Chapter 10: Living Creatures

MUST KNOW!

What Makes it "Living"?

An object is alive if it demonstrates ALL of these vital signs:

Movement (Internal or External)
Nutrition (Energy & Food)
Respiration (Breathing & Energy)
Excretion (Waste Elimination)
Stimuli Response (React to Changes)
Reproduction (Continuity of Kind)
Growth & Death (Life to End)

Note: Absence of any of these over its lifespan indicates it is non-living.

Plant Movements?!

Plants don't walk, but they certainly move in clever ways!

Insect Trap (*Drosera*): Saucer-shaped leaves with sticky, hair-like projections. When insects land, hairs fold inward and trap the insect for nutrition.

Climber Vines: Climbers search for support and actively wind around poles, branches, or walls.

Sleep & Bloom: Opening and closing of flower petals and leaves in response to daylight.

Seed Germination Ingredients

To wake up a tiny embryo, a seed needs precise conditions:

Water

Softens the seed coat & activates embryo.

Air & Soil

Gives space & oxygen for root respiration.

Fun Fact: Light vs. Dark

*Coleus & Petunia*: Need light to sprout!
*Calendula & Zinnia*: Need complete darkness!
Most crops do not require light until *after* germination.

Growth & Stimuli responses

Directional Rules:

Roots grow downward (towards water/gravity).
Shoots grow upward (towards sunlight).

Scientist Spotlight:

J.C. Bose

Jagadish Chandra Bose (1858-1937) built the Crescograph to record plant responses to stimuli (heat, electricity, gravity).

Bean Plant Life Cycle

I

Seed: Resting embryo protected by a seed coat.

II

Germination: Roots sprout down, shoots up.

III

Leaves: Photosynthesis begins, growth bursts.

IV

Flowers: Plant transitions to sexual reproduction.

V

Fruits/Pods: Seeds form. Plant eventually dies.

Seed → Sprout → Leaves → Flower → Pod/Fruit → Death → Seed

Mosquito Cycle & Control

Mosquitoes spread malaria, dengue, & chikungunya by breeding in stagnant water.

1. Eggs (Laid on stagnant water)

2. Larva (Worm-like, actively swimming)

3. Pupa (Resting stage, shape changing)

4. Adult (Emerges and flies away)

Biological Hack: Kerosene Spray

Spraying a thin layer of kerosene oil over stagnant water blocks the surface tension. Larvae & pupae can't pierce it to breathe oxygen → they suffocate & die.

Life Cycle of a Frog

Frogs undergo radical change called Metamorphosis:

Spawn (Day 1): White jelly-like egg clusters floating on pond surface.
Embryo (Day 3-4): Growth inside the egg capsule.
Tadpole (Day 7-10): Swims in water, breathes via gills, has a long tail.
Tadpole with legs (Week 8-10): Grows hind & front limbs.
Froglet (Week 12): Tail shrinks; lungs develop. Transition to land.
Adult Frog (Week 14): Fully formed, no tail, lives on land & water.

Crazy Plant Stimuli

A stimulus is any external change that triggers an instant response.

1. Touch-me-not (*Mimosa pudica* / *Chhui-mui*):

Leaves instantly fold up & drop when touched. This is a rapid defense mechanism!

2. Amla (Indian Gooseberry):

Leaves face each other and fold inward right after sunset. (Sleep movement)

3. Climbers:

Wind tightly around obstacles. The touch of the object triggers asymmetric growth!

Shorthand Glossary

Respiration: Inhaling air to extract oxygen to release energy.

Excretion: Discarding harmful chemical metabolic wastes.

Stomata: Tiny pores on plant leaves for gas exchange.

Spawn: White jelly-like egg clutches of frogs.

Germination: Process of seed sprouting to form a seedling.

Metamorphosis: Transforming radically from larva to adult.