✅5: Photosynthesis

Question 1

What is an autotrophic organism

Answer 1

Makes complex organic compounds from simple compounds in their environment.

Question 2

What is photosynthesis

Answer 2

Process by which living organisms capture the energy of the sun using chlorophyll and use it to covert co2 and water into simple sugars

Question 3

What are heterotrophic organisms

Answer 3

Obtain complex molecules by feeding on other living organisms on their dead remains

Question 4

What is the process of photosynthesis

Answer 4

Carbon dioxide and water goes to glucose and oxygen.

6co2 and 6h2o goes to c6h12o6 and 6o2,

Question 5

What does the light do to the compounds?

Answer 5

The energy in the light is used to slit the strong H-O bonds in the water molecules. The hydrogen releases is combined with carbon dioxide to form fuel for the cells, glucose. Oxygen is releases in the atmosphere as a waste product.

Question 6

Structure of the chloroplast

Answer 6

Relatively large organelles, green parts of the plant. Each chloroplast is surrounded by an outer and inner membrane with a space between the two called an envelope. Inside there is a system of membranes arranged in a stack called the GRANA. A single GRANUM is made up of stacks of membrane discs called THYLAKOIDS. This is where green pigment is. The grana are joined together by the LAMELLAE, extensions of the thylakoids membranes. The lamella acts as a skeleton within the chloroplast, these membrane stacks are surrounded my MATRIX. Called the STROMA.

Question 7

Importance of chloroplast

Answer 7

The pigment molecules on the thylakoids are arranged on the membrane in the bets possible position to trap light energy. Evidence in light microscopes. Granal membranes are covering in particles that seen to involved ATP synthesis. The lamella maintains working distance between the grana so they get maximum ,igniting and function efficiently,

Question 8

What do the stroma in chloroplast contain

Answer 8

Contain all enzymes needed to complete the process of photosynthesis and produce glucose.

Question 9

What can glucose be used for

Answer 9

Cellular respiration, converted to starch for Storage, used as an intermediate for the synthesis of other organic compounds such as amino acids and lipids.

Question 10

What is a chlorophyll

Answer 10

In the chloroplast, they are light capturing photosynthetic pigments. Involves chlorophyll A which is blue-green and chlorophyll B which is yellow green. Also carotenoids which are orange carotene and yellow. And phaephytin , which is a breakdown product of the others,

Question 11

Where is chlorophyll A found

Answer 11

In all photosynthesising plants and is the most abundant of the 5.

Question 12

Where are the other chlorophyll

Answer 12

Varying proportions , and it is these that causes different shades of green. Each pigment absorbs and captures light from particular areas of the spectrum.

Question 13

What is the absorption spectrum?

Answer 13

Describes the range of amount of light of different wavelengths that a photosynthetic pigment absorbs. Usually represenated in a graph. The absorption spectra of the different photosynthetic pigments are found by measuring their absorption o flight of differing wavelengths.

Question 14

How do you compare the rate of photosynthesis?

Answer 14

With the wavelength of light. Can use bacteria that move towards oxygen to show where the most oxygen is given off, which is directionally proportional to the rate of photosynthesis.

Question 15

What is the action spectrum

Answer 15

Way of demonstrating the rate of photosynthesis against the wavelength of light

Question 16

What is chromatography

Answer 16

With a suitable solvent, the pigments travel up the paper at different speeds and are readily separated, to show the different shades of green found in a plant.

Question 17

How do you work our Rf values

Answer 17

Once you have carried out the chromatography, you can compare the Rf values to known values. Rf value is the ratio of distance travelled by the pigment to the distance travelled by the solvent alone.

Distance traveled by solute (pigment) % by the distance travelled by solvent.

Question 18

What are photosystems?

Answer 18

The photosynthetic pigments carry out the absorption of light in 2 distinct chlorophyll complexes called PHOTOSYSTEM 1 and PHOTOSYSTEM II.

Question 19

What do the photosystems contain

Answer 19

Different combination of chlorophyll pigments and so absorb light in a slightly different area of the spectrum.

Question 20

What are both of the photosystems

Answer 20

PSI particles are mainly on the intergranal lamellae.

PSII articles are on the grana themselves,

Question 21

What is the light dependent stage of photosynthesis?

Answer 21

Reactions that take place in the light on the thylakoids membranes of the chloroplast, they produce ATP and split water molecules in a photochemical reaction, providing hydrogen ions to reduce the carbon dioxide and produce carbohydrates,

Question 22

What is light?

Answer 22

Light is a form of electromagnetic radiation and the smallest unit of light is a photon.

Question 23

What happens when light hits a chlorophyll molcecule in light dependent photosynthesis

Answer 23

When a photon of light hits a chlorophyll molecule, the energy is transferred to the electrons of that molecule. The electrons get existed and are raised to higher energy levels. If an electron is raised to a sufficiently high energy level, it will leave the chlorophyll completely empty.

Question 24

What happens to the excited electron during light dependent photosynthesis

Answer 24

The excited electron can be picked up by an electron acceptor and result in the synthesis of ATP by cyclic phosphorylation and non cyclic.

Question 25

What is cyclic photophosphorylation

Answer 25

Process that drives the production of ATP. Light excited electrons from PS1 are taken up by an electron acceptor and passed directly along an ETC to produce ATP, with the electron returning to PS1. When the electron returns to the chlorophyll molecule in PS1, it can act in the same way again when the light comes again.

