C1.3 Photosynthesis SL

Question 1

How do producers obtain energy and what are the products?

Answer 1

Producers, such as plants, algae and cyanobacteria, absorb light and produce glucose and other carbon compounds

Question 2

How do primary consumers obtain energy?

Answer 2

Primary consumers eat the producers, absorbing the energy they have stored.

Question 3

How do secondary consumers obtain energy?

Answer 3

Secondary consumers then eat those creatures(primary consumers) and so on.

Question 4

Where does all organisms energy ultimately come from?

Answer 4

Every organism, regardless of the trophic level it belongs to, relies upon the energy from the sun that was converted using photosynthesis.

Question 5

What is a summary of photosynthesis and the processes that occur in the chloroplasts?

Answer 5

Question 6

COMPARE the source of glucose for cellular respiration in mammals and flowering plants

Answer 6

Mammals get source of glucose from consuming/digestive.
Flowering plants get source of glucose from photosynthesis.

Question 7

What is the importance of photosynthesis?

Answer 7

• Maintains the composition of the Earth’s atmosphere.
• Some of the oxygen released by plants is converted in the upper layers of the atmosphere into ozone due to the action of UV light from the Sun. The ozone forms a layer in the stratosphere which protects terrestrial life from UV light by reducing the quantity of UV that reaches the Earth’s surface.
• All (or almost all) the food chains on our planet start with plants as the producers.

Question 8

What is a summary of photosynthesis?

Answer 8

Photosynthesis is a series of chemical reactions that happens in the chloroplasts of plant cells when there is light!

Question 9

What are the two main sets of reactions in photosynthesis?

Answer 9

Light-dependent reaction and Light-independent reaction

Question 10

What is photolysis?

Answer 10

Photolysis is part of the light-dependent reactions, whose role is to generate energy in the form of ATP, using the electrons from the splitting of water. This requires light and happens in the chloroplast on membranes called thylakoids. The result is the production of the waste gas OXYGEN.

Question 11

What is photolysis equation?

Answer 11

Question 12

Which reaction does photolysis belong to?

Answer 12

Light-dependent reaction

Question 13

What occurs in light-independent reaction?

Answer 13

In the second part of reaction, the energy in the form of ATP is used together with the hydrogen (H+ and e-) that were removed from the water molecule, in the light-independent reactions, to produce a carbon compound: glucose. This is called carbon fixation and involves changing inorganic carbon (CO2) to organic carbon. These reactions form a cycle called the CALVIN cycle and do not require light. They happen in the stroma of chloroplasts.

Question 14

What does radiation have?

Answer 14

Radiation has a frequency and a wavelength.

Question 15

What does low frequency waves have?

Answer 15

Waves with a low frequency are more spaced out so have a longer wavelength.

Question 16

What does high waves and small waves look like?

Answer 16

Question 17

What does high frequency radiation have? And what does low frequency radiation?

Answer 17

High frequency radiation has many waves per unit of time and therefore a lot of energy. Low frequency radiation is very low in energy and generally not useful for living organisms.

Question 18

Which wave lengths are harmful and what are their effects?

Answer 18

UV, X-rays and gamma rays are harmful to living organisms because they cause damage to cells, increasing mutation rates of DNA and leading to skin cancer and other tumours.

Question 19

What part of electromagnetic spectrum is visible to us?

Answer 19

Only a small part of the electromagnetic spectrum is visible to our eyes.

Question 20

What is the relationship between pigments and wavelengths?

Answer 20

The pigments in plants - chlorophyll and other pigments - absorb useful wavelengths of light.

Question 21

Why do plants use wavelengths?

Answer 21

Plants can use these wavelengths for photolysis of water in the light dependent reactions of photosynthesis.

Question 22

Which colour of light has the shortest wavelength? And the longest?

Answer 22

Mnemonic:
Richard of York gave battle in vain”
(red, orange, yellow, green, blue, indigo, violet).

Question 23

Why do leaves look green?

Answer 23

Because leaves don’t absorb green wavelengths but reflect them.

Question 24

What are chlorophyll molecules? And what happens when they absorb light?

Answer 24

Chlorophyll molecules (and there are two, called a and b) are photosynthetic pigments responsible for the absorption of light. When they absorb light (energy), they release electrons which are used for the synthesis of ATP (chemical energy). (Don’t need to know how to draw but need to recognise)

Question 25

What light do these two types of chlorophyll and other photosynthetic pigments absorb and reflect?

Answer 25

• Absorb light most strongly in the blue part of the EM spectrum, followed by the red portion
• Reflect light most strongly in the green part of the spectrum

Question 26

What are the two types of graphs that can show what wavelengths chlorophyll absorb and reflect?

Answer 26

We consider two graphs to represent these peaks and troughs of absorption and activity and call them the absorption and action spectra (sg spectrum) of photosynthesis.

