bioenergetics

Question 1

What does photosynthesis do

Answer 1

Uses energy to change carbon dioxide and water into glucose and oxygen

Question 2

Where does photosynthesis take place and why

Answer 2

Takes place in chloroplasts in green plant cells as they contain pigments like chlorophyll that absorb light. Energy’s transferred to the chloroplasts from the environment by light

Question 3

Symbol equation for photosynthesis

Answer 3

6CO2 + 6H2O → C6H12O6 + 6O2

Question 4

Five ways plants use glucose

Answer 4

Cellulose - converted to cellulose to make strong plant cell walls
Lipids - Glucose is turned into lipids (fats and oils) for storing in seeds
Amino acids - combined with nitrate ions from soil to make them
Proteins - Amino acids then make proteins
Starch - Glucose is turned into starch and stored in roots, stems and leaves, ready for use when photosynthesis isn’t happening.

Question 5

Why is starch good to use for storing

Answer 5

Starch is insoluble where as a cell with lots of glucose in would draw in loads of water and swell up

Question 6

What is the rate of photosynthesis affected by

Answer 6

The intensity of light , conc of co2 and temp

Question 7

What is the limiting factor of photosynthesis at night

Answer 7

Light

Question 8

What is the limiting factor of photosynthesis in winter

Answer 8

Temperature

Question 9

What is the limiting factor of photosynthesis when it is warm enough and bright enough

Answer 9

Usually carbon dioxide

Question 10

How can the amount of chlorophyll in a plant affect the rate of photosynthesis

Answer 10

The amount of chlorophyll in a plant can be affected by disease or environmental stress such as a lack of nutrients. These factors can cause chloroplasts to become damaged or to not make enough chlorophyll. This means the rate of photosynthesis is reduced as they cannot absorb as much light

Question 11

Why do graphs for the rate of photosynthesis flatten out

Answer 11

The factor increasing the rate of photosynthesis can only work for a certain amount of time before another factor becomes limiting.

Question 12

How to tell what factor is limiting from a graph that shows more than one limiting factor

Answer 12

See what has changed when the lines separate

Question 13

Practical for testing the affect of light intensity on rate of photosynthesis

Answer 13

• A source of LED light is placed at a specific distance from the boiling tube
• Fill tube with sodium hydrogen carbonate solution which releases carbon dioxide used for photosynthesis
• Put a piece of pondweed on a boiling tube with the cut end at the top
• The pondweed is left top photosynthesise for a specific amount of time - as it photosynthesises the oxygen
• Start a stopwatch and count the number of oxygen bubbles being produced in one minute
• Repeat the steps twice more and find an average
• Keeping the the temp and time the pondweed is left to photosynthesise the same, change the distance of the light source and repeat all steps.

Question 14

Why is an LED light source used

Answer 14

Used as they don’t project that much light, as too much light would affect the result of the experiment

Question 15

Problems with the photosynthesis practical

Answer 15

• The number of bubbles can be too fast to count accurately
• Bubbles are not always the same size

Question 16

How do we solve the problems of the photosynthesis practical

Answer 16

Place the pondweed under a funnel and catch the bubbles in a measuring cylinder filled with water.
use cylinder to measure the volume of oxygen

Question 17

How does the inverse square law link light intensity and distance

Answer 17

The distance and light intensity are inversely proportional to each other

Question 18

Inverse square law formula

Answer 18

Light intensity is inversely proportional to 1 divided by distance (d) squared

Question 19

How do greenhouses create the ideal conditions for farming

Answer 19

Help to trap the sun’s heat and make sure that the temp does not become limiting

Question 20

How is light artificially used to create ideal conditions for farming

Answer 20

Farmers often supply artificial light after the sun goes down to give their plants more quality photosynthesis time

Question 21

How are carbon dioxide levels artificially used to create ideal conditions for farming

Answer 21

Using paraffin heater - as the paraffin burns it makes carbon dioxide as a by-product

Question 22

Why are plants enclosed in a greenhouse

Answer 22

To stop pests and diseases from entering.

Question 23

Why is it important that the farmers provide the right amount of heat, light ect.

Answer 23

Need enough to make the plants grow well

Question 24

What is respiration

Answer 24

The process of transferring energy from the breakdown of glucose which goes in every cell

Question 25

How do organisms use their energy

Answer 25

• To build up larger molecules from smaller ones
• Used to allow muscles to contract in animals
• In mammals used to keep body temp steady in colder surroundings

Question 26

Metabolism

Answer 26

All the chemical reactions in an organisms controlled by enzymes

Question 27

Aerobic respiration

Answer 27

Respiration using oxygen

Question 28

Where does aerobic respiration take place

Answer 28

Mitochondria

Question 29

Symbol equation for respiration

Answer 29

602 + C6H12O6—->6CO2 + 6H20

Question 30

When does anaerobic respiration take place

Answer 30

When you do vigorous exercise and your body cannot supply enough oxygen to your muscles you start doing anaerobic respiration as well as the anaerobic respiration

Question 31

Word equation for anaerobic respiration in muscle cells

Answer 31

glucose ——-> lactic acid

Question 32

Difference between aerobic respiration and anaerobic respiration

Answer 32

Anaerobic respiration does not transfer as much energy as glucose isn’t fully oxidised.

Question 33

Word equation for anaerobic respiration in plants and yeast

Answer 33

glucose —–> ethanol + carbon dioxide

Question 34

Anaerobic respiration in yeast cells

Answer 34

Fermentation

Question 35

Use of fermentation by yeast

Answer 35

Used to make bread and alcoholic drinks

Question 36

What does “oxygen debt” mean

Answer 36

Oxygen debt is the amount of extra oxygen your body needs to react with the build up of lactic acud

Question 37

What do we have to do due to oxygen debt

Answer 37

Keep breathing hard for a while once you have stopped in order to get more oxygen. into your blood which will be transported to the muscle cells