Why do plants need to de-starch a leaf before performing an iodine test for starch?

To ensure any starch detected was newly formed during the experiment

To make the leaf softer for testing

To ensure any starch detected was newly formed during the experiment

To remove chlorophyll and make the color change visible

To kill any microorganisms on the leaf surface

Which of the following experimental setups would best demonstrate that sunlight is necessary for photosynthesis?

One plant in sunlight, another in the dark, both watered.

One plant watered, another unwatered, both in sunlight.

One plant with CO2, another without CO2, both in sunlight.

One plant with green leaves, another with variegated leaves, both in sunlight.

What is the role of sodium hydroxide solution in the experiment to show that carbon dioxide is essential for photosynthesis?

To absorb carbon dioxide from the air

To provide nutrients to the leaf

The diagram shows an experimental setup. What is the purpose of placing the pot in the dark for two to three days initially?

To destarch the plant, ensuring any starch detected later is newly formed

To kill the plant for easier experimentation

To make the leaves soft for inserting into the bottle

To destarch the plant, ensuring any starch detected later is newly formed

To prevent water loss from the leaves

What is the primary function of the vascular tissue labeled 'Y' in the diagram, which is responsible for transporting food?

Transport of food (sugars) from leaves

Assertion (A): Leaves are generally broad and flat. Reason (R): This structure helps in efficient capture of sunlight and exchange of gases for photosynthesis.

A and R both correct, R explains A

A gardener observes that a plant kept in a dimly lit room is growing tall and spindly with pale yellow leaves, while an identical plant in a sunny spot is short and bushy with dark green leaves. Which of the following factors is most likely responsible for the difference in growth and color?

Difference in water availability

Difference in carbon dioxide levels

Which two of the following are true regarding the process of photosynthesis?

It converts light energy into chemical energy.

It consumes oxygen and releases carbon dioxide.

It converts light energy into chemical energy.

It produces glucose and oxygen.

It occurs only during the night.

Assertion (A): Plants perform respiration throughout the day and night. Reason (R): Respiration is necessary to release energy for the plant's continuous life processes.

A and R both correct, R explains A

Assertion (A): Decolorizing a leaf in alcohol is an important step in the starch test. Reason (R): Alcohol removes the green pigment chlorophyll, making the blue-black color change of iodine visible if starch is present.

A and R both correct, R explains A

A scientist is studying a new plant species and observes that it has very few stomata on its leaves. Which two of the following processes would likely be significantly affected in this plant?

Exchange of carbon dioxide for photosynthesis

Transport of food through phloem

Observe the experimental setup. If the lime water in the test tube turns milky, what does this indicate about the germinating seeds?

They are respiring and releasing carbon dioxide.

They are performing photosynthesis.

They are respiring and releasing carbon dioxide.

They are absorbing water from the cotton.

A farmer notices that his crop plants are wilting despite regular watering. Upon inspection, he finds that the soil is waterlogged. Which of the following is the most likely reason for the wilting?

Waterlogging reduces oxygen availability to roots, impairing water absorption.

Excess water is promoting rapid growth, leading to wilting.

Waterlogging reduces oxygen availability to roots, impairing water absorption.

The plants are absorbing too much water, causing cell burst.

The waterlogged soil is too cold for the roots to function.

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This quiz for CBSE Class 7 Science Chapter 10, 'Life Processes in Plants,' contains 40 questions across easy, medium, and hard difficulty levels.

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Yes, detailed explanations are provided for every question, helping you understand the concepts better and learn from your mistakes.

What topics does this quiz cover?

The quiz covers key topics from Chapter 10, including photosynthesis, plant respiration, the role of chlorophyll, stomata, transport of water and food via xylem and phloem, and factors affecting plant growth.

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Regularly attempting this quiz will reinforce your understanding of the chapter, identify your weak areas, and improve your problem-solving skills, making you well-prepared for school tests and competitive exams.

