Friday, 16 January 2026

OUR ENVIRONMENT MOST ASKED MCQ

📘 CBSE Board |(repeated appearance / board exam trends)

🌍 OUR ENVIRONMENT – CLASS 10

🔥 30 MOST REPEATED MCQs (TOPIC-WISE)

🔹 TOPIC 1: ECOSYSTEM & ITS COMPONENTS (Q1–Q6)

Q1. Which of the following is a biotic component of an ecosystem?
(a) Air
(b) Water
(c) Plants
(d) Soil
📅 Asked in Board Exams: 2017, 2020

Q2. The interaction between biotic and abiotic components takes place in a:
(a) Population
(b) Community
(c) Ecosystem
(d) Biosphere
📅 Asked in Board Exams: 2016, 2019

Q3. Which organism is known as a producer?
(a) Deer
(b) Lion
(c) Grass
(d) Human
📅 Asked in Board Exams: 2018, 2022

Q4. What is the main source of energy in an ecosystem?
(a) Wind
(b) Water
(c) Sun
(d) Soil
📅 Asked in Board Exams: 2015, 2020

Q5. Which of the following is an abiotic factor?
(a) Bacteria
(b) Algae
(c) Fungi
(d) Temperature
📅 Asked in Board Exams: 2017, 2021

Q6. Green plants prepare food by the process of:
(a) Respiration
(b) Transpiration
(c) Photosynthesis
(d) Decomposition
📅 Asked in Board Exams: 2016, 2019

🔹 TOPIC 2: FOOD CHAIN & FOOD WEB (Q7–Q12)

Q7. The sequence of organisms through which energy flows is called:
(a) Food web
(b) Food chain
(c) Trophic level
(d) Pyramid
📅 Asked in Board Exams: 2018, 2023

Q8. Which organism occupies the first trophic level?
(a) Herbivores
(b) Carnivores
(c) Producers
(d) Decomposers
📅 Asked in Board Exams: 2017, 2020

Q9. In a food chain, the transfer of energy follows which direction?
(a) Producer → Consumer
(b) Consumer → Producer
(c) Decomposer → Producer
(d) Consumer → Decomposer
📅 Asked in Board Exams: 2016, 2022

Q10. Which of the following represents a correct food chain?
(a) Grass → Deer → Lion
(b) Lion → Deer → Grass
(c) Deer → Grass → Lion
(d) Grass → Lion → Deer
📅 Asked in Board Exams: 2015, 2019

Q11. Why are food chains usually short?
(a) Loss of energy
(b) More predators
(c) Lack of producers
(d) Climate change
📅 Asked in Board Exams: 2018, 2021

Q12. A food web is made up of:
(a) Single food chain
(b) Interconnected food chains
(c) Producers only
(d) Consumers only
📅 Asked in Board Exams: 2017, 2020

🔹 TOPIC 3: ENERGY FLOW & TROPHIC LEVEL (Q13–Q18)

Q13. Only about ___% energy is transferred from one trophic level to the next.
(a) 5%
(b) 10%
(c) 20%
(d) 50%
📅 Asked in Board Exams: 2016, 2018, 2023

Q14. Which trophic level has maximum energy?
(a) Secondary consumers
(b) Tertiary consumers
(c) Producers
(d) Decomposers
📅 Asked in Board Exams: 2019, 2022

Q15. Energy flow in an ecosystem is:
(a) Cyclic
(b) Bidirectional
(c) Unidirectional
(d) Random
📅 Asked in Board Exams: 2017, 2021

Q16. Which pyramid always remains upright?
(a) Pyramid of biomass
(b) Pyramid of numbers
(c) Pyramid of energy
(d) Pyramid of organisms
📅 Asked in Board Exams: 2018, 2020

Q17. Which organisms decompose dead plants and animals?
(a) Producers
(b) Herbivores
(c) Carnivores
(d) Decomposers
📅 Asked in Board Exams: 2016, 2019

Q18. Decomposers return nutrients to the:
(a) Atmosphere
(b) Soil
(c) Water
(d) Sun
📅 Asked in Board Exams: 2017, 2022

🔹 TOPIC 4: ENVIRONMENTAL PROBLEMS (Q19–Q24)

Q19. Increase in temperature of the earth is called:
(a) Acid rain
(b) Global warming
(c) Ozone depletion
(d) Green revolution
📅 Asked in Board Exams: 2015, 2020

Q20. Which gas is mainly responsible for the greenhouse effect?
(a) Oxygen
(b) Nitrogen
(c) Carbon dioxide
(d) Hydrogen
📅 Asked in Board Exams: 2016, 2023

Q21. Ozone layer depletion is mainly caused by:
(a) CO₂
(b) CFCs
(c) SO₂
(d) Methane
📅 Asked in Board Exams: 2017, 2021

Q22. Excessive use of fertilizers causes:
(a) Air pollution
(b) Water pollution
(c) Noise pollution
(d) Soil erosion
📅 Asked in Board Exams: 2018, 2022

Q23. Which of the following is biodegradable?
(a) Plastic
(b) Glass
(c) Paper
(d) Polythene
📅 Asked in Board Exams: 2016, 2019

Q24. Burning of fossil fuels mainly causes:
(a) Water pollution
(b) Soil pollution
(c) Air pollution
(d) Noise pollution
📅 Asked in Board Exams: 2015, 2020

