ENERGY for life�

PART 1

In the beginning… 4 billion years ago

…the land surface of our planet looked like this

Photo of the surface of Mars. Wikipedia

…later, there was plant life

Lichen and moss on granite

….created from the Sun’s energy in early plant forms.

…these plants are able to break down (over long time) the surface of the rock.

​

Aided from weathering, by wind and water, a soil was created.

moss

lichen

These early plants had no flowers – reproducing by shedding ‘spores’

As roots were able to grow, soil nutrients and water were taken up to the leaves

Male & female spores need water as a medium to enable fertilisation

Dicksonia

And then came flowering plants, with male pollen and female ovules

Kingia australis

Seeds and pollen allowed plants to evolve without water…

…and plants were able to invade dry land.

Sheoaks – Allocasuarina campestris

Eucalyptus torquata

HOW DID PLANTS MAKE FOOD FOR ANIMAL LIFE?

They harnessed the energy from the Sun

THE SUN MAKES ENERGY FROM NUCLEAR FUSION

The pressure inside the Sun forces 4 atoms to combine (fuse) and form 1 atom

https://www.youtube.com/watch?v=2U3ucaVzRqQ

4 Hydrogen atoms…

_e-

+

_e-

+

_e-

+

_e-

+

proton

neutron

_e-

_e-

_e-

electron

…. fuse to form 1 Helium atom

+

+

+

….giving out energy

Energy travels as particles (photons) and waves

Waves are measured by the distance, in nanometres (nm)

from one peak to the next (1nm =1x10^-9 m)

WHAT IS VISIBLE LIGHT?

…energy between 400 and 700nm

‘Beyond’ the visible spectrum

Energy with longer wave-lengths (INFRA-RED) is HEAT

‘Before’ the visible spectrum

Energy with shorter wave-lengths is called ULTRA-VIOLET

We ‘see’ the visible spectrum (interpreted by retinal cells in our eyes) when wave-lengths between 400 and 700nm pass through water droplets in air that act as a prism (refraction)

WHAT BEES SEE

• Bees also see ultra‐violet light patterns, invisible to us, that are a different colour from the rest of the petals.

​

• From a bee's eye‐view, these colours and patterns guide the bee to the flower's store of nectar. 

• The light spectrum bees see is from 600 ‐300 nm, with ‘colours’ from blue‐green, blue, violet, and into the ultraviolet.

​

• If deprived of UV light, bees lose interest in foraging, and remain in the hive until forced out by severe food shortages.

​

PLANTS

AND VISIBLE LIGHT

PART 2

WHAT A LEAF ‘SEES’

• Very little energy is absorbed in the green region (500 – 550), which, is why our eyes see leaves as green

• PIGMENTS are molecules that absorb energy of particular wave lengths in the light spectrum, interpreting the energy as COLOUR

• The pigment, CHLOROPHYLL (a) absorbs best in the red area of the spectrum (650 – 700nm), and a little less in the blue region (400 – 480nm).

WHAT A LEAF ‘SEES’

• 𝛃-CAROTENE, absorbs energy maximally between 400-500nm in the spectrum, reflecting back colours of yellow and red.

• Some leaves are red in the cold season. This is due to other pigments (anthocyanins) ‘masking’ light energy reaching the chloroplasts.

https://www.khanacademy.org/science/biology/photosynthesis-in-plants/the-light-dependent-reactions-of-photosynthesis/a/light-and-photosynthetic-pigments

• Other pigments, CAROTENOIDS, selectively absorb wavelength energies giving leaves (and fruits) colours other than green.

WHERE IS CHLOROPHYLL?

Inside the chloroplast

in the leaf cell…

…in the surface layers of the leaf.

ENERGISING �CHLOROPHYLL

magnesium atom

chlorophyll molecule

ADP

NADPH

ATP

NADP

e^-

energy carriers for for making sugars

e^-

e^-

e^-

e^-

e^-

& DRIVE THIS REACTION

water + carbon-dioxide

sugar + oxygen

+ 6O₂

ATP

NADP

6H₂O

+

6CO₂

C₆H₁₂O₆

(glucose)

LET’S MAKE SUGAR

1. What is the molecular structure of water?
2. What is the molecular structure of carbon dioxide?

hydrogen

H

carbon

oxygen

HH (H₂)

OO (O₂)

oxygen gas

ATOMS

H₂ O

WATER

MOLECULES

COO

CO₂ gas

CARBON DIOXIDE

C

hydrogen gas

O

MAKING SUGAR

17

Step 1. Make 6 molecules of water

Step 2. Make 6 molecules of carbon dioxide

1.

2.

C

H

H

O O

O

Step 3. Separate one H atom from the water molecule

Step 4. This leaves one O atom joined with one H atom (OH molecule)

3.

​

4.

H

OH

5.

Step 5. From the carbon dioxide molecule (made in step 1) separate the C atoms from the two O atoms

C

O

Step 6. Have 5 C atoms and one O atom ready

6.

Step 7. Make a 6-sided ring (hexagon) with 5 C atoms and 1 O atom

7.

O

C

Step 8. Attach 5 H atoms to the 5 C atoms inside the hexagon

8.

C

O

H

Step 9. Attach 4 OH molecules (made in step 4) to the outer edge of 4 C atoms

22

OH

OH

9.

STEP 10.

To the remaining carbon atom (from step 6) add 2 H and 1 OH (from step 4)

STEP 11.

Attach this group of atoms to C atom no. 1

11.

10.

H

OH

C

You have made a molecule of sugar!

GLUCOSE

contains energy

What is left?

12 oxygen atoms, or 6 molecules of O₂ (gas)

Do your maths!

6

6 x 2 = 12

how many entered the leaf?

6 + 12 = 18

how many did the leaf use to make sugar?

12 6

6

how many are left over?

0

remember that the oxygen molecule is 2 atoms bound together

= 6O₂

O

H

C

6H₂O + 6CO₂ = C₆H₁₂O₆ + 6O₂

0

12

Worksheet for equation (6H₂O + 6CO₂ = C₆H₁₂O₆ + 6O₂)

Ben Tisdale, Yrs 4/5/6 Science teacher, Bull Creek PS

GLUCOSE MOLECULES

…using various media!

Year 5-6 Mt Pleasant PS

THE EQUATION IS REVERSIBLE…

6H₂O + 6CO₂

C₆H₁₂O₆ + 6O₂

photo – syn – the - sis

met – ab – o - lism

C₆H₁₂O₆ + 6O₂

6H₂O + 6CO₂

+ ENERGY

… enabling air-breathing animals to evolve

CHEMICAL CONCEPTS…introduced

• Difference between an atom and a molecule
• Chemical notation
• Building an equation
• Energy from the Sun creates the energy in plants
• Oxygen from plants allowed animal evolution on land
• How animals derive energy from eating plants