B12

Question 1

What is the primary energy source (input) for biological systems?

Answer 1

The sun

Question 2

Define food chain

Answer 2

Food chains show the transfer of energy from one organism to another, starting with the producer

Question 3

Define food web and an example of the domino effect of a decrease in population of a species

Answer 3

A network of interconnected food chains
Shows interdependance and how changes in one population can affect others in the food web

Ex:
Earthworm population decreases
Grass plant population increase (less species eating it)
Population of frogs and mice would dramatically decrease (earthworm only food source)
Population of sparrows decrease slightly (have other food sources)

Most changes in population are caused by human impact
Over harvesting of food species or introduction of a foreign species
Interdependance-> leads to long lasting domino effects

Question 4

Define producer

Answer 4

An organism that can make its own organic nutrients, usually using energy from sunshine (photosynthesis)

Question 5

Define consumer

Answer 5

An organism that gets its energy by feeding on other organisms

Question 6

Define herbivores

Answer 6

An animal that get its energy by eating plants

Question 7

Define carnivore

Answer 7

An animals that gets its energy by eating other animals

Question 8

Define decomposer

Answer 8

An organism that gets its energy from dead or waste organic matter (usually bacteria and fungi that secretes enzymes to break them down)

Question 9

Define ecosystem

Answer 9

A unit containing all of the organisms and their environment, interacting together in a given area

Question 10

Define trophic level

Answer 10

The position of an organism in the food chain, web or pyramid
Animals can be on multiple levels as they may eat both primary and secondary / tertiary consumers

Question 11

Describe the ‘movement’ of energy between trophic levels

Answer 11

Energy from sun (light) -> first trophic level (producers), convert light energy into chemical energy -> flows from primary consumers (eats producers) -> secondary consumer (eat primary consumers) -> tertiary consumer (eat secondary consumers) -> etc …

Energy flow is non-cyclical -> energy gets to the top of food chain/web -> not recycled but ‘lost’ to the environment

Question 12

How is energy lost in energy transfer between organisms? How much is lost?

Answer 12

Some energy is stored in parts of the organism that doesn’t usually get eaten (bones, roots)

Energy received is used through:
Making waste product (urine) and removal from the organism
Movement
Heat (maintain a constant body temperature)
Undigested waste (faeces) removed (food for decomposers)
So only 10% of energy gained is actually passed on
90% is used by the organism

Question 13

Why do food chains usually have less than 5 trophic levels?

Answer 13

The amount of energy lost at each level is why there is rarely more than 5 trophic levels

More levels would probably require animals on higher levels to eat extremely amounts and not used much energy hunting

Question 14

Construct a food chain

Answer 14

Ex: plant -> snail -> frog -> wolf

Question 15

What is a pyramid of numbers?

Answer 15

They show how many organism there are on each level of the food chain

Width of the box indicates the number of organisms
(Isn’t always pyramid shaped)

Question 16

What are some rules to remember when creating a pyramid of numbers?

Answer 16

They must stay in the same order as in the food chain (producers bottom -> last consumer on top)
-> Generally larger organism -> less amount

Question 17

What is a pyramid of biomass?

Answer 17

It shows how much mass the creatures at each level would have without water (so dry mass)
Should ALWAYS be a pyramid (mass must decrease as you go up the pyramid)

Provides better idea of quantity of the organism at each level and better represents interdependance