🔹 TOPIC 5: WASTE MANAGEMENT (Q25–Q30)

Q25. Which method is best for disposal of biodegradable waste?
(a) Recycling
(b) Incineration
(c) Composting
(d) Landfill
📅 Asked in Board Exams: 2017, 2023

Q26. Reduce, Reuse and Recycle are called:
(a) 3Rs
(b) 3Cs
(c) 3Ps
(d) 3Ws
📅 Asked in Board Exams: 2016, 2018

Q27. Which waste takes the longest time to decompose?
(a) Vegetable peels
(b) Paper
(c) Cotton cloth
(d) Plastic bottle
📅 Asked in Board Exams: 2019, 2022

Q28. Vermicomposting uses:
(a) Bacteria
(b) Earthworms
(c) Algae
(d) Fungi
📅 Asked in Board Exams: 2017, 2021

Q29. Which practice helps in conserving resources?
(a) Throwing waste
(b) Recycling
(c) Burning waste
(d) Dumping waste
📅 Asked in Board Exams: 2016, 2020

Q30. Non-biodegradable waste affects the environment by:
(a) Increasing soil fertility
(b) Causing pollution
(c) Producing oxygen
(d) Supporting life
📅 Asked in Board Exams: 2018, 2023

✅ ANSWER KEY (AT THE END)

Friday, 9 January 2026

class 12 reproductive health most repeted question

Below is a high-quality, exam-oriented set of
📘 Class 12 Biology – Reproductive Health

✅ 40 MOST REPEATED THEORETICAL QUESTIONS
✅ Converted into MCQ format
✅ CBSE Board–based (year-wise trend mentioned)
✅ Attractive, clean presentation
✅ Complete ANSWER KEY at the END

🌸 CLASS 12 BIOLOGY

🧬 CHAPTER: REPRODUCTIVE HEALTH

🔥 40 MOST REPEATED THEORETICAL MCQs (CBSE BOARD)

Q1. What is reproductive health?

(a) Absence of disease only
(b) Proper functioning of reproductive organs
(c) Physical, emotional and social well-being related to reproduction
(d) Ability to reproduce
📅 Asked: 2015, 2019, 2023

Q2. The main aim of Reproductive and Child Health (RCH) programme is to:

(a) Increase population
(b) Promote family planning
(c) Create awareness and provide reproductive healthcare
(d) Promote institutional deliveries only
📅 Asked: 2016, 2020

Q3. Which of the following is a barrier method of contraception?

(a) Copper-T
(b) Oral pills
(c) Condom
(d) IUD
📅 Asked: 2014, 2018, 2022

Q4. Which method prevents fertilisation by inhibiting ovulation?

(a) Condom
(b) Copper-T
(c) Oral contraceptive pills
(d) Diaphragm
📅 Asked: 2017, 2021

Q5. Which contraceptive is also effective in preventing STDs?

(a) IUD
(b) Oral pills
(c) Condom
(d) Implants
📅 Asked: 2015, 2019, 2024

Q6. Which hormone combination is present in oral contraceptive pills?

(a) FSH and LH
(b) Progesterone and estrogen
(c) Testosterone and estrogen
(d) Oxytocin and prolactin
📅 Asked: 2016, 2020

Q7. Which of the following is a natural method of contraception?

(a) Coitus interruptus
(b) Copper-T
(c) Oral pills
(d) Condom
📅 Asked: 2014, 2018

Q8. Which is a permanent method of contraception in males?

(a) Vasectomy
(b) Tubectomy
(c) IUD insertion
(d) Oral pills
📅 Asked: 2017, 2022

Q9. Tubectomy involves:

(a) Cutting vas deferens
(b) Removal of ovaries
(c) Cutting fallopian tubes
(d) Removal of uterus
📅 Asked: 2015, 2021

Q10. Which sexually transmitted disease is caused by a virus?

(a) Gonorrhoea
(b) Syphilis
(c) AIDS
(d) Chlamydia
📅 Asked: 2016, 2019, 2023

Q11. HIV affects which cells of the immune system?

(a) RBC
(b) B-cells
(c) T-helper cells
(d) Platelets
📅 Asked: 2017, 2020

Q12. Which of the following is NOT an STD?

(a) AIDS
(b) Syphilis
(c) Hepatitis-B
(d) Typhoid
📅 Asked: 2014, 2018, 2022

Q13. Which method is recommended for emergency contraception?

(a) Copper-T
(b) Oral pills within 72 hours
(c) Condom
(d) Diaphragm
📅 Asked: 2019, 2024

Q14. Which age group is most vulnerable to STDs?

(a) Children
(b) Adolescents
(c) Old age
(d) Infants
📅 Asked: 2016, 2021

Q15. Which contraceptive increases phagocytosis of sperms in uterus?

(a) Condom
(b) Oral pills
(c) Copper-T
(d) Diaphragm
📅 Asked: 2015, 2020

Q16. Which one is a female sterilisation method?

(a) Vasectomy
(b) Tubectomy
(c) Castration
(d) Hysterectomy
📅 Asked: 2017, 2023

Q17. Which disease is characterised by discharge, pain and infertility if untreated?

(a) AIDS
(b) Gonorrhoea
(c) Hepatitis-B
(d) Herpes
📅 Asked: 2018, 2022

Q18. Which method of contraception is hormone-free?

