Ecosystems

Question 1

What is a community?

Answer 1

All the organisms of different species present in a habitat/ ecosystem

Question 2

What is a population?

Answer 2

All the individuals of one species in a habitat at a given time, that can interbreed to prodice fertile offspring

Question 3

What in an ecosystem?

Answer 3

The community and abiotic factors of an environment

Question 4

Describe the two types of competition

Answer 4

Interspecific- competition between different species
Intraspecific- competition between individuals of the same soecies for the same resources

Question 5

What is a niche?

Answer 5

An organisms role in its ecosystem

Question 6

Why can no two species occupy the same niche?

Answer 6

There would be too much interspecific competition between the species for the same resources

Question 7

What is a predator?

Answer 7

An organisms that hunts, kills and eats other organisms (prey)

Question 8

Explain how the population of prey and predators effects eachother

Answer 8

Their populations fluctuate within narrow limits
If predators increase, more prey are hinted and killed so prey decrease.
As prey decrease, there is less food sources for predators, more intraspecific competition, less reproduction and more mortality. Predator decrease
Prey then increase as less are eaten and more survive and bread

Question 9

What is the carrying capacity of a species?

Answer 9

The maximum size that a population can remain sustainable in its habitat.

Question 10

What happens if carrying capacity is exceeded?

Answer 10

The population increases as the environment can no longer sustain the excess numbers
Intraspecific competition increases as respurces become limited to the population

Question 11

What can cause changes to the population of a species?

Answer 11

Abiotic factors, or interactions between organisms

Question 12

What are autotrophs?

Answer 12

Primary producers. Energy is transferred from autotrophs to heterotrophs

Question 13

What are heterotrophs?

Answer 13

Can be primary, secondary or tertiary consumers, energy is transfered to heterotrophs from autotrophs

Question 14

What are the main trophic levels?

Answer 14

Primary, secondary and tertiary consumers

Question 15

What is the difference between a food chain and food web?

Answer 15

A food chain is a series of trophoc levels, energy is passed down the trophic levels
A food web is more complex and includes interconnected food chains

Question 16

What are saproboints? Give examples of them

Answer 16

Organisms that digest dead remains of waste material (detritus) from other organisms. They release inorganic ions and molecules
Bacteria and fungi

Question 17

How do saproboints digest waste products?

Answer 17

Via extracellular digestion- They secrete enzymes onto the detritus and absorb the digested products

Question 18

Why is not all energy from the sun used by plants flr photosynthesis?

Answer 18

Some light is not appropriate wavelengths to be absorbed
Light may not be absorbed by photosynthsising parts of the plant
Light reflected or transmitted

Question 19

Why might not all light used in photosynthesis be converted into energy of glucose?

Answer 19

May be limiting factors of photosynthesis
Energy lost in inefficient reactions in photosynthesis

Question 20

Why is only 5% of energy produced by photosyntehsis used to make biomass?

Answer 20

Most synthesised sugars are used for respiration

Question 21

What is biomass?

Answer 21

The mass of organic matter in an organisms

Question 22

How can you estimate the biomass of a plant?

Answer 22

Collect the plant, including roots.
Weigh the initial mass, then dry it at 80*. Weigh and dry again until the mass stays constant. This is the plants biomass

Question 23

How can you calculate the energy of biomass?

Answer 23

Use a bomb calorimeter
The dry biomass is burnt in oxygen in the bomb calorimeter and the heat energy given off heats up water
The rise in temperature is used to calculate the energy in calories of the biomass

Question 24

When estimating biomass, why is it important to dry the material?

Answer 24

The amount of water in any living organisms varies over time

Question 25

What is production measured in?

Answer 25

KJm-2

Question 26

What is net orimary production? What is its equation?

Answer 26

The chemical energy store in plant biomass after respiratory losses
= gross primary production- respiration

Question 27

What is gross primary production?

Answer 27

The chemical energy store in plant biomass, in a given area or volume.

Question 28

What are the units for productivity?

Answer 28

The units of energy per unit of area or volume

Question 29

What is the equation for efficiency of energy transfer?

Answer 29

Energy available after tranfer/ energy available before transfer X100

Question 30

Why might energy transfered between consumers be lost?

Answer 30

• Some food taken in isn’t digested so is lost as faeces
• Some is lost by excretion of metabolic waste products like urea
• Some energy remains in parts of the organism that are not consumed
• Energy lost as heat due to consumer respiration

Question 31

Hat is the secondary production?

Answer 31

The net production of consumers, after losses of energy between consumers

Question 32

What is the equation for secondary production?

Answer 32

I (ingested food) -[F (enegy lost in faeces) + R (respiratory losses)]

Question 33

What are endotherms?

Answer 33

Organisms that maintain a constant body temperature

Question 34

How can energy transfer be made more efficient in cattle farming?

Answer 34

• Slaughter cattle when still young, so more energy is transferred to biomass
  • Feed them on a controlled diet so a higher proportion of digested food is absorbed
  • Restrict movement to reduce respiratory losses
  • Keep inside so no energy lost to heat, no predators
  • Genetically select for higher productivity

Question 35

What is succession?

Answer 35

The way in which dofferemt species that make up a community change over a oeriod of time

Question 36

Describe the events of succession

Answer 36

• Pioneer species colonise a hostile environment
• The abiotic environment of the habitat changes
• The changed environment becomes more suitable to support new species
• New plant species increase species diversity, earlier colonisers are replaced by new species
• changes in the abiotic factors again to produce a less hostile environment, increases biodiversity and creates a climax community

Question 37

What is the difference between primary succession and secondary succesision?

Answer 37

Primary succession occurs where no community has been previously established
Secondary succession occurs in an area that has been previously colognised or disturbed