Home › CBSE › Class 7 › Science › Life Processes in Plants

CBSE · Class 7 · 🔬 Science · Chapter 10

Life Processes in Plants

PhotosynthesisRespiration in plantsTransport of water and foodStomataChlorophyllXylem and Phloem

Chapter 10, 'Life Processes in Plants,' introduces students to the fundamental biological activities that sustain plant life. It covers how plants grow, obtain food through photosynthesis, exchange gases, transport water and nutrients, and respire. Understanding these processes is crucial for comprehending the role of plants in ecosystems and their importance for all living organisms.

Factors Affecting Plant Growth

Plants ki growth ke liye kai factors important hote hain. Inko samajhna zaroori hai taaki hum plants ki needs ko fulfill kar sakein.

Essential Factors:
Sunlight: Photosynthesis ke liye primary energy source. Sunlight ke bina plants food nahi bana sakte.
Water: Photosynthesis ka ek raw material hai aur nutrients ke transport ke liye bhi essential hai. Plants ko hydrated rakhta hai.
Carbon Dioxide (CO2): Photosynthesis ke liye ek aur raw material, jo air se milta hai.
Nutrients (Minerals): Soil se absorb hote hain, growth aur development ke liye zaroori hain (e.g., Nitrogen, Phosphorus, Potassium).
Temperature: Optimal temperature range mein hi plants achhe se grow karte hain. Too hot or too cold conditions growth ko inhibit karti hain.

Experiment (Activity 10.1) se Learning:
Pot A (Sunlight + Water): Healthy growth dikhayega, leaves green rahenge, height badhegi. Ideal conditions.
Pot B (Sunlight - Water): Plant wilting (murjha jayega), growth ruk jayegi, leaves yellow ho sakte hain ya gir sakte hain. Water ki importance.
Pot C (Dark + Water): Plant yellow ya pale ho jayega (etiolation), weak growth dikhayega. Sunlight ki importance.

Conclusion: Plant ki healthy growth ke liye sunlight aur water dono bahut zaroori hain. Inmein se kisi ek ki bhi kami growth ko negatively affect karti hai.

[IMAGE: experiment_on_factors_affecting_plant_growth_fig101] (Yeh image onion bulb sprouting roots dikhati hai, jo water ki importance ko highlight karti hai.)

❗Important

Plants autotrophs hote hain, matlab woh apna food khud banate hain. Animals heterotrophs hote hain, jo plants ya dusre animals par depend karte hain food ke liye.

Leaves as Food Factories and Chlorophyll

Plants ke liye leaves 'food factories' ka kaam karte hain. Yahin par photosynthesis ki process hoti hai.

Leaves ka Structure:
Generally broad aur flat hote hain, taaki maximum sunlight absorb kar sakein.
Inmein tiny pores hote hain jinhe stomata kehte hain, gas exchange ke liye.
Leaves mein chlorophyll naam ka green pigment hota hai.

Chlorophyll:
Yeh ek green pigment hai jo leaves aur other green parts mein present hota hai.
Iska main function sunlight energy ko capture karna hai. Yeh energy photosynthesis ke liye use hoti hai.
Chlorophyll ke bina photosynthesis possible nahi hai, isliye plants green dikhte hain.

Why Leaves are Green?
Chlorophyll green light ko reflect karta hai aur baaki colors ko absorb kar leta hai. Isliye humein leaves green dikhte hain.

Starch Storage:
Plants apna food glucose ke form mein banate hain.
Yeh glucose instant energy ke liye use hota hai aur excess glucose ko starch ke form mein store kiya jaata hai, mainly leaves mein aur roots, fruits mein bhi.
Starch ek complex carbohydrate hai.

📖Definition

Chlorophyll: Woh green pigment jo plants mein sunlight energy ko capture karta hai, photosynthesis ke liye essential hai.

⭐Remember

Sirf green parts hi photosynthesis kar sakte hain, kyunki unmein chlorophyll hota hai. Non-green parts (jaise stem ya roots) food ke liye leaves par depend karte hain.

Photosynthesis Process and Equation

Photosynthesis woh process hai jisse green plants apna food (glucose) banate hain, sunlight energy ko use karke.