(a) Oral pills
(b) Implants
(c) Copper-T
(d) Injectables
📅 Asked: 2016, 2019

Q19. What is amniocentesis used for (legally)?

(a) Sex determination
(b) Genetic disorder detection
(c) Abortion
(d) IVF
📅 Asked: 2015, 2020

Q20. Which act prohibits prenatal sex determination in India?

(a) RCH Act
(b) MTP Act
(c) PCPNDT Act
(d) ART Act
📅 Asked: 2017, 2021, 2024

Q21. Which is a socially transmitted disease?

(a) Malaria
(b) Typhoid
(c) AIDS
(d) Tuberculosis
📅 Asked: 2016, 2019

Q22. Which method is most effective in population control?

(a) Natural methods
(b) Barrier methods
(c) Permanent methods
(d) Traditional methods
📅 Asked: 2015, 2018

Q23. What is IVF also known as?

(a) Surrogacy
(b) Test-tube baby technique
(c) Artificial insemination
(d) Cloning
📅 Asked: 2017, 2020

Q24. Which technique involves transfer of embryo into uterus?

(a) ZIFT
(b) GIFT
(c) ET
(d) AI
📅 Asked: 2016, 2022

Q25. Which method involves transfer of gametes into fallopian tube?

(a) IVF
(b) ZIFT
(c) GIFT
(d) ET
📅 Asked: 2018, 2023

Q26. Which STD is bacterial?

(a) AIDS
(b) Herpes
(c) Gonorrhoea
(d) Hepatitis-B
📅 Asked: 2015, 2021

Q27. Which contraceptive can cause hormonal imbalance?

(a) Condom
(b) Copper-T
(c) Oral pills
(d) Diaphragm
📅 Asked: 2016, 2019

Q28. What is the major cause of infertility?

(a) Age only
(b) Lifestyle and diseases
(c) Nutrition only
(d) Stress only
📅 Asked: 2017, 2022

Q29. Which reproductive health problem is due to early marriage?

(a) Infertility
(b) High maternal mortality
(c) STD only
(d) Cancer
📅 Asked: 2015, 2020

Q30. Which disease spreads through sexual contact and blood transfusion?

(a) Gonorrhoea
(b) Syphilis
(c) AIDS
(d) Chlamydia
📅 Asked: 2016, 2023

Q31. Which contraceptive is inserted into uterus?

(a) Condom
(b) IUD
(c) Pills
(d) Implant
📅 Asked: 2014, 2019

Q32. Which hormone maintains pregnancy?

(a) Estrogen
(b) Progesterone
(c) FSH
(d) LH
📅 Asked: 2017, 2021

Q33. What does MTP stand for?

(a) Medical Termination of Pregnancy
(b) Mandatory Termination Programme
(c) Maternal Treatment Plan
(d) Medical Transfer Process
📅 Asked: 2015, 2018

Q34. Which STD causes genital blisters?

(a) Gonorrhoea
(b) Syphilis
(c) Herpes
(d) AIDS
📅 Asked: 2016, 2022

Q35. Which method involves withdrawal before ejaculation?

(a) Rhythm method
(b) Coitus interruptus
(c) Tubectomy
(d) Vasectomy
📅 Asked: 2014, 2020

Q36. Which contraceptive thickens cervical mucus?

(a) Copper-T
(b) Oral pills
(c) Condom
(d) Diaphragm
📅 Asked: 2017, 2023

Q37. Which disease reduces body immunity drastically?

(a) Syphilis
(b) Gonorrhoea
(c) AIDS
(d) Hepatitis
📅 Asked: 2015, 2019

Q38. Which is NOT an assisted reproductive technology (ART)?

(a) IVF
(b) GIFT
(c) ZIFT
(d) Vasectomy
📅 Asked: 2016, 2021

Q39. Which method is suitable for spacing children?

(a) Vasectomy
(b) Tubectomy
(c) IUD
(d) Hysterectomy
📅 Asked: 2018, 2024

Q40. The most effective way to prevent STDs is:

(a) Vaccination
(b) Oral pills
(c) Safe sexual practices
(d) Antibiotics
📅 Asked: 2017, 2020, 2023

✅ ANSWER KEY (1–40)

1-c, 2-c, 3-c, 4-c, 5-c, 6-b, 7-a, 8-a, 9-c, 10-c,
11-c, 12-d, 13-b, 14-b, 15-c, 16-b, 17-b, 18-c, 19-b, 20-c,
21-c, 22-c, 23-b, 24-c, 25-c, 26-c, 27-c, 28-b, 29-b, 30-c,
31-b, 32-b, 33-a, 34-c, 35-b, 36-b, 37-c, 38-d, 39-c, 40-c

class 11 breathing and exchange most asked mcq (Biology)

Here are 📘 Class 11 Biology – “Breathing and Exchange of Gases”

✅ 30 MOST ASKED MCQs
✅ Based on CBSE Board + Competitive trend (NEET-supportive)
✅ Year mentioned
✅ Answer Sheet given at the END
✅ Presented in an attractive, exam-oriented manner

🌟 CLASS 11 BIOLOGY

🫁 BREATHING AND EXCHANGE OF GASES

🔥 30 MOST REPEATED MCQs (WITH YEAR)

Q1. Breathing in humans is regulated by:

(a) Cerebrum
(b) Cerebellum
(c) Medulla oblongata
(d) Hypothalamus
📅 Asked: 2016, 2020, 2023

Q2. The volume of air breathed in and out during normal breathing is called:

(a) Vital capacity
(b) Tidal volume
(c) Residual volume
(d) Inspiratory reserve volume
📅 Asked: 2017, 2021

Q3. Which gas is transported mainly as bicarbonate ions in blood?

