proteins (apart from vitamins, minerals and roughage). (a) Digestion of nutrient R happens in the stomach. Identify R. (b) Consider fats and oils from your diet as large globules in your digestive tract. Name the reaction that can help in making these easier to absorb. (c) What is the difference in the kind of medium required for digestive enzymes in the stomach and the small intestine to work? Q.99 In a population of 10,000 ladybugs spread over the entire country, there are 2 7500 red-colored with black spots, 1200 purple-colored with black spots, and remaining are white-colored with black spots. Which colored ladybugs have an evolutionary advantage? Why? Bindu wants to produce a hybrid variety of tomatoes. She has tomato plants X and Y belonging to two different varieties, one with smooth, long fruits and the other one with wrinkled, round fruits. Tomatoes have bisexual flowers. Bindu carries out the following steps carefully to cross pollinate the flowers of plants X and Y: 1. She removes a part of the flowers of tomato plant X just before the flowers bloom. 2. She manually pollinates the flowers of tomato plant X using pollen from the flowers of tomato plant Y. 3. She ties small plastic bags around the pollinated flowers of tomato plant X. The plastic bags are removed after a couple of days. Q.100 Bindu now wants to try producing a hybrid variety of pumpkins from two 2 varieties P and Q. Pumpkin plants have unisexual flowers, with both male and female flowers on all plants. There is a slight variation in the procedure as described below: - She does NOT remove any part from the pumpkin flowers she wants to pollinate. Competency Focused Practice Questions | Science | Grade 10 52  - However, she still ties small plastic bags around the manually pollinated flowers. Explain why Bindu does not remove any part from the flowers to be pollinated, but still ties small plastic bags after pollination. Q.101 Read the two statements below. 1 (P) Adrenaline is also called the fight or flight hormone. (Q) Adrenaline affects the heart to increase heart rate for optimum delivery of oxygen to muscles. Does statement (Q) offer a valid explanation for statement (P)? Justify your answer. Q.102 Human systems work in coordination with each other. 2 Pratik spent an hour in the swimming pool and found himself breathing heavily. (a) Name the: (i) system/s that help his body regain normalcy (ii) system/s that help the systems mentioned in (a-i) to function (b) What can happen to the composition of Pratik's blood if the system/s mentioned in (a-i) does/do not respond properly? Q.103 Vasectomy is a method of contraception in males where the vasa deferentia 3 are tied or sealed so as to prevent sperm from entering the urethra. The diagram below represents the human female reproductive system with some of its parts marked P, Q, R, S, T. (a) Identify the labelled part that will be operated on for 'tubectomy' in females. State its function. (b) Kavya says that if part R is removed the female would not be able to produce eggs. Is she correct? Justify. Q.104 A new sugarcane plant is genetically the same as the parent plant, but a child 2 of human parents is genetically not the same as its parents. Explain why. Q.105 Cyanobacteria, also known as blue-green algae, are a group of photosynthetic 3 bacteria that can fix atmospheric nitrogen and thrive in diverse habitats. They Competency Focused Practice Questions | Science | Grade 10 53  have the ability to produce large amounts of biomass and accumulate lipids suitable for biofuel production. Shown below are two boxes, X and Y. Containers with water that contains cyanobacteria are placed in both boxes. (a) Ideally, how should the samples of water with cyanobacteria be kept in order to get products that can be used for maximum production of biofuels? (b) In which of the boxes, is cyanobacteria likely to have better growth and why? Q.106 Hormones in Animals are secreted in specific quantities by glands in the body. 3 The secretion of these hormones is also regulated by the body. (a) The table below gives the normal reading of blood glucose levels before and after eating. Before eating After eating 80-100 170-200 Ram's blood glucose level is 275. Name the hormone that would be released to regulate the blood glucose level. (b) Explain the regulation of the hormone named in answer (a) in TWO points. Q.107 The stimulus of touch triggers different responses in different plants. 4 A blue pea plant is kept in a well-lit area. The shoot tip curls around the support while growing. (a) The curling of the shoot tip is in response to touch, not sunlight. Describe an experiment to prove this statement. Competency Focused Practice Questions | Science | Grade 10 54  (b) Explain the steps by which the Venus flytrap plant traps insects. Q.108 Nitu and Ria went for a routine health check. The doctor tapped the patellar 4 tendon that is below the kneecap. Nitu showed a knee-jerk reaction but Ria didn't show any reaction. (a) What does the lack of reaction in Ria indicate? (b) If Ria sees a sharp object and does not step on it, what kind of action is it? Describe the neural path followed for this action. (C) Write TWO points explaining the neural pathway followed for the knee-jerk reaction in Nitu. Q.109 Here is a conversation between Ria and Lipa: 2 Ria: The sky appears blue as the blue light scatters the most. Lipa: The sky is blue because it reflects the blue of the seas and oceans. Who is correct? Justify your answer. Q.110 Roopa conducts an experiment with