Raw Materials:
Carbon Dioxide (CO2): Air se stomata ke through absorb hota hai.
Water (H2O): Roots se absorb hota hai aur xylem ke through leaves tak pahunchta hai.

Conditions Required:
Sunlight: Energy source, chlorophyll absorb karta hai.
Chlorophyll: Sunlight energy ko capture karne wala pigment.

Products:
Glucose (C6H12O6): Plant ka food, ek simple carbohydrate.
Oxygen (O2): By-product, stomata ke through air mein release hota hai.

Word Equation:

$$ \text{Carbon Dioxide} + \text{Water} \xrightarrow{\text{Sunlight/Chlorophyll}} \text{Glucose} + \text{Oxygen} $$

Chemical Equation (for higher classes, but good to know):

$$ 6CO_2 + 6H_2O \xrightarrow{\text{Sunlight/Chlorophyll}} C_6H_{12}O_6 + 6O_2 $$

Importance of Photosynthesis:
Food Production: Earth par saare organisms ke liye food ka ultimate source hai.
Oxygen Release: Atmosphere mein oxygen release karta hai, jo breathing ke liye essential hai.
Carbon Dioxide Absorption: Atmosphere se CO2 ko absorb karke carbon cycle maintain karta hai, global warming ko control karne mein help karta hai.

[IMAGE: the_process_of_photosynthesis_fig105] (Yeh diagram photosynthesis ki poori process ko clearly dikhata hai.)

📖Definition

Photosynthesis: Woh process jismein green plants sunlight energy, carbon dioxide aur water ka use karke apna food (glucose) banate hain aur oxygen release karte hain.

💡Tip

Photosynthesis ki word equation aur uske raw materials & products ko acche se yaad kar lena. Yeh frequently pucha jaata hai.

Testing for Starch in Leaves

Hum kaise pata lagayenge ki plant ne food banaya hai? Hum starch test karte hain, kyunki plants glucose ko starch ke form mein store karte hain.

Iodine Test for Starch:
Iodine solution starch ke presence mein blue-black colour deta hai.

Procedure (Activity 10.2 & 10.3):

Boil in Water: Leaf ko boiling water mein 5 minutes ke liye rakho. Isse cells soft ho jaate hain aur cell membrane permeable ho jaati hai.
Boil in Alcohol (Water Bath): Leaf ko test tube mein alcohol ke saath boiling water bath mein rakho. Alcohol chlorophyll ko dissolve kar deta hai, jisse leaf decolourise ho jaata hai (pale white/yellowish ho jaata hai). Yeh step zaroori hai taaki iodine ka colour change clearly visible ho.
Wash with Water: Decolourised leaf ko thande paani se dho lo, taaki alcohol remove ho jaaye.
Iodine Solution: Leaf par kuch drops diluted iodine solution ki daalo.

Observation:
Agar starch present hai, toh leaf ka colour blue-black ho jayega.
Agar starch absent hai, toh leaf ka colour brownish-yellow (iodine ka original colour) hi rahega.

Experiments showing necessity of factors:
Chlorophyll (Activity 10.3): Variegated leaf (green aur non-green patches wala) par starch test karne par, sirf green parts hi blue-black hote hain. Non-green parts mein starch nahi banta, proving chlorophyll is essential.
CO2 (Activity 10.4): Ek destarched plant ke ek leaf ke part ko bottle mein NaOH (Sodium Hydroxide) ke saath rakho. NaOH CO2 ko absorb kar leta hai. Jab starch test karte hain, toh bottle ke andar wala part blue-black nahi hota, jabki bahar wala part ho jaata hai. Yeh prove karta hai ki CO2 photosynthesis ke liye zaroori hai.
Sunlight (Activity 10.3): Ek plant ko dark mein rakhne ke baad uski leaf par starch test karne par blue-black colour nahi aata, jabki sunlight mein rakhe plant ki leaf par aata hai. Yeh prove karta hai ki sunlight essential hai.

[IMAGE: starch_test_in_a_leaf_fig102] (Starch test ki step-by-step process dikhata hai.) [IMAGE: experiment_to_show_co2_is_essential_for_photosynthesis_fig103] (CO2 ki necessity demonstrate karta hai.)