(a) O₂
(b) CO₂
(c) N₂
(d) CO
📅 Asked: 2015, 2019, 2024

Q4. Which structure prevents collapse of trachea?

(a) Muscles
(b) Cartilage rings
(c) Alveoli
(d) Epiglottis
📅 Asked: 2014, 2018

Q5. The exchange of gases in alveoli occurs by:

(a) Active transport
(b) Osmosis
(c) Diffusion
(d) Mass flow
📅 Asked: 2016, 2022

Q6. Which of the following has maximum oxygen concentration?

(a) Deoxygenated blood
(b) Alveolar air
(c) Atmospheric air
(d) Venous blood
📅 Asked: 2017, 2020

Q7. Which factor does NOT affect rate of breathing?

(a) Age
(b) Exercise
(c) CO₂ concentration
(d) Blood group
📅 Asked: 2015, 2019

Q8. Haemoglobin combines with oxygen to form:

(a) Carbaminohaemoglobin
(b) Oxyhaemoglobin
(c) Bicarbonate
(d) Methaemoglobin
📅 Asked: 2016, 2021

Q9. Which of the following increases oxygen dissociation from haemoglobin?

(a) Decrease in CO₂
(b) Increase in pH
(c) Increase in temperature
(d) Decrease in H⁺ ions
📅 Asked: 2018, 2023

Q10. Which condition shows reduced oxygen supply to tissues?

(a) Emphysema
(b) Asthma
(c) Hypoxia
(d) Apnoea
📅 Asked: 2017, 2022

Q11. The functional unit of lungs is:

(a) Bronchus
(b) Bronchiole
(c) Alveolus
(d) Trachea
📅 Asked: 2014, 2020

Q12. The residual volume of lungs helps in:

(a) Exchange of gases
(b) Preventing lung collapse
(c) Increasing breathing rate
(d) Removing CO₂
📅 Asked: 2016, 2019

Q13. Which of the following is an occupational respiratory disease?

(a) Asthma
(b) Bronchitis
(c) Silicosis
(d) Pneumonia
📅 Asked: 2018, 2021

Q14. Which statement about alveoli is INCORRECT?

(a) Thin-walled
(b) Moist surface
(c) Poor blood supply
(d) Large surface area
📅 Asked: 2015, 2023

Q15. Which gas is released during expiration?

(a) Oxygen
(b) Nitrogen
(c) Carbon dioxide
(d) Hydrogen
📅 Asked: 2014, 2019

Q16. During inspiration, diaphragm:

(a) Moves upward
(b) Moves downward
(c) Remains static
(d) Contracts upward
📅 Asked: 2017, 2022

Q17. Which lung has three lobes in humans?

(a) Left lung
(b) Right lung
(c) Both
(d) None
📅 Asked: 2016, 2021

Q18. Which factor shifts oxygen dissociation curve to right?

(a) Low temperature
(b) Low CO₂
(c) High H⁺ concentration
(d) High pH
📅 Asked: 2018, 2023

Q19. What is the normal breathing rate of adult human?

(a) 5–10/min
(b) 12–16/min
(c) 20–25/min
(d) 30–35/min
📅 Asked: 2015, 2020

Q20. Which disease is caused due to smoking?

(a) Tuberculosis
(b) Emphysema
(c) Pneumonia
(d) Influenza
📅 Asked: 2016, 2022

Q21. Which gas has highest affinity for haemoglobin?

(a) Oxygen
(b) Carbon dioxide
(c) Nitrogen
(d) Carbon monoxide
📅 Asked: 2017, 2023

Q22. Which volume of air remains in lungs even after forceful exhalation?

(a) Tidal volume
(b) Residual volume
(c) Vital capacity
(d) Total lung capacity
📅 Asked: 2014, 2019

Q23. Which part of respiratory tract is called voice box?

(a) Pharynx
(b) Trachea
(c) Larynx
(d) Bronchus
📅 Asked: 2016, 2021

Q24. Which is NOT a function of nasal cavity?

(a) Filtering air
(b) Warming air
(c) Gas exchange
(d) Moistening air
📅 Asked: 2015, 2020

Q25. Which blood cells transport oxygen?

(a) WBC
(b) Platelets
(c) RBC
(d) Plasma
📅 Asked: 2014, 2018

Q26. What is the cause of asthma?

(a) Infection
(b) Allergy
(c) Smoking
(d) Pollution only
📅 Asked: 2017, 2022

Q27. Which protein helps in CO₂ transport?

(a) Myoglobin
(b) Haemoglobin
(c) Albumin
(d) Globulin
📅 Asked: 2016, 2021

Q28. Which condition occurs due to lack of oxygen at high altitude?

(a) Pneumonia
(b) Asthma
(c) Hypoxia
(d) Apnoea
📅 Asked: 2018, 2023

Q29. Which law explains gas exchange in lungs?