Question 26

What is non cyclic photophosphorylation

Answer 26

Process involving BOTH PSI and PSII. In which water moles are split using light energy to provide reducing power to make carbohydrates and at the same time produce more ATP.

Question 27

What is the shape of non cyclic photophosphorylation

Answer 27

An N shape. The hydrogen electron travels through PSII, and then down an ETC to the PSI, and up to an electron acceptor NADP. Light hits both photosystems, but the electron originally came form water.

Question 28

Why does PS1 in non cyclic p pick up the electron ?

Answer 28

To replace the one that was lost during light independent reactions.

Question 29

What is photolysis

Answer 29

Splitting of a molecule using light

Question 30

What are light independent stages of photosynthesis

Answer 30

Reactions that use the reduced NADP and ATo predicted by the light dependent stage of photosynthesis in a pathway called Calvin cycle. , which takes place in the stroma of the chloroplast and result in the reduction of CO2 from the air to bring about the synthesis of carbohydrates.

Question 31

What happens during non cyclic photophosphorylation

Answer 31

Light conditions: photons hit chlorophyll in PsI and PSII, excited electrons are lost and picked up by NADP. Excited electrom from PSII is picked up by another acceptor and passed along ETC, to PSI, driving ATP synthesis. PSI receives an electron.
Chlorophyll in PSII in short of electron and unstable. Original cannot be returned as it is at PSI! Therefore electron must be found somewhere to restore chlorophyll to its original state. Splitting of water by photolysis causes electron, H plus ions and hydroxide ions.
Replaces lost electrons.
Once PSII restored, ready to be excited again and its hit by ANTOHER photon of light,
Meanwhile, in PsI, also being excited by Keith, and lost to NADP, which also takes up dissociated water at same time.

Question 32

What does The produces of non cyclic photophosphorylation used for

Answer 32

As a source of reducing power and energy

Question 33

What happens in the calvin cycle?

Carbon fixation

Answer 33

This is first stage

co2 from air combines with ribulose bisphosphate 5 carbon compound. Co2 is fixed therefore called carbon fixation.

Question 34

What is a necssary compound in the first stage of the Calvin cycle?

Answer 34

The enzyme ribulose bisphosphate carboxylase (RUBSICO), is necessary for this step.

Question 35

What is the second stage of Calvin cycle?

Answer 35

The result of the reaction between ribulose bisphosphate and carbon dioxide is a 6 carbon compound, very unstable, and it immediately splits into 2 moles, giving:
Glycerate 3 phosphate. A 3 carbon compound.

Question 36

What is the third stage of Calvin cycle

Answer 36

Glycerate 3 phosphate is reduced (hydrogen is added) to form:
Glyceradehyde 3 phosphate (GALP) a 3 carbon sugar.

Question 37

Where does the hyd4en come from for glyceraldehyde 3 phosphate

Answer 37

Comes from reduced NADP, and the energy required comes from ATP, but produced in light dependent stage.

Question 38

What is the fourth stage of the Calvin cycle

Answer 38

The 3 carbon GALP passes through series of steps to replace ribulose bisphosphate needed for the first step of the Calvin cycle. However,
Some of it is synthesised into 6 carbon sugar glucose, or passed directly into glycolysis pathway for synthesis of other molecules.

Question 39

When does the Calvin cycle happen?

Answer 39

In the light and the dark. These can only stop when the products o flight reaction run our, leaving no reduced NADP or ATP available in the chloroplasts,

Question 40

What are the products of photosynthesis used for?

Answer 40

GALP is the primary end product and it is the key molecules for the synthesis of everything else needed for the plant. Some is passed directly to glycolysis and kerbs. Some is used to produce glucose in ‘gluconeogenesis’ reaction. This glucose may be converted into sucrose, for transport around plant, or staff as energy store, or cellulose, for structural support,
Also provide energy in the form of ATP.
Also for building blocks of amino acids, combining the molecules of nitrates from the soil.
Some is converted into acetyl coA which can synthesis fatty acids into production of phospholipids for membranes.

Question 41

What are alternative routes for photosynthesis?

Answer 41

The plants who use the normal way are called C3 plants, as the CO2 is fixed on 3 carbon compound.
Some plants have alternative ways of fixing carbon dioxide, and produce compound with 4 carbon atoms, to raise the levels of carbon dioxide. Known as C4 plants. Evolved in hot and dry ecosystems

Question 42

How is light a limiting factor of photosynthesis?

Answer 42

The amount of light available affects the amount of chlorophyll which is excited and therefore reduces the amount of reduced NADP and ATP produced in the night dependent stage.
If low levels of light, insufficient NaDp and ATP will be produced to allow the reactions of the light independent o progress and max rate, therefore limiting factor

Question 43

Why is carbon dioxide a limiting factor in photosynthesis

Answer 43

If not enough carbon dioxide, not enough for fixation in the Calvin cycle and the reaction cannot proceed at max rate. Carbon dioxide is most common limiting factor due to small levels in atmosphere.

Question 44

How to resolve carbon dioxide limiting factor

Answer 44

Greenhouses with carbon dioxide enriched atmosphere to increase production.

Question 45

How is temperature a limiting factor to photosynthesis

Answer 45

All of Calvin cycle and many of the light dependent reactions are controlled by enzymes, therefore temperature affects them. Even if light and co2 levels are good, unless temperature is good, plant will be unable to take advantage of conditions,

Question 46

What do plants vary in?

Answer 46

Nutrients. In the real world, plants need nutrients to convert carbohydrates into proteins and fats.