Photosynthesis

Question 1

define photosynthesis

Answer 1

the process used by green plants to make their own food using light energy

Question 2

photosynthesis location

Answer 2

takes place in special organelles in the plant called chloroplasts, which are only present in parts of the plant exposed to light
occurs only in the green parts of the plant, mainly the leaves

Question 3

photosynthesis word equation

Answer 3

carbon dioxide + water + light (in presence of chlorophyll and enzymes) = glucose + oxygen

Question 4

photosynthesis chemical equation

Answer 4

CO2 + H2O + light (in presence of chlorophyll and enzymes) = C6H12O6 + O2

Question 5

photosynthesis essentials

Answer 5

to work out if photosynthesis has taken place you need to find out if starch is present in the plant. this is because the glucose that is formed during photosynthesis is stored in the form of starch.
enzymes are required for the process of photosynthesis. they are biological catalysts which speed up chemical reactions within organisms.

Question 6

products of photosynthesis

Answer 6

carbohydrates, stored in the form of starch
the water that is needed in photosynthesis is split into hydrogen ions and oxygen gas. the oxygen that is released is another end-product of photosynthesis.

Question 7

PHASES OF PHOTOSYNTHESIS: light-dependent phase

Answer 7

-occurs in the thylakoid
-light energy is trapped by the chlorophyll and used for the following processes:
PHOTOLYSIS
-energy used to split water into hydrogen ions and oxygen molecules which is given off as gas
-H is carried to the light-independent phase by NADP in the form of NADPH (an energy-carrier)
PHOTOPHOSPHORYLATION
Energy used to combine a phosphate group with Adenosine diphosphate (ADP) to form Adenosine triphosphate (ATP) - an energy carrier

Question 8

PHASES OF PHOTOSYNTHESIS: light-independent phase

Answer 8

• also known as the CALVIN CYCLE
• NADPH carries H-ion and ATP carries energy from light-dependent phase
• H is released and bonds with CO2 using energy from ATP
• Product is GLUCOSE (C6H12O6)

Question 9

IMPORTANCE OF PHOTOSYNTHESIS: a source of energy within food chains

Answer 9

all organisms obtain their nutrients either directly or indirectly from green plants

Question 10

IMPORTANCE OF PHOTOSYNTHESIS: regulating the composition of air

Answer 10

global concentrations of O2 and CO2 are largely kept in check by photosynthesis

• O2 levels increased
• CO2 levels decreased

Question 11

FACTORS AFFECTING RATE OF PHOTOSYNTHESIS: light

Answer 11

• brighter light = increased rate of photosynthesis

- up to a certain point, as plants have a maximum photosynthetic rate

Question 12

FACTORS AFFECTING RATE OF PHOTOSYNTHESIS: carbon dioxide

Answer 12

• more CO2 in the air = increased rate of photosynthesis

- at very high levels of CO2 photosynthetic rate decreases as environment becomes too acidic

Question 13

FACTORS AFFECTING RATE OF PHOTOSYNTHESIS: temperature

Answer 13

• up to a certain point, higher temperature = increased rate of photosynthesis
• temperature increases of 10*C doubles the rate
• flourish in greenhouse-maintained warmth
• temperatures above 40*C slows down photosynthesis and eventually it stops