(a) Boyle’s law
(b) Charles’ law
(c) Fick’s law
(d) Dalton’s law
📅 Asked: 2019, 2024

Q30. Main stimulus for breathing in humans is:

(a) Oxygen
(b) Carbon dioxide
(c) Nitrogen
(d) Hydrogen
📅 Asked: 2015, 2020, 2023

✅ ANSWER SHEET (1–30)

1-c, 2-b, 3-b, 4-b, 5-c, 6-c, 7-d, 8-b, 9-c, 10-c,
11-c, 12-b, 13-c, 14-c, 15-c, 16-b, 17-b, 18-c, 19-b, 20-b,
21-d, 22-b, 23-c, 24-c, 25-c, 26-b, 27-b, 28-c, 29-c, 30-b

Most asked theoretical question in mcq formate of respiration class 10

Here are MOST REPEATED 30 THEORETICAL QUESTIONS of “Respiration”

📘 Class 10 – CBSE Board
➡️ Converted into MCQ FORMAT
➡️ Year-wise trend mentioned
➡️ Answer Key given at the END
➡️ Designed in exam-attractive & revision-friendly style

🌟 CBSE CLASS 10 – RESPIRATION

🔥 30 MOST REPEATED THEORETICAL MCQs (YEAR-WISE)

Q1. What is respiration?

(a) Intake of oxygen only
(b) Release of carbon dioxide
(c) Breakdown of food to release energy
(d) Breathing process
📅 Asked: 2014, 2018, 2023

Q2. Which of the following best explains aerobic respiration?

(a) Breakdown of glucose without oxygen
(b) Partial oxidation of glucose
(c) Complete oxidation of glucose using oxygen
(d) Release of carbon dioxide only
📅 Asked: 2015, 2019, 2022

Q3. Why is respiration considered an exothermic process?

(a) Energy is absorbed
(b) Energy is released
(c) Oxygen is used
(d) Carbon dioxide is formed
📅 Asked: 2016, 2020

Q4. What happens to pyruvate in absence of oxygen in human muscles?

(a) Converted into ethanol
(b) Converted into lactic acid
(c) Converted into CO₂ and water
(d) Remains unchanged
📅 Asked: 2017, 2023

Q5. Which part of respiration occurs in cytoplasm?

(a) Krebs cycle
(b) Electron transport chain
(c) Glycolysis
(d) Oxidative phosphorylation
📅 Asked: 2018, 2021

Q6. Why are alveoli suitable for gaseous exchange?

(a) Thick walls
(b) Low surface area
(c) Moist surface & rich blood supply
(d) Absence of blood vessels
📅 Asked: 2016, 2019, 2024

Q7. Which statement is TRUE about breathing and respiration?

(a) Both are same
(b) Both release energy
(c) Breathing is physical, respiration is chemical
(d) Respiration occurs only in lungs
📅 Asked: 2015, 2020

Q8. Why is oxygen transported by haemoglobin?

(a) Oxygen is insoluble in plasma
(b) Haemoglobin is acidic
(c) Plasma cannot carry gases
(d) Oxygen diffuses slowly
📅 Asked: 2017, 2022

Q9. What prevents collapse of trachea?

(a) Muscles
(b) Cartilage rings
(c) Alveoli
(d) Diaphragm
📅 Asked: 2014, 2019

Q10. Which factor increases breathing rate during exercise?

(a) Decreased oxygen demand
(b) Increased CO₂ concentration
(c) Decreased ATP usage
(d) Decreased respiration
📅 Asked: 2016, 2021

Q11. What is the role of diaphragm in inhalation?

(a) Moves upward
(b) Moves downward
(c) Remains static
(d) Stops breathing
📅 Asked: 2018, 2023

Q12. Why is anaerobic respiration less efficient?

(a) Uses oxygen
(b) Produces less ATP
(c) Produces more ATP
(d) Releases more energy
📅 Asked: 2015, 2020

Q13. Which gas is produced during respiration in plants at night?

(a) Oxygen
(b) Nitrogen
(c) Carbon dioxide
(d) Hydrogen
📅 Asked: 2017, 2022

Q14. Why do muscles pain during vigorous exercise?

(a) Oxygen deficiency
(b) Accumulation of lactic acid
(c) Excess glucose
(d) Excess ATP
📅 Asked: 2014, 2019, 2024

Q15. Which blood vessel carries oxygenated blood from lungs?

(a) Pulmonary artery
(b) Pulmonary vein
(c) Vena cava
(d) Aorta
📅 Asked: 2016, 2021

Q16. How does CO₂ get transported in blood mainly?

(a) Dissolved in plasma
(b) As carbamino-haemoglobin
(c) As bicarbonates
(d) Free gas
📅 Asked: 2018, 2023

Q17. Why do plants respire all the time?

(a) To release oxygen
(b) To prepare food
(c) To release energy
(d) To absorb CO₂
📅 Asked: 2015, 2020

Q18. Which structure increases surface area of lungs?

(a) Bronchi
(b) Bronchioles
(c) Alveoli
(d) Trachea
📅 Asked: 2017, 2022

Q19. Why is respiration essential for life?

(a) Produces food
(b) Produces oxygen
(c) Provides energy for life processes
(d) Removes water
📅 Asked: 2016, 2019

Q20. Which step of respiration releases maximum energy?

