Chapter 32 - Energy Flow, Food Chains and Food Webs

Question 1

Explain why the sun can be described as the principle source of energy

Answer 1

All energy originates from the sun, and life cannot exist without energy. The sun’s energy sustains all terrestrial and aquatic life

Question 2

Describe the process by which energy is transferred from the sun to plants and animals

Answer 2

Chlorophyll in green plants traps light energy and uses it during photosynthesis. Light energy is then converted into chemical energy, which is stored in organic molecules like proteins. Animals consume plants and obtain the organic molecules. During respiration, the energy is then released for use by living organisms

Question 3

Describe the non-cyclical flow of energy

Answer 3

• Energy flows in only one direction through an ecosystem
• Energy never returns to the sun
• Energy can not be created or destroyed, only changed from one form into another
• During transformation, some energy is converted to heat energy

Question 4

Define ecology

Answer 4

The study of living organisms in relation to one another and to their environment

Question 5

Define an ecosystem

Answer 5

Self-contained area which include all living organisms and their non-living environment

Question 6

Describe a producer

Answer 6

Organims with the ability to produce their own nutrients from inorganic sources using light, carbon dioxide and water. They are autotrophic and can produce nutrients by photosynthesis

Question 7

Describe a consumer in general

Answer 7

An organism which depends on the nutrients produced by a producer and are unable to utilise light energy to manufacture nutrients. They must therefore consume other organisms in order to obtain nutrients

Question 8

Describe a primary consumer

Answer 8

Herbivore feeding on plants

Question 9

Describe a secondary consumer

Answer 9

Carnivores feeding on the flesh of other organisms

Question 10

Describe a tertiary consumer

Answer 10

Carnivore feeding on the flesh of other carnivores and herbivores

Question 11

Describe a quaternary consumer

Answer 11

Carnivores feeding on the flesh of other organisms

Question 12

Name one adaptation of a herbivore

Answer 12

Dentition and digestion especially adapted to deal with tough plant material

Question 13

Name one adaptation of a carnivore

Answer 13

Powerful claws and dentition adapted to tear flesh

Question 14

Describe a scavenger

Answer 14

Especially carnivorous animals that feed on dead animals rather than hunt for prey

Question 15

Name one function of detrivores in the ecosystem, and also name what they feed on

Answer 15

Detrivores feed on dead organic waste. Detrivores speed up decomposition by consuming dead matter and increasing the surface area availible to putrifying bacteria

Question 16

Explain the process of decomposition

Answer 16

Decomposers obtain nutrients by feeding on dead organisms and breaking them down into smaller substances, making nutrients availible to producers

Question 17

Name one function of decomposers

Answer 17

Clean up the environment

Question 18

Describe a decomposer

Answer 18

Saptrotrophic micro-organisms which exploit the energy of dead organisms by breaking or decaying them down

Question 19

Describe a predator

Answer 19

An organism which obtains nutrients by killing and feeding on other animals

Question 20

Define a population

Answer 20

A group of organisms of the same species which occupies a particular place over a given period of time and has the ability to interbreed and produce fertile offspring

Question 21

Define a species

Answer 21

Organisms which have the potential to interbreed and produce fertile offspring of the same species

Question 22

Define a habitat

Answer 22

A place or part of an ecosystem where organisms live, because the environmental conditions are essentially uniform

Question 23

Define a community

Answer 23

The total of all populations living in a habitat and interacting with one another in an ecosystem

Question 24

Explain energy losses

Answer 24

• Energy is lost everytime energy passes through a link in a food chain
• On average only one 10th of energy is transferred from one organism to the next
• The longer the food chain, the more energy will be lost

Question 25

Explain why all light falling on plants is not absorbed

Answer 25

• Some light energy is reflected
• Plants appear green due to the wavelengths of relected light
• Reflected light falls on other objects and are reflected back into space
• Most of the light energy absorbed is not used for photosynthesis
• Excess energy is lost as heat

Question 26

Explain why all energy from plants are not tranferred to herbivores

Answer 26

• Herbivores only eat the leaves
• Herbivores are not able to digest all the plant material
• Some energy is lost when the leaves fall

Question 27

Explain why all the energy from herbivores is not transferred to carnivores

Answer 27

• Herbivores use obtained energy and energy is lost due to loss of heat
• Energy is used during urination
• Energy is lost during egestion
• Not all parts of a herbivore can be consumed
• Some parts are indigestible
• Energy is lost during growth
• Energy is lost in hair loss or milk production
• Energy is lost during respiration

Question 28

Define ecological efficiency

Answer 28

The percentage of energy transferred from one trophic level to the next

Question 29

What does a pyramid of numbers display?

Answer 29

The total number of individual organisms at each trophic level

Question 30

Name three problems associated with pyramids of number

Answer 30

• All organisms are counted, regardless size
• The pyramid may be inverted
• The range of numbers may be enormous, causing difficulty when drawing the pyramid to scale

Question 31

Name the problems associated with pyramids of biomass

Answer 31

• Impossible to measure the biomass of all living organisms
• Time affects results
• One organism may have a much bigger mass than the organisms feeding of it
• Inversion

Question 32

State why pyramids of energy is more widely used

Answer 32

Comparisons can be made between trophic levels of different ecosystems