B4: Bioenergetics

What is photosynthesis?

A chemical reaction that converts light energy into chemical energy

Is photosynthesis exothermic or endothermic?

Endothermic

What does endothermic mean?

Reaction that takes in energy from the surroundings

What is the word equation for photosynthesis?

Carbon dioxide + water ---> glucose + oxygen

What is the balanced symbol equation for photosynthesis?

6CO2 + 6H2O -----> C6H12O6 + 6O2

What are the 5 ways plants use glucose?

Respiration

Making cellulose

Making amino acids

Stored as fats

Stored as starch

T or F: Starch made from glucose is soluble?

F - starch made from glucose is insoluble

What is a limiting factor?

Something that limits how fast something can happen

What are the 4 limiting factors of photosynthesis?

Temperature

Carbon dioxide conc

Light intensity

Chlorophyll

How does the rate of photosynthesis change as light intensity increases?

Rate of photosynthesis increases until a point that another factor becomes limiting

How does the rate of photosynthesis change as carbon dioxide concentration increases?

Rate of photosynthesis increases until another factor becomes limiting

How does the rate of photosynthesis change when temperature is increased?

Rate of photosynthesis increases until it gets too hot and enzymes become denatured

What are the independent, dependant and control variables in the investigating photosynthesis practical?

Ind = Light intensity

Dep = Amount of oxygen produced

Con = Temperature, CO2 conc and amount/size of pondweed

What substance is dissolved into the water to provide carbon dioxide in the investigating photosynthesis practical?

Sodium hydrogencarbonate

What does the inverse square law state?

Light intensity decreases in proportion to the square of the distance

What is the inverse square law formula?

Light intensity ∞ 1 / distance^2

What do farmers grow plants in to create the best growing environment?

Greenhouses

How do greenhouses make sure temperature doesn't become limiting?

They trap the heat from the sun to keep it warm

How can farmers increase the temperature of a greenhouse in the winter?

A heater

How might a farmer decrease temperature of a greenhouse in summer?

Ventilation or shades

How do farmers make sure photosynthesis can continue at night

Using artificial lights

How can farmers increase carbon dioxide levels in a greenhouse?

Use a paraffin heater as it makes carbon dioxide as a by-product

How can farmers provide plants with the minerals they need to grow healthily?

Adding fertilisers to the soil

Why is it important farmers provide just the right amount of light, heat, CO2 etc.?

So they produce a good crop but don't waste money

Define respiration.

The process of transferring energy from glucose which happens in every cell

Is respiration exothermic or endothermic?

Exothermic

What is an exothermic reaction?

A reaction that released energy to the surroundings

Give 3 uses of emergy transferred by respiration.

Build larger molecules

Give muscles energy to contract

Keep body temp steady

What are the 2 types of respiration?

Aerobic and Anaerobic

Define metabolism

All of the chemical reactions in an organism

What 3 things can be formed by joining lots of small glucose molecules together?

Starch

Glycogen

Cellulose

What does glucose combine with to make amino acids?

Nitrate ions

What is excess protein broken down into?

Urea

What is the difference between aerobic and anaerobic respiration?

Aerobic respiration uses oxygen but anaerobic respiration doesnt

Where does most aerobic respiration happen in cells?

Mitochondria

What is the word equation for aerobic respiration?

Glucose + oxygen -----> carbon dioxide + water

What is the symbol equation for aerobic respiration?

C6H12O6 + 6O2 -----> 6CO2 + 6H2O

What is the word equation for anaerobic respiration in humans?

Glucose -----> lactic acid

Why does anaerobic respiration transfer less energy than aerobic respiration?

The glucose isnt fully oxidised

What is the word equation for anaerobic respiration in plant and yeast cells?

Glucose ----> ethanol + carbon dioxide

What is the name for anaerobic respiration in yeast cells?

Fermentation

What 2 foods use fermentation?

Bread and alcohol

What causes your muscles to hurt during exercise?

Build up of lactic acid

What is oxygen debt?

The amount of extra oxygen your body needs to react with the build up of lactic acid to remove it from the cells

Where does blood transport lactic acid?

The liver

What happens to lactic acid in the liver?

It is coverted back to glucose