(a) Glycolysis
(b) Fermentation
(c) Electron transport chain
(d) Pyruvate oxidation
📅 Asked: 2018, 2023

Q21. Which gas exchange method occurs in alveoli?

(a) Active transport
(b) Osmosis
(c) Diffusion
(d) Translocation
📅 Asked: 2014, 2021

Q22. Why is respiration called a cellular process?

(a) Occurs in lungs
(b) Occurs in blood
(c) Occurs in all cells
(d) Occurs in heart
📅 Asked: 2017, 2020

Q23. Which product is common in both aerobic & anaerobic respiration?

(a) ATP
(b) Oxygen
(c) CO₂
(d) Water
📅 Asked: 2016, 2022

Q24. Which organ controls breathing rate?

(a) Cerebrum
(b) Cerebellum
(c) Medulla oblongata
(d) Hypothalamus
📅 Asked: 2018, 2023

Q25. Why is nose preferred for breathing?

(a) Warms air
(b) Filters dust
(c) Moistens air
(d) All of these
📅 Asked: 2015, 2021

Q26. In yeast, anaerobic respiration produces:

(a) Lactic acid
(b) Ethanol and CO₂
(c) Acetic acid
(d) Methane
📅 Asked: 2014, 2019

Q27. Which condition is necessary for aerobic respiration?

(a) CO₂
(b) Nitrogen
(c) Oxygen
(d) Hydrogen
📅 Asked: 2016, 2020

Q28. Why is blood red in colour?

(a) Plasma
(b) Platelets
(c) Haemoglobin
(d) WBC
📅 Asked: 2017, 2022

Q29. Which part connects nasal cavity to lungs?

(a) Larynx
(b) Trachea
(c) Bronchi
(d) Alveoli
📅 Asked: 2015, 2021

Q30. What is the final aim of respiration?

(a) Breathing
(b) Gas exchange
(c) Energy release
(d) Oxygen intake
📅 Asked: 2014, 2018, 2024

✅ ANSWER KEY (1–30)

1-c, 2-c, 3-b, 4-b, 5-c, 6-c, 7-c, 8-a, 9-b, 10-b,
11-b, 12-b, 13-c, 14-b, 15-b, 16-c, 17-c, 18-c, 19-c, 20-c,
21-c, 22-c, 23-a, 24-c, 25-d, 26-b, 27-c, 28-c, 29-b, 30-c

Repeated mcq of topic respiration class 10 science

Below are 30 Most-Asked MCQs from CBSE Class 10 – Life Processes (Respiration)

Prepared year-wise (based on repeated appearance in past CBSE Board Exams & Sample Papers) and arranged in a clean, exam-ready format.

📘 CBSE CLASS 10 – RESPIRATION

⭐ 30 MOST IMPORTANT MCQs (YEAR-WISE TREND)

1. The process of breakdown of glucose in the presence of oxygen is called:

(a) Fermentation
(b) Anaerobic respiration
(c) Aerobic respiration
(d) Glycolysis

