Science: Class 6 — Chapter 10: Living Creatures: Exploring their Characteristics

10.1 What Sets the Living Apart from the Non-living?

Living beings share common characteristics that distinguish them from non-living things:

Movement: Animals move from place to place. Plants do not move locations but show internal movements (e.g., opening of flowers, winding of climbers, and trapping of insects by the insectivorous plant Drosera).
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 inhaling oxygen and exhaling carbon dioxide to release energy from food. Plants respire using tiny pores called stomata on their leaves.
Excretion: The removal of toxic waste products from the body (e.g., sweat and urine in animals, water droplets on grass/roses).
Response to Stimuli: Reaction to changes in the environment. A change that prompts a reaction is a stimulus (e.g., touching a hot object, or the folding of leaves in the Touch-me-not / Mimosa plant).
Reproduction: The process of producing offspring of one's own kind to ensure the continuity of life.
Death: The end of all life activities in an organism.

10.2 Essential Conditions for Germination of a Seed

Germination: The process of a seed turning into a sprout.
Water: Softens the outer seed coat and helps the internal embryo develop.
Air and Soil: Seeds require oxygen from the spaces between soil particles to respire and grow.
Light and Darkness: Most seeds do not require light to germinate, but some (like Coleus) require light, while others (like Zinnia) require darkness.

10.3 Growth and Movement in Plants

Shoots of plants exhibit movement towards sunlight (upward growth).
Roots of plants grow downwards into the soil (towards gravity and moisture).
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 Life Cycle of a Plant

The life cycle represents the entire process from a seed to a mature plant, and then to the next generation of seeds:

10.5 Life Cycle of Animals

Passes through four distinct 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 air supply, killing larvae and pupae.
Note: The silk moth also undergoes similar stages (egg, larva, pupa, adult), where larvae secrete silk fibers.

Spawn: A jelly-like cluster of frog eggs laid on the water surface.
Stages: Spawn → Embryo → Tadpole (with tail, lives in water) → Froglet (develops legs, begins spending time on land) → Adult Frog (lives on both land and water).