Chapter 1: Nutrition in Plants

Chapter at a Glance – Nutrition in Plants

🔹 Introduction to Nutrition

  • All living organisms require food for survival, energy, growth, repair, and maintaining body functions.
  • The mode of taking in food and its utilization is called nutrition.

🔹 Modes of Nutrition in Plants

  • Autotrophic Nutrition:
    • Plants prepare their own food using sunlight, water, carbon dioxide, and chlorophyll.
    • Example: Green plants.
  • Heterotrophic Nutrition:
    • Organisms depend on others for food.
    • Example: Animals, fungi, some plants (like Cuscuta).

🔹 Photosynthesis – Food Making Process in Plants

  • Definition: The process by which green plants prepare food using sunlight, water, CO₂, and chlorophyll.
  • Raw materials: Carbon dioxide (from air), water (from soil).
  • Site: Leaves (contain chloroplasts with chlorophyll).
  • Equation: Carbon dioxide+Water→Sunlight, ChlorophyllGlucose+Oxygen\text{Carbon dioxide} + \text{Water} \xrightarrow{\text{Sunlight, Chlorophyll}} \text{Glucose} + \text{Oxygen}Carbon dioxide+WaterSunlight, Chlorophyll​Glucose+Oxygen 6CO2+6H2O→LightC6H12O6+6O26CO₂ + 6H₂O \xrightarrow{\text{Light}} C₆H₁₂O₆ + 6O₂6CO2​+6H2​OLight​C6​H12​O6​+6O2​

🔹 Important Structures

  • Stomata: Tiny pores on the underside of leaves – allow gas exchange.
  • Chlorophyll: Green pigment in leaves that captures sunlight.

🔹 Other Modes of Nutrition in Plants

  • Parasitic plants: Get food from host plant.
    • Example: Cuscuta (Amarbel)
  • Insectivorous plants: Trap insects to fulfill nitrogen requirement.
    • Example: Pitcher plant
  • Saprotrophic plants: Feed on dead and decaying matter.
    • Example: Fungi like mushrooms
  • Symbiotic relationship: Two organisms live together and benefit from each other.
    • Example: Lichens (algae + fungi), Rhizobium bacteria and leguminous plants.

🔹 How Nutrients are Replenished in Soil

  • Plants absorb minerals from soil, which get depleted.
  • Fertilizers and manures are added to restore them.
  • Rhizobium bacteria in roots of legumes fix nitrogen from air into soil naturally.

🔹 Examples & Activities

  • Activity to test starch in leaves (boiling leaf in alcohol and iodine test).
  • Observation of parasitic or insectivorous plants.
  • Growing fungus on bread in moist, dark place.

2. Key Terms and Definitions – Nutrition in Plants

TermDefinition
NutritionThe process by which living organisms obtain and utilize food.
AutotrophicMode of nutrition in which organisms make their own food (e.g., green plants).
HeterotrophicMode of nutrition in which organisms depend on others for food.
PhotosynthesisThe process by which green plants prepare food using CO₂, water, and sunlight.
ChlorophyllGreen pigment in plants that captures sunlight for photosynthesis.
StomataTiny pores on leaf surfaces through which gas exchange occurs.
Parasitic plantA plant that derives nutrients from another living plant (host).
Cuscuta (Amarbel)A parasitic plant that does not have chlorophyll and depends on host plants.
Insectivorous plantA plant that traps and digests insects to get nutrients.
Pitcher plantAn insectivorous plant that traps insects inside a pitcher-like structure.
SaprotrophicA mode of nutrition where organisms feed on dead and decaying matter.
FungiNon-green organisms like mushrooms that grow on decaying matter.
SymbiosisA relationship in which two organisms live together and benefit each other.
LichensSymbiotic association between algae and fungi.
RhizobiumBacteria that live in root nodules of leguminous plants and fix nitrogen.

