B8 Photosynthesis

Question 1

what energy type do plants store?

Answer 1

light energy

Question 2

what is the chemical reaction where plants trap light energy called?

Answer 2

photosynthesis

Question 3

what type of reaction is photosynthesis?

Answer 3

an endothermic reaction

Question 4

where does photosynthesis take place?

Answer 4

in the leaves of the plant
they contain chlorophyll which absorbs energy

Question 5

what is the word equation for photosynthesis?

Answer 5

carbon dioxide + water –light–> glucose + oxygen

Question 6

what is the chemical formula for photosythesis?

Answer 6

6CO2 + 6H2O –> C6H12O6 + 6O2

Question 7

how does light intensity affect photosynthesis?

Answer 7

as the light intensity increases, the rate of photosynthesis increases
this is because the plant has more light to carry out the photosynthesis reaction so the reaction gets faster
there is a point where the rate of photosynthesis no longer increases
this means it is no longer the limiting factor. something else is the limiting factor

Question 8

what does limiting mean?

Answer 8

the reaction of photosynthesis was not as fast as it could have been due to a factor

Question 9

how do levels of carbon dioxide affect the rate of photosynthesis?

Answer 9

as CO2 increases, so does photosynthesis
at a certain point, the rate of photosynthesis no longer increases so is no longer the limiting factor
(the same as light intensity)

Question 10

how does the amount of chlorophyll in the leaves affect photosynthesis?

Answer 10

if there is less chlorophyll, the rate of photosynthesis is lower as the leaves cannot trap as much light energy

Question 11

how does temperature affect the rate of photosynthesis?

Answer 11

as temperature increases, the enzymes work faster so the rate of photosynthesis increases
if the temperature continues to increase, the enzymes denature so the rate falls

Question 12

how is glucose used in respiration?

Answer 12

to release energy in the mitochondria

Question 13

why is starch produced?

Answer 13

to store glucose from photosynthesis
it can be converted back to glucose when it is needed

Question 14

what are fats and oils made from glucose used for?

Answer 14

a storage form of energy

Question 15

what is cellulose made from?

Answer 15

glucose produced in respiration

Question 16

what are amino acids used for in plants?

Answer 16

to synthesise proteins

Question 17

what is used to make amino acids?

Answer 17

glucose from respiration
nitrate ions from the soil

Question 18

why is an LED light source used to investigate photosynthesis?

Answer 18

they do not release much heat

Question 19

why is sodium hydrogen carbonate solution used when investigating photosynthesis?

Answer 19

it releases carbon dioxide needed for photosynthesis

Question 20

what is wrong with counting bubbles in the investigation of photosynthesis?

Answer 20

the bubbles may be too fast to count
the bubbles are not always the same size

Question 21

how can the issues of counting the bubbles when investigating photosynthesis be resolved?

Answer 21

place the pondweed under a funnel and catch the bubbles in a measuring cylinder
this set-up can be used to measure the volume of oxygen produced

Question 22

what is the trend for the number of bubbles/minute (or volume of oxygen) and the distance from a lamp? (when investigating photosynthesis)

Answer 22

if the distance is doubled, the number of bubbles falls by a factor of 4
this is the inverse square law
this happens because if the distance is doubled, the light intensity falls by four times. because light is needed in photosynthesis, this causes the number of bubbles to fall by four times

Question 23

how do farmers increase the rate of photosynthesis in greenhouses?

Answer 23

light and heat the greenhouse
add extra carbon dioxide

Question 24

what is the problem with farmers altering conditions inside greenhouses?

Answer 24

it is quite expensive so the extra cost has to be justified by the increase in yield