Class 6 Science Notes Chapter 7 (Chapter 7) – Examplar Problem Book

Detailed Notes with MCQs of Chapter 7, "Getting to Know Plants," from your Science Exemplar book. This is a fundamental chapter, and understanding it well is crucial not just for your regular studies but also for various competitive government exams where basic science is tested. We'll break down the key concepts systematically.

Chapter 7: Getting to Know Plants - Detailed Notes for Exam Preparation

1. Classification of Plants:

Plants are broadly categorized based on their height, stem nature, and branching pattern:

• Herbs:

  • Short plants with green, tender (soft) stems.
  • Usually have few or no branches.
  • Examples: Tomato, Wheat, Paddy (Rice), Grass, Coriander, Mint.

• Shrubs:

  • Medium-sized plants.
  • Stems are hard but not very thick.
  • Branching occurs near the base of the stem, giving a bushy appearance.
  • Examples: Lemon, Rose, Jasmine, China Rose (Hibiscus).

• Trees:

  • Tall plants with hard, thick, brown stems called the trunk.
  • Branches arise from the upper part of the stem, much above the ground.
  • Examples: Mango, Neem, Banyan, Peepal.

• Other Categories (Based on Stem Weakness):

  • Creepers: Plants with weak stems that cannot stand upright and spread on the ground. Examples: Pumpkin, Watermelon, Strawberry.
  • Climbers: Plants with weak stems that take support from neighbouring structures (like walls, trees, sticks) to climb up. Examples: Grapevine, Money Plant, Pea Plant, Bean Plant.

2. Parts of a Plant and Their Functions:

A typical plant consists of the root system (below ground) and the shoot system (above ground).

• Stem:

  • Function:
    • Provides support to the plant, holding branches, leaves, flowers, and fruits.
    • Conducts water and minerals absorbed by the roots upwards to the leaves and other parts (through xylem tissues - extra info).
    • Conducts food prepared by the leaves downwards to other parts, including roots (through phloem tissues - extra info).
    • Some stems store food (e.g., Potato, Ginger, Onion - These are modified stems).
    • Some stems perform photosynthesis when green.
  • Structure: Has nodes (points where leaves arise) and internodes (part between two nodes).

• Leaf:

  • Function:
    • Photosynthesis: The primary site for preparing food using carbon dioxide, water, sunlight, and chlorophyll (the green pigment). Oxygen is released as a byproduct. The food prepared is usually starch.
      • Equation (Conceptual): Carbon Dioxide + Water ---(Sunlight + Chlorophyll)---> Food (Glucose/Starch) + Oxygen
    • Transpiration: The process of loss of excess water in the form of water vapour through tiny pores (stomata), usually on the underside of leaves. This helps cool the plant and creates a 'pull' for water absorption by roots.
  • Structure:
    • Petiole: The stalk that attaches the leaf blade to the stem.
    • Lamina: The broad, green, flat part of the leaf (leaf blade).
    • Veins: Network of lines on the lamina, containing vascular tissues for transport.
    • Midrib: The prominent central vein.
  • Venation: The arrangement of veins in the lamina.
    • Reticulate Venation: Veins form a net-like pattern on both sides of the midrib. (Common in dicot plants like Mango, Rose, Peepal).
    • Parallel Venation: Veins run parallel to each other. (Common in monocot plants like Grass, Maize, Wheat, Banana).

• Root:

  • Function:
    • Anchorage: Firmly holds the plant in the soil.
    • Absorption: Absorbs water and essential mineral nutrients from the soil.
    • Prevents soil erosion.
    • Some roots store food (e.g., Carrot, Radish, Turnip, Sweet Potato, Beetroot - These are modified roots).
  • Types:
    • Taproot System: Consists of a main primary root (taproot) that grows vertically down, from which smaller lateral roots arise. (Typically found in plants with reticulate leaf venation).
    • Fibrous Root System: Consists of a cluster of thin, moderately branching roots arising from the base of the stem. There is no main root. (Typically found in plants with parallel leaf venation).
  • Relationship: There is often a strong correlation: Plants with reticulate venation in leaves usually have taproots, while plants with parallel venation usually have fibrous roots.

