Astrobiology MCQs set for students preparing for school boards (CBSE, ICSE), national entrance exams (NEET, CUET, CSIR-NET, GATE, DBT-BET JRF, etc.), medical licensing exams (USMLE, PLAB, AMC), and international exams (SAT Biology Subject Test, GRE Biology Subject Test, BMAT, IMAT).

Astrobiology MCQs — Part 1 (Q1–Q25)

Q1. Astrobiology is the study of:

A. Stars and galaxies
B. Life in the universe, its origin, evolution, and distribution ✅
C. Only microorganisms
D. Chemical reactions in cells

A: Astronomy, not astrobiology.
B: Astrobiology explores life’s potential beyond Earth, combining biology, chemistry, and astronomy.
C: Microbiology is narrower.
D: Biochemistry, not astrobiology.

Q2. Which planet is often called Earth’s twin in the search for life?

A. Mars
B. Venus ✅
C. Jupiter
D. Saturn

A: Mars is Earth-like but smaller.
B: Venus is similar in size and mass to Earth.
C/D: Gas giants, very different from Earth.

Q3. The “habitable zone” around a star refers to:

A. A region where gas giants form
B. The distance where liquid water can exist ✅
C. The star’s surface temperature
D. The asteroid belt location

A/C/D: Not the definition.
B: Liquid water stability is key to defining habitable zones.

Q4. Which molecule is considered most essential for life as we know it?

A. Methane
B. Water ✅
C. Carbon monoxide
D. Ammonia

A/C/D: Important, but not as universal.
B: Water is vital for biochemical reactions and is the main focus in life detection.

Q5. The Miller–Urey experiment (1953) demonstrated:

A. Evolution of species on Earth
B. Abiotic synthesis of organic molecules under primitive Earth conditions ✅
C. Photosynthesis in plants
D. Formation of galaxies

B: Miller–Urey simulated early Earth and produced amino acids spontaneously.

Q6. Which planet shows strongest evidence for past liquid water?

A. Mercury
B. Mars ✅
C. Neptune
D. Pluto

A: Too hot.
B: Mars shows dried river valleys, polar ice caps, and hydrated minerals.
C/D: Too cold/icy.

Q7. Extremophiles are organisms that:

A. Live only at room temperature
B. Survive extreme conditions like heat, cold, acidity, or radiation ✅
C. Only exist in outer space
D. Cannot survive without oxygen

B: Extremophiles on Earth suggest life may survive harsh extraterrestrial environments.

Q8. Which moon of Jupiter is considered most promising for extraterrestrial life?

A. Io
B. Europa ✅
C. Ganymede
D. Callisto

A: Volcanic, hostile.
B: Europa likely has a subsurface ocean beneath ice.
C/D: Also interesting, but Europa is prime candidate.

Q9. The Drake Equation estimates:

A. Earth’s age
B. The number of intelligent civilizations in the galaxy ✅
C. The speed of light
D. The size of the Milky Way

B: Drake Equation combines factors like star formation, planets, and life probability.

Q10. Which gas is considered a biosignature in planetary atmospheres?

A. CO₂
B. O₂ (oxygen) / O₃ (ozone) ✅
C. H₂
D. N₂

A/C/D: Present abiotically.
B: Oxygen/ozone strongly indicate biological activity (photosynthesis).

Q11. The panspermia hypothesis suggests:

A. Life began only on Earth
B. Life could be transferred between planets via meteors/comets ✅
C. Life started in oceans
D. Life came from volcanoes

B: Panspermia proposes interplanetary transfer of microbial life.

Q12. Which space telescope focuses on detecting exoplanets?

A. Hubble
B. Kepler Space Telescope ✅
C. Spitzer
D. Chandra

A: General observations.
B: Kepler revolutionized exoplanet detection using transit method.
C: Infrared studies.
D: X-rays.

Q13. The “rare Earth hypothesis” proposes:

A. Life is common everywhere
B. Complex life is rare due to specific planetary conditions needed ✅
C. Planets exist only near giant stars
D. Only microbes exist in universe

B: Suggests Earth-like conditions for complex life may be very rare.

Q14. Which molecule on Titan (Saturn’s moon) suggests possible prebiotic chemistry?

A. Methane and hydrocarbons ✅
B. Oxygen
C. Iron oxides
D. Sodium chloride

A: Titan’s methane lakes and hydrocarbon-rich atmosphere are promising for prebiotic studies.

