photosynthesis

Question 1

What is the photosynthesis equation

Answer 1

Carbon dioxide+ water —–> carbohydrates and oxygen

Question 2

In what ways are leaves adapted to absorb sunlight?

Answer 2

• large surface area
• arranged to minamise overlap
• transparent waxy cuticle
• transparent and have waxy cuticle
• multiple chloroplasts in the upper palisade mesophyll cells

Question 3

How are leaves adapted for carbon dioxide capture

Answer 3

• thin so short diffusion pathway
• multiple stomata which let air in
• Stomata that open in sunlight
• Air spaces in the spongey mesophyll so air can circulate around all of the cell.

Question 4

How are leaves adapted to bring in water

Answer 4

• Xylem transport water from the roots to the leaves
• Phloem delivers the products of photosynthesis to the rest of the plant

Question 5

Fill in missing words-

1. Chlorophyll molecules and other photosynthetic _________ are found on the ________ membranes.

Answer 5

pigments
thylakoid

Question 6

Why are pigments in the thylakoid membrane useful for photosynthesis?

Answer 6

The different pigments absorb different wavelengths.
Plants have the pigments that will allow them to absorb the most light

Question 7

Fill in missing words-

2. When the light hits the chlorophyll molecule it raises the __________ level of a pair of ________ and they are said to have become excited

Answer 7

energy
electrons

Question 8

Fill in missing words-

4. The electrons are passed along a series of electron _______ in the thylakoid membrane that make up the electron ___________

Answer 8

carriers
transport chain

Question 9

Fill in missing words-

5. Each electron carrier has a slightly _______ energy level than the previous one. Some of the energy that is lost during this process is used to produce a _______concentration gradient

Answer 9

lower
proton (H+)

Question 10

Fill in missing words-

6. The photolysis of _______ releases _______ which adds to the increased proton concentration

Answer 10

water
protons

Question 11

Fill in missing words-

7. The electrons released during photolysis replace the ________ electrons that leave the ________ molecule when light hits it. The _______ released can by used by plants for respiration.

Answer 11

excited
chlorophyll
oxygen

Question 12

Fill in missing words-

8. The enzyme ATP _________ (also called a ______ granule) is a channel protein located on the ________ membrane.

Answer 12

Synthase
Stalked
Thylakoid

Question 13

Fill in the missing words-

9. When the protons move _______ their concentration gradient through the ATP ____________ channels they cause structural changes which allows the enzyme to catalyse the addition of ________________ _______________ to ADP forming ______. This process is known as ___________.

Answer 13

down
synthase
inorganic phosphate
ATP
Phosphorylation

Question 14

Fill in the missing words-

10. The final electron acceptor (NADP+) takes up the protons resulting in the production of __________ NADP (NADPH)

Answer 14

reduced

Question 15

Fill in the missing words-

3. The excited electrons leave the chlorophyll molecule and are taken up by (reduces) an ____________ ____________ and the chlorophyll becomes _____________. This process is called ________________.

Answer 15

electron acceptor
ionised
photoionisation.

Question 16

How do membrane create a proton concentration gradient?

Answer 16

Membranes are selectively permeable to H+ to create a proton gradient.

Question 17

Non cyclic phosphorylation vs cyclic phosphorylation

Answer 17

Non cyclic- The electrons that origionated in the chlorophyll molecule in PS11 (photosystem 11) end up in a totally different molecule (NADPH)

Cyclic phosphorylation- Occurs when only the PS1 and the electrons return to the chlorophyll in PS1

Question 18

Cyclic phosphorylation (tick box)

Answer 18

Photosystem- PS1
Photolysis- No
Fate of electrons- Returns to chlorophyll
Products- ATP

Question 19

Non cyclic phosphorylation (tick box)

Answer 19

Photosystem- PS1 and PS11
Photolysis- Yes
Fate of electrons- Accepted by NADP+
Products- Oxygen, NADPH, and ATP

Question 20

Adaptations of chloroplasts

Answer 20

• Large surface area membrane
• Chlorophyll held in place by protein network to maximise absorbsion
• Membranes have ATP synthase channels
• Membranes selectively permeable to H+ to create a gradient
• Own DNA and Ribsosomes to produce the necessary proteins

Question 21

What is the location of the light dependant reactions

Answer 21

Thylakoid

Question 22

What are the raw materials needed in the light dependant reactions

Answer 22

Light, water

Question 23

Products of the light dependant reactions

Answer 23

ATP, oxygen, NADPH

Question 24

What is the location of the calvin cycle

Answer 24

Stroma

Question 25

What are the raw materials needed for the calvin cycle

Answer 25

NADPH, ATP, CO2

Question 26

What are the products of the calvin cycle

Answer 26

Carbohydrates

Question 27

Fill in the gaps of the calvin cycle- CO2 from the atmosphere diffuses into the ………………… of the chloroplast CO2 reacts with RuBP to form an unstable 6 carbon intermediate molecule. This reaction is catalysed by the enzyme ……………………… The unstable 6 carbon intermediate splits into 2 molecules of 3 carbon ………………………. 3 phosphate (GP) Reduced …………………. is used to reduce GP into …………….. phosphate (TP) using energy supplied by ………. Most of the TP is used to regenerate RuBP using energy from …… A small quantity of the TP is converted into organic molecules such as starch, cellulose, lipids, amino acids, and ....................

Answer 27

Stroma rubisco glycerate NADP triose ATP ATP nucleotides

Question 28

Where do the molecules of ATP and NADPH come from?

Answer 28

The light dependant reaction

Question 29

Suggest what happens to the molecules of ADP and NADP that are produced during the Calvin cycle.

Answer 29

They are re- energised into the light dependant reaction

Question 30

How many molecules of carbon dioxide (1C) are required to produce on molecule of glucose(6C)?

Answer 30

6

Question 31

Describe the ways in which the stroma is in ideal environment for the Light Independent Reaction to occur.

Answer 31

- Contains own DNA and ribosomes to produce proteins required (rubulose) - Double membranes surround the stroma fluid keeping high concentrations of the enzymes and substrates required for the calvin cycle - The grana are surrounded by the stroma fluid so short diffusion path for the ATP and NADPH produced during the light dependant stage

Question 32

Describe the law of limiting factors.

Answer 32

At any given moment the rate of a physiological process is limited by the factors that is its least favourable value

Question 33

Which part of photosynthesis is affected by low CO2 levels?

Answer 33

Calvin cycle

Question 34

What molecules would you expect to build up if carbon dioxide has become a limiting factor?

Answer 34

RuBP, NADPH, ATP

Question 35

Describe the relationship between temperature and photosynthesis rates between 0 and 25 oC.

Answer 35

increasing molecular collisions- increased kinetic energy meaning an increased rate of photosynthesis

Question 36

Describe and explain what happens to photosynthesis at higher temperatures than 25oC.

Answer 36

Hydrogen bonds in the enzymes will break which changes the tertiary structure of the enzymes, and the active site shape changes. This means no enzyme substrate complex is formed.

Question 37

When measuring photosynthesis (pondweed experiment) what control measures must be taken?

Answer 37

Temperature Ph of liquid (co2 levels would change) Plant species Size of plant

Question 38

In photosynthesis experiments why is the gas collected not necessarily an accurate measurement of photosynthesis rates

Answer 38

- some of the oxygen is used in respiration or dissolved in the water - other gases might be dissolved in water