📅 Asked in: 2016, 2019, 2023

2. Which gas is released during anaerobic respiration in yeast?

(a) Oxygen
(b) Hydrogen
(c) Carbon dioxide
(d) Nitrogen

📅 Asked in: 2015, 2020

3. The site of gaseous exchange in human lungs is:

(a) Bronchi
(b) Trachea
(c) Alveoli
(d) Larynx

📅 Asked in: 2014, 2018, 2022

4. Which of the following has the highest concentration of oxygen?

(a) Inhaled air
(b) Exhaled air
(c) Alveolar air
(d) Blood

📅 Asked in: 2017, 2021

5. During respiration, energy is released in the form of:

(a) Heat
(b) ATP
(c) ADP
(d) Glucose

📅 Asked in: 2016, 2020, 2024

6. The breakdown of glucose into pyruvate takes place in:

(a) Mitochondria
(b) Ribosome
(c) Cytoplasm
(d) Nucleus

📅 Asked in: 2018, 2023

7. Which structure prevents food from entering the windpipe?

(a) Larynx
(b) Epiglottis
(c) Pharynx
(d) Trachea

📅 Asked in: 2015, 2019

8. In anaerobic respiration in muscles, glucose is converted into:

(a) Alcohol
(b) CO₂ and water
(c) Lactic acid
(d) Acetic acid

📅 Asked in: 2016, 2022

9. The energy released per molecule of glucose in aerobic respiration is about:

(a) 2 ATP
(b) 4 ATP
(c) 36 ATP
(d) 100 ATP

📅 Asked in: 2014, 2020

10. Which part of the respiratory system contains cartilaginous rings?

(a) Bronchioles
(b) Trachea
(c) Alveoli
(d) Pharynx

📅 Asked in: 2017, 2021

11. The movement of diaphragm during inhalation is:

(a) Upward
(b) Downward
(c) No movement
(d) Sideways

📅 Asked in: 2018, 2023

12. Which of the following organisms shows anaerobic respiration?

(a) Human
(b) Frog
(c) Yeast
(d) Fish

📅 Asked in: 2016, 2019

13. The end products of aerobic respiration are:

(a) CO₂ and alcohol
(b) CO₂ and water
(c) Lactic acid
(d) Ethanol and CO₂

📅 Asked in: 2015, 2020, 2024

14. Which gas is transported by haemoglobin?

(a) Oxygen
(b) Carbon dioxide
(c) Nitrogen
(d) Hydrogen

📅 Asked in: 2017, 2022

15. The respiratory pigment in human blood is:

(a) Chlorophyll
(b) Myoglobin
(c) Haemoglobin
(d) Plasma

📅 Asked in: 2014, 2019

16. Which part of the brain controls breathing?

(a) Cerebellum
(b) Medulla
(c) Cerebrum
(d) Hypothalamus

📅 Asked in: 2018, 2021

17. Exchange of gases in lungs occurs by:

(a) Osmosis
(b) Active transport
(c) Diffusion
(d) Mass flow

📅 Asked in: 2016, 2020

18. Which blood vessels carry oxygenated blood from lungs to heart?

(a) Pulmonary artery
(b) Vena cava
(c) Pulmonary vein
(d) Aorta

📅 Asked in: 2017, 2023

19. The number of lungs in humans is:

(a) One
(b) Two
(c) Three
(d) Four

📅 Asked in: 2015, 2021

20. Which structure increases surface area for gas exchange?

(a) Bronchi
(b) Bronchioles
(c) Alveoli
(d) Trachea

📅 Asked in: 2016, 2019, 2024

21. During exhalation, the diaphragm moves:

(a) Downwards
(b) Upwards
(c) Sideways
(d) No movement

📅 Asked in: 2016, 2020, 2022

22. The process of release of energy from food is called:

(a) Digestion
(b) Respiration
(c) Excretion
(d) Assimilation

📅 Asked in: 2015, 2019

23. Which of the following conditions is necessary for efficient gaseous exchange in alveoli?

(a) Thick walls
(b) Dry surface
(c) Rich blood supply
(d) Low surface area

📅 Asked in: 2018, 2023

24. In plants, exchange of gases occurs mainly through:

(a) Roots
(b) Stomata
(c) Xylem
(d) Phloem

📅 Asked in: 2017, 2020

25. The energy currency of the cell is:

(a) DNA
(b) RNA
(c) ATP
(d) ADP

📅 Asked in: 2014, 2019, 2024

26. Which of the following is NOT a respiratory organ?

(a) Lungs
(b) Gills
(c) Skin
(d) Heart

📅 Asked in: 2016, 2021

27. The incomplete breakdown of glucose in absence of oxygen is called:

(a) Aerobic respiration
(b) Anaerobic respiration
(c) Transpiration
(d) Photosynthesis

📅 Asked in: 2015, 2018

28. In plants, respiration occurs:

(a) Only during day
(b) Only during night
(c) Only in leaves
(d) All the time

📅 Asked in: 2017, 2022

29. Which of the following increases breathing rate?

(a) Sleeping
(b) Sitting
(c) Running
(d) Resting

📅 Asked in: 2016, 2020

30. The main function of respiration is to:

(a) Remove waste
(b) Produce oxygen
(c) Release energy
(d) Store food

📅 Asked in: 2014, 2018, 2023

ANSWERSHEET

1.✔ Answer: (c) 2.✔ Answer: (c) 3.✔ Answer: (c)

4.✔ Answer: (a) 5.✔ Answer: (b) 6.✔ Answer: (c)

7.✔ Answer: (b) 8.✔ Answer: (c) 9.✔ Answer: (c)

10.✔ Answer: (b) 11.✔ Answer: (b) 12.✔ Answer: (c)

13.✔ Answer: (b) 14.✔ Answer: (a) 15.✔ Answer: (c)

16.✔ Answer: (b) 17.✔ Answer: (c) 18.✔ Answer: (c)

19.✔ Answer: (b) 20.✔ Answer: (c) 21.✔ Answer: (b)

22.✔ Answer: (b) 23.✔ Answer: (c) 24.✔ Answer: (b)

25.✔ Answer: (c) 26.✔ Answer: (d) 27.✔ Answer: (b)

28.✔ Answer: (d) 29.✔ Answer: (c) 30.✔ Answer: (c)

Tuesday, 6 January 2026

Most important question of life process

30 most repeated CBSE Class 10 Science (Life Processes) questions based on previous year board exams (last ~4 years and earlier trends) — and the year in which each question was asked wherever available. This list is extremely useful for revision and board preparation.

📘 Life Processes (Class 10 CBSE Science) — 30 Most Repeated Board Questions with Years

Boost your preparation with the most asked questions from the Life Processes chapter! These are collected from CBSE papers and important PYQ compilations to help you score high. 🌿🧠

🍃 A. Definitions & Basic Concepts

Define life processes and list the basic life processes common to all organisms. (Repeated many times — e.g., Board Exams)
What is photosynthesis? (Common in multiple years)
Write the balanced chemical equation for photosynthesis. (Often asked)
State the raw materials required for photosynthesis. (2020)
Explain the role of chlorophyll in photosynthesis. (Frequently asked)
What are enzymes? Give one example from human digestion. (Often included in PYQs)

🍽️ B. Nutrition & Digestion

Most of the digestion and absorption of food takes place in the — (a) small intestine (b) stomach (c) liver (d) large intestine. (2020)
State the location and function of gastric glands. (2014)
State the role of trypsin and lipase in digestion. (2020 — from PYQ compilations)
What will happen if less saliva is secreted in the mouth? (2025)
Name enzymes present in the human digestive system and their functions. (Repeated in several specimen papers)