⭐Remember

Starch test mein leaf ko alcohol mein boil karna decolourisation ke liye hota hai, taaki chlorophyll remove ho jaaye aur iodine test ka result clear dikhe.

💡Tip

Starch test ke steps aur har step ka reason bahut important hai. Diagram-based questions mein bhi aa sakta hai.

Gas Exchange through Stomata

Plants mein gas exchange (CO2 lena aur O2 chhodna) mainly leaves ki surface par present tiny pores ke through hota hai, jinhe stomata kehte hain.

Stomata ka Structure:
Stomata (singular: stoma) tiny pores hote hain, jo leaves ki lower surface par zyada hote hain.
Har stoma do bean-shaped guard cells se surrounded hota hai.
Guard cells stomata ki opening aur closing ko regulate karte hain.

Function of Stomata:
Carbon Dioxide Uptake: Photosynthesis ke liye CO2 air se stomata ke through andar aata hai.
Oxygen Release: Photosynthesis ke by-product ke roop mein bani O2 stomata ke through air mein release hoti hai.
Transpiration: Water vapour ka release bhi stomata ke through hota hai. Yeh process plants ko cool rakhti hai aur water transport mein help karti hai.

Mechanism of Stomatal Opening & Closing:
Opening: Jab guard cells mein water enter karta hai, toh woh swell (phool jaate hain) aur curve ho jaate hain, jisse stoma open ho jaata hai.
Closing: Jab guard cells se water bahar nikalta hai, toh woh shrink ho jaate hain aur straight ho jaate hain, jisse stoma close ho jaata hai.
Light aur water availability is process ko control karti hai.

Experiment (Activity 10.5):
Water plant ko sunlight mein rakhne par usse air bubbles nikalte hain. Yeh bubbles oxygen ke hote hain, jo photosynthesis ke dauran release hoti hai. Yeh oxygen stomata ke through hi release hoti hai.

[IMAGE: stomata_on_a_leaf_surface_fig106] (Stomata ka magnified view aur guard cells dikhata hai.) [IMAGE: experiment_showing_release_of_oxygen_during_photosynthesis_fig104] (Oxygen release ko demonstrate karta hai.)

📖Definition

Stomata: Leaves ki surface par maujood tiny pores, jo gas exchange (CO2 intake, O2 release) aur transpiration ke liye responsible hote hain.

❗Important

Stomata sirf gas exchange hi nahi, balki transpiration (plants se water loss in the form of vapor) mein bhi important role play karte hain.

Transport of Water, Minerals and Food in Plants

Plants mein substances ko ek part se dusre part tak le jaane ke liye special transport system hota hai, jise vascular system kehte hain. Ismein do main tissues hote hain: Xylem aur Phloem.

Transport of Water and Minerals (Xylem):
Absorption: Roots soil se water aur dissolved minerals absorb karte hain.
Path: Yeh water aur minerals roots se stem tak aur phir leaves tak xylem vessels ke through transport hote hain.
Xylem: Yeh thin tube-like structures hote hain jo plant mein water aur minerals ko upar ki taraf (unidirectionally) transport karte hain.
Driving Force: Transpiration pull (leaves se water loss) aur root pressure water ko upar khinchne mein help karte hain.

Transport of Food (Phloem):
Production: Food (glucose, phir starch) leaves mein photosynthesis se banta hai.
Path: Yeh food leaves se plant ke baaki saare parts tak (roots, growing points, storage organs) phloem vessels ke through transport hota hai.
Phloem: Yeh bhi thin tube-like structures hote hain jo food ko plant ke sabhi parts tak (bidirectionally) transport karte hain.

Vascular Bundles: Xylem aur Phloem aksar ek saath milkar vascular bundles banate hain, jo stem aur leaves mein hote hain.

Experiment (Activity 10.7):
Ek plant twig ko red coloured water mein rakhne par, kuch ghanto mein ya agle din, twig ke stem aur leaves mein red colour dikhta hai. Yeh prove karta hai ki water stem ke through upar transport hota hai.
Red colour xylem vessels mein dikhta hai, confirming xylem ka role in water transport.

