Energy Transfers

Question 1

Where does LDR in photosynthesis occur?

Answer 1

In the grana

Question 2

How are ATP and reduced NADP produced during the LDR?

Answer 2

1. Chlorophyll absorbs light photons causing e- to excite out (photo ionisation)
2. E- transport along ETC and electron loses energy
3. This energy is used to form ATP from ADP + Pi
4. Light striking chlorophyll causes photolysis of H2O- produces H+ that reduced NADP

Question 3

What are the stages of light independent reaction (Calvin Cycle)?

Answer 3

1. CO2 combines with RuBP (using rubisco enzyme)
2. Produces 2* GP
3. Reduced NADP provides reducing power to form 2* TP using ATP
4. TP loses 1 C which is used for organic substances and RuBP is regenerated

Question 4

Limiting factors of photosynthesis?

Answer 4

light intensity
co2 conc
temp

Question 5

Similarities between respiration and photosynthesis?

Answer 5

Both produce ATP using oxidative phosphorylation

Question 6

Where does glycolysis occur?

Answer 6

In the cytoplasm

Question 7

Describe the process of glycolysis?

Answer 7

1. Glucose phosphorylated to glucose phosphate using ATP
2. glucose phosphate splits in TP
3. TP is oxidised using energy from ATP to pyruvate

G—->GP—–>2TP—–>2 pyruvate

Question 8

What is pyruvate converted to during anaerobic respiration in plants?

Answer 8

ethanol, CO2

reduced NAD is oxidised to NAD so it can be reused in further glycolysis

Question 9

What is pyruvate converted into during anaerobic respiration in animal cells?

Answer 9

lactate

again, reduced NAD is oxidised to NAD so it can reused in further glycolysis

Question 10

Describe the process of the link reaction?

Answer 10

1. pyruvate is oxidised to acetate using NAD
2. pyruvate loses CO2
3. acetate combines w/coenzyme A to form acetyl coenzyme A

Question 11

Where does the link reaction occur?

Answer 11

Matrix of mitochondria

Question 12

Describe process of Kreb’s cycle

Answer 12

1. acetylcoenzyme A combines with 4C to produce 6C molecule
2. 6C molecule make a 4C molecule in a series of oxidation (of reduced NAD/FAD) reactions and decarboxylation reactions (losing 2* CO2)

Question 13

Describe process of Ox Phos

Answer 13

1. reduced FAD and NAD release H atoms
2. H atoms split into H+ and e-
3. e- went along the ETC and loses energy
4. The H+ are actively transported from inner mitochondrial space—–>inner membrane space
5. H+ accumulate in the inner membrane before they diffuse back into inner mitochondrial space through ATP synthase
6. ATP synthase produces ATP
7. O2 acts as final e- acceptor and forms water

Question 14

How can you measure photosynthesis? and what factors must you consider?

Answer 14

Using a photosynthometer

1. must be kept in the dark before hand so no LDR can occur
2. sample of KHCO3 acts as CO2 source so CO2 is not a limiting factor
3. Kept airtight to prevent O2 from escaping

Question 15

Why is measuring photosynthesis not always accurate?

Answer 15

Because some O2 is used up during respiration

Question 16

Why cant a plant rely on ATP produced solely by the LDR?

Answer 16

Doesn’t produce sufficient ATP
Photosynthesis doesn’t take place in the dark
Cells without chlorophyll cant produce ATP otherwise

Question 17

Why is it necessary for humans to synthesise a large amount of ATP every day?

Answer 17

ATP cannot be stored

ATP is unstable

Question 18

How is ATP a suitable source of energy in biological process?

Answer 18

Energy released in small manageable chunks
ATP can be resynthesised
Energy is released in a single step

Question 19

What is biomass?

Answer 19

total dry mass of an organism in a specific area in a given time
Unit: kJha-1year-1

Question 20

what is gross primary production (GPP)?

Answer 20

total chemical energy stored in plant in a given area or volume in a given time

Question 21

examples of intensive rearing

Answer 21

predators are excluded- simplifies food chain
reduced movement- more energy used for growth
kept warm- reduces heat loss
feeding is controlled- given more nutritious food

Question 22

Steps of eutrophication

Answer 22

1. nitrates cause an algal bloom at the surface
2. blocks light for plants lower down the surface of the water
3. they can’t photosynthesise so they die
4. Dead material is broken down by decomposers
5. The decomposers respire and deplete oxygen in the water
6. Aerobic organisms cannot survive

Question 23

two types of nitrogen fixing

Answer 23

free living: convert nitrogen gas to NH3 which is used for amino acids
mutualistic: live on nodules on roots of plants such as peas and beans
Bacteria obtain carbs from the plant and plant obtains amino acids from the bacteria

Question 24

nitrification

Answer 24

carried out by nitrifying bacteria
converts NH4+ to NO2- to NO3-
Oxidation reaction: needs to be carried out in soil with air spaces

Question 25

ammonification

Answer 25

Saprobionts carry out extracellular digestion on dead and waste material and release NH4+ into the soil

Question 26

denitrification

Answer 26

occurs in water logged soil Converts NO3- to nitrogen gas Leads to an increase in anaerobic denitrifying bacteria

Question 27

function of mychorrihzae

Answer 27

attaches to roots of plants and increase surface area for absorption Plants gain ions and water from the fungi whilst fungi gains sugars and organic compounds (amino acids) from the plant

Question 28

definition of producers

Answer 28

photosynthetic organisms that produce organic substances using light energy

Question 29

definition of consumers

Answer 29

organisms that gain energy by feeding another organism

Question 30

definition of net primary production

Answer 30

total quantity of chemical energy stored in plant biomass in a given volume or area in a given time minus respiratory losses (measured in kJha-1year-1)

Question 31

why isn't most sunlight converted into organic matter?

Answer 31

not all the light hits the chlorophyll 90% of light is reflected back not all wavelengths of light can be absorbed

Question 32

why is there only a low percentage of energy transferred to each trophic level?

Answer 32

some parts of the organism are not consumed some is lost in waste some is lost as heat from respiration

Question 33

where is energy from net primary production used?

Answer 33

used in growth and reproduction or is transferred to next trophic levels

Question 34

how do using fertilisers increase crop productivity?

Answer 34

nitrates are incorporated in amino acids, ATP and nucleic acids. They help the plant grow Taller plants=greater leaf area= increased rate of photosynthesis= increased crop productivity

Question 35

definition of food chain

Answer 35

feeding relationship in which primary consumers eat producers

Question 36

why is heat produced during respiration?

Answer 36

any energy that is not used in producing ATP

Question 37

Effects of less CO2 on photosynthesis?

Answer 37

Less CO2 binds with RuBP to form GP Less GP reduced to TP Less TP to regenerate RuBP

Question 38

Why is only a little amount of energy passed to the next trophies level?

Answer 38

Some light is reflected Some light misses chlorophyll Producers loses energy as heat Producers lose energy due to movement and respiration Not all parts of an animal can be eaten- eg bones