Q15. What is the main source of energy for life at deep-sea hydrothermal vents?

A. Sunlight
B. Chemosynthesis using hydrogen sulfide ✅
C. Photosynthesis
D. Nuclear fission

B: Chemolithoautotrophs use chemical energy instead of sunlight.

Q16. SETI stands for:

A. Space Exploration and Telescope Initiative
B. Search for Extraterrestrial Intelligence ✅
C. Solar Energy Tracking Institute
D. Space Engineering Training Institute

B: SETI scans for radio/optical signals from alien civilizations.

Q17. What does LUCA stand for?

A. Last Universal Common Ancestor ✅
B. Largest Universe Cosmic Anomaly
C. Life Under Carbon Atmosphere
D. Local Universal Chemical Association

A: LUCA is the hypothetical ancestor of all current life on Earth.

Q18. Which feature of Enceladus (moon of Saturn) suggests habitability?

A. Surface volcanoes
B. Subsurface ocean with hydrothermal activity ✅
C. No atmosphere
D. Permanent ice cover only

B: Cassini mission detected water plumes with organic molecules.

Q19. Which element is considered the backbone of life?

A. Nitrogen
B. Oxygen
C. Carbon ✅
D. Hydrogen

C: Carbon’s versatility in forming complex molecules makes it central to life.

Q20. The Great Oxidation Event on Earth was caused by:

A. Volcanoes
B. Photosynthetic cyanobacteria producing oxygen ✅
C. Meteor impacts
D. Ice ages

B: Cyanobacteria oxygenated Earth’s atmosphere ~2.4 billion years ago.

Q21. The field of astrobiology overlaps most with:

A. Medicine
B. Astronomy, biology, and planetary science ✅
C. Mechanical engineering
D. Architecture

B: It is interdisciplinary, combining space science and biology.

Q22. Which biosignature has been proposed for exoplanet detection besides oxygen?

A. Helium
B. Methane (CH₄) coexisting with oxygen ✅
C. Nitrogen gas
D. Carbon dioxide only

B: Methane + oxygen together suggest biological activity (non-equilibrium chemistry).

Q23. What does the term exobiology mean?

A. Study of genetics
B. Study of Earth’s oceans
C. Study of life beyond Earth ✅
D. Study of fossils

C: Exobiology is an earlier term for astrobiology.

Q24. Which mission discovered water ice and organic molecules on comets?

A. Apollo 11
B. Rosetta Mission (ESA) ✅
C. Voyager 1
D. Hubble

B: Rosetta orbited Comet 67P and detected organic molecules.

Q25. The term “Goldilocks Zone” means:

A. A place with extreme radiation
B. Region not too hot, not too cold, where life may exist ✅
C. The area near black holes
D. Earth’s magnetic field

B: Named after the fairy tale, it refers to habitable zone conditions.

Astrobiology MCQs — Part 2 (Q26–Q50)

Q26. Which mission first landed successfully on Mars?

A. Apollo 11
B. Viking 1 (NASA, 1976) ✅
C. Curiosity Rover
D. Pathfinder

A: Moon landing, not Mars.
B: Viking 1 was the first successful lander on Mars.
C/D: Later Mars missions.

Q27. The Fermi Paradox refers to:

A. Lack of planets in the universe
B. Contradiction between high probability of alien life and no evidence ✅
C. Origin of stars
D. Black hole radiation

B: Fermi Paradox = “Where is everybody?” despite many habitable worlds.

Q28. Which layer of Earth’s atmosphere is critical for shielding life from UV radiation?

A. Troposphere
B. Ozone layer (stratosphere) ✅
C. Mesosphere
D. Exosphere

B: Ozone absorbs harmful UV, protecting surface life.

Q29. Which of the following is an extremophile living in acidic environments?

A. Thermophiles
B. Acidophiles ✅
C. Halophiles
D. Psychrophiles

A: High temperatures.
B: Acidophiles thrive in low pH (acidic) conditions.
C: High salt.
D: Cold environments.

Q30. Which instrument is used to detect exoplanets via Doppler shifts?

A. Telescope mirror
B. Spectrograph ✅
C. X-ray scanner
D. Electron microscope

B: Spectrographs measure stellar wobble (radial velocity method).

Q31. Which exoplanet was the first discovered around a Sun-like star (1995)?

