Life Processes in Plants MCQs for UPSC Prelims

105 practice questions covering Life Processes in Plants, organised into 1 topics. 105 questions include a written explanation. Pick a topic below, or try the samples first.

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Sample questions

Q1
medium
Moist germinating seeds are shut inside a sealed flask overnight. In the morning the air of the flask is passed through clear limewater, which turns milky. This shows that the seeds have
  1. A given out carbon dioxide while respiring
  2. B used up all the carbon dioxide in the flask
  3. C given out oxygen while making food
  4. D stored starch inside the flask
Show answer and explanation

Correct answer: A - given out carbon dioxide while respiring

Limewater turns milky only where carbon dioxide is present, and the seeds in the dark flask could only have produced it by respiring. They made no food in the sealed dark flask, so they added carbon dioxide rather than using it up, and starch cannot be tested by limewater.
Q2
hard
A plant is first kept in the dark until its leaves hold no starch. A strip of black paper is then clipped over part of one leaf and the plant is left in sunlight for a whole day. When that leaf is tested with iodine, the result will be that
  1. A the covered part turns blue-black while the uncovered part does not
  2. B the uncovered part turns blue-black while the covered part does not
  3. C no part of the leaf turns blue-black
  4. D the whole leaf turns blue-black
Show answer and explanation

Correct answer: B - the uncovered part turns blue-black while the covered part does not

Only the part reached by sunlight could make food, so only that part stores starch and gives the blue-black colour. The covered strip stayed in the dark, so it stays pale, and since one part did receive light, neither the whole leaf nor none of it can give the colour.
Q3
medium
A leaf that has been making food turns blue-black when iodine solution is dropped on it. This colour shows the presence of
  1. A chlorophyll
  2. B oxygen
  3. C carbon dioxide
  4. D starch
Show answer and explanation

Correct answer: D - starch

The blue-black colour appears only where starch is present, so the test shows that food has been made and stored in the leaf. Oxygen and carbon dioxide are gases that iodine does not detect, and chlorophyll is deliberately removed before the test is carried out.
Q4
easy
A money plant is kept inside a dark cupboard and watered regularly. Over a few weeks it turns pale and weak. The factor missing here is
  1. A soil
  2. B air
  3. C sunlight
  4. D water
Show answer and explanation

Correct answer: C - sunlight

The plant is being watered and is sitting in soil with air all around it, so the only thing it lacks inside the cupboard is light. Without light a green plant cannot make food, and it slowly loses its colour and its strength.
Q5
easy
Water taken in by the roots reaches the leaves by passing through the
  1. A root hairs alone
  2. B stem
  3. C fruits
  4. D flowers
Show answer and explanation

Correct answer: B - stem

The stem is the passage that joins the roots to the leaves and carries water upward through it. Root hairs are where water enters at the very beginning, and flowers and fruits are not on the path from the soil to the leaves.
Q6
easy
The food made in the leaves of a plant is carried
  1. A out of the plant and into the soil
  2. B only to the flowers of the plant
  3. C to all the other parts of the plant, including the roots
  4. D only upward to the topmost leaves
Show answer and explanation

Correct answer: C - to all the other parts of the plant, including the roots

Every part of a plant needs food, and the food made in the leaves is carried to the stem, the roots, the flowers and the fruits alike. Sending it only to the flowers or only upward would starve the rest, and a plant does not pour its food into the soil.

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Other subjects

Environment & Ecology 1179 Economy 1062 Logical Reasoning 995 Quantitative Aptitude 897 Polity & Governance 889 Geography 877 Science & Technology 823 Ancient & Medieval History 735 Art & Culture 704 International Relations 580 Modern History 580 Data Interpretation 514 Reading Comprehension 408 Number Play 317 Probability 225 Statistics 162 Reproduction: How Life Continues 155 Relations and Functions 150 Biomolecules 150 Journey Inside the Atom 145 Tissues in Action 145 Fractions 142 Patterns in Life: Diversity and Classification 135 Exploring Algebraic Identities 135 I'm Up and Down, and Round and Round 134 How Forces Affect Motion 133 Work, Energy, and Simple Machines 130 Describing Motion Around Us 130 Predicting What Comes Next: Exploring Sequences and Progressions 128 Exploring Mixtures and their Separation 126 Atomic Foundations of Matter 125 The World of Numbers 125 Introduction to Linear Polynomials 125 Hydrocarbons 125 Earth as a System: Energy, Matter, and Life 125 A Peek Beyond the Point 125 Sound Waves: Characteristics and Applications 125 Measuring Space: Perimeter and Area 125 Changes Around Us: Physical and Chemical 120 Cell: The Building Block of Life 120 Light: Shadows and Reflections 120 Proportional Reasoning-1 120 Quadrilaterals 120 The Mathematics of Maybe: Introduction to Probability 120 Organic Chemistry - Some Basic Principles and Techniques 118 Light: Mirrors and Lenses 116 Prime Time 116 Measurement of Length and Motion 116 Exploring Substances: Acidic, Basic, and Neutral 116 Nature's Treasures 115 Measurement of Time and Motion 115 Structure of Atom 115 Lines and Angles 115 Mindful Eating: A Path to a Healthy Body 115 Parallel and Intersecting Lines 115 Exploring Forces 115 Pressure, Winds, Storms, and Cyclones 115 Power Play 114 The Invisible Living World: Beyond Our Naked Eye 112 Electricity: Magnetic and Heating Effects 110 The Amazing World of Solutes, Solvents, and Solutions 110 Electricity: Circuits and their Components 110 The World of Metals and Non-metals 110 Large Numbers Around Us 110 How Nature Works in Harmony 110 Diversity in the Living World 110 Nature of Matter: Elements, Compounds, and Mixtures 110 Working with Fractions 110 A Tale of Three Intersecting Lines 110 We Distribute, Yet Things Multiply 110 A Journey through States of Water 110 A Square and A Cube 109 Chemical Bonding and Molecular Structure 108 The Other Side of Zero 106 Laws of Motion 105 Living Creatures: Exploring their Characteristics 105 Health: The Ultimate Treasure 105 Methods of Separation in Everyday Life 105 Expressions using Letter-Numbers 105 Our Home: Earth, a Unique Life Sustaining Planet 105 Exploring Magnets 105 Equilibrium 105 Beyond Earth 105 Aldehydes, Ketones and Carboxylic Acids 105 Heat Transfer in Nature 105 Life Processes in Animals 105 Patterns in Mathematics 103 Particulate Nature of Matter 100 Orienting Yourself: The Use of Coordinates 100 Fundamentals of Nursing 100 Materials Around Us 100 A Story of Numbers 100 System of Particles and Rotational Motion 100 Perimeter and Area 100 Earth, Moon, and the Sun 100