Chapter 10: Living Creatures: Exploring their Characteristics
10.1 What Sets the Living Apart from the Non-living?
Core Characteristics of Living Beings
- Movement: Animals move from place to place. Plants do not move locations but show internal movements (e.g., opening of flowers, climbers winding around supports, and insectivorous plants like Drosera trapping insects).
- Growth: Living organisms increase in size over time (e.g., a child growing into an adult, a seed growing into a tree).
- Nutrition: Living beings require food for energy, growth, and development.
- Respiration: The process of obtaining energy from food. Breathing is a part of respiration. Plants exchange gases through tiny pores called stomata.
- Excretion: Removal of toxic waste products from the body (e.g., sweat and urine in animals; excess water droplets on leaves in plants).
- Response to Stimuli: Reacting to changes in the environment. A change that prompts a reaction is a stimulus (e.g., touching a hot object, or the touch-me-not / chhui-mui plant folding its leaves when touched).
- Reproduction: The process of producing new individuals of one's own kind to ensure the continuity of life.
- Death: The final stage of life when an organism stops exhibiting life characteristics.
10.2 Essential Conditions for Germination of a Seed
Requirements for Seed Germination
- Water: Softens the seed coat and activates the tiny embryo inside to develop.
- Air and Soil: Seeds require oxygen from air spaces between soil particles to respire during germination.
- Light/Dark Conditions: Most seeds do not require light to germinate (some like Coleus require light, while Zinnia requires darkness), but sunlight is essential for the seedling's growth after germination.
10.3 Growth and Movement in Plants
Directional Growth
- Shoots: Grow upwards and bend towards the direction of sunlight.
- Roots: Grow downwards into the soil, even if the plant is placed inverted.
- Jagadish Chandra Bose: An Indian scientist who invented the crescograph to measure plant growth and proved that plants can sense and respond to stimuli.
10.4 & 10.5 Life Cycles of Plants and Animals
Life Cycle of a Plant
- Life Cycle: The entire developmental sequence from a seed to a mature plant, producing the next generation of seeds, and eventually death.
- Bean Plant Stages: Seed (Stage I) → Seed Germination (Stage II) → Appearance of Leaves (Stage III) → Appearance of Flowers (Stage IV) → Appearance of Fruits/Pods (Stage V) → Death.
Life Cycle of a Mosquito
- Four Stages: Egg → Larva → Pupa → Adult.
- Larvae and pupae live in stagnant water and breathe air at the surface.
- Disruption: Spraying kerosene oil on stagnant water forms a thin layer that cuts off the oxygen supply, killing larvae and pupae.
Life Cycle of a Frog
- Stages: Spawn (cluster of eggs) → Embryo → Tadpole (aquatic, has a tail, no legs) → Tadpole with legs → Froglet (develops legs, loses tail) → Adult Frog (amphibious).
Chapter Summary & Learning Enhancement
Key Takeaways
- Objects are classified as living or non-living based on essential life processes.
- Significant structural and habitat changes occur during the life cycles of organisms like frogs and mosquitoes.
- Proper storage of grains and pulses requires keeping them dry and cool to prevent premature seed germination.