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3. Multiple Choice Questions (MCQs) – Nutrition in Plants

❓ Choose the correct option:

  1. The green pigment present in leaves is: a) Hemoglobin
    b) Chlorophyll
    c) Carotene
    d) Xanthophyll
  2. The process of making food by plants is known as: a) Respiration
    b) Transpiration
    c) Photosynthesis
    d) Digestion
  3. Which of the following is a parasitic plant?
    a) Rose
    b) Cuscuta
    c) Sunflower
    d) Neem
  4. Rhizobium bacteria help in:
    a) Photosynthesis
    b) Digestion
    c) Nitrogen fixation
    d) Growth of fruits
  5. The plant that traps and feeds on insects is:
    a) Cuscuta
    b) Rose
    c) Pitcher Plant
    d) Mango
  6. Food prepared in leaves is transported to other parts of the plant by:
    a) Phloem
    b) Xylem
    c) Stomata
    d) Roots
  7. The tiny pores on leaves for gas exchange are called:
    a) Lenticels
    b) Veins
    c) Stomata
    d) Glands
  8. Fungi obtain their food by:
    a) Photosynthesis
    b) Saprotrophic mode of nutrition
    c) Symbiosis
    d) Ingestion
  9. Lichens are formed due to association between:
    a) Fungus and plant
    b) Fungus and algae
    c) Bacteria and algae
    d) Insect and plant
  10. Which of the following is not required for photosynthesis?
    a) Water
    b) Carbon dioxide
    c) Oxygen
    d) Sunlight

Answer Key

Q1Q2Q3Q4Q5
bcbcc
Q6Q7Q8Q9Q10
acbbc

4. Fill in the Blanks

Fill in the blanks with the correct words:

  1. The process by which green plants make their food is called __________.
  2. Leaves have tiny pores called __________ for exchange of gases.
  3. Plants take in __________ gas during photosynthesis.
  4. The end product of photosynthesis is __________.
  5. __________ is a yellow tubular parasitic plant.
  6. __________ bacteria fix nitrogen in leguminous plant roots.
  7. A __________ plant traps and digests insects.
  8. Fungi obtain nutrition through __________ mode.
  9. __________ is the green pigment present in leaves.
  10. The association between algae and fungi is called __________.

Answer Key – 2×5 Table Format

1. Photosynthesis2. Stomata3. Carbon dioxide4. Starch5. Cuscuta
6. Rhizobium7. Insectivorous8. Saprotrophic9. Chlorophyll10. Lichen

5. True or False – Nutrition in Plants

Write True or False for the following statements:

  1. All plants prepare their food through photosynthesis.
  2. Fungi are green plants and make their own food.
  3. Chlorophyll is essential for the process of photosynthesis.
  4. Insectivorous plants obtain all their nutrition from insects only.
  5. Stomata help in the exchange of gases in leaves.
  6. Plants take nitrogen directly from the air during photosynthesis.
  7. Cuscuta is an example of a parasitic plant.
  8. The sun is the ultimate source of energy for all living beings.
  9. Pitcher plant is an example of a saprotrophic plant.
  10. Rhizobium bacteria help in fixing atmospheric nitrogen in the soil.

Answer Key

Q1Q2Q3Q4Q5
FalseFalseTrueFalseTrue
Q6Q7Q8Q9Q10
FalseTrueTrueFalseTrue

6. Match the Following – Nutrition in Plants

Match the items in Column A with their correct pair in Column B:

Column AColumn B
A. Cuscuta1. Insectivorous plant
B. Rhizobium2. Tiny pores on leaves
C. Photosynthesis3. Parasite
D. Pitcher Plant4. Fixes nitrogen in soil
E. Stomata5. Food-making process in plants
F. Chlorophyll6. Green pigment
G. Fungi7. Symbiotic relationship
H. Lichens8. Non-green saprotrophs
I. Autotrophs9. Make their own food
J. Saprotrophic nutrition10. Nutrition from dead organisms

Answer Key

A – 3B – 4C – 5D – 1E – 2
F – 6G – 8H – 7I – 9J – 10

7. Short Answer Questions – Nutrition in Plants

✍️ Answer the following in 2–3 sentences:

  1. What is photosynthesis?
    Answer: Photosynthesis is the process by which green plants make their own food using sunlight, carbon dioxide from the air, and water from the soil. The food is stored in the form of glucose, and oxygen is released as a by-product.
  2. Why are plants called autotrophs?
    Answer: Plants are called autotrophs because they make their own food using simple substances like carbon dioxide and water, with the help of sunlight and chlorophyll.
  3. What are heterotrophic plants? Give one example.
    Answer: Heterotrophic plants are those that cannot prepare their own food and depend on other plants or animals. An example is Cuscuta (Amarbel), which is a parasitic plant.
  4. What role does chlorophyll play in photosynthesis?
    Answer: Chlorophyll is the green pigment in leaves that absorbs sunlight, which is necessary to carry out the process of photosynthesis.
  5. Name the raw materials required for photosynthesis.
    Answer: The raw materials required for photosynthesis are carbon dioxide (CO₂), water (H₂O), and sunlight.
  6. What is the function of stomata in leaves?
    Answer: Stomata are tiny pores on the surface of leaves that allow the exchange of gases like oxygen and carbon dioxide during photosynthesis and respiration.
  7. What are insectivorous plants? Name one example.
    Answer: Insectivorous plants are those that trap and digest insects to obtain nutrients, especially nitrogen. An example is the Pitcher Plant.
  8. What is the role of Rhizobium bacteria in plants?
    Answer: Rhizobium bacteria live in the root nodules of leguminous plants and fix atmospheric nitrogen, enriching the soil with nutrients.
  9. What is saprotrophic nutrition? Give one example.
    Answer: Saprotrophic nutrition is a mode of nutrition in which organisms feed on dead and decaying matter. Fungi like mushrooms are examples.
  10. What are lichens?
    Answer: Lichens are a symbiotic association between algae and fungi. The algae prepare food through photosynthesis, and the fungi provide shelter and absorb water and nutrients.

8. Long Answer Questions – Nutrition in Plants

✍️ Answer the following in 5–6 sentences:

  1. Explain the process of photosynthesis with the help of an equation.
    Answer: Photosynthesis is the process by which green plants prepare their own food using sunlight, carbon dioxide, and water. Chlorophyll in the leaves absorbs sunlight and uses its energy to convert carbon dioxide from the air and water from the soil into glucose (a form of sugar). Oxygen is released as a by-product. This process occurs in the chloroplasts present in leaf cells.
    The equation for photosynthesis is: Carbon dioxide+WaterSunlight + Chlorophyll​Glucose+Oxygen
    6CO2​+6H2​O ———————-> ​C6​H12​O6​+6O2​
  2. Differentiate between autotrophic and heterotrophic modes of nutrition. Give examples.
    Answer: Autotrophic nutrition is a mode where organisms prepare their own food using simple substances like carbon dioxide and water in the presence of sunlight. Green plants are autotrophs.
    Heterotrophic nutrition, on the other hand, is where organisms depend on other organisms for food. Animals and non-green plants like Cuscuta and fungi are heterotrophs.
    Example of autotroph: Mango tree
    Example of heterotroph: Mushroom or Human being
  3. Describe how nutrients are replenished in the soil naturally.
    Answer: Nutrients in the soil are replenished naturally through various methods. One important way is by the action of Rhizobium bacteria, which live in the root nodules of leguminous plants and fix atmospheric nitrogen into the soil. This enriches the soil with nitrogen compounds that are essential for plant growth.
    Decomposition of dead plants and animals by microorganisms also adds nutrients back into the soil. Additionally, natural processes like rain and the breakdown of rocks contribute minerals to the soil.
  4. Write a short note on insectivorous plants. Why do they feed on insects?
    Answer: Insectivorous plants are green plants that can perform photosynthesis but grow in soil deficient in nutrients, especially nitrogen. To meet their nitrogen requirement, they trap and digest insects. These plants have special structures to catch insects.
    For example, the Pitcher Plant has a modified leaf shaped like a pitcher with a lid and digestive juices at the bottom to trap and digest insects. The nutrients from the insects help the plant to grow in poor soil conditions.
  5. Explain the symbiotic relationship with an example from the plant kingdom.
    Answer: A symbiotic relationship is a type of nutrition in which two different organisms live together and benefit from each other. In plants, an example is the association between Rhizobium bacteria and leguminous plants. The bacteria live in root nodules and convert atmospheric nitrogen into a form usable by plants.
    In return, the plant provides the bacteria with shelter and nutrients. Another example is lichens, which are a symbiotic relationship between algae and fungi. The algae make food, and the fungi provide water and support.

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