A. Kepler-186f
B. Proxima b
C. 51 Pegasi b ✅
D. Gliese 581c

C: 51 Pegasi b was the first exoplanet orbiting a Sun-like star.

Q32. Astrochemistry focuses on:

A. Human exploration in space
B. Chemical processes in space relevant to life’s origin ✅
C. Rocket engineering
D. DNA replication

B: Astrochemistry studies molecules in interstellar space, comets, planets.

Q33. Which extremophiles suggest that life could exist in Europa’s ocean?

A. Acidophiles
B. Halophiles and psychrophiles ✅
C. Thermophiles only
D. Obligate aerobes

B: Salt-loving and cold-loving microbes support analogs for Europa.

Q34. Which mission discovered water vapor plumes on Enceladus?

A. Voyager 1
B. Hubble
C. Cassini spacecraft ✅
D. Apollo 17

C: Cassini detected active water plumes venting from Enceladus.

Q35. The extremophile Deinococcus radiodurans is known for:

A. Surviving high pressure
B. Exceptional resistance to radiation ✅
C. Living in acid
D. Surviving without water

B: “Conan the bacterium” survives extreme ionizing radiation.

Q36. Which technique is MOST commonly used to detect exoplanet transits?

A. X-ray diffraction
B. Light curve photometry ✅
C. Radio telescopes
D. Microscopy

B: Periodic dimming of stars indicates planets passing in front.

Q37. Which gas on Earth is primarily produced by photosynthesis?

A. Carbon dioxide
B. Nitrogen
C. Oxygen ✅
D. Methane

C: Oxygen is a biosignature linked to photosynthesis.

Q38. The “Wow! Signal” detected in 1977 was:

A. A confirmed alien message
B. A strong unexplained radio signal ✅
C. A spacecraft malfunction
D. Background noise

B: Detected by Big Ear telescope; unexplained, possibly extraterrestrial.

Q39. Which planet is studied as an analog for early Earth due to thick atmosphere?

A. Mercury
B. Venus ✅
C. Neptune
D. Uranus

B: Venus’ CO₂ atmosphere and greenhouse effect resemble early Earth conditions.

Q40. Which Earth environment resembles Martian soil?

A. Amazon rainforest
B. Atacama Desert (Chile) ✅
C. Himalayas
D. Sahara Desert

B: Atacama Desert has hyper-arid soil with similarities to Mars.

Q41. The Kuiper Belt is a region of:

A. Stars beyond the galaxy
B. Icy bodies and dwarf planets beyond Neptune ✅
C. Black holes near Earth
D. Jupiter’s orbit

B: Kuiper Belt includes Pluto, comets, icy bodies.

Q42. Which process allows microbes to survive deep underground without sunlight?

A. Photosynthesis
B. Chemolithotrophy (chemical energy from rocks) ✅
C. Respiration with oxygen
D. Aerobic fermentation

B: Rock-eating microbes support possibility of subsurface Martian life.

Q43. What is the main requirement for habitability on exoplanets?

A. Thick clouds
B. Liquid water ✅
C. Oxygen atmosphere
D. Volcanic activity

B: Liquid water is the universal requirement for life as we know it.

Q44. Which molecule is a universal energy currency in cells?

A. DNA
B. ATP (adenosine triphosphate) ✅
C. RNA
D. NADH

B: ATP powers nearly all biological processes.

Q45. Which Martian rover first confirmed evidence of water on Mars?

A. Opportunity
B. Curiosity Rover (2012) ✅
C. Sojourner
D. Perseverance

B: Curiosity found hydrated minerals, confirming past water.

Q46. Which space agency operates the Roscosmos program?

A. NASA
B. ESA
C. Russia ✅
D. ISRO

C: Roscosmos is Russia’s national space agency.

Q47. Which is considered an alternative solvent for life besides water?

A. CO₂
B. Liquid methane/ethane ✅
C. Nitrogen
D. Oxygen

B: On Titan, methane and ethane may act as potential solvents.

Q48. Which biosignature is produced by methanogenic archaea?

A. CO₂
B. Methane (CH₄) ✅
C. Ozone
D. Nitrogen

B: Methane from microbes is a detectable biosignature.

Q49. What is the importance of extremophiles in astrobiology?

A. They prove aliens exist
B. They show life can adapt to extreme conditions, suggesting extraterrestrial possibilities ✅
C. They only live in labs
D. They prevent evolution

B: Extremophiles expand our definition of habitable environments.