[IMAGE: experiment_transport_of_water_in_plants_fig107] (Water transport ka experiment dikhata hai.) [IMAGE: transport_of_water_and_minerals_in_plants_fig108] (Xylem aur Phloem ka structure aur function dikhata hai.)

📖Definition

Xylem: Plant mein water aur minerals ko roots se leaves tak transport karne wala tissue.

📖Definition

Phloem: Plant mein leaves se bane food ko plant ke sabhi parts tak transport karne wala tissue.

Respiration in Plants

Jaise animals, waise hi plants bhi respire karte hain. Respiration woh process hai jismein plants store kiye hue food (glucose) ko break down karke energy release karte hain.

Respiration Process:
Plants oxygen (O2) lete hain aur carbon dioxide (CO2) chhodte hain.
Yeh process din aur raat dono time hoti hai, jabki photosynthesis sirf din mein (sunlight mein) hoti hai.
Respiration mein, glucose oxygen ki presence mein break down hota hai.

Word Equation:

$$ \text{Glucose} + \text{Oxygen} \longrightarrow \text{Carbon Dioxide} + \text{Water} + \text{Energy} $$

Chemical Equation (for higher classes):

$$ C_6H_{12}O_6 + 6O_2 \longrightarrow 6CO_2 + 6H_2O + \text{Energy} $$

Energy ka Use:
Respiration se release hui energy plants apni growth, development, repair aur other metabolic activities ke liye use karte hain.

Gas Exchange in Respiration:
Leaves mein gas exchange stomata ke through hota hai.
Stems mein lenticels (tiny pores) aur roots mein root hair ke through bhi gas exchange hota hai.

Experiment (Activity 10.8):
Germinating seeds ko conical flask mein rakhne par, woh respire karte hain aur CO2 release karte hain.
Yeh CO2 delivery tube ke through lime water (calcium hydroxide solution) mein jaati hai.
Lime water CO2 ki presence mein milky ho jaata hai, jo prove karta hai ki plants (germinating seeds) respiration ke dauran CO2 release karte hain.

Photosynthesis vs. Respiration:
Photosynthesis: Food banata hai, O2 release karta hai, CO2 consume karta hai, energy store karta hai, sirf din mein hota hai.
Respiration: Food break karta hai, CO2 release karta hai, O2 consume karta hai, energy release karta hai, din aur raat dono time hota hai.

[IMAGE: setup_to_demonstrate_respiration_in_plants_fig109] (Respiration experiment setup dikhata hai.)

❗Important

Plants din mein photosynthesis aur respiration dono karte hain. Raat mein sirf respiration karte hain (kyunki sunlight nahi hoti).

💡Tip

Photosynthesis aur Respiration ke beech ka difference table form mein yaad karna bahut helpful hai. Yeh board exams mein frequently pucha jaata hai.

Easy (15)

