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IB Biology > C1.3 > Flashcards

C1.3 Flashcards

Photosynthesis

1
Q

State the by-product of the photolysis stage of photosynthesis.

A

oxygen

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2
Q

Identify the molecule used as a source of hydrogen during photosynthesis.

A

water (H2O)

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3
Q

Identify the correct description of an absorption spectrum.

A

A graph that shows the wavelengths of light absorbed by each pigment

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4
Q

Identify the correct range of wavelengths that make up visible light.

A

400–700 nm

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5
Q

Retention factor (Rf) is calculated in chromatography.

A

Distance travelled by sample divided by distance travelled by solvent

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6
Q

Determine what can be deduced by comparing the calculated Rf value of pigments in an extract to known Rf values of plant pigments.

A

The pigments present in the plant extract

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7
Q

Identify the main limiting factors of photosynthesis in nature.

A

Carbon dioxide concentration, light intensity and temperature

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8
Q

In an experiment to determine the effect of light intensity on the rate of photosynthesis using algal balls and hydrogen carbonate indicator, determine what would be a suitable control.

A

A tube with indicator but no algal balls

  • It would be a suitable control since you can see the change in the indicator’s color.
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9
Q

In a carbon dioxide enrichment experiment, determine what would be a suitable control group.

A

Plants exposed to normal atmospheric carbon dioxide levels

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10
Q

Identify the main function of photosystems.

A

To absorb and transfer light energy in order to excite electrons

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11
Q

Identify the correct description of a photosystem.

A

Arrays of pigments within protein complexes

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12
Q

During the light-dependent reactions, which component provides the electrons needed to replace those lost from photosystem II?

A

Electrons from water molecules

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13
Q

Identify which of the following is an advantage of having an array of pigments in a photosystem, compared with individual pigment molecules.

A

Higher light absorption efficiency

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14
Q

Identify which of the following correctly describes the role of cyclic photophosphorylation.

A

It produces ATP solely through the action of photosystem I

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15
Q

Why is non-cyclic photophosphorylation essential to the light-independent reactions of photosynthesis?

A

Only non-cyclic photophosphorylation generates reduced NADP

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16
Q

Which of the following conditions would you expect to find within the intermembrane space of the thylakoids while light is being absorbed?

A
  • becomes acidic
    Low pH conditions due to the high concentration of H+
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17
Q

Identify the first step of the light-independent reactions in photosynthesis.

A

Carbon fixation
-carbon dioxide is combined with RuBP using the enzyme Rubisco.

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18
Q

How many molecules of triose phosphate are produced from the fixation of six molecules of carbon dioxide.

A

12

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19
Q

Determine how many molecules of CO2, ATP and reduced NADP are required to regenerate 6 molecules of RuBP.

A

6 CO2, 18 ATP and 12 reduced NADP

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20
Q

Identify what would happen to photosystem II if there was a lack of carbon dioxide.

A

It would stop functioning as electron flow would be disrupted

21
Q

Determine what would happen if the light-independent reactions used up all their supplies of ATP and reduced NADP.

A

The light-independent reactions would stop

22
Q

State which photosystem would be most affected if there was a lack of NADP.

A

Photosystem II
- Photosystem II would be most affected as non-cyclic photophosphorylation would stop. Photosystem I could still carry out cyclic photophosphorylation without NADP.

23
Q

Photosynthesis chemical equation

A

6(CO2) + 6(H2O) → C6H12O6 + 6(O2)

24
Q

Outline how light energy is converted to chemical energy in carbon compounds.
- Draw a flowchart to illustrate the energy conversions performed by living organisms.

A

-Producers take in sunlight
-make chemical energy (glucose) (ex. carbs, lipids, proteins, nucleic acids)
-energy is passed along consumers through tropic levels

25
Q

List three reasons why living organisms need energy for cell activities.

A
  • Maintain homeostasis
  • speed up chemical processes to synthesize complex molecules
  • cellular respiration to break down nutrients
25
Q

Sunlight is the ___________ in most ecosystems. ​

A

principal energy source

26
Q

Outline the source of the atoms used to form glucose (C6H12O6) during photosynthesis.

A

The carbon atoms in glucose come from carbon dioxide, while the hydrogen atoms come from water

27
Q

Define photolysis.

A

using energy from light to break water

-using light energy to split water

-process makes hydrogen
-Hydrogen converts CO2 into glucose

28
Q

State the source of the _____ produced as a _____ in photosynthesis.

A

oxygen, by-product

29
Q

Outline the process of separating pigments using chromatography.