Q50. Which Mars mission recently brought back rock samples (planned for Earth return)?

A. Viking 1
B. Perseverance Rover (Mars 2020) ✅
C. Pathfinder
D. Apollo 12

B: Perseverance is caching samples for future Mars Sample Return mission.

Astrobiology MCQs — Part 3 (Q51–Q75)

Q51. Which Mars lander first confirmed the presence of water ice beneath the surface?

A. Viking 1
B. Pathfinder
C. Phoenix Lander (2008) ✅
D. Curiosity Rover

A/B: Earlier missions, no direct water ice confirmation.
C: Phoenix dug into Martian soil and found ice sublimating.
D: Curiosity studied hydrated minerals.

Q52. Which type of star is considered best for long-term planetary habitability?

A. Blue giants
B. K- and M-type dwarfs ✅
C. White dwarfs
D. Neutron stars

A/D: Short lifespans or extreme conditions.
B: K/M dwarfs live billions of years, allowing stable habitability.
C: Post-main-sequence, unstable.

Q53. The Allen Telescope Array is dedicated to:

A. Observing galaxies
B. SETI (Search for Extraterrestrial Intelligence) ✅
C. Detecting black holes
D. Imaging asteroids

B: ATA continuously scans radio signals for alien civilizations.

Q54. Which molecule is central to carbon-based life on Earth?

A. Silicon
B. Carbon (C) ✅
C. Iron
D. Sodium

B: Carbon forms complex, stable, and diverse molecules for life.

Q55. Which moon of Saturn has methane lakes on its surface?

A. Enceladus
B. Titan ✅
C. Mimas
D. Iapetus

B: Titan has stable liquid methane/ethane lakes and rivers.

Q56. The term astrobiology triangle emphasizes the connection between:

A. Physics, chemistry, geology
B. Astronomy, biology, and planetary science ✅
C. Medicine, genetics, biochemistry
D. Mechanics, robotics, electronics

B: Astrobiology is interdisciplinary, integrating these three fields.

Q57. Which extremophile thrives in high-salt environments?

A. Thermophile
B. Halophile ✅
C. Acidophile
D. Psychrophile

B: Halophiles survive extreme salt levels, e.g., Dead Sea, salt mines.

Q58. The exoplanet detection method that observes star dimming when a planet passes in front is called:

A. Radial velocity
B. Transit method ✅
C. Microlensing
D. Direct imaging

B: Transit method detects dips in starlight → most exoplanets discovered this way.

Q59. Which biosignature gas is unstable and must be continually replenished by life?

A. Nitrogen
B. Methane (CH₄) ✅
C. Argon
D. Carbon dioxide

B: Methane breaks down quickly in atmospheres → constant replenishment suggests biology.

Q60. Which technique helps identify organic molecules in Martian soil?

A. Mass spectrometry
B. Chromatography
C. Gas Chromatography–Mass Spectrometry (GC-MS) ✅
D. X-ray diffraction

C: GC-MS detects organics, used in Viking and Curiosity missions.

Q61. Which type of radiation is most damaging to potential life on unprotected planets?

A. Infrared radiation
B. Ultraviolet (UV) and ionizing radiation ✅
C. Radio waves
D. Visible light

B: UV and cosmic ionizing radiation damage DNA and biomolecules.

Q62. Which planetary system has the famous seven Earth-sized planets?

A. Kepler-22
B. TRAPPIST-1 ✅
C. Proxima Centauri
D. Gliese 581

B: TRAPPIST-1 has 7 terrestrial planets, some in habitable zone.

Q63. Which hypothesis suggests that life may originate in deep-sea hydrothermal vents?

A. Gaia hypothesis
B. Panspermia
C. Iron–sulfur world hypothesis ✅
D. Rare Earth hypothesis

C: Iron–sulfur minerals may have catalyzed early biochemical reactions.

Q64. Which space mission studied Pluto and Kuiper Belt objects?

A. Voyager 1
B. New Horizons (2015 flyby) ✅
C. Cassini
D. Galileo

B: New Horizons revealed Pluto’s geology, atmosphere, and ice structures.

Q65. Which molecules are called the “building blocks of life”?

A. Silicates
B. Amino acids ✅
C. Noble gases
D. Salts

B: Amino acids form proteins, key biomolecules of life.

Q66. Which phenomenon stabilizes Earth’s climate for habitability?

