B14

Question 1

What is photosynthesis?

Answer 1

Process that converts light energy into biochemical energy which is then used to drive the assimilation of low energy inorganic carbon into high energy organic biochemicals.

Question 2

What is the photosynthesis equation?

Answer 2

6CO2 + 6H20 -> C6H1206 + 6O2

Question 3

What are the two phases of photosynthesis?

Answer 3

Light phase (grana) which is a physical phase
Dark phase (stroma) which is a chemical phase

Question 4

What happens in the light phase?

Answer 4

Light energy absorbed by pigments is funnelled to reaction centres and used to drive the production of ATP (metabolic energy) and NADPH (reducing energy). Oxygen is also formed during the light phase

Question 5

What happens in the dark phase?

Answer 5

Uses ATP and NADPH formed in the light phase in a series of enzyme catalysed reactions to assimilate CO2 into high energy organic form

Question 6

What is climate change?

Answer 6

Large-scale, long-term shift in the planets weather patterns or average temperatures. Earth has had tropical climates and ice ages many times in its 4.5billion years.

Question 7

How much did the ice shelf reduce by?

Answer 7

12%

Question 8

What other changing weather patterns are there?

Answer 8

Rainfall, storms, hurricanes, typhoons, tornados, hurricanes. These create knock on effects and unpredictable patterns

Question 9

What causes greater damage by floods and rainfall?

Answer 9

Compounded changes in land use

Question 10

What are hurricanes and cyclones?

Answer 10

A hurricane is a tropical cyclone that occurs in the Atlantic Ocean and northeastern Pacific Ocean. A cyclone is a large scale air mass that rotates around a strong centre of low atmospheric pressure.

Question 11

What is happening to crop yields due to climate change?

Answer 11

Decrease in some yields.

Question 12

What factors limit photosynthesis?

Answer 12

Light, CO2, Temperature, mineral deficiencies, herbicides, pollutants

Question 13

What does the light saturation curve show

Answer 13

Below compensation point is the dark respiration rate. At low PAR, photosynthesis is masked by respiration. The PAR level where CO2 uptake is equal to CO2 output is called the compensation point. During the light limitation phase, photosynthesis is limited by the light phase. At light saturation, photosynthesis is limited by the dark phase.

Question 14

What is the light saturation curve for a C3 plant?

Answer 14

The carboxylation reaction limits photosynthesis under high light conditions. Photorespiration occurs under low CO2 levels, as stomata close and O2 is added to RuBP instead.

Question 15

What happens in photoinhibition?

Answer 15

A decrease in photosynthesis induced by high fluxes of PAR. Caused by an excess of PAR quanta absorbed due to exposure to excess irradiance, exposure to chilling under normal radiance, exposure to conditions that decrease CO2 fixation under normal irradiance.

Question 16

What follows photoinhibition?

Answer 16

Photo-oxidation

Question 17

What is photo-oxidation?

Answer 17

Bleaching of photosynthetic pigments, unless there is prolonged stress resulting in photodamage, photoinhibition is reversible and there is no permanent damage to thylakoid membranes

Question 18

When considering responses of plants to climate change ; what factors need to be considered?

Answer 18

Change in temp and climate, change in the CO2 conc, mineral availability.

Question 19

In biomes what determines the distribution of vegetation?

Answer 19

Climate

Question 20

What ecosystems have the highest productivity?

Answer 20

Tropical rainforest, fresh water wetland, saltwater wetland

Question 21

What provide data on past climatic conditions?

Answer 21

Ice cores they contain CO2 bubbles which are formed as snow falls and traps air between flakes

Question 22

What effects does anthropogenic activity have on climate change?

Answer 22

Unprecedented increases in atmospheric CO2.

Question 23

In what form is CO2 available to terrestrial and aquatic plants?

Answer 23

CO2 to terrestrial, HCO3- to aquatic.

Question 24

How does CO2 diffuse into plants?

Answer 24

Via stomata

Question 25

What does the rate of CO2 uptake equate to and how is it measured?

Answer 25

It equates to rate of photosynthesis and is measured by infra red gas analysis.

Question 26

What is the equation for CO2 uptake?

Answer 26

[CO2]ext - [CO2]int / Ra + Rs + Rm. R = resistance to diffusion offered by boundary layer (a) stomata (s) and mesophyll (m)

Question 27

What effects does the CO2 saturation curve show on CO2 concentration on net photosynthesis?

Answer 27

Current atmospheric CO2 is approx 411ppm, a doubling of CO2 in the atmosphere is widely predicted.

Question 28

What effect does increasing CO2 on vegetation have for C3 plants?

Answer 28

An increase in the rate of net photosynthesis, at least in the short term, because : increase in CO2 as substrate for photosynthesis, decrease in photorespiration. Also an increased water use efficiency.

Question 29

What effect does increasing CO2 on vegetation have for C4 plants?

Answer 29

Saturated at current CO2 concentration

Question 30

How does CO2 enrichment experiments compare biomass?

Answer 30

Compare biomass production at 35Pa and 70Pa in growth chambers. This gives a biomass enhancement ratio.

Question 31

What are some experimental issues related to studying the effect of increasing CO2 on vegetation?

Answer 31

Data available for <1% of world higher plant flora. Large variation, inter-specific differences. Some species show a negative response. Length of experiment is important, short term experiments, many C3 plants show a significant stimulation in net CO2 assimilation.

Question 32

What is the free-air CO2 enrichment (FACE)?

Answer 32

Opportunity to make long term observation of forests under elevated CO2 in realistic forest stand conditions.

Question 33

What is the effect if CO2 in water use efficiency?

Answer 33

CO2 affects stomatal conductance, decreases stomatal aperture, decreased number of stomata per unit area.

Question 34

What do studies on the effect of CO2 on water use efficiency show?

Answer 34

Average reduction in stomatal density with CO2 enrichment. Also, decreased stomatal conductance. CO2 enrichment will increase water use efficiency by decreasing transpiration.

Question 35

What are carbon:nitrogen ratios?

Answer 35

Plants must maintain C:N ratios within certain limits. Above these, C accumulates as carbohydrate and C-fixation is down-regulated, plants become N deficient. CO2 fertilisation may be limited by availability of nitrogen and more significant where there is nitrogen pollution

Question 36

What do in situ studies into CO2 enrichment find?

Answer 36

Enriching CO2 alone does not stimulate enough long-term fertilisation. If CO2 concentration is doubled and temperature is raised by 4 degrees, CO2 fertilisation is sustained and there is increased carbon storage. Warmer temp may have stimulated extra mineralisation in tundra soils.

Question 37

What have studies found about the effects of invasive species and global climate change?

Answer 37

Responses of 6 invasive weedy plants, 46% stimulation in biomass with CO2 fertilisation from current to future levels. Biggest stimulation was in the 20th century so therefore those changes may have played a significant role in selecting invasive species.

Question 38

How does climate change affect plants?

Answer 38

Temperature has great effects, some species are cold intolerant. Boundaries between vegetation types are generally determined by summer warmth.

Question 39

How does rainfall affect plants?

Answer 39

It affects the balance of grasses to woody vegetation. Other factors such as soil type of herbivory may also be affected by climate change.

Question 40

How is plant biodiversity affected by climate change?

Answer 40

Species left behind, as they cannot change distribution fast enough. Species with long life cycles and/or slow dispersal are particularly vulnerable. Isolated or disjunct species are particularly vulnerable. Invasive species most successful.

Question 41

What is phenology?

Answer 41

The study of the timing of events in the natural calendar. Mismatch between timing of lifecycles between animals and plants