Question 27

What does the absorption spectrum graph show? And what trend does it show?

Answer 27

The absorption spectrum shows the absorbance of light by the pigment chlorophyll (solid line) for all the wavelengths of light.

Question 28

What does the action spectrum graph show? And what trend does it show?

Answer 28

The action spectrum of photosynthesis shows the rate of photosynthesis for all the wavelengths of light as % of the maximum possible rate.

Question 29

What do plants do to increase their photosynthetic efficiency?

Answer 29

To increase photosynthetic efficiency, plants have a range of pigments that allow them to absorb light in a wider section of the electromagnetic spectrum. These accessory pigments allow some plants to take advantage of the green wavelengths of light which can give them a competitive advantage.

Question 30

What are the differences and similarities between absorption and action spectra

Answer 30

Question 31

What happens to a pigment when it absorbs light?

Answer 31

It excites the pigment/molecule and an electron leaves.

Question 32

State the precise location of the pigments involved in photosynthesis within the leaf.

Answer 32

The pigments involved in photosynthesis are embedded in the thylakoid membrane in chloroplasts.
Chloroplasts have an internal membrane system of flattened sacs called thylakoids, stacked together to form grana, with grana joined by lamellae (extended sacs). These thylakoids, grana and lamellae are made of this thylakoid membrane.

Question 33

Name 5 photosynthetic pigments (or types of pigment) found in leaves.

Answer 33

Chlorophyll a
Chlorophyll b
Carotenes (a category of carotenoids)
Xanthophylls (a category of carotenoids)
Pheophytins (a and b)

Question 34

Outline the role of the leaf pigments in photosynthesis.

Answer 34

These photosynthetic pigments are involved in the “capturing” of light energy and its conversion to chemical energy.
The primary photosynthetic pigment is chlorophyll which uses energy from light to excite electrons. The carotenoids are accessory pigments that “channel” more captured light energy to the chlorophyll. The pheophytins are electron carriers that are part of the electron transport chain where the excited electrons are passed from one molecule to the next in a series of chemical reactions.

Question 35

Explain why many plants have a variety of photosynthetic pigments.

Answer 35

Different photosynthetic pigments absorb light best at different wavelengths. By having more photosynthetic pigments plants can absorb light energy over a wider range of wavelengths. This allows plants to capture more energy for the same sunlight intensity.

Question 36

Describe how to conduct chromatography to separate pigments from a leaf and explain the importance of each step.

Answer 36

Question 37

List 3 characteristics of the solute (in this case a pigment) that influences how far it travels during chromatography, and for each describe the effect it has.

Answer 37

Question 38

Describe how to calculate the Rf value for a particular substance.

Answer 38

Question 39

Explain how a chromatogram can be used to identify an unknown substance.

Answer 39

Calculate the Rf value for the substance and compare this to the Rf values for known substances (specific to that solvent and that type of chromatography plate). The unknown substance should be one of the substances with the same Rf value.
However more than one substance can have the same Rf value for a particular solvent and chromatography paper and so it’s possible that multiple chromatograms will need to be run with different solvents (and/or chromatography paper) in order to find out the exact identity of the unknown substance. (other characteristics of the chemical may also help identification – e.g. the colour of photosynthetic pigments).

Question 40

Which factors can affect the rate of photosynthesis?

Answer 40

Concentration of carbon dioxide, temperature, light intensity and wavelength, water!(to much or little die), pH of stroma, chlorophyll

Question 41

Graphs for limiting factors of carbon dioxide concentration, light, temperature.

Answer 41

Question 42

What are carbon dioxide enrichment experiments and how do they help predict future rates of photosynthesis and plant growth?

Answer 42

Carbon dioxide enrichment experiments are experiments that manipulate the concentration of carbon dioxide in the air to simulate future conditions. They help predict future rates of photosynthesis and plant growth by studying the effects of increased carbon dioxide levels on plants in controlled environments.

Question 43

How do enclosed greenhouse experiments differ from free-air carbon dioxide enrichment (FACE) experiments in terms of their experimental setup and the variables they can control?

Answer 43

Enclosed greenhouse experiments use greenhouses or polytunnels to control variables such as sunlight, light wavelength, and temperature. They manipulate these variables to study the effects on photosynthesis. On the other hand, FACE experiments pump carbon dioxide into natural ecosystems and cannot control variables like rainfall and sunlight. They aim to investigate the effects of carbon dioxide enrichment on large producers like trees.

Question 44

What was the purpose of Duke University’s FACE project and what were the key findings?

Answer 44

The purpose of Duke University’s FACE project was to study the response of temperate coniferous forests to high levels of atmospheric carbon dioxide. The project aimed to monitor tree growth and productivity under conditions of at least 550 parts per million of carbon dioxide, which is over 1.25 times higher than present levels. The key findings of the project provided insights into the potential impacts of elevated carbon dioxide levels on forest ecosystems.