Which pigment helps plants capture sunlight efficiently for photosynthesis?
- Xanthophyll
- Chlorophyll (correct)
- Carotene
- Anthocyanin
Why: Chlorophyll is the green pigment essential for capturing sunlight during photosynthesis.
The process by which plants prepare their own food is called ______________.
Why: Photosynthesis is the process plants use to make food.
Tiny pores on the surface of leaves that help in the exchange of gases are called stomata.
Why: Stomata are indeed the tiny pores responsible for gas exchange in leaves.
Which of the following is a raw material required for photosynthesis?
- Oxygen
- Glucose
- Carbon dioxide (correct)
- Nitrogen
Why: Carbon dioxide is a key raw material for photosynthesis.
The food prepared by plants is stored in the form of ______________.
Why: Plants store excess food as starch.
Water and minerals are transported from the roots to other parts of the plant through the phloem.
Why: Xylem transports water and minerals, not phloem.
Which part of the plant is primarily responsible for preparing food?
- Roots
- Stem
- Leaves (correct)
- Flowers
Why: Leaves are often called the 'food factories' of plants.
Plants use energy produced during respiration for their growth and development.
Why: Respiration releases energy from glucose for plant activities.
Identify the part of the leaf labeled 'A' in the diagram, which is responsible for gas exchange.
- Guard cell
- Stomatal pore (correct)
- Epidermis
- Chloroplast
Why: The stomatal pore is the opening through which gas exchange occurs.
The process of breaking down glucose to release energy in plants is called ______________.
Why: Respiration is the process that releases energy from glucose.
Which of the following is an output product of photosynthesis?
- Water
- Carbon dioxide
- Oxygen (correct)
- Minerals
Why: Oxygen is a byproduct released during photosynthesis.
The experiment shown in the diagram demonstrates the release of which gas during photosynthesis?
- Carbon dioxide
- Nitrogen
- Oxygen (correct)
- Hydrogen
Why: The bubbles observed in the experiment indicate the release of oxygen.
Plants absorb water and minerals from the soil through their leaves.
Why: Roots absorb water and minerals, not leaves.
Which of the following conditions is NOT essential for plant growth?
- Sunlight
- Water
- Darkness (correct)
- Nutrients
Why: Plants need sunlight for photosynthesis, not darkness, for optimal growth.
The experiment showing a plant twig in red coloured water demonstrates the transport of ______________ in plants.
Why: The red dye moving up the stem shows water transport.

Medium (15)

Why do plants need to de-starch a leaf before performing an iodine test for starch?
- To make the leaf softer for testing
- To ensure any starch detected was newly formed during the experiment (correct)
- To remove chlorophyll and make the color change visible
- To kill any microorganisms on the leaf surface
Why: De-starching ensures that any starch found is a result of the experimental conditions.
Match the plant structure with its primary function.
Why: Xylem for water, phloem for food, stomata for gas exchange, and chlorophyll for light capture.
What is the primary product of photosynthesis that serves as an instant source of energy for plants?
Why: Glucose is the immediate energy source produced during photosynthesis.
Arrange the steps of the starch test in a leaf in the correct order.
Why: The correct sequence is boiling, decolorizing with alcohol, washing, then adding iodine.
Which of the following experimental setups would best demonstrate that sunlight is necessary for photosynthesis?
- One plant in sunlight, another in the dark, both watered. (correct)
- One plant watered, another unwatered, both in sunlight.
- One plant with CO2, another without CO2, both in sunlight.
- One plant with green leaves, another with variegated leaves, both in sunlight.
Why: Comparing plants in light vs. dark, with all other conditions constant, shows sunlight's necessity.
What is the function of the structure labeled 'X' in the given diagram of a plant stem?
- Transport of water and minerals (correct)
- Transport of food from leaves
- Storage of starch
- Exchange of gases
Why: Xylem (X) is responsible for transporting water and minerals.
Match the process with its primary purpose.
Why: Photosynthesis makes food, respiration releases energy, transpiration moves water, and roots absorb nutrients.
What is the role of sodium hydroxide solution in the experiment to show that carbon dioxide is essential for photosynthesis?
- To provide water to the leaf
- To absorb carbon dioxide from the air (correct)
- To decolorize the leaf
- To provide nutrients to the leaf
Why: Sodium hydroxide absorbs carbon dioxide, creating a CO2-free environment.
Which component of the process of respiration is represented by 'Y' in the equation: Glucose + Y → Carbon dioxide + Water + Energy?
Why: Oxygen is consumed during respiration to break down glucose.
Arrange the following events in the correct order as they occur during photosynthesis.
Why: Photosynthesis starts with light absorption, then energy conversion, water splitting, and finally CO2 reduction.
Match the plant part with the substance it primarily transports.
Why: Roots absorb water/minerals, leaves produce food, xylem transports water, and phloem transports food.
What is the term for the overall process by which plants obtain the food they need to grow?
Why: Photosynthesis is the process of food synthesis in plants.
The diagram shows an experimental setup. What is the purpose of placing the pot in the dark for two to three days initially?
- To kill the plant for easier experimentation
- To make the leaves soft for inserting into the bottle
- To destarch the plant, ensuring any starch detected later is newly formed (correct)
- To prevent water loss from the leaves
Why: Placing the plant in the dark removes existing starch, making the experiment results clearer.
Which of the following is NOT a factor affecting plant growth as observed in Activity 10.1?
- Availability of sunlight
- Availability of water
- Type of soil (correct)
- Presence of chlorophyll
Why: Activity 10.1 focused on sunlight and water, not soil type.
What is the primary function of the vascular tissue labeled 'Y' in the diagram, which is responsible for transporting food?
- Transport of water and minerals
- Transport of food (sugars) from leaves (correct)
- Support for the plant stem
- Storage of excess water
Why: Phloem (Y) transports food from the leaves to other plant parts.