• Flower:

  • Function: The reproductive part of the plant. Its main function is to produce fruits and seeds.
  • Structure (Parts of a typical flower):
    • Pedicel: The stalk of the flower.
    • Sepals: The outermost whorl, usually green, leaf-like structures. Protect the flower in the bud stage. Collectively called the calyx.
    • Petals: Usually brightly coloured structures inside the sepals. Attract insects and birds for pollination. Collectively called the corolla.
    • Stamens: The male reproductive part, located inside the petals. Each stamen consists of:
      • Anther: Swollen tip that produces pollen grains (containing male gametes).
      • Filament: The stalk that supports the anther.
      • Collectively called the androecium.
    • Pistil (or Carpel): The female reproductive part, usually located in the centre of the flower. Each pistil consists of:
      • Stigma: The sticky tip that receives pollen grains.
      • Style: The tube-like structure connecting the stigma to the ovary.
      • Ovary: The swollen base containing ovules (which contain the female gamete).
      • Collectively called the gynoecium.

• Fruit:

  • Develops from the ovary of the flower after fertilization.
  • Protects the seed(s).
  • Examples: Mango, Apple, Tomato, Cucumber (Yes, botanically tomatoes and cucumbers are fruits!).

• Seed:

  • Develops from the ovules inside the ovary after fertilization.
  • Contains an embryo (baby plant) and stored food.
  • Protected by a seed coat.
  • Germinates under favourable conditions (water, air, warmth) to grow into a new plant.

Key Processes:

• Photosynthesis: Food making process in leaves. Requires CO2, Water, Sunlight, Chlorophyll. Produces Food (Starch) and Oxygen.
• Transpiration: Loss of water vapour from leaves. Cools the plant, helps in water transport.
• Pollination: Transfer of pollen grains from the anther to the stigma.
• Fertilization: Fusion of male gamete (from pollen) with the female gamete (in ovule) inside the ovary.

Multiple Choice Questions (MCQs)

Here are 10 MCQs based on the chapter for your practice:

1. Which of the following is classified as a shrub?
   (a) Tomato
   (b) Mango
   (c) Lemon
   (d) Grass

2. The primary function of the stem does NOT include:
   (a) Conduction of water
   (b) Bearing leaves and flowers
   (c) Absorption of minerals from soil
   (d) Providing support to the plant

3. A leaf shows veins running parallel to each other. What type of root system is this plant likely to have?
   (a) Taproot system
   (b) Fibrous root system
   (c) Prop root system
   (d) No root system

4. Which part of the flower develops into the fruit after fertilization?
   (a) Sepal
   (b) Petal
   (c) Ovary
   (d) Ovule

5. The process by which plants lose excess water in the form of water vapour through their leaves is called:
   (a) Photosynthesis
   (b) Respiration
   (c) Transpiration
   (d) Absorption

6. Potato is a modified form of which plant part that stores food?
   (a) Root
   (b) Stem
   (c) Leaf
   (d) Fruit

7. Which of the following are the requirements for photosynthesis?
   (a) Carbon dioxide, Oxygen, Sunlight
   (b) Water, Minerals, Oxygen
   (c) Carbon dioxide, Water, Chlorophyll, Sunlight
   (d) Oxygen, Water, Chlorophyll

8. The male reproductive part of a flower is the:
   (a) Pistil
   (b) Sepal
   (c) Petal
   (d) Stamen

9. Reticulate venation is commonly found in plants having:
   (a) Fibrous roots
   (b) Taproots
   (c) Parallel venation
   (d) No roots

10. Ovules are present inside which part of the flower?
    (a) Anther
    (b) Stigma
    (c) Ovary
    (d) Petal

Answer Key for MCQs:

1. (c) Lemon
2. (c) Absorption of minerals from soil (This is a function of roots)
3. (b) Fibrous root system
4. (c) Ovary
5. (c) Transpiration
6. (b) Stem
7. (c) Carbon dioxide, Water, Chlorophyll, Sunlight
8. (d) Stamen
9. (b) Taproots
10. (c) Ovary

Study these notes carefully, focus on the functions and structures of each plant part, and understand the key processes. This will build a strong foundation for your exams. Good luck!