Topic 5A - Ecosystems and Photosynthesis

Question 1

EQ. Explain the relationship between GPP and NPP. (3 marks)

Answer 1

• NPP=GPP-R
• energy is lost as heat
• to provide energy for active transport

Question 2

EQ. Suggest why NPP values would be of use to a farmer who wanted to use this land for cattle. (3 marks)

Answer 2

• because cattle are primary consumers
• they gain energy through NPP
• the more energy moving into the cattle, the higher yield they will receive from the cattle

Question 3

In which part of the chloroplast do the light-independent reactions take place.

Answer 3

stroma

Question 4

What is the name of the enzyme used by plants to fix carbon dioxide

Answer 4

RUBISCO

Question 5

What is the immediate product of the light-independent

reactions of photosynthesis

Answer 5

GP

Question 6

Describe light-dependent photosynthesis.

Answer 6

• occurs in the thylakoid membrane
• light energy excites electrons in the chlorophyll
• electrons travel down the electron transport chain losing energy
• photolysis occurs to break down a water molecule producing oxygen, H+ ions and electrons
• these electrons replace the ones lost in photosystemII
• energy is lost to synthesise ATP in photophosphorylation
• the electrons combine with NADP to form NADPH

Question 7

EQ. Explain why the value for GPP is lower than the light energy available to the ecosystem (3 marks)

Answer 7

• because not all light falls on the leaf
• some light is reflected
• some light isn’t the right wavelength

Question 8

Define ecosystem

Answer 8

interactions of biotic and abiotic factors

Question 9

Define habitat

Answer 9

the place where an organism lives

Question 10

Define population

Answer 10

all the organisms of one species in a habitat

Question 11

Define population size/ abundance

Answer 11

the number of individuals of one species in a specific area

Question 12

What are biotic factors

Answer 12

living factors

Question 13

What are abiotic factors

Answer 13

non-living factors

Question 14

Define distribution

Answer 14

where a species is within a particular area

Question 15

What is interspecific competition

Answer 15

different species compete with each other for the same resources

Question 16

What is intraspecific competition

Answer 16

organisms from the same species compete with each other for the same resources

Question 17

How does abudance vary because of abiotic factors

Answer 17

when abiotic factors are ideal for a species, its organism will grow fast and reproduce succesfully and vice versa

Question 18

How does abundance vary because of biotic factors

Answer 18

cuz of intra and interspecific competition

Question 19

Give 2 example of how abiotic factors can affect the distribution of organisms

Answer 19

• some plants cannot grow too close to the shoreline because of the high level of salinity
• some plants only grow south facing because of the high solar exposure

Question 20

Describe a random sampling method to investigate populations in a field

Answer 20

• divide field into a grid
• use random number generator to select coordinates
• to remove bias

Question 21

EQ. Describe a non-random sampling method to investigate populations in a area where abiotic factors change gradually (4 marks)

Answer 21

• place frame quadrats
• in fixed intervals (every 10m)
• along a transect
• estimate percentage cover by counting occupied squares

Question 22

Describe how we would measure temperature

Answer 22

thermometer

Question 23

Describe how we would measure rainfall

Answer 23

rain gauge which is a funnel attched to a measuring cylinder

Question 24

Describe how we would measure humidity

Answer 24

electronic hygrometer

Question 25

Describe how we would measure pH

Answer 25

a sample of soil is mixed with water and an indicator liquid (litmus). it is matched against a chart to determine the pH of the soil.

Question 26

Describe how we would measure water content

Answer 26

the mass of a sample of soil is measured before and after being dried until it reaches a constant mass. find the difference in mass as a percentage.

Question 27

EQ. Explain how ecosystems have developed on Surtsey since 1965 (6 marks)

Answer 27

• primary succession took place
• pioneer species took place
• these produced soil called humus
• and provided minerals and nutrients for plants to grow
• habitats and niches are provided for animals
• herbaceous shrubs and trees become established and climax community is established