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Session 7: How Life Got Started

Start thinking: 4 billion years ago Earth had no plants, �no animals, no people. Just oceans, gases, volcanoes, and lightning. How is it possible that life could come from this?

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In 1953, two scientists, Stanley Miller and Harold Urey, built a miniature, glass version of early Earth in a laboratory flask

They sealed the ancient gases inside, boiled water, and zapped it with electricity to mimic constant lightning strikes to see if life’s raw ingredients would appear.

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Today’s Big Question:

How did life start on a bare lump of rock like Earth?

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PATHWAY 1

How Did Life on Earth Start?

Explore primordial Earth
Deconstruct the Urey-Miller experiment

10 mins

PATHWAY 2

The First Life

Define what counts as ‘alive’
Investigate life’s starting locations and first cell

10 mins

How did life start on a bare lump of rock like Earth?

Finished? Complete the Origins of Life Minigame

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Is It Alive?

Today you are scientific investigators. Your job is to identify if each item is alive or not alive. How do you know? What is the fatal flaw for the non-living items on the list?

Example:

Items	MRS GREN (/7)	The Fatal Flaw
A robot	2/7 - Movement, Sensitivity - NOT ALIVE	Cannot reproduce or create cellular energy via metabolic respiration. It has no biological cells, metabolism or DNA instructions.

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Items	MRS GREN	The Fatal Flaw
Icicle
Fire
Virus
Seed

Is It Alive?

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Items	MRS GREN	The Fatal Flaw
Icicle

1/7 - Growth - NOT ALIVE

It grows from the outside by mineral accretion (stacking lattice structures). It has no internal nutrition, excretion, respiration, or sensitivity.

Is It Alive?

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Items	MRS GREN	The Fatal Flaw
Fire

3/7 - Movement, Growth, and Nutrition (consumes fuel) - NOT ALIVE

It is an exothermic chemical reaction, not an organism. It completely lacks Reproduction (cannot pass on genetic instructions) and has no cells.

Is It Alive?

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Items	MRS GREN	The Fatal Flaw
Virus

1/7 - Reproduction (but only by hijacking a host) NOT ALIVE

It cannot carry out any other MRS GREN processes independently. It doesn't eat, grow, excrete waste or move on its own.

Is It Alive?

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Items	MRS GREN	The Fatal Flaw
Seed

7/7 - ALIVE

It looks dead, but it is actually dormant (alive but on pause). It respires at an ultra-slow rate inside its shell, waiting for water and temperature to wake up its internal instructions.

Is It Alive?

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WE HAVE COVERED:

The hostile conditions of early Earth
What the Urey-Miller experiment showed and why it mattered
The 7 characteristics that define a living thing
Where on early Earth life might have appeared
The structure of a simple cell and what it could do

Learner Journal

Part 1: Three Things I Learnt Today

Open your Learner Journal. Write down three things you learnt. These can be facts, ideas, or things that surprised you.

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Has today's evidence challenge

what you assumed it means to

be ‘alive’?

Write your response in your Learner Journal, then ﬁnish sections 3-5.

Learner Journal

Part 2: Reflective Question

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“Life is not a strange accident. It is simply what happens when the natural laws of physics and chemistry get to work.” Brian Cox, physicist and broadcaster (2013)

Every living thing on Earth today started somewhere on this planet, in a tidal pool or a deep-sea vent, around 3.7 billion years ago. Everything alive today is descended from that first simple cell.

Lock-In Quote

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Extension Activities

Extension 1

Extension 2

What Does An Egg Do?

The Power Of Flowers