Topic 2.9: Photosynthesis Flashcards Preview

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Flashcards in Topic 2.9: Photosynthesis Deck (27)
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1

Definition of photosynthesis

Process by which cells synthesize organic compounds from inorganic molecules using light energy

2

Chemical equation of photosynthesis

6CO2 + 12H2O + Light => C6H12O2 + 6O2

3

Definition of electromagnetic spectrum

Range of all possible frequencies of electromagnetic radiation

4

Relationship between wavelength and energy

The shorter the wavelength, the greater the energy

5

Wavelength range of visible light

400 – 700 nm

6

Function of chlorophyll

Pigment responsible for the absorption of light and its conversion into chemical energy (ATP)

7

Light absorption and reflection of chlorophyll

a) Absorption of blue and red light most effectively
b) Reflection of green light more than other colors

8

Photosynthesis => Type of reaction

a) Endothermic
b) Anabolic

9

Steps in photosynthesis

a) Light dependent reactions
b) Light independent reactions

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Purpose of light dependent reactions

Light is converted into chemical energy

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What happens in light dependent reactions?

a) Light is absorbed by chlorophyll to produce ATP
b) Photolysis of water forms oxygen and hydrogen

12

Purpose of light independent reactions

Carbon compounds are made from chemical energy

13

What happens in light independent reactions?

ATP and hydrogen are fixed with carbon dioxide

14

Definition of chromatography

Experimental technique by which mixtures can be separated

15

Procedure of chromatography

a) A mixture is dissolved in a fluid and passed through a static material
b) The different components of the mixture travel at different speeds, causing them to separate
c) A retardation factor is calculated

16

Consequences of photosynthesis on Earth in Oceans

a) Oxidation of dissolved iron in water
b) Precipitation of iron oxide, creating banded iron formations

17

Consequences of photosynthesis on Earth in Atmosphere

a) Rise in oxygen concentration to 20%
b) Formation of ozone layer, protecting Earth from UV radiation

18

Limiting factors of photosynthesis

a) CO2
b) Light intensity
c) Temperature

19

CO2 as a limiting factor

a) CO2 is involved in the fixation of carbon to form organic molecules
b) Increasing CO2 concentration increases the rate of photosynthesis, until the enzymes involved in the Calvin cycle reach their saturation point and can no longer increase reaction rates.

20

Temperature as a limiting factor

a) Photosynthesis is controlled by enzymes, which are sensitive to temperature fluctuations
b) As temperature increases reaction rate will increase, as reactants have greater kinetic energy and more collisions result
c) Above a certain temperature the rate of photosynthesis will decrease as essential enzymes begin to denature

21

Light intensity as a limiting factor

a) Light is absorbed by chlorophyll, which converts the radiant energy into chemical energy (ATP)
b) As light intensity increases, reaction rate will increase since more chlorophyll are being photoactivated
c) At a certain light intensity photosynthetic rate will plateau, as all available chlorophyll are saturated with light

22

Ways to measure rate of photosynthesis

a) Measuring CO2 uptake
b) Measuring O2 production
c) Measuring Biomass

23

Measuring CO2 uptake

a) CO2 uptake can be measured by placing leaf tissue in an enclosed space with water
b) Water free of dissolved CO2 can be produced by oiling and cooling water
c) CO2 interacts with H2O molecules, producing bicarbonate and H+, which changes the pH
d) Increased uptake of CO2 by the plant will lower the concentration in solution and increase the alkalinity

24

Measuring O2 production

a) O2 production can be measured by submerging a plant in an enclosed water filled space attached to a sealed gas syringe
b) Any oxygen gas produced will bubble out of solution and can be measured by a change in meniscus level on the syringe

25

Measuring biomass

a) Glucose production can be indirectly measured by a change in the plant’s biomass (weight)
b) This requires the plant tissue to be completely dehydrated prior to weighing to ensure the change in biomass represents organic matter and not water content

26

Pigments in plants

Chlorophyll
Carotene
Xanthophyll

27

Definition of limiting factor

Factor nearest its minimum/furthest from its optimum that increasing it while maintaining other factors constant increases reaction rate