light. She notices that when light rays fall 3 on the surface of a certain object, the light rays change direction. When the light leaves the object from another surface, the light rays bend again. (a) What could be the object that Roopa used to conduct this experiment? (b) Why does the light bend twice? Explain with two points. Q.111 Tina was star gazing. She observed celestial objects P and Q. They were visible 3 brightly in the night sky. She concluded that one was a star and the other was a planet. (a) What could she have observed to arrive at her conclusion? (b) If these celestial objects P and Q were to be observed from the moon, would Tina be able to distinguish them as a star and a planet? Why or Why not? Q.112 Nia looked at an object X that was kept near her. She could see it clearly. She 3 then looked at object Y which was kept farther away. She could see object Y also clearly. (a) Which part of the eye enables a person to see clearly, both, objects that are near and those that are far away? Why? (b) Describe the eye changes that enable nearby objects to be seen clearly. (c) Describe the eye changes that enable far-away objects to be seen clearly. Q.113 The figures P and Q show the state of the heart at stages of the cardiac cycle. 2 Competency Focused Practice Questions | Science | Grade 10 55  Identify the blood pressure values that will be obtained at the stages of the heart, shown in figures P and Q, for a normal person at rest. Q.114 In the digestive tract, food is moved forward by the rhythmic contraction of 3 muscles lining the tract. This process is called peristalsis. List ALL the parts of the digestive tract in which peristalsis occurs. Q.115 In most adults, the left atrium is separated from the right atrium by a septum 1 (wall) to prevent the oxygen-rich blood in the left atrium from mixing with the blood containing a higher amount of carbon dioxide in the right atrium. The patent foramen ovale (PFO) is a hole in the septum separating the left and right atria (upper chambers) of the heart. This hole exists in everyone before birth, but most often closes shortly after a baby is born. Explain why the hole in the septum separating the atria does not cause problems in a baby before it is born. Q.116 Shown below are the diagrammatic representations of the circulatory systems 3 of three organisms X, Y and Z. (a) Identify which organism is a fish. Give a reason for your answer. (b) Identify the organism(s) that does/do NOT require energy to maintain their body temperature. Competency Focused Practice Questions | Science | Grade 10 56  Q.117 The two pictures below illustrate tropism in plants. P shows a plant bending 1 towards light. Q shows a plant twining around a pole. Based on the pictures, what is true about the growth rate of the plant cells on the side away from the stimulus as compared to the growth rate of the plant cells on the side towards the stimulus? Q.118 The picture below shows a cow looking for food in the garbage. 1 Very often, while eating some food the animal also swallows plastic. The plastic that the animal swallows remains undigested and accumulates in the stomach. This eventually leads to starvation as there is less and less space for real food. Give one reason for plastic remaining undigested in an cow's stomach. Q.119 In the food chain given below, which position would a vulture occupy? Justify 2 your answer. Plants -------> Rabbit --------> wild cat --------- > lion Q.120 Observe the food chain shown below. 2 Competency Focused Practice Questions | Science | Grade 10 57  Is such a food chain likely to exist in nature? Justify your answer. Q.121 'Plants and animals give out carbon dioxide all the time.' 2 Is this statement true or false? Justify your answer. Q.122 State what is required for two or more food chains to form a food web. 1 Q.123 Raman's mother moved her leg immediately as she saw that she was about to 2 step on Raman's toy. Netra says this action is a reflex action as it was a quick action whereas Kabir says it was a reflex action because it was an involuntary response. Is either of them CORRECT? Justify your answer. Q.124 A scientist wanted to determine whether a tall pea plant X was TT or Tt. 5 To do this he crossed two X plants: (i) one with a pea plant known to carry the TT traits (ii) one with a pea plant known to carry the tt traits (a) Considering that X could be TT or Tt, what ratios would he obtain in both crosses - (i) and (ii)? Show the crosses. (b) Based on the ratios obtained in (a), a cross with which parent - (i) or (ii) - would help in identifying whether X was TT or Tt? Justify. Q.125 Genetic drift can greatly increase variation in a population. 2 Is this statement TRUE? Justify. Q.126 Give ONE reason why genetic drift is not the same as natural selection. 1 Q.127 Before Darwin's theory of evolution, another theory existed that postulated 2 that any physical changes that occurred in an organism through its lifetime could be transmitted to its offspring. Using one example, explain why this theory cannot be true. Q.128 One parent suffered from a disease which was then seen only in the male 1 children of subsequent generations and not seen in the female children. Is this disorder likely to be linked to the sex chromosome of the individuals or not? Justify your answer. Q.129 Justify the following statements: 2 (a) Organisms that originate from a common ancestor may look very different from each other. Competency Focused Practice Questions | Science | Grade 10 58  (b) Organisms that have similar-l