Hard (10)

Assertion (A): Leaves are generally broad and flat. Reason (R): This structure helps in efficient capture of sunlight and exchange of gases for photosynthesis.
Why: The broad, flat shape of leaves maximizes light absorption and gas exchange.
A gardener observes that a plant kept in a dimly lit room is growing tall and spindly with pale yellow leaves, while an identical plant in a sunny spot is short and bushy with dark green leaves. Which of the following factors is most likely responsible for the difference in growth and color?
- Difference in water availability
- Difference in soil nutrients
- Difference in light intensity (correct)
- Difference in carbon dioxide levels
Why: Light intensity directly affects chlorophyll production and overall plant growth.
Which two of the following are true regarding the process of photosynthesis?
- It consumes oxygen and releases carbon dioxide.
- It converts light energy into chemical energy. (correct)
- It produces glucose and oxygen. (correct)
- It occurs only during the night.
Why: Photosynthesis uses light to make glucose and oxygen, storing chemical energy.
Assertion (A): Plants perform respiration throughout the day and night. Reason (R): Respiration is necessary to release energy for the plant's continuous life processes.
Why: Plants respire constantly to get energy for all their functions.
A student sets up an experiment to study the transport of water in plants using a white flower and blue-colored water. After a few hours, the petals of the flower start turning blue. Which part of the flower's stem is primarily responsible for this observation?
- Phloem
- Cambium
- Xylem (correct)
- Cortex
Why: Xylem vessels transport water, causing the blue color to reach the petals.
Observe the diagram showing the overall process of photosynthesis. Which two components are absorbed from the environment and are essential for this process?
- Oxygen and Glucose
- Carbon dioxide and Water (correct)
- Sunlight and Oxygen
- Minerals and Glucose
Why: Plants take in carbon dioxide and water for photosynthesis.
Assertion (A): Decolorizing a leaf in alcohol is an important step in the starch test. Reason (R): Alcohol removes the green pigment chlorophyll, making the blue-black color change of iodine visible if starch is present.
Why: Removing chlorophyll makes the iodine-starch reaction visible.
A scientist is studying a new plant species and observes that it has very few stomata on its leaves. Which two of the following processes would likely be significantly affected in this plant?
- Absorption of water by roots
- Exchange of carbon dioxide for photosynthesis (correct)
- Transport of food through phloem
- Release of oxygen during photosynthesis (correct)
Why: Few stomata limit both CO2 intake and O2 release, impacting photosynthesis.
Observe the experimental setup. If the lime water in the test tube turns milky, what does this indicate about the germinating seeds?
- They are performing photosynthesis.
- They are releasing oxygen.
- They are respiring and releasing carbon dioxide. (correct)
- They are absorbing water from the cotton.
Why: Milky lime water indicates CO2 release, a product of respiration.
A farmer notices that his crop plants are wilting despite regular watering. Upon inspection, he finds that the soil is waterlogged. Which of the following is the most likely reason for the wilting?
- Excess water is promoting rapid growth, leading to wilting.
- Waterlogging reduces oxygen availability to roots, impairing water absorption. (correct)
- The plants are absorbing too much water, causing cell burst.
- The waterlogged soil is too cold for the roots to function.
Why: Waterlogged soil deprives roots of oxygen, hindering their ability to absorb water.