Energy Transfers

Question 1

What is energy

Answer 1

A property of matter and or radiation that allows work to be done

Question 2

What are producers

Answer 2

At the start of food chains
They are auto autotrophic so tgey build up organic compounds from simple molecules needed for growth
Usually photosynthetic

Question 3

What are primary consumers

Answer 3

Consume producers (eat them) because they are hetrotrophic so rely on external sources of organic compound

Question 4

What is a secondary consumer

Answer 4

A heliotrope that eats primary consumers

Question 5

What is a saprobiont

Answer 5

A decomposer thar breaks down complex organic compounds in dead organisms

Release extra-cellular enzymes that hydrolyse material so it can be absorbed across their cell membrane

Examples are bacteria and fungi

Question 6

What is a food web

Answer 6

Many food chains in a particular habitat that can be linked together to show energy flow in a feeding relationship of a habitat

Question 7

What is a food chain

Answer 7

A chain of the flow of energy in a feeding relationship usually 4 or 4 tropic levels

Question 8

What do the arrows represent in a food chain

Answer 8

The direction of energy being transfered when an animal or plant is eaten (consumed)

Question 9

What is a tropic level

Answer 9

One level in the feeding relationship between different groups of a food chain

Question 10

What is biomass

Answer 10

The total mass of organic material (carbon) at a specific area at a given time

Question 11

Features of wet/fresh biomass

Answer 11

Living
Easy to assess
Variable water content so unreliable
Variable food indigested so unreliable

Question 12

Features of dry biomass

Answer 12

Dead
Hard to assess
Non variable water content so reliable
Unreliable and unrepresentative since samples must be small because large samples are unethical

Question 13

How do you make wet biomass dry

Answer 13

Heat at hot temperatures (e.g 100°C)

Keep until egested non-digestable food and direct then flush out their opened gut

Question 14

How can a bomb calorimeter be used to find biomass

Answer 14

Allows chemical energy stored in biomass to be estimated

Sample of dry biomass is combusted in a sealed container
Chamber is surrounded by a water bath and the heat energy released causes a temperature increase in water
Using the specific heat capacity and volume of water with the rise in temperature, the energy released can be calculated

Question 15

Why is a pyramid of energy shaped the way it is

Answer 15

Energy is lost at each level

Question 16

Explain the energy losses from sun to producer

Answer 16

Some light reflected
Some light absorbed by water vapour in atmosphere
Some light is the wrong wavelength
Some light doesn’t strike chlorophyll
Only 1-3% of available light energy trapped and used

Question 17

What is GPP

Answer 17

Gross Primary Production

Rate of photosynthesis

Question 18

What is NPP

Answer 18

Net Primary Production

This is passed on to the next trophic level (the energy stored as biomass)

Question 19

Explain energy losses from producer to primary consumer

Answer 19

Large amounts are indigestible and lost as faeces
Not all parts can be eaten e.g roots, bones, bark
Some energy lost in excretion e.g urea
Some energy lost via respiration as heat to the environment

Question 20

Why are there 4 or 5 max trophic levels in a food chain

Answer 20

Energy transfer is inefficient and results in large losses at each trophic level
So usually not enough energy to support a breeding population at a higher trophic level

Question 21

Equation for net production of a producer

Answer 21

NPP=GPP-R

Where R is respiratory losses
Biomass is also lost as CO2 in respiration

Question 22

Equation for net product production of a consumer

Answer 22

N=I-(F+R)

N= Net production
I= Chemical energy store in indigested food
F= Energy lost in faeces
R= Energy lost via respiration

Question 23

Suitable units for efficiency of Energy transfer

Answer 23

Land:KJm-²year-¹

Aquatic:KJm-³year-¹

Question 24

Advantage of dry not fresh biomass

Answer 24

Water content variable in fresh but this will not affect dry mass

Question 25

How can energy conversion rate be increased

Answer 25

Restricting movement = less respiratory loss due to less muscle contraction

Keeping indoors and heating = reduce heat loss from body

Using more nutritious food = increased growth

Food easy to absorb = less energy lost in egestion

Selective breading = some breeds more efficient at transfer of energy into biomass

Slaughtered before adulthood = more energy transfer to biomass

Question 26

Monoculture

Answer 26

Growing one particular crop over very large areas

Question 27

Issue with monocultures

Answer 27

Easy for disease to spread
Easy for insects to travel from plant to plant
Very large area can be affected in a very short space of time
Really decrease biodiversity through loss of niches

Question 28

Types of pesticides

Answer 28

Insecticides
Herbicides
Fungicides

Question 29

Pesticides

Answer 29

Kill a local population of pests at a particular time