Photosynthesis Details

Question 1

What happens in photosynthesis?

Answer 1

light is absorbed by pigments(e.g. chlorophyll) and is changed into chemical energy in carbon compounds

Question 2

Main groups of carbon compounds produced in photosynthesis

Answer 2

-Carbohydrates
-Proteins
-Lipids
-Nucleic acids

Question 3

Word equation for photosynthesis

Answer 3

Carbon dioxide + Water → Glucose + Oxygen

Question 4

Chemical equation for photosynthesis

Answer 4

6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂

Question 5

What is needed for the reduction reaction that converts carbon dioxide to glucose in photosynthesis

Answer 5

Hydrogen

Question 6

Where does the hydrogen required for photosynthesis come from?

Answer 6

It comes from the photolysis of water (hydrogen is released from water as separated protons(hydrogen ions) and electrons)

Question 7

Condition for photolysis to occur

Answer 7

Light must be available to provide energy

Question 8

Chemical equation for the photolysis of water

Answer 8

2H₂O → 4e⁻ + 4H⁺ + O₂

Question 9

What happens to oxygen in the photolysis of water?

Answer 9

It diffuses out of photosynthesizing cells(as it is a waste product in this reaction)

Question 10

Twelve water molecules are split for each glucose molecule made(T/F)

Answer 10

True(the chemical equation is below):
12H₂O → 24H + 6O₂

Question 11

What happens to the hydrogen atoms produced from the photolysis of water?

Answer 11

-Half of the hydrogen atoms become part of a glucose molecule
-The other half are used to remove one oxygen atom from carbon dioxide and convert it into water

The chemical equation for this is below:
6CO₂ + 24H → C₆H₁₂O₆ + 6H₂O

Question 12

Prokaryotes were the first organisms to perform photosynthesis. Millions of years later, algae and plants also began carrying out photosynthesis using chloroplasts(T/F)

Answer 12

True

Question 13

How and why does the oxygen produced by the photolysis of water diffuse out of the leaf?

Answer 13

-Photolysis increases the concentration of oxygen inside chloroplasts
-This causes oxygen to diffuse out of chloroplasts and then out of leaf cells to air spaces inside the leaf
-The oxygen then diffuses through stomata to the air outside the leaf

Question 14

Chloroplasts contain several types of chlorophyll, along with other pigments called accessory pigments(T/F)

Answer 14

True

Question 15

The pigments in chlorophyll absorb different ranges of wavelength of light, so they look like different colours to us(T/F)

Answer 15

True

Question 16

Formula for Rf value

Answer 16

Question 17

The colours we see depend on…

Answer 17

the wavelengths of light that the pigment absorbs, reflects and transmits

Question 18

What do white pigments do(in relation to wavelengths of light)?

Answer 18

Reflect all wavelengths of light

Question 19

What do transparent pigments do(in relation to wavelengths of light)?

Answer 19

Allow all wavelengths of light to pass through

Question 20

What do black pigments do(in relation to wavelengths of light)?

Answer 20

Absorb all wavelengths of light

Question 21

What do coloured pigments do(in relation to wavelengths of light)?

Answer 21

Absorb all wavelengths of light apart from the wavelengths associated with the colour of the pigment(those are reflected)

Question 22

The longer the wavelength of a photon,…

Answer 22

the more energy the photon holds

Question 23

How is solar energy transformed into chemical energy in photosynthesis?

Answer 23

When the photons are absorbed by pigment molecules, the energy that the photons hold causes an electron in an atom of the pigment molecule to jump to a higher energy level(i.e. excitation)

Question 24

Conditions for excitation to occur

Answer 24

A specific amount of energy is required(which can only be supplied by certain wavelengths of light)

Question 25

The main photosynthetic pigments are chlorophyll(T/F)

Answer 25

True(although photosynthesis involves a range of pigments)

Question 26

Why do all forms of chlorophyll appear a shade of green to us?

Answer 26

Photons in the red and blue part of the spectrum of wavelengths of light can excite an electron in the chlorophyll, but wavelengths in the green parts of the spectrum(between red and blue) cannot. Hence, most of the green part of the wavelength of light is reflected

Question 27

The wavelengths of light absorbed by a pigment are shown on a graph called...

Answer 27

the absorption spectrum

Question 28

Range of wavelengths for visible light

Answer 28

400nm-700nm

Question 29

Photosynthesis can only occur in wavelengths of light that are absorbed by chlorophyll or other photosynthetic pigments(T/F)

Answer 29

True

Question 30

Features of the absorption spectrum

Answer 30

-Represents the amount of light energy being absorbed by the photosynthetic pigments -For the plant, it represents the light absorbed by all the pigments present

Question 31

Features of the action spectrum

Answer 31

-Represents the rate of the photosynthetic process being carried out by the pigments -For the plant, it represents the rate of photosynthesis as a result of the pigments present

Question 32

The spectrum for visible light is continuous, with no clear boundaries(T/F)

Answer 32

True

Question 33

Wavelength range for violet

Answer 33

380-450nm

Question 34

Wavelength range for blue

Answer 34

450-495nm

Question 35

Wavelength range for green

Answer 35

495-570nm

Question 36

Wavelength range for yellow

Answer 36

570-590nm

Question 37

Wavelength range for orange

Answer 37

590-620nm

Question 38

Wavelength range for red

Answer 38

620-750nm

Question 39

Limiting factors for photosynthesis

Answer 39

-Temperature -Light intensity -Carbon dioxide concentration

Question 40

When conducting an experiment for photosynthesis, only one limiting factor should be investigated at a time; this is the independent variable(T/F)

Answer 40

True

Question 41

When conducting an experiment on photosynthesis, a suitable range should be chosen for the independent variable, from the lowest possible level to a level at which the factor is no longer limiting(T/F)

Answer 41

True

Question 42

How to control temperature in an experiment on photosynthesis

Answer 42

Setting the thermostat of a waterbath to a specific temperature and keeping it there throughout the experiment

Question 43

How to control light intensity in an experiment on photosynthesis

Answer 43

Keeping the light source at a constant distance

Question 44

How to control CO₂ concentration in an experiment on photosynthesis

Answer 44

Adding enough sodium bicarbonate(NaHCO₃) to give a high CO₂ concentration

Question 45

How to vary temperature in an experiment on photosynthesis

Answer 45

Placing the plant in a thermostatically controlled water bath or on a hot plate and adjusting the temperature

Question 46

How to vary light intensity in an experiment on photosynthesis

Answer 46

Moving the light source to different distances and measuring the light intensity with a lux meter

Question 47

How to vary CO₂ concentration in an experiment on photosynthesis

Answer 47

Boiling water and then waiting for it to cool(to remove some/most of the CO₂), before adding measured quantities of sodium bicarbonate(NaHCO₃) to increase the CO₂ concentration