Photosynthesis

plants need four things to grow, these are, sunlight, soil, water, and carbon dioxide

The word equation for photosynthesis is carbon dioxide + water → (light) glucose + energy

The symbol equation for photosynthesis is 6CO2 + 6H20 → (light) C6H12O6 + 6O2

photosynthesis is an endothermic reaction as it takes energy from its surroundings

Energy is stored as chemical energy within glucose molecules to be used later

photosynthesis takes placed in the chloroplast, chloroplast contains chlorophyll which makes the leaf green chlorophyll absorbs light energy

The adapt For photosynthesis are:

1. then leaves have a smaller diffusion distance so more diffusion takes place

2. broad leaves have large surface area so it can absorb more sunlight

3. chloroplast are filled with chlorophyll so it can absorb more light energy for photosynthesis

4. Xylem supply water phloem remove sugars

5. airspaces and spongy mesophyll allow carbon dioxide to come in to close contact with cells

6. guard cells open and close the stomata to regulate gas exchange and water loss

We use glucose for

Cellulose - cell walls

Respiration - release energy

Oils and fats - seeds

Proteins - growth

Starch - storage molecule

we use the antonym CROPS to remember this

TESTING LEAVES FOR STARCH

• Leaf from a plants kept in the dark tested with iodine. The iodine did not turn black meaning there’s no photosynthesis due to no light.

• Leaf from a plant kept in the light tested with iodine that iodine turned black meaning photosynthesis took place and glucose was produced forming starch

LIMITING FACTORS

A limiting factor affects the rate of photosynthesis which prevents the optimum rate being achieved

light intensity, temperature, concentration of carbon dioxide, amount of chlorophyll are the full limiting factors of photosynthesise

• as light intensity increases the rate of photosynthesis also increases however as light intensity increases too much photosynthesis plateaus

• as carbon dioxide increases rate a photosynthesis also increases as carbon dioxide increases too much rate of photosynthesis plateaus

• as temperature increases rate of photosynthesis also increases however when reaches optimum temperature photosynthesis rapidly decreases

independent variable is the thing we change each time in order to see an effect

dependent variable is a thing we measure in order to see if the independent has an effect

Control variable is what we keep the same

HIGHER TIER ONLY

the inverse square law is:

light intensity (directionally proportional) 1/distance squared

therefore more light intensity, more photosynthesis

AEROBIC RESPIRATION

aerobic respiration uses air

The word equation for aerobic respiration is

oxygen + glucose → carbon dioxide + water (+energy)

keep in mind energy is released not produced

on average us humans breathe in 21% of oxygen and breathe out 19% of it

on average us humans breathe in 0.04% of carbon dioxide and breathe out 2% of it

we use the energy for:

• digestion

• temperature

• Muscle contractions

• Making large molecules

• Growth

ANAEROBIC RESPIRATION

Anaerobic respiration does not require air

anaerobic respiration produces lactic acid instead of carbon dioxide and water not releasing as much energy therefore is it less efficient then aerobic respiration.

after exercise the heart pumps faster in order to give oxygen to the muscles therefore we breathe quicker and deeper to complete more aerobic respiration to produce oxygen for the muscles and throughout the blood

OXYGEN DEBT

oxygen debt is the amount of extra oxygen needed by the body after exercise to breakdown lactic

explaining why we continue to breathe heavily after intense exercise

ANAEROBIC RESPIRATION IN YEAST

glucose → ethanol + carbon dioxide