💨 C. Respiration

Define respiration. (Previous papers)
Differentiate between aerobic and anaerobic respiration. (Repeated & seen in PYQs)
Why is respiratory pigment needed in multicellular organisms? (2024)
Difference between breathing and respiration. (asked repeatedly before 2020)
Describe how breathing occurs in humans with a neat diagram. (Frequently asked in board papers)

🌿 D. Transport in Plants & Animals

Explain how water and minerals are transported in plants. (Repeated)
What is translocation? Which tissue is responsible for it? (Repeated)
Name the pigment present in red blood cells and its role. (Commonly asked)
Which blood vessel carries oxygenated blood from lungs to heart? (2017)
What is the function of capillaries in the circulatory system? (Repeated across sample/board papers)
Which one of the following statements is correct about the human circulatory system? — Valves ensure that blood does not flow backwards. (2020)

🩸 E. Excretion

Define excretion. (Common short-answer)
Name the organs of the human excretory system. (Repeated)
Explain how urine is formed in the human body. (2020)
Name four types of metabolic wastes produced by humans. (2013/earlier)

📊 F. Application & Reason-Based Questions

Why do desert plants close their stomata during the day yet perform photosynthesis? (Seen in many important questions lists)
Give reason: Stomata close when water flows out of guard cells. (2024 MCQ style)
Why is diffusion insufficient to meet oxygen needs of multicellular organisms? (Board Term I, 2017)
Suggest reasons for the movement of food in the alimentary canal. (Appears in important questions)

✨ Exam Preparation Tips for Life Processes

✔ Practice PYQs and sample papers — Revise board questions which are repeated.
✔ Focus on diagrams — digestive system, respiratory system, heart ,stomata, and nephron are high-yield.
✔ Know definitions and processes word-to-word — Read NCERT carefully.

Most repeted question Of Life Process Class 10

the 25 most repeated and high-yield questions from the Chapter: Life Processes (Class 10 CBSE Science), based on previous year question trends (last ~4–5 years) and commonly tested concepts. These mirror real board exam questions and help boost your preparation. (Manoj Sir)

📘 Life Processes (Class 10 Science) — 25 Most Repeated CBSE Board Questions

Prepare like a topper: Cover key questions that have appeared multiple times in CBSE exams! 🌿🧠

📌 Introduction

The chapter Life Processes is a scoring unit in Class 10 Biology. It consistently contributes to board exam marks through a mix of definitions, explanations, chemical equations, diagrams, and application-based questions. Over the last few years, certain questions have shown up repeatedly in various exam formats — board papers, pre-boards, and sample papers.

🍃 A. Fundamental Definitions & Concepts

Define life processes.
— Mention the basic processes necessary for living organisms to survive.
List the life processes common to all living organisms.
— Such as nutrition, respiration, transport, and excretion.
Define photosynthesis.
— Often asked as a short-answer.
Write the balanced chemical equation for photosynthesis.
— A guarantee in board exams. (
Explain the role of chlorophyll in photosynthesis.
— Most papers expect the function of chlorophyll.
What are the raw materials required for photosynthesis?
— Another frequently repeated sub-question.

🌞 B. Nutrition & Digestion

Describe human digestion.
— List organs and functions of digestive juices.
State the role of amylase in digestion.
— Appears repeatedly in short-answer sections.
Most of the digestion and absorption of food occurs in the — ?
(a) Small intestine (b) Stomach (c) Liver (d) Large intestine
Function of gastric glands in the stomach.
— Asked with location and role.

💨 C. Respiration

Define respiration.
— Often appears as a direct definition. Differentiate between aerobic and anaerobic respiration.
— Classic 2-mark question.
Why is respiratory pigment needed in multicellular organisms?
— Recently asked with reasoning.

🌿 D. Transport in Plants & Animals

How is water transported in plants?
— Expect explanation of xylem, transpiration pull etc.
What is translocation?
— Often an MCQ/short-answer item.
Name the pigment present in RBCs and its role.
— Repeats almost every year.
Which blood vessel carries oxygenated blood to the heart?
— Purse question from circulation.
What is the role of capillaries in transport?
— Seen in structured responses.

🩸 E. Excretion

Define excretion.
— Repeated as a definition question.
What is a nephron? Describe its function.
— Mark-scoring question on excretion.
Explain how urine formation occurs.
— Typically for 3-4 marks.

📊 F. Application/Reason Based Questions

Why do desert plants close their stomata in day but still perform photosynthesis?
— Reason-based from plant adaptation.
What happens if there is less secretion of saliva in the mouth?
— Application in digestion.
Give reasons: Stomata close when water moves out of guard cells.
— Recently asked in multiple choice/long format.
Suggest reasons for the movement of food in the alimentary canal.
— Linked to peristalsis and smooth muscles.

✨ Exam Strategy Tips

✅ Memorise definitions word-to-word — CBSE loves quoting NCERT language.
✅ Practice chemical equations & diagrams — balanced photosynthesis and labeled nephron/ digestive system often fetch marks.
✅ Understand reasoning questions — many recent board papers twist basics into reasoning parts (e.g., stomatal function, respiratory pigments).