A
  • pigments absorbs different wavelengths of light
    1.transfer plant pigments to chromatography paper
    2.allow paper to come into contact with solvent (at bottom of tube)
    3. separations of pigments across paper
    4. measure distance pigment/distance solvent = Rf value
30
Q

Identify pigments that result from chromatography by color and calculated Rf value. ​

A

By comparing the color and Rf values of the separated pigments to known standards, the specific pigments can be identified.

  • compare known Rf value to your experiment’s Rf value
    -find name of each pigment(color)
31
Q

State the range of wavelengths that fall within the visible spectrum.

A

400nm-700nm (nanometers)

32
Q

Outline the function of pigments.

A

Chemical substances; which provide colours and also have an ability to absorb some wavelengths

33
Q

Explain why most plants look green.

A
  • they don’t absorb green light
34
Q

State the primary and accessory pigments found in chloroplasts.

A
  • primary pigment is chlorophyll a
  • accessory pigments chlorophyll b and carotenoids.
35
Q

Sketch the chlorophyll pigment absorption spectrum, including both wavelengths and colors of light on the X-axis.​

A

(view diagram)

36
Q

Compare and contrast the action spectrum and absorption spectrum.

A

absorption - shows the wavelengths of light a pigment absorbs
action - photosynthesis rates at different wavelengths (% of max)

37
Q

How to measure photosynthesis on action spectrum?

A
  • measure oxygen production (pondweed plant - bubbles)
  • CO2 consumption
38
Q

Explain the shape of the curve of the photosynthesis action spectrum.

A

(same graph as absorption spectrum)

39
Q

Define “limiting factor.”

A

things that can limit the rate of photosynthesis

40
Q

Explain how the following factors limit the rate of photosynthesis: temperature, light intensity, CO2 concentration.

A
  • CO2:maximum capacity of energy from enzymes, active sites occupied
  • light intensity: more intense, faster photosynthesis, reaches saturation
  • temp: warm makes faster; until optimum point- enzymes denature
41
Q

Identify manipulated (independent), responding (dependent) and controlled variables in experiments testing limiting factors on the rate of photosynthesis.

A

independent:
- CO2 (sodium hydrogen carbonate)
- light intensity (light further/closer)
- Temp. (water bath)
DEPENDENT:
-counting oxygen bubbles
-leaf float time
-oxygen/pH sensor
CONTROL:
-the other independent variables you aren’t testing

42
Q

Outline techniques for measuring the rate of photosynthesis while manipulating either temperature, light intensity, or CO2 concentration.

A

-boil water : remove CO2 from water
- pour from one beaker to another with pondweed plant
-count oxygen bubbles (none/less photosynthesis)

  • add CO2 (sodium hydrogen carbonate)
  • inc. rate of photosynthesis
43
Q

State the source of atmospheric carbon dioxide beyond the historical average of about 300 ppm.

A

anthropogenic activities
- burning of fossil fuels (such as coal, oil, and natural gas) for energy, deforestation, industrial processes, and agriculture.

44
Q

Compare enclosed greenhouse and free-air carbon dioxide enrichment (FACE) experiments.

A
  • ENCLOSED
  • Carbon dioxide levels can be artificially increased in indoor greenhouses by adding CO2 from compressed gas tanks
  • closed system, (control temp. and light)
  • conditions do not reflect those that occur in the natural environment
  • only plants that grow in small spaces can be measured
    FACE
    -placement of pipes which emit CO2 around an experimental area
  • CO2 concentration is monitored by sensors which then adjust the flow of CO2 from the pipes
  • open systems which incorporate natural conditions like rainfall and temperature fluctuations
  • measure the effects of CO2 enrichment on larger trees and consider the impact of competition between plant species
  • The disadvantage of experimenting on open systems is that certain conditions (such as sunlight) cannot be controlled
45
Q

List the questions that are addressed in carbon dioxide enrichment experiments.

A

Will rising CO2 levels increase photosynthesis rates?

46
Q

What is CO2 enrichment experiment? Why is it performed?

A
  • CO2 enrichment is the process of increasing the amount of carbon dioxide to a level higher than what is normally in fresh air
  • CO2 enrichment experiments are commonly undertaken as a means of predicting future rates of photosynthesis and plant growth in response to human activity
47
Q

What are CO2 enrichment experiments measuring?

A

-plant growth
-limiting factors (CO2 concentration, temp, light intensity)
-effects on other parts of ecosystem

IB Biology (21 decks)

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