Topic 5

Question 1

Define heterotrophic

Answer 1

Organisms generally eat plants or other animals which have eaten plants

Question 2

Describe the structure of ATP

Answer 2

Nucleotide with 3 phosphate groups attached

Adenine
Ribose. P. P. P

Question 3

When energy is needed what happens to ATP

Answer 3

The third phosphate bond can be broken by a hydrolysis reaction, catalysed by ATPase
Result- ADP and Pi and energy

Question 4

Where does the energy come from to synthesise ATP from ADP

Answer 4

Comes from catabolic (breakdown) reactions or redox reactions

Question 5

In a chloroplast what happens in the stroma?

Answer 5

Site of light-independent step

The stroma contains all the enzymes needed to complete photosynthesis

Question 6

What happens in the grana

Answer 6

Site of light-dependent step

Question 7

Describe the structure and use of the envelope in chloroplast molecules

Answer 7

Made from two layers of membrane, contains ATP synthase enzymes

Question 8

Explain the electron transport chain

Answer 8

Hydrogen acceptors pick up hydrogen
The acceptor becomes reduced
Electrons passed along a series of carriers known as an ETC
The components of the chain are reduced when they receive the electrons and oxidised again when they pass them on
These redox reactions can release a small amount of energy which is used to drive synthesis of a molecule of ATP

Question 9

Equation for photosynthesis

Answer 9

6co2 + 6H2O –> C6H12O6 + 6O2

Question 10

What is the energy from the sun used for in photosynthesis

Answer 10

Energy used to split the strong H-O bond in water molecules

Hydrogen released is combined with co2 to for glucose, oxygen released as waste product

Question 11

Describe the structure of a granum

Answer 11

Made up of stacks of membrane dics known as thylakoids

This is where the chlorophyll molecules are arranged on the membranes for trapping light energy

Question 12

Describe chlorophyll, what 5 pigments make it up (give colours)

Answer 12

Chlorophyll Is a group of five closely related pigments:
Chlorophyll a (blue-green)
Chlorophyll b (yellow-green)
Carotenoids (orange carotene and yellow )
Phaephytin (grey)

Question 13

Which pigment is most abundant in photosynthesising plants

Answer 13

Chlorophyll a

The other pigments are found in varying proportions

Question 14

What do the photosynthetic pigments do? What is the advantage of having more than one pigment?

Answer 14

Absorb and capture light from particular areas of the spectrum
Far more of the energy from the light falling on the plant can be used than if only one pigment was involved

Question 15

State 2 chlorophyll complexes and where they are found

Answer 15

Photosystem 1 lamellae
Photosystem 11 grana

Each contain a different combination of chlorophyll pigments and so absorb light in slightly different area of the spectrum. They are different sized particles attached to the membranes in the chloroplast

Question 16

Describe what is involved in cyclic photophosphorylation

Answer 16

PsI

Light hits molecule, excited electrons leave. Taken up by electron acceptors and passed along ETC to produce ATP

Question 17

What does non-cyclic photophosphorylation involve?

Answer 17

PsI and PSII

Question 18

What electron acceptor accepts electrons from ps1

Answer 18

NADP –> reduced NADP

Question 19

What are the advantages of using ATP as a power supply

Answer 19

ATP is regenerated therefore it doesn’t need to be stored
ATP is small and can pass in/out of cells easily
You can generate ATP in lots of different ways

Question 20

What is the light- independent stage of photosynthesis

Answer 20

Calvin cycle takes place in the stroma of the chloroplast

Question 21

Describe the steps of the Calvin cycle

Answer 21

Co2 from air combines with 5c compound (carbon dioxide fixed)
Rubisco -rate limiting enzyme 
Form unstable 6c 
Splits to 3c 
Hydrogen added to form 2 Galp
(H from reduced NADP)

Question 22

Define habitat

Answer 22

Place where organisms live

Question 23

Define population

Answer 23

A group of organisms of that same species living and breeding together in a habitat

Question 24

Define community

Answer 24

All the populations of the different species of organisms living in a habitat at any one time

Question 25

Define niche

Answer 25

The role of the organism in the community

Broken down into food niche or the habitats niche

Question 26

Define abiotic factors

Give examples

Answer 26

Non- living elements of the habitat of an organism

Light 
Wind/water currents 
Water availability 
Soil structure/ mineral content 
Oxygen availability

Question 27

Define biotic factors

Examples

Answer 27

Living elements of a habitat 
Predation 
Finding a mate
Territory 
Parasitism/disease

Question 28

Define autotrophic

Answer 28

Make organic compounds from carbon dioxide by photosynthesis