A. High rotation speed
B. Carbon cycle with plate tectonics ✅
C. Weak magnetic field
D. Thin atmosphere

B: Plate tectonics regulate CO₂ through weathering and volcanism.

Q67. Which moon is believed to have an underground salty ocean beneath an icy crust?

A. Titan
B. Europa (Jupiter’s moon) ✅
C. Io
D. Ganymede

B: Europa’s ocean under ice is a prime candidate for life.

Q68. The Gaia hypothesis suggests:

A. Earth is a rare planet
B. Earth functions as a self-regulating system maintaining habitability ✅
C. Life began on Mars
D. Only microbes exist in space

B: Gaia hypothesis by Lovelock → Earth systems interact to sustain life.

Q69. Which exoplanet is closest to Earth and lies in the habitable zone of its star?

A. Kepler-452b
B. Proxima Centauri b ✅
C. TRAPPIST-1e
D. 51 Pegasi b

B: Proxima b orbits our nearest star (4.2 ly away).

Q70. Which molecules detected in interstellar clouds support prebiotic chemistry?

A. Only CO₂
B. Amino acids, alcohols, and organic molecules ✅
C. Metals only
D. DNA

B: Complex organic molecules detected in interstellar space indicate prebiotic potential.

Q71. Which planet has methane storms and large hydrocarbon lakes?

A. Mars
B. Venus
C. Titan ✅
D. Neptune

C: Titan has methane storms and stable methane lakes.

Q72. The “Red Edge” effect refers to:

A. Mars dust storms
B. Vegetation reflectance signature in near-infrared spectrum ✅
C. Solar radiation pressure
D. Cosmic microwave background

B: Used as potential biosignature when studying exoplanets.

Q73. Which planetary protection principle prevents contamination of other worlds?

A. Biohazard law
B. Planetary protection policy ✅
C. Exoplanet defense strategy
D. Space mining treaty

B: Policies ensure spacecraft sterilization to prevent biological contamination.

Q74. Which mission recently detected organic molecules on Mars?

A. Viking 1
B. Curiosity Rover ✅
C. Hubble Telescope
D. Cassini

B: Curiosity detected organics in Martian rocks and soil.

Q75. Which element is central to silicon-based life hypothesis?

A. Carbon
B. Silicon ✅
C. Oxygen
D. Nitrogen

B: Silicon-based life is a speculative alternative to carbon-based life.

Perfect 🌠 Let’s finish with Part 4 (Q76–Q100) of the Astrobiology MCQs set. Each question has four options, the correct answer is marked, and I’ve added short explanations for clarity.

Astrobiology MCQs — Part 4 (Q76–Q100)

Q76. Which feature makes Europa a strong candidate for life?

A. Thick carbon dioxide atmosphere
B. Volcanic surface
C. Subsurface liquid ocean beneath ice crust ✅
D. Rocky deserts

C: Evidence of a salty subsurface ocean makes Europa a key target in astrobiology.

Q77. Which of the following missions studied Jupiter and its moons?

A. Apollo 13
B. Galileo spacecraft ✅
C. New Horizons
D. Chandrayaan-1

B: Galileo orbited Jupiter (1995–2003) and studied its moons.

Q78. Which space telescope is most useful for identifying exoplanet atmospheres?

A. Chandra X-ray
B. James Webb Space Telescope (JWST) ✅
C. Spitzer IR telescope
D. Hubble

B: JWST uses infrared spectroscopy to analyze exoplanet atmospheres.

Q79. What is the main limitation of the Drake Equation?

A. It ignores alien intelligence
B. Its parameters are highly uncertain and speculative ✅
C. It excludes exoplanets
D. It cannot be calculated

B: Many factors (e.g., life probability) are uncertain → wide estimates.

Q80. Which kind of extremophile survives very high temperatures?

A. Psychrophile
B. Halophile
C. Thermophile ✅
D. Acidophile

C: Thermophiles thrive in boiling springs and vents, analogs for early Earth/Mars.

Q81. Which planet is called the “Red Planet”?

A. Venus
B. Mercury
C. Mars ✅
D. Neptune

C: Mars appears red due to iron oxide on its surface.

Q82. Which gas in Earth’s atmosphere is a strong indicator of biological activity?

A. CO₂
B. Argon
C. Oxygen (O₂) ✅
D. Helium

C: Oxygen, maintained by photosynthesis, is a strong biosignature.

Q83. Which mission first detected exoplanets using microlensing?

