Topic 5- Energy and ecosystems

Question 1

What do ecosystems depend on?

Answer 1

Primary producers

Question 2

What do primary producers make?

Answer 2

There own glucose

Question 3

What is chemosynthesis

Answer 3

deep-sea ecosystems such as those around hydrothermal vents (where there is no light) depend on primary producers (in this case bacteria)- make glucose from the chemicals released from these vents

Question 4

In ecosystems where sunlight and water is available, the process of photosynthesis enables plants to synthesise organic compounds (glucose and other sugars) from carbon dioxide, where do terrestrial (land-based) ecosystems and aquatic (water-based) ecosystems get their co2 from?

Answer 4

terrestrial (land-based) ecosystems= CO2 from the atmosphere
In aquatic (water-based) ecosystems=CO2 dissolved in the water

Question 5

photosynthesis transforms 1._____ energy into 2.____energy held in biological molecules

Answer 5

1. light
   2.chemical

Question 6

The chemical energy in these biological molecules can then be used by other organisms within the community known as ?

Answer 6

Consumers -(herbivores, carnivores, omnivores)(i.e. the organisms in higher trophic levels)

Question 7

Most of these sugars synthesised by plants are used by the plant as?

Answer 7

Respiratory substrates

Question 8

What is a respiratory substrate?

Answer 8

a molecule (such as glucose) that can be used in respiration, to release energy for growth

Question 9

What are the other sugars that are not used in respiration used for? Give examples

Answer 9

-to make other groups of biological molecules
Starch- acts a short term energy store
Cellulose- structural component of plant call walls
Lipids- longer term energy store
Proteins- sugars can combine with nitrates to make amino acids which can produce proteins

Question 10

What is biomass made up of?

Answer 10

The different groups of biological molecules

Question 11

Define biomass

Answer 11

The mass of living material of the organism or tissue/
The chemical energy that is stored within the organism or tissue

Question 12

How can biomass be measured

Answer 12

The dry mass of an organism or tissue (in a given area) and
the mass of carbon that an organism or tissue contains- organic chemicals are made from chains of carbon )

(The mass of carbon that a sample (i.e. an organism or tissue) contains is generally taken to be 50% of the dry mass of the sample)

Question 13

What is dry mass?

Answer 13

the mass of the organism or tissue after all the water has been removed

Question 14

What is calorimetry used for?

Answer 14

used to estimate the chemical energy stored in dry biomass

Question 15

How is calorimetry carried out?

Answer 15

-Burning the sample of dry biomass in a piece of equipment known as a calorimeter
-The burning sample heats a known volume of water
-The change in temperature of the water provides an estimate of the chemical energy the sample contains

Question 16

What are some limitations of calorimetry

Answer 16

-It can take a long time to fully dehydrate (dry out) a plant sample to find its dry mass
-Precise equipment is needed, which may not be available
-The more simple and basic the calorimeter, the less accurate the estimate will be for the chemical energy contained within the plant sample

Question 17

What is gross primary production

Answer 17

the amount of chemical energy stored in the carbohydrates within plants (during photosynthesis)

Question 18

What is GPP measured in

Answer 18

energy per unit area or mass per unit area

Question 19

what is gross primary productivity

Answer 19

The rate at which plants are able to store chemical energy via photosynthesis

Question 20

what is gross primary production measured in?

Answer 20

energy/mass per unit area per unit time

Question 21

what is net primary production?

Answer 21

the amount of energy available to herbivores in the plant’s biomass after plant respiratory losses

Question 22

What is the equation for NPP?

Answer 22

NPP = GPP - R (respiratory loss)