A. Kepler
B. Hubble
C. OGLE (Optical Gravitational Lensing Experiment) ✅
D. Viking

C: OGLE discovered exoplanets via gravitational microlensing.

Q84. Which hypothesis suggests Earth’s oceans may have formed from cometary impacts?

A. Gaia hypothesis
B. Delivery of water via icy comets and asteroids ✅
C. Rare Earth hypothesis
D. Abiogenesis

B: Cometary/asteroid impacts may have delivered water to early Earth.

Q85. Which star type is MOST common in the galaxy?

A. Blue giants
B. Yellow dwarfs
C. Red dwarfs (M-type) ✅
D. White dwarfs

C: Red dwarfs are small, long-lived, and most abundant.

Q86. Which molecule detected on Mars is controversial as a potential biosignature?

A. Nitrogen
B. Methane (CH₄) ✅
C. Oxygen
D. Carbon dioxide

B: Seasonal methane spikes on Mars are debated as potential signs of life.

Q87. The Astrobiology Roadmap by NASA provides:

A. Rocket launch dates
B. Scientific goals and strategies for searching life in the universe ✅
C. Exoplanet distance tables
D. Telescope building guides

B: Roadmap guides global astrobiology research priorities.

Q88. Which extremophile thrives in extremely cold environments?

A. Halophile
B. Acidophile
C. Psychrophile ✅
D. Thermophile

C: Psychrophiles survive in polar ice, analogs for Europa/Titan.

Q89. Which is a potential biosignature combination on exoplanets?

A. Nitrogen and argon
B. Oxygen and methane together ✅
C. CO₂ and helium
D. Hydrogen only

B: O₂ + CH₄ coexistence indicates disequilibrium → possible biology.

Q90. Which project first mapped genetic diversity in humans (SNPs)?

A. Human Genome Project
B. HapMap Project ✅
C. ENCODE Project
D. SETI

B: HapMap catalogued human genetic variation, aiding astrobiology through evolutionary insights.

Q91. Which space mission is currently exploring Mars with advanced instruments (2021)?

A. Viking
B. Curiosity
C. Perseverance Rover ✅
D. Apollo

C: Perseverance studies rocks, caches samples, and searches for biosignatures.

Q92. Which space probe famously carried the Golden Record with sounds of Earth?

A. Pioneer 10
B. Voyager 1 & 2 ✅
C. Cassini
D. Galileo

B: Voyager probes carried Golden Records with Earth’s messages.

Q93. Which extremophile tolerates very high pressure, like in deep oceans?

A. Halophile
B. Acidophile
C. Piezophile (barophile) ✅
D. Thermophile

C: Piezophiles survive in extreme pressure conditions (deep-sea).

Q94. Which is the closest star system to Earth?

A. Kepler-22
B. Alpha Centauri (includes Proxima Centauri) ✅
C. TRAPPIST-1
D. Betelgeuse

B: Alpha Centauri system is ~4.2 light years away.

Q95. What is the significance of ribozymes in origin-of-life studies?

A. They encode proteins
B. They are RNA molecules with catalytic activity, supporting RNA world hypothesis ✅
C. They form DNA
D. They break down proteins

B: Ribozymes show RNA could act as both catalyst and genetic material.

Q96. Which mission studied comets and landed on one’s surface?

A. Voyager
B. Rosetta–Philae mission (ESA) ✅
C. Galileo
D. Apollo

B: Rosetta orbited Comet 67P; Philae lander touched down.

Q97. Which method is MOST promising for detecting exoplanet atmospheres?

A. Mass spectrometry
B. Transit spectroscopy ✅
C. Electrophoresis
D. PCR

B: Transit spectroscopy measures starlight filtered through exoplanet atmospheres.

Q98. Which planet is believed to have once had rivers, lakes, and maybe oceans?

A. Mercury
B. Mars ✅
C. Neptune
D. Pluto

B: Mars shows clear evidence of past surface water.

Q99. Which mission will bring back Mars rock samples to Earth?

A. Rosetta
B. Viking 2
C. Mars Sample Return (future mission, linked to Perseverance) ✅
D. Apollo 17

C: Perseverance is caching samples → MSR mission planned.

Q100. Why is astrobiology important?

A. Only for space travel
B. To replace biology classes
C. To understand life’s origins, evolution, and existence beyond Earth ✅
D. To study only comets

C: Astrobiology asks fundamental questions about life in the universe.

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